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4219 lines
139 KiB
4219 lines
139 KiB
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/* pngread.c - read a PNG file |
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* |
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* Last changed in libpng 1.6.35 [July 15, 2018] |
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* Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson |
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* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) |
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* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) |
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* |
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* This code is released under the libpng license. |
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* For conditions of distribution and use, see the disclaimer |
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* and license in png.h |
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* |
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* This file contains routines that an application calls directly to |
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* read a PNG file or stream. |
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*/ |
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|
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#include "pngpriv.h" |
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#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED) |
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# include <errno.h> |
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#endif |
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|
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#ifdef PNG_READ_SUPPORTED |
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|
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/* Create a PNG structure for reading, and allocate any memory needed. */ |
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PNG_FUNCTION(png_structp,PNGAPI |
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png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr, |
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png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED) |
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{ |
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#ifndef PNG_USER_MEM_SUPPORTED |
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png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, |
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error_fn, warn_fn, NULL, NULL, NULL); |
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#else |
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return png_create_read_struct_2(user_png_ver, error_ptr, error_fn, |
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warn_fn, NULL, NULL, NULL); |
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} |
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|
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/* Alternate create PNG structure for reading, and allocate any memory |
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* needed. |
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*/ |
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PNG_FUNCTION(png_structp,PNGAPI |
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png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr, |
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png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, |
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png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED) |
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{ |
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png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, |
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error_fn, warn_fn, mem_ptr, malloc_fn, free_fn); |
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#endif /* USER_MEM */ |
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if (png_ptr != NULL) |
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{ |
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png_ptr->mode = PNG_IS_READ_STRUCT; |
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|
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/* Added in libpng-1.6.0; this can be used to detect a read structure if |
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* required (it will be zero in a write structure.) |
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*/ |
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# ifdef PNG_SEQUENTIAL_READ_SUPPORTED |
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png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE; |
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# endif |
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# ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED |
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png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN; |
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/* In stable builds only warn if an application error can be completely |
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* handled. |
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*/ |
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# if PNG_RELEASE_BUILD |
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png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN; |
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# endif |
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# endif |
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/* TODO: delay this, it can be done in png_init_io (if the app doesn't |
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* do it itself) avoiding setting the default function if it is not |
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* required. |
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*/ |
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png_set_read_fn(png_ptr, NULL, NULL); |
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} |
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return png_ptr; |
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} |
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#ifdef PNG_SEQUENTIAL_READ_SUPPORTED |
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/* Read the information before the actual image data. This has been |
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* changed in v0.90 to allow reading a file that already has the magic |
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* bytes read from the stream. You can tell libpng how many bytes have |
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* been read from the beginning of the stream (up to the maximum of 8) |
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* via png_set_sig_bytes(), and we will only check the remaining bytes |
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* here. The application can then have access to the signature bytes we |
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* read if it is determined that this isn't a valid PNG file. |
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*/ |
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void PNGAPI |
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png_read_info(png_structrp png_ptr, png_inforp info_ptr) |
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{ |
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#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED |
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int keep; |
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#endif |
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png_debug(1, "in png_read_info"); |
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if (png_ptr == NULL || info_ptr == NULL) |
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return; |
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/* Read and check the PNG file signature. */ |
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png_read_sig(png_ptr, info_ptr); |
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for (;;) |
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{ |
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png_uint_32 length = png_read_chunk_header(png_ptr); |
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png_uint_32 chunk_name = png_ptr->chunk_name; |
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|
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/* IDAT logic needs to happen here to simplify getting the two flags |
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* right. |
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*/ |
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if (chunk_name == png_IDAT) |
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{ |
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if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) |
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png_chunk_error(png_ptr, "Missing IHDR before IDAT"); |
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else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && |
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(png_ptr->mode & PNG_HAVE_PLTE) == 0) |
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png_chunk_error(png_ptr, "Missing PLTE before IDAT"); |
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else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0) |
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png_chunk_benign_error(png_ptr, "Too many IDATs found"); |
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png_ptr->mode |= PNG_HAVE_IDAT; |
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} |
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else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) |
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{ |
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png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT; |
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png_ptr->mode |= PNG_AFTER_IDAT; |
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} |
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/* This should be a binary subdivision search or a hash for |
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* matching the chunk name rather than a linear search. |
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*/ |
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if (chunk_name == png_IHDR) |
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png_handle_IHDR(png_ptr, info_ptr, length); |
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else if (chunk_name == png_IEND) |
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png_handle_IEND(png_ptr, info_ptr, length); |
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#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED |
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else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) |
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{ |
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png_handle_unknown(png_ptr, info_ptr, length, keep); |
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if (chunk_name == png_PLTE) |
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png_ptr->mode |= PNG_HAVE_PLTE; |
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else if (chunk_name == png_IDAT) |
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{ |
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png_ptr->idat_size = 0; /* It has been consumed */ |
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break; |
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} |
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} |
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#endif |
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else if (chunk_name == png_PLTE) |
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png_handle_PLTE(png_ptr, info_ptr, length); |
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|
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else if (chunk_name == png_IDAT) |
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{ |
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png_ptr->idat_size = length; |
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break; |
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} |
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#ifdef PNG_READ_bKGD_SUPPORTED |
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else if (chunk_name == png_bKGD) |
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png_handle_bKGD(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_cHRM_SUPPORTED |
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else if (chunk_name == png_cHRM) |
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png_handle_cHRM(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_eXIf_SUPPORTED |
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else if (chunk_name == png_eXIf) |
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png_handle_eXIf(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_gAMA_SUPPORTED |
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else if (chunk_name == png_gAMA) |
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png_handle_gAMA(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_hIST_SUPPORTED |
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else if (chunk_name == png_hIST) |
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png_handle_hIST(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_oFFs_SUPPORTED |
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else if (chunk_name == png_oFFs) |
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png_handle_oFFs(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_pCAL_SUPPORTED |
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else if (chunk_name == png_pCAL) |
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png_handle_pCAL(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_sCAL_SUPPORTED |
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else if (chunk_name == png_sCAL) |
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png_handle_sCAL(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_pHYs_SUPPORTED |
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else if (chunk_name == png_pHYs) |
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png_handle_pHYs(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_sBIT_SUPPORTED |
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else if (chunk_name == png_sBIT) |
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png_handle_sBIT(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_sRGB_SUPPORTED |
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else if (chunk_name == png_sRGB) |
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png_handle_sRGB(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_iCCP_SUPPORTED |
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else if (chunk_name == png_iCCP) |
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png_handle_iCCP(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_sPLT_SUPPORTED |
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else if (chunk_name == png_sPLT) |
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png_handle_sPLT(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_tEXt_SUPPORTED |
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else if (chunk_name == png_tEXt) |
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png_handle_tEXt(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_tIME_SUPPORTED |
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else if (chunk_name == png_tIME) |
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png_handle_tIME(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_tRNS_SUPPORTED |
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else if (chunk_name == png_tRNS) |
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png_handle_tRNS(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_zTXt_SUPPORTED |
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else if (chunk_name == png_zTXt) |
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png_handle_zTXt(png_ptr, info_ptr, length); |
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#endif |
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#ifdef PNG_READ_iTXt_SUPPORTED |
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else if (chunk_name == png_iTXt) |
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png_handle_iTXt(png_ptr, info_ptr, length); |
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#endif |
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else |
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png_handle_unknown(png_ptr, info_ptr, length, |
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PNG_HANDLE_CHUNK_AS_DEFAULT); |
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} |
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} |
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#endif /* SEQUENTIAL_READ */ |
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|
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/* Optional call to update the users info_ptr structure */ |
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void PNGAPI |
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png_read_update_info(png_structrp png_ptr, png_inforp info_ptr) |
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{ |
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png_debug(1, "in png_read_update_info"); |
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if (png_ptr != NULL) |
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{ |
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if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) |
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{ |
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png_read_start_row(png_ptr); |
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# ifdef PNG_READ_TRANSFORMS_SUPPORTED |
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png_read_transform_info(png_ptr, info_ptr); |
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# else |
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PNG_UNUSED(info_ptr) |
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# endif |
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} |
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|
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/* New in 1.6.0 this avoids the bug of doing the initializations twice */ |
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else |
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png_app_error(png_ptr, |
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"png_read_update_info/png_start_read_image: duplicate call"); |
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} |
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} |
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#ifdef PNG_SEQUENTIAL_READ_SUPPORTED |
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/* Initialize palette, background, etc, after transformations |
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* are set, but before any reading takes place. This allows |
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* the user to obtain a gamma-corrected palette, for example. |
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* If the user doesn't call this, we will do it ourselves. |
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*/ |
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void PNGAPI |
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png_start_read_image(png_structrp png_ptr) |
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{ |
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png_debug(1, "in png_start_read_image"); |
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if (png_ptr != NULL) |
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{ |
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if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) |
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png_read_start_row(png_ptr); |
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|
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/* New in 1.6.0 this avoids the bug of doing the initializations twice */ |
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else |
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png_app_error(png_ptr, |
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"png_start_read_image/png_read_update_info: duplicate call"); |
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} |
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} |
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#endif /* SEQUENTIAL_READ */ |
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#ifdef PNG_SEQUENTIAL_READ_SUPPORTED |
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#ifdef PNG_MNG_FEATURES_SUPPORTED |
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/* Undoes intrapixel differencing, |
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* NOTE: this is apparently only supported in the 'sequential' reader. |
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*/ |
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static void |
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png_do_read_intrapixel(png_row_infop row_info, png_bytep row) |
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{ |
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png_debug(1, "in png_do_read_intrapixel"); |
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|
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if ( |
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(row_info->color_type & PNG_COLOR_MASK_COLOR) != 0) |
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{ |
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int bytes_per_pixel; |
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png_uint_32 row_width = row_info->width; |
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|
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if (row_info->bit_depth == 8) |
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{ |
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png_bytep rp; |
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png_uint_32 i; |
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if (row_info->color_type == PNG_COLOR_TYPE_RGB) |
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bytes_per_pixel = 3; |
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else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) |
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bytes_per_pixel = 4; |
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else |
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return; |
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for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel) |
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{ |
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*(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff); |
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*(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff); |
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} |
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} |
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else if (row_info->bit_depth == 16) |
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{ |
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png_bytep rp; |
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png_uint_32 i; |
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|
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if (row_info->color_type == PNG_COLOR_TYPE_RGB) |
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bytes_per_pixel = 6; |
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else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) |
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bytes_per_pixel = 8; |
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else |
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return; |
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for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel) |
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{ |
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png_uint_32 s0 = (png_uint_32)(*(rp ) << 8) | *(rp + 1); |
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png_uint_32 s1 = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3); |
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png_uint_32 s2 = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5); |
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png_uint_32 red = (s0 + s1 + 65536) & 0xffff; |
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png_uint_32 blue = (s2 + s1 + 65536) & 0xffff; |
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*(rp ) = (png_byte)((red >> 8) & 0xff); |
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*(rp + 1) = (png_byte)(red & 0xff); |
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*(rp + 4) = (png_byte)((blue >> 8) & 0xff); |
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*(rp + 5) = (png_byte)(blue & 0xff); |
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} |
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} |
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} |
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} |
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#endif /* MNG_FEATURES */ |
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|
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void PNGAPI |
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png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row) |
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{ |
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png_row_info row_info; |
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|
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if (png_ptr == NULL) |
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return; |
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png_debug2(1, "in png_read_row (row %lu, pass %d)", |
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(unsigned long)png_ptr->row_number, png_ptr->pass); |
|
|
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/* png_read_start_row sets the information (in particular iwidth) for this |
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* interlace pass. |
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*/ |
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if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) |
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png_read_start_row(png_ptr); |
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|
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/* 1.5.6: row_info moved out of png_struct to a local here. */ |
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row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */ |
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row_info.color_type = png_ptr->color_type; |
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row_info.bit_depth = png_ptr->bit_depth; |
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row_info.channels = png_ptr->channels; |
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row_info.pixel_depth = png_ptr->pixel_depth; |
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row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width); |
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|
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#ifdef PNG_WARNINGS_SUPPORTED |
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if (png_ptr->row_number == 0 && png_ptr->pass == 0) |
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{ |
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/* Check for transforms that have been set but were defined out */ |
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#if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED) |
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if ((png_ptr->transformations & PNG_INVERT_MONO) != 0) |
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png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined"); |
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#endif |
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|
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#if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED) |
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if ((png_ptr->transformations & PNG_FILLER) != 0) |
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png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined"); |
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#endif |
|
|
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#if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \ |
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!defined(PNG_READ_PACKSWAP_SUPPORTED) |
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if ((png_ptr->transformations & PNG_PACKSWAP) != 0) |
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png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined"); |
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#endif |
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|
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#if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED) |
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if ((png_ptr->transformations & PNG_PACK) != 0) |
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png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined"); |
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#endif |
|
|
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#if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED) |
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if ((png_ptr->transformations & PNG_SHIFT) != 0) |
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png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined"); |
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#endif |
|
|
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#if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED) |
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if ((png_ptr->transformations & PNG_BGR) != 0) |
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png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined"); |
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#endif |
|
|
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#if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED) |
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if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0) |
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png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined"); |
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#endif |
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} |
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#endif /* WARNINGS */ |
|
|
|
#ifdef PNG_READ_INTERLACING_SUPPORTED |
|
/* If interlaced and we do not need a new row, combine row and return. |
|
* Notice that the pixels we have from previous rows have been transformed |
|
* already; we can only combine like with like (transformed or |
|
* untransformed) and, because of the libpng API for interlaced images, this |
|
* means we must transform before de-interlacing. |
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*/ |
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if (png_ptr->interlaced != 0 && |
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(png_ptr->transformations & PNG_INTERLACE) != 0) |
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{ |
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switch (png_ptr->pass) |
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{ |
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case 0: |
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if (png_ptr->row_number & 0x07) |
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{ |
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if (dsp_row != NULL) |
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png_combine_row(png_ptr, dsp_row, 1/*display*/); |
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png_read_finish_row(png_ptr); |
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return; |
|
} |
|
break; |
|
|
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case 1: |
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if ((png_ptr->row_number & 0x07) || png_ptr->width < 5) |
|
{ |
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if (dsp_row != NULL) |
|
png_combine_row(png_ptr, dsp_row, 1/*display*/); |
|
|
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png_read_finish_row(png_ptr); |
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return; |
|
} |
|
break; |
|
|
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case 2: |
|
if ((png_ptr->row_number & 0x07) != 4) |
|
{ |
|
if (dsp_row != NULL && (png_ptr->row_number & 4)) |
|
png_combine_row(png_ptr, dsp_row, 1/*display*/); |
|
|
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png_read_finish_row(png_ptr); |
|
return; |
|
} |
|
break; |
|
|
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case 3: |
|
if ((png_ptr->row_number & 3) || png_ptr->width < 3) |
|
{ |
|
if (dsp_row != NULL) |
|
png_combine_row(png_ptr, dsp_row, 1/*display*/); |
|
|
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png_read_finish_row(png_ptr); |
|
return; |
|
} |
|
break; |
|
|
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case 4: |
|
if ((png_ptr->row_number & 3) != 2) |
|
{ |
|
if (dsp_row != NULL && (png_ptr->row_number & 2)) |
|
png_combine_row(png_ptr, dsp_row, 1/*display*/); |
|
|
|
png_read_finish_row(png_ptr); |
|
return; |
|
} |
|
break; |
|
|
|
case 5: |
|
if ((png_ptr->row_number & 1) || png_ptr->width < 2) |
|
{ |
|
if (dsp_row != NULL) |
|
png_combine_row(png_ptr, dsp_row, 1/*display*/); |
|
|
|
png_read_finish_row(png_ptr); |
|
return; |
|
} |
|
break; |
|
|
|
default: |
|
case 6: |
|
if ((png_ptr->row_number & 1) == 0) |
|
{ |
|
png_read_finish_row(png_ptr); |
|
return; |
|
} |
|
break; |
|
} |
|
} |
|
#endif |
|
|
|
if ((png_ptr->mode & PNG_HAVE_IDAT) == 0) |
|
png_error(png_ptr, "Invalid attempt to read row data"); |
|
|
|
/* Fill the row with IDAT data: */ |
|
png_ptr->row_buf[0]=255; /* to force error if no data was found */ |
|
png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1); |
|
|
|
if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE) |
|
{ |
|
if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST) |
|
png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1, |
|
png_ptr->prev_row + 1, png_ptr->row_buf[0]); |
|
else |
|
png_error(png_ptr, "bad adaptive filter value"); |
|
} |
|
|
|
/* libpng 1.5.6: the following line was copying png_ptr->rowbytes before |
|
* 1.5.6, while the buffer really is this big in current versions of libpng |
|
* it may not be in the future, so this was changed just to copy the |
|
* interlaced count: |
|
*/ |
|
memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1); |
|
|
|
#ifdef PNG_MNG_FEATURES_SUPPORTED |
|
if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 && |
|
(png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING)) |
|
{ |
|
/* Intrapixel differencing */ |
|
png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1); |
|
} |
|
#endif |
|
|
|
#ifdef PNG_READ_TRANSFORMS_SUPPORTED |
|
if (png_ptr->transformations) |
|
png_do_read_transformations(png_ptr, &row_info); |
|
#endif |
|
|
|
/* The transformed pixel depth should match the depth now in row_info. */ |
|
if (png_ptr->transformed_pixel_depth == 0) |
|
{ |
|
png_ptr->transformed_pixel_depth = row_info.pixel_depth; |
|
if (row_info.pixel_depth > png_ptr->maximum_pixel_depth) |
|
png_error(png_ptr, "sequential row overflow"); |
|
} |
|
|
|
else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth) |
|
png_error(png_ptr, "internal sequential row size calculation error"); |
|
|
|
#ifdef PNG_READ_INTERLACING_SUPPORTED |
|
/* Expand interlaced rows to full size */ |
|
if (png_ptr->interlaced != 0 && |
|
(png_ptr->transformations & PNG_INTERLACE) != 0) |
|
{ |
|
if (png_ptr->pass < 6) |
|
png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass, |
|
png_ptr->transformations); |
|
|
|
if (dsp_row != NULL) |
|
png_combine_row(png_ptr, dsp_row, 1/*display*/); |
|
|
|
if (row != NULL) |
|
png_combine_row(png_ptr, row, 0/*row*/); |
|
} |
|
|
|
else |
|
#endif |
|
{ |
|
if (row != NULL) |
|
png_combine_row(png_ptr, row, -1/*ignored*/); |
|
|
|
if (dsp_row != NULL) |
|
png_combine_row(png_ptr, dsp_row, -1/*ignored*/); |
|
} |
|
png_read_finish_row(png_ptr); |
|
|
|
if (png_ptr->read_row_fn != NULL) |
|
(*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass); |
|
|
|
} |
|
#endif /* SEQUENTIAL_READ */ |
|
|
|
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED |
|
/* Read one or more rows of image data. If the image is interlaced, |
|
* and png_set_interlace_handling() has been called, the rows need to |
|
* contain the contents of the rows from the previous pass. If the |
|
* image has alpha or transparency, and png_handle_alpha()[*] has been |
|
* called, the rows contents must be initialized to the contents of the |
|
* screen. |
|
* |
|
* "row" holds the actual image, and pixels are placed in it |
|
* as they arrive. If the image is displayed after each pass, it will |
|
* appear to "sparkle" in. "display_row" can be used to display a |
|
* "chunky" progressive image, with finer detail added as it becomes |
|
* available. If you do not want this "chunky" display, you may pass |
|
* NULL for display_row. If you do not want the sparkle display, and |
|
* you have not called png_handle_alpha(), you may pass NULL for rows. |
|
* If you have called png_handle_alpha(), and the image has either an |
|
* alpha channel or a transparency chunk, you must provide a buffer for |
|
* rows. In this case, you do not have to provide a display_row buffer |
|
* also, but you may. If the image is not interlaced, or if you have |
|
* not called png_set_interlace_handling(), the display_row buffer will |
|
* be ignored, so pass NULL to it. |
|
* |
|
* [*] png_handle_alpha() does not exist yet, as of this version of libpng |
|
*/ |
|
|
|
void PNGAPI |
|
png_read_rows(png_structrp png_ptr, png_bytepp row, |
|
png_bytepp display_row, png_uint_32 num_rows) |
|
{ |
|
png_uint_32 i; |
|
png_bytepp rp; |
|
png_bytepp dp; |
|
|
|
png_debug(1, "in png_read_rows"); |
|
|
|
if (png_ptr == NULL) |
|
return; |
|
|
|
rp = row; |
|
dp = display_row; |
|
if (rp != NULL && dp != NULL) |
|
for (i = 0; i < num_rows; i++) |
|
{ |
|
png_bytep rptr = *rp++; |
|
png_bytep dptr = *dp++; |
|
|
|
png_read_row(png_ptr, rptr, dptr); |
|
} |
|
|
|
else if (rp != NULL) |
|
for (i = 0; i < num_rows; i++) |
|
{ |
|
png_bytep rptr = *rp; |
|
png_read_row(png_ptr, rptr, NULL); |
|
rp++; |
|
} |
|
|
|
else if (dp != NULL) |
|
for (i = 0; i < num_rows; i++) |
|
{ |
|
png_bytep dptr = *dp; |
|
png_read_row(png_ptr, NULL, dptr); |
|
dp++; |
|
} |
|
} |
|
#endif /* SEQUENTIAL_READ */ |
|
|
|
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED |
|
/* Read the entire image. If the image has an alpha channel or a tRNS |
|
* chunk, and you have called png_handle_alpha()[*], you will need to |
|
* initialize the image to the current image that PNG will be overlaying. |
|
* We set the num_rows again here, in case it was incorrectly set in |
|
* png_read_start_row() by a call to png_read_update_info() or |
|
* png_start_read_image() if png_set_interlace_handling() wasn't called |
|
* prior to either of these functions like it should have been. You can |
|
* only call this function once. If you desire to have an image for |
|
* each pass of a interlaced image, use png_read_rows() instead. |
|
* |
|
* [*] png_handle_alpha() does not exist yet, as of this version of libpng |
|
*/ |
|
void PNGAPI |
|
png_read_image(png_structrp png_ptr, png_bytepp image) |
|
{ |
|
png_uint_32 i, image_height; |
|
int pass, j; |
|
png_bytepp rp; |
|
|
|
png_debug(1, "in png_read_image"); |
|
|
|
if (png_ptr == NULL) |
|
return; |
|
|
|
#ifdef PNG_READ_INTERLACING_SUPPORTED |
|
if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) |
|
{ |
|
pass = png_set_interlace_handling(png_ptr); |
|
/* And make sure transforms are initialized. */ |
|
png_start_read_image(png_ptr); |
|
} |
|
else |
|
{ |
|
if (png_ptr->interlaced != 0 && |
|
(png_ptr->transformations & PNG_INTERLACE) == 0) |
|
{ |
|
/* Caller called png_start_read_image or png_read_update_info without |
|
* first turning on the PNG_INTERLACE transform. We can fix this here, |
|
* but the caller should do it! |
|
*/ |
|
png_warning(png_ptr, "Interlace handling should be turned on when " |
|
"using png_read_image"); |
|
/* Make sure this is set correctly */ |
|
png_ptr->num_rows = png_ptr->height; |
|
} |
|
|
|
/* Obtain the pass number, which also turns on the PNG_INTERLACE flag in |
|
* the above error case. |
|
*/ |
|
pass = png_set_interlace_handling(png_ptr); |
|
} |
|
#else |
|
if (png_ptr->interlaced) |
|
png_error(png_ptr, |
|
"Cannot read interlaced image -- interlace handler disabled"); |
|
|
|
pass = 1; |
|
#endif |
|
|
|
image_height=png_ptr->height; |
|
|
|
for (j = 0; j < pass; j++) |
|
{ |
|
rp = image; |
|
for (i = 0; i < image_height; i++) |
|
{ |
|
png_read_row(png_ptr, *rp, NULL); |
|
rp++; |
|
} |
|
} |
|
} |
|
#endif /* SEQUENTIAL_READ */ |
|
|
|
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED |
|
/* Read the end of the PNG file. Will not read past the end of the |
|
* file, will verify the end is accurate, and will read any comments |
|
* or time information at the end of the file, if info is not NULL. |
|
*/ |
|
void PNGAPI |
|
png_read_end(png_structrp png_ptr, png_inforp info_ptr) |
|
{ |
|
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED |
|
int keep; |
|
#endif |
|
|
|
png_debug(1, "in png_read_end"); |
|
|
|
if (png_ptr == NULL) |
|
return; |
|
|
|
/* If png_read_end is called in the middle of reading the rows there may |
|
* still be pending IDAT data and an owned zstream. Deal with this here. |
|
*/ |
|
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED |
|
if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0) |
|
#endif |
|
png_read_finish_IDAT(png_ptr); |
|
|
|
#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED |
|
/* Report invalid palette index; added at libng-1.5.10 */ |
|
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && |
|
png_ptr->num_palette_max > png_ptr->num_palette) |
|
png_benign_error(png_ptr, "Read palette index exceeding num_palette"); |
|
#endif |
|
|
|
do |
|
{ |
|
png_uint_32 length = png_read_chunk_header(png_ptr); |
|
png_uint_32 chunk_name = png_ptr->chunk_name; |
|
|
|
if (chunk_name != png_IDAT) |
|
png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT; |
|
|
|
if (chunk_name == png_IEND) |
|
png_handle_IEND(png_ptr, info_ptr, length); |
|
|
|
else if (chunk_name == png_IHDR) |
|
png_handle_IHDR(png_ptr, info_ptr, length); |
|
|
|
else if (info_ptr == NULL) |
|
png_crc_finish(png_ptr, length); |
|
|
|
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED |
|
else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) |
|
{ |
|
if (chunk_name == png_IDAT) |
|
{ |
|
if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED)) |
|
|| (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0) |
|
png_benign_error(png_ptr, ".Too many IDATs found"); |
|
} |
|
png_handle_unknown(png_ptr, info_ptr, length, keep); |
|
if (chunk_name == png_PLTE) |
|
png_ptr->mode |= PNG_HAVE_PLTE; |
|
} |
|
#endif |
|
|
|
else if (chunk_name == png_IDAT) |
|
{ |
|
/* Zero length IDATs are legal after the last IDAT has been |
|
* read, but not after other chunks have been read. 1.6 does not |
|
* always read all the deflate data; specifically it cannot be relied |
|
* upon to read the Adler32 at the end. If it doesn't ignore IDAT |
|
* chunks which are longer than zero as well: |
|
*/ |
|
if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED)) |
|
|| (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0) |
|
png_benign_error(png_ptr, "..Too many IDATs found"); |
|
|
|
png_crc_finish(png_ptr, length); |
|
} |
|
else if (chunk_name == png_PLTE) |
|
png_handle_PLTE(png_ptr, info_ptr, length); |
|
|
|
#ifdef PNG_READ_bKGD_SUPPORTED |
|
else if (chunk_name == png_bKGD) |
|
png_handle_bKGD(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_cHRM_SUPPORTED |
|
else if (chunk_name == png_cHRM) |
|
png_handle_cHRM(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_eXIf_SUPPORTED |
|
else if (chunk_name == png_eXIf) |
|
png_handle_eXIf(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_gAMA_SUPPORTED |
|
else if (chunk_name == png_gAMA) |
|
png_handle_gAMA(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_hIST_SUPPORTED |
|
else if (chunk_name == png_hIST) |
|
png_handle_hIST(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_oFFs_SUPPORTED |
|
else if (chunk_name == png_oFFs) |
|
png_handle_oFFs(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_pCAL_SUPPORTED |
|
else if (chunk_name == png_pCAL) |
|
png_handle_pCAL(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_sCAL_SUPPORTED |
|
else if (chunk_name == png_sCAL) |
|
png_handle_sCAL(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_pHYs_SUPPORTED |
|
else if (chunk_name == png_pHYs) |
|
png_handle_pHYs(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_sBIT_SUPPORTED |
|
else if (chunk_name == png_sBIT) |
|
png_handle_sBIT(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_sRGB_SUPPORTED |
|
else if (chunk_name == png_sRGB) |
|
png_handle_sRGB(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_iCCP_SUPPORTED |
|
else if (chunk_name == png_iCCP) |
|
png_handle_iCCP(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_sPLT_SUPPORTED |
|
else if (chunk_name == png_sPLT) |
|
png_handle_sPLT(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_tEXt_SUPPORTED |
|
else if (chunk_name == png_tEXt) |
|
png_handle_tEXt(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_tIME_SUPPORTED |
|
else if (chunk_name == png_tIME) |
|
png_handle_tIME(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_tRNS_SUPPORTED |
|
else if (chunk_name == png_tRNS) |
|
png_handle_tRNS(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_zTXt_SUPPORTED |
|
else if (chunk_name == png_zTXt) |
|
png_handle_zTXt(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
#ifdef PNG_READ_iTXt_SUPPORTED |
|
else if (chunk_name == png_iTXt) |
|
png_handle_iTXt(png_ptr, info_ptr, length); |
|
#endif |
|
|
|
else |
|
png_handle_unknown(png_ptr, info_ptr, length, |
|
PNG_HANDLE_CHUNK_AS_DEFAULT); |
|
} while ((png_ptr->mode & PNG_HAVE_IEND) == 0); |
|
} |
|
#endif /* SEQUENTIAL_READ */ |
|
|
|
/* Free all memory used in the read struct */ |
|
static void |
|
png_read_destroy(png_structrp png_ptr) |
|
{ |
|
png_debug(1, "in png_read_destroy"); |
|
|
|
#ifdef PNG_READ_GAMMA_SUPPORTED |
|
png_destroy_gamma_table(png_ptr); |
|
#endif |
|
|
|
png_free(png_ptr, png_ptr->big_row_buf); |
|
png_ptr->big_row_buf = NULL; |
|
png_free(png_ptr, png_ptr->big_prev_row); |
|
png_ptr->big_prev_row = NULL; |
|
png_free(png_ptr, png_ptr->read_buffer); |
|
png_ptr->read_buffer = NULL; |
|
|
|
#ifdef PNG_READ_QUANTIZE_SUPPORTED |
|
png_free(png_ptr, png_ptr->palette_lookup); |
|
png_ptr->palette_lookup = NULL; |
|
png_free(png_ptr, png_ptr->quantize_index); |
|
png_ptr->quantize_index = NULL; |
|
#endif |
|
|
|
if ((png_ptr->free_me & PNG_FREE_PLTE) != 0) |
|
{ |
|
png_zfree(png_ptr, png_ptr->palette); |
|
png_ptr->palette = NULL; |
|
} |
|
png_ptr->free_me &= ~PNG_FREE_PLTE; |
|
|
|
#if defined(PNG_tRNS_SUPPORTED) || \ |
|
defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) |
|
if ((png_ptr->free_me & PNG_FREE_TRNS) != 0) |
|
{ |
|
png_free(png_ptr, png_ptr->trans_alpha); |
|
png_ptr->trans_alpha = NULL; |
|
} |
|
png_ptr->free_me &= ~PNG_FREE_TRNS; |
|
#endif |
|
|
|
inflateEnd(&png_ptr->zstream); |
|
|
|
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED |
|
png_free(png_ptr, png_ptr->save_buffer); |
|
png_ptr->save_buffer = NULL; |
|
#endif |
|
|
|
#if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \ |
|
defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) |
|
png_free(png_ptr, png_ptr->unknown_chunk.data); |
|
png_ptr->unknown_chunk.data = NULL; |
|
#endif |
|
|
|
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED |
|
png_free(png_ptr, png_ptr->chunk_list); |
|
png_ptr->chunk_list = NULL; |
|
#endif |
|
|
|
/* NOTE: the 'setjmp' buffer may still be allocated and the memory and error |
|
* callbacks are still set at this point. They are required to complete the |
|
* destruction of the png_struct itself. |
|
*/ |
|
} |
|
|
|
/* Free all memory used by the read */ |
|
void PNGAPI |
|
png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, |
|
png_infopp end_info_ptr_ptr) |
|
{ |
|
png_structrp png_ptr = NULL; |
|
|
|
png_debug(1, "in png_destroy_read_struct"); |
|
|
|
if (png_ptr_ptr != NULL) |
|
png_ptr = *png_ptr_ptr; |
|
|
|
if (png_ptr == NULL) |
|
return; |
|
|
|
/* libpng 1.6.0: use the API to destroy info structs to ensure consistent |
|
* behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API. |
|
* The extra was, apparently, unnecessary yet this hides memory leak bugs. |
|
*/ |
|
png_destroy_info_struct(png_ptr, end_info_ptr_ptr); |
|
png_destroy_info_struct(png_ptr, info_ptr_ptr); |
|
|
|
*png_ptr_ptr = NULL; |
|
png_read_destroy(png_ptr); |
|
png_destroy_png_struct(png_ptr); |
|
} |
|
|
|
void PNGAPI |
|
png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn) |
|
{ |
|
if (png_ptr == NULL) |
|
return; |
|
|
|
png_ptr->read_row_fn = read_row_fn; |
|
} |
|
|
|
|
|
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED |
|
#ifdef PNG_INFO_IMAGE_SUPPORTED |
|
void PNGAPI |
|
png_read_png(png_structrp png_ptr, png_inforp info_ptr, |
|
int transforms, voidp params) |
|
{ |
|
if (png_ptr == NULL || info_ptr == NULL) |
|
return; |
|
|
|
/* png_read_info() gives us all of the information from the |
|
* PNG file before the first IDAT (image data chunk). |
|
*/ |
|
png_read_info(png_ptr, info_ptr); |
|
if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep))) |
|
png_error(png_ptr, "Image is too high to process with png_read_png()"); |
|
|
|
/* -------------- image transformations start here ------------------- */ |
|
/* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM |
|
* is not implemented. This will only happen in de-configured (non-default) |
|
* libpng builds. The results can be unexpected - png_read_png may return |
|
* short or mal-formed rows because the transform is skipped. |
|
*/ |
|
|
|
/* Tell libpng to strip 16-bit/color files down to 8 bits per color. |
|
*/ |
|
if ((transforms & PNG_TRANSFORM_SCALE_16) != 0) |
|
/* Added at libpng-1.5.4. "strip_16" produces the same result that it |
|
* did in earlier versions, while "scale_16" is now more accurate. |
|
*/ |
|
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED |
|
png_set_scale_16(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported"); |
|
#endif |
|
|
|
/* If both SCALE and STRIP are required pngrtran will effectively cancel the |
|
* latter by doing SCALE first. This is ok and allows apps not to check for |
|
* which is supported to get the right answer. |
|
*/ |
|
if ((transforms & PNG_TRANSFORM_STRIP_16) != 0) |
|
#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED |
|
png_set_strip_16(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported"); |
|
#endif |
|
|
|
/* Strip alpha bytes from the input data without combining with |
|
* the background (not recommended). |
|
*/ |
|
if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0) |
|
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED |
|
png_set_strip_alpha(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported"); |
|
#endif |
|
|
|
/* Extract multiple pixels with bit depths of 1, 2, or 4 from a single |
|
* byte into separate bytes (useful for paletted and grayscale images). |
|
*/ |
|
if ((transforms & PNG_TRANSFORM_PACKING) != 0) |
|
#ifdef PNG_READ_PACK_SUPPORTED |
|
png_set_packing(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported"); |
|
#endif |
|
|
|
/* Change the order of packed pixels to least significant bit first |
|
* (not useful if you are using png_set_packing). |
|
*/ |
|
if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0) |
|
#ifdef PNG_READ_PACKSWAP_SUPPORTED |
|
png_set_packswap(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported"); |
|
#endif |
|
|
|
/* Expand paletted colors into true RGB triplets |
|
* Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel |
|
* Expand paletted or RGB images with transparency to full alpha |
|
* channels so the data will be available as RGBA quartets. |
|
*/ |
|
if ((transforms & PNG_TRANSFORM_EXPAND) != 0) |
|
#ifdef PNG_READ_EXPAND_SUPPORTED |
|
png_set_expand(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported"); |
|
#endif |
|
|
|
/* We don't handle background color or gamma transformation or quantizing. |
|
*/ |
|
|
|
/* Invert monochrome files to have 0 as white and 1 as black |
|
*/ |
|
if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0) |
|
#ifdef PNG_READ_INVERT_SUPPORTED |
|
png_set_invert_mono(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported"); |
|
#endif |
|
|
|
/* If you want to shift the pixel values from the range [0,255] or |
|
* [0,65535] to the original [0,7] or [0,31], or whatever range the |
|
* colors were originally in: |
|
*/ |
|
if ((transforms & PNG_TRANSFORM_SHIFT) != 0) |
|
#ifdef PNG_READ_SHIFT_SUPPORTED |
|
if ((info_ptr->valid & PNG_INFO_sBIT) != 0) |
|
png_set_shift(png_ptr, &info_ptr->sig_bit); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported"); |
|
#endif |
|
|
|
/* Flip the RGB pixels to BGR (or RGBA to BGRA) */ |
|
if ((transforms & PNG_TRANSFORM_BGR) != 0) |
|
#ifdef PNG_READ_BGR_SUPPORTED |
|
png_set_bgr(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported"); |
|
#endif |
|
|
|
/* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */ |
|
if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0) |
|
#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED |
|
png_set_swap_alpha(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported"); |
|
#endif |
|
|
|
/* Swap bytes of 16-bit files to least significant byte first */ |
|
if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0) |
|
#ifdef PNG_READ_SWAP_SUPPORTED |
|
png_set_swap(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported"); |
|
#endif |
|
|
|
/* Added at libpng-1.2.41 */ |
|
/* Invert the alpha channel from opacity to transparency */ |
|
if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0) |
|
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED |
|
png_set_invert_alpha(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported"); |
|
#endif |
|
|
|
/* Added at libpng-1.2.41 */ |
|
/* Expand grayscale image to RGB */ |
|
if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0) |
|
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED |
|
png_set_gray_to_rgb(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported"); |
|
#endif |
|
|
|
/* Added at libpng-1.5.4 */ |
|
if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0) |
|
#ifdef PNG_READ_EXPAND_16_SUPPORTED |
|
png_set_expand_16(png_ptr); |
|
#else |
|
png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported"); |
|
#endif |
|
|
|
/* We don't handle adding filler bytes */ |
|
|
|
/* We use png_read_image and rely on that for interlace handling, but we also |
|
* call png_read_update_info therefore must turn on interlace handling now: |
|
*/ |
|
(void)png_set_interlace_handling(png_ptr); |
|
|
|
/* Optional call to gamma correct and add the background to the palette |
|
* and update info structure. REQUIRED if you are expecting libpng to |
|
* update the palette for you (i.e., you selected such a transform above). |
|
*/ |
|
png_read_update_info(png_ptr, info_ptr); |
|
|
|
/* -------------- image transformations end here ------------------- */ |
|
|
|
png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0); |
|
if (info_ptr->row_pointers == NULL) |
|
{ |
|
png_uint_32 iptr; |
|
|
|
info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr, |
|
info_ptr->height * (sizeof (png_bytep)))); |
|
|
|
for (iptr=0; iptr<info_ptr->height; iptr++) |
|
info_ptr->row_pointers[iptr] = NULL; |
|
|
|
info_ptr->free_me |= PNG_FREE_ROWS; |
|
|
|
for (iptr = 0; iptr < info_ptr->height; iptr++) |
|
info_ptr->row_pointers[iptr] = png_voidcast(png_bytep, |
|
png_malloc(png_ptr, info_ptr->rowbytes)); |
|
} |
|
|
|
png_read_image(png_ptr, info_ptr->row_pointers); |
|
info_ptr->valid |= PNG_INFO_IDAT; |
|
|
|
/* Read rest of file, and get additional chunks in info_ptr - REQUIRED */ |
|
png_read_end(png_ptr, info_ptr); |
|
|
|
PNG_UNUSED(params) |
|
} |
|
#endif /* INFO_IMAGE */ |
|
#endif /* SEQUENTIAL_READ */ |
|
|
|
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED |
|
/* SIMPLIFIED READ |
|
* |
|
* This code currently relies on the sequential reader, though it could easily |
|
* be made to work with the progressive one. |
|
*/ |
|
/* Arguments to png_image_finish_read: */ |
|
|
|
/* Encoding of PNG data (used by the color-map code) */ |
|
# define P_NOTSET 0 /* File encoding not yet known */ |
|
# define P_sRGB 1 /* 8-bit encoded to sRGB gamma */ |
|
# define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */ |
|
# define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */ |
|
# define P_LINEAR8 4 /* 8-bit linear: only from a file value */ |
|
|
|
/* Color-map processing: after libpng has run on the PNG image further |
|
* processing may be needed to convert the data to color-map indices. |
|
*/ |
|
#define PNG_CMAP_NONE 0 |
|
#define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */ |
|
#define PNG_CMAP_TRANS 2 /* Process GA data to a background index */ |
|
#define PNG_CMAP_RGB 3 /* Process RGB data */ |
|
#define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */ |
|
|
|
/* The following document where the background is for each processing case. */ |
|
#define PNG_CMAP_NONE_BACKGROUND 256 |
|
#define PNG_CMAP_GA_BACKGROUND 231 |
|
#define PNG_CMAP_TRANS_BACKGROUND 254 |
|
#define PNG_CMAP_RGB_BACKGROUND 256 |
|
#define PNG_CMAP_RGB_ALPHA_BACKGROUND 216 |
|
|
|
typedef struct |
|
{ |
|
/* Arguments: */ |
|
png_imagep image; |
|
png_voidp buffer; |
|
png_int_32 row_stride; |
|
png_voidp colormap; |
|
png_const_colorp background; |
|
/* Local variables: */ |
|
png_voidp local_row; |
|
png_voidp first_row; |
|
ptrdiff_t row_bytes; /* step between rows */ |
|
int file_encoding; /* E_ values above */ |
|
png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */ |
|
int colormap_processing; /* PNG_CMAP_ values above */ |
|
} png_image_read_control; |
|
|
|
/* Do all the *safe* initialization - 'safe' means that png_error won't be |
|
* called, so setting up the jmp_buf is not required. This means that anything |
|
* called from here must *not* call png_malloc - it has to call png_malloc_warn |
|
* instead so that control is returned safely back to this routine. |
|
*/ |
|
static int |
|
png_image_read_init(png_imagep image) |
|
{ |
|
if (image->opaque == NULL) |
|
{ |
|
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image, |
|
png_safe_error, png_safe_warning); |
|
|
|
/* And set the rest of the structure to NULL to ensure that the various |
|
* fields are consistent. |
|
*/ |
|
memset(image, 0, (sizeof *image)); |
|
image->version = PNG_IMAGE_VERSION; |
|
|
|
if (png_ptr != NULL) |
|
{ |
|
png_infop info_ptr = png_create_info_struct(png_ptr); |
|
|
|
if (info_ptr != NULL) |
|
{ |
|
png_controlp control = png_voidcast(png_controlp, |
|
png_malloc_warn(png_ptr, (sizeof *control))); |
|
|
|
if (control != NULL) |
|
{ |
|
memset(control, 0, (sizeof *control)); |
|
|
|
control->png_ptr = png_ptr; |
|
control->info_ptr = info_ptr; |
|
control->for_write = 0; |
|
|
|
image->opaque = control; |
|
return 1; |
|
} |
|
|
|
/* Error clean up */ |
|
png_destroy_info_struct(png_ptr, &info_ptr); |
|
} |
|
|
|
png_destroy_read_struct(&png_ptr, NULL, NULL); |
|
} |
|
|
|
return png_image_error(image, "png_image_read: out of memory"); |
|
} |
|
|
|
return png_image_error(image, "png_image_read: opaque pointer not NULL"); |
|
} |
|
|
|
/* Utility to find the base format of a PNG file from a png_struct. */ |
|
static png_uint_32 |
|
png_image_format(png_structrp png_ptr) |
|
{ |
|
png_uint_32 format = 0; |
|
|
|
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) |
|
format |= PNG_FORMAT_FLAG_COLOR; |
|
|
|
if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0) |
|
format |= PNG_FORMAT_FLAG_ALPHA; |
|
|
|
/* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS |
|
* sets the png_struct fields; that's all we are interested in here. The |
|
* precise interaction with an app call to png_set_tRNS and PNG file reading |
|
* is unclear. |
|
*/ |
|
else if (png_ptr->num_trans > 0) |
|
format |= PNG_FORMAT_FLAG_ALPHA; |
|
|
|
if (png_ptr->bit_depth == 16) |
|
format |= PNG_FORMAT_FLAG_LINEAR; |
|
|
|
if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0) |
|
format |= PNG_FORMAT_FLAG_COLORMAP; |
|
|
|
return format; |
|
} |
|
|
|
/* Is the given gamma significantly different from sRGB? The test is the same |
|
* one used in pngrtran.c when deciding whether to do gamma correction. The |
|
* arithmetic optimizes the division by using the fact that the inverse of the |
|
* file sRGB gamma is 2.2 |
|
*/ |
|
static int |
|
png_gamma_not_sRGB(png_fixed_point g) |
|
{ |
|
if (g < PNG_FP_1) |
|
{ |
|
/* An uninitialized gamma is assumed to be sRGB for the simplified API. */ |
|
if (g == 0) |
|
return 0; |
|
|
|
return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */); |
|
} |
|
|
|
return 1; |
|
} |
|
|
|
/* Do the main body of a 'png_image_begin_read' function; read the PNG file |
|
* header and fill in all the information. This is executed in a safe context, |
|
* unlike the init routine above. |
|
*/ |
|
static int |
|
png_image_read_header(png_voidp argument) |
|
{ |
|
png_imagep image = png_voidcast(png_imagep, argument); |
|
png_structrp png_ptr = image->opaque->png_ptr; |
|
png_inforp info_ptr = image->opaque->info_ptr; |
|
|
|
#ifdef PNG_BENIGN_ERRORS_SUPPORTED |
|
png_set_benign_errors(png_ptr, 1/*warn*/); |
|
#endif |
|
png_read_info(png_ptr, info_ptr); |
|
|
|
/* Do this the fast way; just read directly out of png_struct. */ |
|
image->width = png_ptr->width; |
|
image->height = png_ptr->height; |
|
|
|
{ |
|
png_uint_32 format = png_image_format(png_ptr); |
|
|
|
image->format = format; |
|
|
|
#ifdef PNG_COLORSPACE_SUPPORTED |
|
/* Does the colorspace match sRGB? If there is no color endpoint |
|
* (colorant) information assume yes, otherwise require the |
|
* 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the |
|
* colorspace has been determined to be invalid ignore it. |
|
*/ |
|
if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags |
|
& (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB| |
|
PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS)) |
|
image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB; |
|
#endif |
|
} |
|
|
|
/* We need the maximum number of entries regardless of the format the |
|
* application sets here. |
|
*/ |
|
{ |
|
png_uint_32 cmap_entries; |
|
|
|
switch (png_ptr->color_type) |
|
{ |
|
case PNG_COLOR_TYPE_GRAY: |
|
cmap_entries = 1U << png_ptr->bit_depth; |
|
break; |
|
|
|
case PNG_COLOR_TYPE_PALETTE: |
|
cmap_entries = (png_uint_32)png_ptr->num_palette; |
|
break; |
|
|
|
default: |
|
cmap_entries = 256; |
|
break; |
|
} |
|
|
|
if (cmap_entries > 256) |
|
cmap_entries = 256; |
|
|
|
image->colormap_entries = cmap_entries; |
|
} |
|
|
|
return 1; |
|
} |
|
|
|
#ifdef PNG_STDIO_SUPPORTED |
|
int PNGAPI |
|
png_image_begin_read_from_stdio(png_imagep image, FILE* file) |
|
{ |
|
if (image != NULL && image->version == PNG_IMAGE_VERSION) |
|
{ |
|
if (file != NULL) |
|
{ |
|
if (png_image_read_init(image) != 0) |
|
{ |
|
/* This is slightly evil, but png_init_io doesn't do anything other |
|
* than this and we haven't changed the standard IO functions so |
|
* this saves a 'safe' function. |
|
*/ |
|
image->opaque->png_ptr->io_ptr = file; |
|
return png_safe_execute(image, png_image_read_header, image); |
|
} |
|
} |
|
|
|
else |
|
return png_image_error(image, |
|
"png_image_begin_read_from_stdio: invalid argument"); |
|
} |
|
|
|
else if (image != NULL) |
|
return png_image_error(image, |
|
"png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION"); |
|
|
|
return 0; |
|
} |
|
|
|
int PNGAPI |
|
png_image_begin_read_from_file(png_imagep image, const char *file_name) |
|
{ |
|
if (image != NULL && image->version == PNG_IMAGE_VERSION) |
|
{ |
|
if (file_name != NULL) |
|
{ |
|
FILE *fp = fopen(file_name, "rb"); |
|
|
|
if (fp != NULL) |
|
{ |
|
if (png_image_read_init(image) != 0) |
|
{ |
|
image->opaque->png_ptr->io_ptr = fp; |
|
image->opaque->owned_file = 1; |
|
return png_safe_execute(image, png_image_read_header, image); |
|
} |
|
|
|
/* Clean up: just the opened file. */ |
|
(void)fclose(fp); |
|
} |
|
|
|
else |
|
return png_image_error(image, strerror(errno)); |
|
} |
|
|
|
else |
|
return png_image_error(image, |
|
"png_image_begin_read_from_file: invalid argument"); |
|
} |
|
|
|
else if (image != NULL) |
|
return png_image_error(image, |
|
"png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION"); |
|
|
|
return 0; |
|
} |
|
#endif /* STDIO */ |
|
|
|
static void PNGCBAPI |
|
png_image_memory_read(png_structp png_ptr, png_bytep out, size_t need) |
|
{ |
|
if (png_ptr != NULL) |
|
{ |
|
png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr); |
|
if (image != NULL) |
|
{ |
|
png_controlp cp = image->opaque; |
|
if (cp != NULL) |
|
{ |
|
png_const_bytep memory = cp->memory; |
|
size_t size = cp->size; |
|
|
|
if (memory != NULL && size >= need) |
|
{ |
|
memcpy(out, memory, need); |
|
cp->memory = memory + need; |
|
cp->size = size - need; |
|
return; |
|
} |
|
|
|
png_error(png_ptr, "read beyond end of data"); |
|
} |
|
} |
|
|
|
png_error(png_ptr, "invalid memory read"); |
|
} |
|
} |
|
|
|
int PNGAPI png_image_begin_read_from_memory(png_imagep image, |
|
png_const_voidp memory, size_t size) |
|
{ |
|
if (image != NULL && image->version == PNG_IMAGE_VERSION) |
|
{ |
|
if (memory != NULL && size > 0) |
|
{ |
|
if (png_image_read_init(image) != 0) |
|
{ |
|
/* Now set the IO functions to read from the memory buffer and |
|
* store it into io_ptr. Again do this in-place to avoid calling a |
|
* libpng function that requires error handling. |
|
*/ |
|
image->opaque->memory = png_voidcast(png_const_bytep, memory); |
|
image->opaque->size = size; |
|
image->opaque->png_ptr->io_ptr = image; |
|
image->opaque->png_ptr->read_data_fn = png_image_memory_read; |
|
|
|
return png_safe_execute(image, png_image_read_header, image); |
|
} |
|
} |
|
|
|
else |
|
return png_image_error(image, |
|
"png_image_begin_read_from_memory: invalid argument"); |
|
} |
|
|
|
else if (image != NULL) |
|
return png_image_error(image, |
|
"png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION"); |
|
|
|
return 0; |
|
} |
|
|
|
/* Utility function to skip chunks that are not used by the simplified image |
|
* read functions and an appropriate macro to call it. |
|
*/ |
|
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED |
|
static void |
|
png_image_skip_unused_chunks(png_structrp png_ptr) |
|
{ |
|
/* Prepare the reader to ignore all recognized chunks whose data will not |
|
* be used, i.e., all chunks recognized by libpng except for those |
|
* involved in basic image reading: |
|
* |
|
* IHDR, PLTE, IDAT, IEND |
|
* |
|
* Or image data handling: |
|
* |
|
* tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT. |
|
* |
|
* This provides a small performance improvement and eliminates any |
|
* potential vulnerability to security problems in the unused chunks. |
|
* |
|
* At present the iCCP chunk data isn't used, so iCCP chunk can be ignored |
|
* too. This allows the simplified API to be compiled without iCCP support, |
|
* however if the support is there the chunk is still checked to detect |
|
* errors (which are unfortunately quite common.) |
|
*/ |
|
{ |
|
static PNG_CONST png_byte chunks_to_process[] = { |
|
98, 75, 71, 68, '\0', /* bKGD */ |
|
99, 72, 82, 77, '\0', /* cHRM */ |
|
103, 65, 77, 65, '\0', /* gAMA */ |
|
# ifdef PNG_READ_iCCP_SUPPORTED |
|
105, 67, 67, 80, '\0', /* iCCP */ |
|
# endif |
|
115, 66, 73, 84, '\0', /* sBIT */ |
|
115, 82, 71, 66, '\0', /* sRGB */ |
|
}; |
|
|
|
/* Ignore unknown chunks and all other chunks except for the |
|
* IHDR, PLTE, tRNS, IDAT, and IEND chunks. |
|
*/ |
|
png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER, |
|
NULL, -1); |
|
|
|
/* But do not ignore image data handling chunks */ |
|
png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT, |
|
chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5); |
|
} |
|
} |
|
|
|
# define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p) |
|
#else |
|
# define PNG_SKIP_CHUNKS(p) ((void)0) |
|
#endif /* HANDLE_AS_UNKNOWN */ |
|
|
|
/* The following macro gives the exact rounded answer for all values in the |
|
* range 0..255 (it actually divides by 51.2, but the rounding still generates |
|
* the correct numbers 0..5 |
|
*/ |
|
#define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8) |
|
|
|
/* Utility functions to make particular color-maps */ |
|
static void |
|
set_file_encoding(png_image_read_control *display) |
|
{ |
|
png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma; |
|
if (png_gamma_significant(g) != 0) |
|
{ |
|
if (png_gamma_not_sRGB(g) != 0) |
|
{ |
|
display->file_encoding = P_FILE; |
|
display->gamma_to_linear = png_reciprocal(g); |
|
} |
|
|
|
else |
|
display->file_encoding = P_sRGB; |
|
} |
|
|
|
else |
|
display->file_encoding = P_LINEAR8; |
|
} |
|
|
|
static unsigned int |
|
decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding) |
|
{ |
|
if (encoding == P_FILE) /* double check */ |
|
encoding = display->file_encoding; |
|
|
|
if (encoding == P_NOTSET) /* must be the file encoding */ |
|
{ |
|
set_file_encoding(display); |
|
encoding = display->file_encoding; |
|
} |
|
|
|
switch (encoding) |
|
{ |
|
case P_FILE: |
|
value = png_gamma_16bit_correct(value*257, display->gamma_to_linear); |
|
break; |
|
|
|
case P_sRGB: |
|
value = png_sRGB_table[value]; |
|
break; |
|
|
|
case P_LINEAR: |
|
break; |
|
|
|
case P_LINEAR8: |
|
value *= 257; |
|
break; |
|
|
|
#ifdef __GNUC__ |
|
default: |
|
png_error(display->image->opaque->png_ptr, |
|
"unexpected encoding (internal error)"); |
|
#endif |
|
} |
|
|
|
return value; |
|
} |
|
|
|
static png_uint_32 |
|
png_colormap_compose(png_image_read_control *display, |
|
png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha, |
|
png_uint_32 background, int encoding) |
|
{ |
|
/* The file value is composed on the background, the background has the given |
|
* encoding and so does the result, the file is encoded with P_FILE and the |
|
* file and alpha are 8-bit values. The (output) encoding will always be |
|
* P_LINEAR or P_sRGB. |
|
*/ |
|
png_uint_32 f = decode_gamma(display, foreground, foreground_encoding); |
|
png_uint_32 b = decode_gamma(display, background, encoding); |
|
|
|
/* The alpha is always an 8-bit value (it comes from the palette), the value |
|
* scaled by 255 is what PNG_sRGB_FROM_LINEAR requires. |
|
*/ |
|
f = f * alpha + b * (255-alpha); |
|
|
|
if (encoding == P_LINEAR) |
|
{ |
|
/* Scale to 65535; divide by 255, approximately (in fact this is extremely |
|
* accurate, it divides by 255.00000005937181414556, with no overflow.) |
|
*/ |
|
f *= 257; /* Now scaled by 65535 */ |
|
f += f >> 16; |
|
f = (f+32768) >> 16; |
|
} |
|
|
|
else /* P_sRGB */ |
|
f = PNG_sRGB_FROM_LINEAR(f); |
|
|
|
return f; |
|
} |
|
|
|
/* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must |
|
* be 8-bit. |
|
*/ |
|
static void |
|
png_create_colormap_entry(png_image_read_control *display, |
|
png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue, |
|
png_uint_32 alpha, int encoding) |
|
{ |
|
png_imagep image = display->image; |
|
const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ? |
|
P_LINEAR : P_sRGB; |
|
const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 && |
|
(red != green || green != blue); |
|
|
|
if (ip > 255) |
|
png_error(image->opaque->png_ptr, "color-map index out of range"); |
|
|
|
/* Update the cache with whether the file gamma is significantly different |
|
* from sRGB. |
|
*/ |
|
if (encoding == P_FILE) |
|
{ |
|
if (display->file_encoding == P_NOTSET) |
|
set_file_encoding(display); |
|
|
|
/* Note that the cached value may be P_FILE too, but if it is then the |
|
* gamma_to_linear member has been set. |
|
*/ |
|
encoding = display->file_encoding; |
|
} |
|
|
|
if (encoding == P_FILE) |
|
{ |
|
png_fixed_point g = display->gamma_to_linear; |
|
|
|
red = png_gamma_16bit_correct(red*257, g); |
|
green = png_gamma_16bit_correct(green*257, g); |
|
blue = png_gamma_16bit_correct(blue*257, g); |
|
|
|
if (convert_to_Y != 0 || output_encoding == P_LINEAR) |
|
{ |
|
alpha *= 257; |
|
encoding = P_LINEAR; |
|
} |
|
|
|
else |
|
{ |
|
red = PNG_sRGB_FROM_LINEAR(red * 255); |
|
green = PNG_sRGB_FROM_LINEAR(green * 255); |
|
blue = PNG_sRGB_FROM_LINEAR(blue * 255); |
|
encoding = P_sRGB; |
|
} |
|
} |
|
|
|
else if (encoding == P_LINEAR8) |
|
{ |
|
/* This encoding occurs quite frequently in test cases because PngSuite |
|
* includes a gAMA 1.0 chunk with most images. |
|
*/ |
|
red *= 257; |
|
green *= 257; |
|
blue *= 257; |
|
alpha *= 257; |
|
encoding = P_LINEAR; |
|
} |
|
|
|
else if (encoding == P_sRGB && |
|
(convert_to_Y != 0 || output_encoding == P_LINEAR)) |
|
{ |
|
/* The values are 8-bit sRGB values, but must be converted to 16-bit |
|
* linear. |
|
*/ |
|
red = png_sRGB_table[red]; |
|
green = png_sRGB_table[green]; |
|
blue = png_sRGB_table[blue]; |
|
alpha *= 257; |
|
encoding = P_LINEAR; |
|
} |
|
|
|
/* This is set if the color isn't gray but the output is. */ |
|
if (encoding == P_LINEAR) |
|
{ |
|
if (convert_to_Y != 0) |
|
{ |
|
/* NOTE: these values are copied from png_do_rgb_to_gray */ |
|
png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green + |
|
(png_uint_32)2366 * blue; |
|
|
|
if (output_encoding == P_LINEAR) |
|
y = (y + 16384) >> 15; |
|
|
|
else |
|
{ |
|
/* y is scaled by 32768, we need it scaled by 255: */ |
|
y = (y + 128) >> 8; |
|
y *= 255; |
|
y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7); |
|
alpha = PNG_DIV257(alpha); |
|
encoding = P_sRGB; |
|
} |
|
|
|
blue = red = green = y; |
|
} |
|
|
|
else if (output_encoding == P_sRGB) |
|
{ |
|
red = PNG_sRGB_FROM_LINEAR(red * 255); |
|
green = PNG_sRGB_FROM_LINEAR(green * 255); |
|
blue = PNG_sRGB_FROM_LINEAR(blue * 255); |
|
alpha = PNG_DIV257(alpha); |
|
encoding = P_sRGB; |
|
} |
|
} |
|
|
|
if (encoding != output_encoding) |
|
png_error(image->opaque->png_ptr, "bad encoding (internal error)"); |
|
|
|
/* Store the value. */ |
|
{ |
|
# ifdef PNG_FORMAT_AFIRST_SUPPORTED |
|
const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 && |
|
(image->format & PNG_FORMAT_FLAG_ALPHA) != 0; |
|
# else |
|
# define afirst 0 |
|
# endif |
|
# ifdef PNG_FORMAT_BGR_SUPPORTED |
|
const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0; |
|
# else |
|
# define bgr 0 |
|
# endif |
|
|
|
if (output_encoding == P_LINEAR) |
|
{ |
|
png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap); |
|
|
|
entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); |
|
|
|
/* The linear 16-bit values must be pre-multiplied by the alpha channel |
|
* value, if less than 65535 (this is, effectively, composite on black |
|
* if the alpha channel is removed.) |
|
*/ |
|
switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) |
|
{ |
|
case 4: |
|
entry[afirst ? 0 : 3] = (png_uint_16)alpha; |
|
/* FALLTHROUGH */ |
|
|
|
case 3: |
|
if (alpha < 65535) |
|
{ |
|
if (alpha > 0) |
|
{ |
|
blue = (blue * alpha + 32767U)/65535U; |
|
green = (green * alpha + 32767U)/65535U; |
|
red = (red * alpha + 32767U)/65535U; |
|
} |
|
|
|
else |
|
red = green = blue = 0; |
|
} |
|
entry[afirst + (2 ^ bgr)] = (png_uint_16)blue; |
|
entry[afirst + 1] = (png_uint_16)green; |
|
entry[afirst + bgr] = (png_uint_16)red; |
|
break; |
|
|
|
case 2: |
|
entry[1 ^ afirst] = (png_uint_16)alpha; |
|
/* FALLTHROUGH */ |
|
|
|
case 1: |
|
if (alpha < 65535) |
|
{ |
|
if (alpha > 0) |
|
green = (green * alpha + 32767U)/65535U; |
|
|
|
else |
|
green = 0; |
|
} |
|
entry[afirst] = (png_uint_16)green; |
|
break; |
|
|
|
default: |
|
break; |
|
} |
|
} |
|
|
|
else /* output encoding is P_sRGB */ |
|
{ |
|
png_bytep entry = png_voidcast(png_bytep, display->colormap); |
|
|
|
entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); |
|
|
|
switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) |
|
{ |
|
case 4: |
|
entry[afirst ? 0 : 3] = (png_byte)alpha; |
|
/* FALLTHROUGH */ |
|
case 3: |
|
entry[afirst + (2 ^ bgr)] = (png_byte)blue; |
|
entry[afirst + 1] = (png_byte)green; |
|
entry[afirst + bgr] = (png_byte)red; |
|
break; |
|
|
|
case 2: |
|
entry[1 ^ afirst] = (png_byte)alpha; |
|
/* FALLTHROUGH */ |
|
case 1: |
|
entry[afirst] = (png_byte)green; |
|
break; |
|
|
|
default: |
|
break; |
|
} |
|
} |
|
|
|
# ifdef afirst |
|
# undef afirst |
|
# endif |
|
# ifdef bgr |
|
# undef bgr |
|
# endif |
|
} |
|
} |
|
|
|
static int |
|
make_gray_file_colormap(png_image_read_control *display) |
|
{ |
|
unsigned int i; |
|
|
|
for (i=0; i<256; ++i) |
|
png_create_colormap_entry(display, i, i, i, i, 255, P_FILE); |
|
|
|
return (int)i; |
|
} |
|
|
|
static int |
|
make_gray_colormap(png_image_read_control *display) |
|
{ |
|
unsigned int i; |
|
|
|
for (i=0; i<256; ++i) |
|
png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB); |
|
|
|
return (int)i; |
|
} |
|
#define PNG_GRAY_COLORMAP_ENTRIES 256 |
|
|
|
static int |
|
make_ga_colormap(png_image_read_control *display) |
|
{ |
|
unsigned int i, a; |
|
|
|
/* Alpha is retained, the output will be a color-map with entries |
|
* selected by six levels of alpha. One transparent entry, 6 gray |
|
* levels for all the intermediate alpha values, leaving 230 entries |
|
* for the opaque grays. The color-map entries are the six values |
|
* [0..5]*51, the GA processing uses PNG_DIV51(value) to find the |
|
* relevant entry. |
|
* |
|
* if (alpha > 229) // opaque |
|
* { |
|
* // The 231 entries are selected to make the math below work: |
|
* base = 0; |
|
* entry = (231 * gray + 128) >> 8; |
|
* } |
|
* else if (alpha < 26) // transparent |
|
* { |
|
* base = 231; |
|
* entry = 0; |
|
* } |
|
* else // partially opaque |
|
* { |
|
* base = 226 + 6 * PNG_DIV51(alpha); |
|
* entry = PNG_DIV51(gray); |
|
* } |
|
*/ |
|
i = 0; |
|
while (i < 231) |
|
{ |
|
unsigned int gray = (i * 256 + 115) / 231; |
|
png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB); |
|
} |
|
|
|
/* 255 is used here for the component values for consistency with the code |
|
* that undoes premultiplication in pngwrite.c. |
|
*/ |
|
png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB); |
|
|
|
for (a=1; a<5; ++a) |
|
{ |
|
unsigned int g; |
|
|
|
for (g=0; g<6; ++g) |
|
png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51, |
|
P_sRGB); |
|
} |
|
|
|
return (int)i; |
|
} |
|
|
|
#define PNG_GA_COLORMAP_ENTRIES 256 |
|
|
|
static int |
|
make_rgb_colormap(png_image_read_control *display) |
|
{ |
|
unsigned int i, r; |
|
|
|
/* Build a 6x6x6 opaque RGB cube */ |
|
for (i=r=0; r<6; ++r) |
|
{ |
|
unsigned int g; |
|
|
|
for (g=0; g<6; ++g) |
|
{ |
|
unsigned int b; |
|
|
|
for (b=0; b<6; ++b) |
|
png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255, |
|
P_sRGB); |
|
} |
|
} |
|
|
|
return (int)i; |
|
} |
|
|
|
#define PNG_RGB_COLORMAP_ENTRIES 216 |
|
|
|
/* Return a palette index to the above palette given three 8-bit sRGB values. */ |
|
#define PNG_RGB_INDEX(r,g,b) \ |
|
((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b))) |
|
|
|
static int |
|
png_image_read_colormap(png_voidp argument) |
|
{ |
|
png_image_read_control *display = |
|
png_voidcast(png_image_read_control*, argument); |
|
const png_imagep image = display->image; |
|
|
|
const png_structrp png_ptr = image->opaque->png_ptr; |
|
const png_uint_32 output_format = image->format; |
|
const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ? |
|
P_LINEAR : P_sRGB; |
|
|
|
unsigned int cmap_entries; |
|
unsigned int output_processing; /* Output processing option */ |
|
unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */ |
|
|
|
/* Background information; the background color and the index of this color |
|
* in the color-map if it exists (else 256). |
|
*/ |
|
unsigned int background_index = 256; |
|
png_uint_32 back_r, back_g, back_b; |
|
|
|
/* Flags to accumulate things that need to be done to the input. */ |
|
int expand_tRNS = 0; |
|
|
|
/* Exclude the NYI feature of compositing onto a color-mapped buffer; it is |
|
* very difficult to do, the results look awful, and it is difficult to see |
|
* what possible use it is because the application can't control the |
|
* color-map. |
|
*/ |
|
if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 || |
|
png_ptr->num_trans > 0) /* alpha in input */ && |
|
((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */) |
|
{ |
|
if (output_encoding == P_LINEAR) /* compose on black */ |
|
back_b = back_g = back_r = 0; |
|
|
|
else if (display->background == NULL /* no way to remove it */) |
|
png_error(png_ptr, |
|
"background color must be supplied to remove alpha/transparency"); |
|
|
|
/* Get a copy of the background color (this avoids repeating the checks |
|
* below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the |
|
* output format. |
|
*/ |
|
else |
|
{ |
|
back_g = display->background->green; |
|
if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0) |
|
{ |
|
back_r = display->background->red; |
|
back_b = display->background->blue; |
|
} |
|
else |
|
back_b = back_r = back_g; |
|
} |
|
} |
|
|
|
else if (output_encoding == P_LINEAR) |
|
back_b = back_r = back_g = 65535; |
|
|
|
else |
|
back_b = back_r = back_g = 255; |
|
|
|
/* Default the input file gamma if required - this is necessary because |
|
* libpng assumes that if no gamma information is present the data is in the |
|
* output format, but the simplified API deduces the gamma from the input |
|
* format. |
|
*/ |
|
if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0) |
|
{ |
|
/* Do this directly, not using the png_colorspace functions, to ensure |
|
* that it happens even if the colorspace is invalid (though probably if |
|
* it is the setting will be ignored) Note that the same thing can be |
|
* achieved at the application interface with png_set_gAMA. |
|
*/ |
|
if (png_ptr->bit_depth == 16 && |
|
(image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) |
|
png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR; |
|
|
|
else |
|
png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE; |
|
|
|
png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; |
|
} |
|
|
|
/* Decide what to do based on the PNG color type of the input data. The |
|
* utility function png_create_colormap_entry deals with most aspects of the |
|
* output transformations; this code works out how to produce bytes of |
|
* color-map entries from the original format. |
|
*/ |
|
switch (png_ptr->color_type) |
|
{ |
|
case PNG_COLOR_TYPE_GRAY: |
|
if (png_ptr->bit_depth <= 8) |
|
{ |
|
/* There at most 256 colors in the output, regardless of |
|
* transparency. |
|
*/ |
|
unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0; |
|
|
|
cmap_entries = 1U << png_ptr->bit_depth; |
|
if (cmap_entries > image->colormap_entries) |
|
png_error(png_ptr, "gray[8] color-map: too few entries"); |
|
|
|
step = 255 / (cmap_entries - 1); |
|
output_processing = PNG_CMAP_NONE; |
|
|
|
/* If there is a tRNS chunk then this either selects a transparent |
|
* value or, if the output has no alpha, the background color. |
|
*/ |
|
if (png_ptr->num_trans > 0) |
|
{ |
|
trans = png_ptr->trans_color.gray; |
|
|
|
if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) |
|
back_alpha = output_encoding == P_LINEAR ? 65535 : 255; |
|
} |
|
|
|
/* png_create_colormap_entry just takes an RGBA and writes the |
|
* corresponding color-map entry using the format from 'image', |
|
* including the required conversion to sRGB or linear as |
|
* appropriate. The input values are always either sRGB (if the |
|
* gamma correction flag is 0) or 0..255 scaled file encoded values |
|
* (if the function must gamma correct them). |
|
*/ |
|
for (i=val=0; i<cmap_entries; ++i, val += step) |
|
{ |
|
/* 'i' is a file value. While this will result in duplicated |
|
* entries for 8-bit non-sRGB encoded files it is necessary to |
|
* have non-gamma corrected values to do tRNS handling. |
|
*/ |
|
if (i != trans) |
|
png_create_colormap_entry(display, i, val, val, val, 255, |
|
P_FILE/*8-bit with file gamma*/); |
|
|
|
/* Else this entry is transparent. The colors don't matter if |
|
* there is an alpha channel (back_alpha == 0), but it does no |
|
* harm to pass them in; the values are not set above so this |
|
* passes in white. |
|
* |
|
* NOTE: this preserves the full precision of the application |
|
* supplied background color when it is used. |
|
*/ |
|
else |
|
png_create_colormap_entry(display, i, back_r, back_g, back_b, |
|
back_alpha, output_encoding); |
|
} |
|
|
|
/* We need libpng to preserve the original encoding. */ |
|
data_encoding = P_FILE; |
|
|
|
/* The rows from libpng, while technically gray values, are now also |
|
* color-map indices; however, they may need to be expanded to 1 |
|
* byte per pixel. This is what png_set_packing does (i.e., it |
|
* unpacks the bit values into bytes.) |
|
*/ |
|
if (png_ptr->bit_depth < 8) |
|
png_set_packing(png_ptr); |
|
} |
|
|
|
else /* bit depth is 16 */ |
|
{ |
|
/* The 16-bit input values can be converted directly to 8-bit gamma |
|
* encoded values; however, if a tRNS chunk is present 257 color-map |
|
* entries are required. This means that the extra entry requires |
|
* special processing; add an alpha channel, sacrifice gray level |
|
* 254 and convert transparent (alpha==0) entries to that. |
|
* |
|
* Use libpng to chop the data to 8 bits. Convert it to sRGB at the |
|
* same time to minimize quality loss. If a tRNS chunk is present |
|
* this means libpng must handle it too; otherwise it is impossible |
|
* to do the exact match on the 16-bit value. |
|
* |
|
* If the output has no alpha channel *and* the background color is |
|
* gray then it is possible to let libpng handle the substitution by |
|
* ensuring that the corresponding gray level matches the background |
|
* color exactly. |
|
*/ |
|
data_encoding = P_sRGB; |
|
|
|
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) |
|
png_error(png_ptr, "gray[16] color-map: too few entries"); |
|
|
|
cmap_entries = (unsigned int)make_gray_colormap(display); |
|
|
|
if (png_ptr->num_trans > 0) |
|
{ |
|
unsigned int back_alpha; |
|
|
|
if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) |
|
back_alpha = 0; |
|
|
|
else |
|
{ |
|
if (back_r == back_g && back_g == back_b) |
|
{ |
|
/* Background is gray; no special processing will be |
|
* required. |
|
*/ |
|
png_color_16 c; |
|
png_uint_32 gray = back_g; |
|
|
|
if (output_encoding == P_LINEAR) |
|
{ |
|
gray = PNG_sRGB_FROM_LINEAR(gray * 255); |
|
|
|
/* And make sure the corresponding palette entry |
|
* matches. |
|
*/ |
|
png_create_colormap_entry(display, gray, back_g, back_g, |
|
back_g, 65535, P_LINEAR); |
|
} |
|
|
|
/* The background passed to libpng, however, must be the |
|
* sRGB value. |
|
*/ |
|
c.index = 0; /*unused*/ |
|
c.gray = c.red = c.green = c.blue = (png_uint_16)gray; |
|
|
|
/* NOTE: does this work without expanding tRNS to alpha? |
|
* It should be the color->gray case below apparently |
|
* doesn't. |
|
*/ |
|
png_set_background_fixed(png_ptr, &c, |
|
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, |
|
0/*gamma: not used*/); |
|
|
|
output_processing = PNG_CMAP_NONE; |
|
break; |
|
} |
|
#ifdef __COVERITY__ |
|
/* Coverity claims that output_encoding cannot be 2 (P_LINEAR) |
|
* here. |
|
*/ |
|
back_alpha = 255; |
|
#else |
|
back_alpha = output_encoding == P_LINEAR ? 65535 : 255; |
|
#endif |
|
} |
|
|
|
/* output_processing means that the libpng-processed row will be |
|
* 8-bit GA and it has to be processing to single byte color-map |
|
* values. Entry 254 is replaced by either a completely |
|
* transparent entry or by the background color at full |
|
* precision (and the background color is not a simple gray |
|
* level in this case.) |
|
*/ |
|
expand_tRNS = 1; |
|
output_processing = PNG_CMAP_TRANS; |
|
background_index = 254; |
|
|
|
/* And set (overwrite) color-map entry 254 to the actual |
|
* background color at full precision. |
|
*/ |
|
png_create_colormap_entry(display, 254, back_r, back_g, back_b, |
|
back_alpha, output_encoding); |
|
} |
|
|
|
else |
|
output_processing = PNG_CMAP_NONE; |
|
} |
|
break; |
|
|
|
case PNG_COLOR_TYPE_GRAY_ALPHA: |
|
/* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum |
|
* of 65536 combinations. If, however, the alpha channel is to be |
|
* removed there are only 256 possibilities if the background is gray. |
|
* (Otherwise there is a subset of the 65536 possibilities defined by |
|
* the triangle between black, white and the background color.) |
|
* |
|
* Reduce 16-bit files to 8-bit and sRGB encode the result. No need to |
|
* worry about tRNS matching - tRNS is ignored if there is an alpha |
|
* channel. |
|
*/ |
|
data_encoding = P_sRGB; |
|
|
|
if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) |
|
{ |
|
if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) |
|
png_error(png_ptr, "gray+alpha color-map: too few entries"); |
|
|
|
cmap_entries = (unsigned int)make_ga_colormap(display); |
|
|
|
background_index = PNG_CMAP_GA_BACKGROUND; |
|
output_processing = PNG_CMAP_GA; |
|
} |
|
|
|
else /* alpha is removed */ |
|
{ |
|
/* Alpha must be removed as the PNG data is processed when the |
|
* background is a color because the G and A channels are |
|
* independent and the vector addition (non-parallel vectors) is a |
|
* 2-D problem. |
|
* |
|
* This can be reduced to the same algorithm as above by making a |
|
* colormap containing gray levels (for the opaque grays), a |
|
* background entry (for a transparent pixel) and a set of four six |
|
* level color values, one set for each intermediate alpha value. |
|
* See the comments in make_ga_colormap for how this works in the |
|
* per-pixel processing. |
|
* |
|
* If the background is gray, however, we only need a 256 entry gray |
|
* level color map. It is sufficient to make the entry generated |
|
* for the background color be exactly the color specified. |
|
*/ |
|
if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 || |
|
(back_r == back_g && back_g == back_b)) |
|
{ |
|
/* Background is gray; no special processing will be required. */ |
|
png_color_16 c; |
|
png_uint_32 gray = back_g; |
|
|
|
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) |
|
png_error(png_ptr, "gray-alpha color-map: too few entries"); |
|
|
|
cmap_entries = (unsigned int)make_gray_colormap(display); |
|
|
|
if (output_encoding == P_LINEAR) |
|
{ |
|
gray = PNG_sRGB_FROM_LINEAR(gray * 255); |
|
|
|
/* And make sure the corresponding palette entry matches. */ |
|
png_create_colormap_entry(display, gray, back_g, back_g, |
|
back_g, 65535, P_LINEAR); |
|
} |
|
|
|
/* The background passed to libpng, however, must be the sRGB |
|
* value. |
|
*/ |
|
c.index = 0; /*unused*/ |
|
c.gray = c.red = c.green = c.blue = (png_uint_16)gray; |
|
|
|
png_set_background_fixed(png_ptr, &c, |
|
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, |
|
0/*gamma: not used*/); |
|
|
|
output_processing = PNG_CMAP_NONE; |
|
} |
|
|
|
else |
|
{ |
|
png_uint_32 i, a; |
|
|
|
/* This is the same as png_make_ga_colormap, above, except that |
|
* the entries are all opaque. |
|
*/ |
|
if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) |
|
png_error(png_ptr, "ga-alpha color-map: too few entries"); |
|
|
|
i = 0; |
|
while (i < 231) |
|
{ |
|
png_uint_32 gray = (i * 256 + 115) / 231; |
|
png_create_colormap_entry(display, i++, gray, gray, gray, |
|
255, P_sRGB); |
|
} |
|
|
|
/* NOTE: this preserves the full precision of the application |
|
* background color. |
|
*/ |
|
background_index = i; |
|
png_create_colormap_entry(display, i++, back_r, back_g, back_b, |
|
#ifdef __COVERITY__ |
|
/* Coverity claims that output_encoding |
|
* cannot be 2 (P_LINEAR) here. |
|
*/ 255U, |
|
#else |
|
output_encoding == P_LINEAR ? 65535U : 255U, |
|
#endif |
|
output_encoding); |
|
|
|
/* For non-opaque input composite on the sRGB background - this |
|
* requires inverting the encoding for each component. The input |
|
* is still converted to the sRGB encoding because this is a |
|
* reasonable approximate to the logarithmic curve of human |
|
* visual sensitivity, at least over the narrow range which PNG |
|
* represents. Consequently 'G' is always sRGB encoded, while |
|
* 'A' is linear. We need the linear background colors. |
|
*/ |
|
if (output_encoding == P_sRGB) /* else already linear */ |
|
{ |
|
/* This may produce a value not exactly matching the |
|
* background, but that's ok because these numbers are only |
|
* used when alpha != 0 |
|
*/ |
|
back_r = png_sRGB_table[back_r]; |
|
back_g = png_sRGB_table[back_g]; |
|
back_b = png_sRGB_table[back_b]; |
|
} |
|
|
|
for (a=1; a<5; ++a) |
|
{ |
|
unsigned int g; |
|
|
|
/* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled |
|
* by an 8-bit alpha value (0..255). |
|
*/ |
|
png_uint_32 alpha = 51 * a; |
|
png_uint_32 back_rx = (255-alpha) * back_r; |
|
png_uint_32 back_gx = (255-alpha) * back_g; |
|
png_uint_32 back_bx = (255-alpha) * back_b; |
|
|
|
for (g=0; g<6; ++g) |
|
{ |
|
png_uint_32 gray = png_sRGB_table[g*51] * alpha; |
|
|
|
png_create_colormap_entry(display, i++, |
|
PNG_sRGB_FROM_LINEAR(gray + back_rx), |
|
PNG_sRGB_FROM_LINEAR(gray + back_gx), |
|
PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB); |
|
} |
|
} |
|
|
|
cmap_entries = i; |
|
output_processing = PNG_CMAP_GA; |
|
} |
|
} |
|
break; |
|
|
|
case PNG_COLOR_TYPE_RGB: |
|
case PNG_COLOR_TYPE_RGB_ALPHA: |
|
/* Exclude the case where the output is gray; we can always handle this |
|
* with the cases above. |
|
*/ |
|
if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0) |
|
{ |
|
/* The color-map will be grayscale, so we may as well convert the |
|
* input RGB values to a simple grayscale and use the grayscale |
|
* code above. |
|
* |
|
* NOTE: calling this apparently damages the recognition of the |
|
* transparent color in background color handling; call |
|
* png_set_tRNS_to_alpha before png_set_background_fixed. |
|
*/ |
|
png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1, |
|
-1); |
|
data_encoding = P_sRGB; |
|
|
|
/* The output will now be one or two 8-bit gray or gray+alpha |
|
* channels. The more complex case arises when the input has alpha. |
|
*/ |
|
if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || |
|
png_ptr->num_trans > 0) && |
|
(output_format & PNG_FORMAT_FLAG_ALPHA) != 0) |
|
{ |
|
/* Both input and output have an alpha channel, so no background |
|
* processing is required; just map the GA bytes to the right |
|
* color-map entry. |
|
*/ |
|
expand_tRNS = 1; |
|
|
|
if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) |
|
png_error(png_ptr, "rgb[ga] color-map: too few entries"); |
|
|
|
cmap_entries = (unsigned int)make_ga_colormap(display); |
|
background_index = PNG_CMAP_GA_BACKGROUND; |
|
output_processing = PNG_CMAP_GA; |
|
} |
|
|
|
else |
|
{ |
|
/* Either the input or the output has no alpha channel, so there |
|
* will be no non-opaque pixels in the color-map; it will just be |
|
* grayscale. |
|
*/ |
|
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) |
|
png_error(png_ptr, "rgb[gray] color-map: too few entries"); |
|
|
|
/* Ideally this code would use libpng to do the gamma correction, |
|
* but if an input alpha channel is to be removed we will hit the |
|
* libpng bug in gamma+compose+rgb-to-gray (the double gamma |
|
* correction bug). Fix this by dropping the gamma correction in |
|
* this case and doing it in the palette; this will result in |
|
* duplicate palette entries, but that's better than the |
|
* alternative of double gamma correction. |
|
*/ |
|
if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || |
|
png_ptr->num_trans > 0) && |
|
png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0) |
|
{ |
|
cmap_entries = (unsigned int)make_gray_file_colormap(display); |
|
data_encoding = P_FILE; |
|
} |
|
|
|
else |
|
cmap_entries = (unsigned int)make_gray_colormap(display); |
|
|
|
/* But if the input has alpha or transparency it must be removed |
|
*/ |
|
if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || |
|
png_ptr->num_trans > 0) |
|
{ |
|
png_color_16 c; |
|
png_uint_32 gray = back_g; |
|
|
|
/* We need to ensure that the application background exists in |
|
* the colormap and that completely transparent pixels map to |
|
* it. Achieve this simply by ensuring that the entry |
|
* selected for the background really is the background color. |
|
*/ |
|
if (data_encoding == P_FILE) /* from the fixup above */ |
|
{ |
|
/* The app supplied a gray which is in output_encoding, we |
|
* need to convert it to a value of the input (P_FILE) |
|
* encoding then set this palette entry to the required |
|
* output encoding. |
|
*/ |
|
if (output_encoding == P_sRGB) |
|
gray = png_sRGB_table[gray]; /* now P_LINEAR */ |
|
|
|
gray = PNG_DIV257(png_gamma_16bit_correct(gray, |
|
png_ptr->colorspace.gamma)); /* now P_FILE */ |
|
|
|
/* And make sure the corresponding palette entry contains |
|
* exactly the required sRGB value. |
|
*/ |
|
png_create_colormap_entry(display, gray, back_g, back_g, |
|
back_g, 0/*unused*/, output_encoding); |
|
} |
|
|
|
else if (output_encoding == P_LINEAR) |
|
{ |
|
gray = PNG_sRGB_FROM_LINEAR(gray * 255); |
|
|
|
/* And make sure the corresponding palette entry matches. |
|
*/ |
|
png_create_colormap_entry(display, gray, back_g, back_g, |
|
back_g, 0/*unused*/, P_LINEAR); |
|
} |
|
|
|
/* The background passed to libpng, however, must be the |
|
* output (normally sRGB) value. |
|
*/ |
|
c.index = 0; /*unused*/ |
|
c.gray = c.red = c.green = c.blue = (png_uint_16)gray; |
|
|
|
/* NOTE: the following is apparently a bug in libpng. Without |
|
* it the transparent color recognition in |
|
* png_set_background_fixed seems to go wrong. |
|
*/ |
|
expand_tRNS = 1; |
|
png_set_background_fixed(png_ptr, &c, |
|
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, |
|
0/*gamma: not used*/); |
|
} |
|
|
|
output_processing = PNG_CMAP_NONE; |
|
} |
|
} |
|
|
|
else /* output is color */ |
|
{ |
|
/* We could use png_quantize here so long as there is no transparent |
|
* color or alpha; png_quantize ignores alpha. Easier overall just |
|
* to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube. |
|
* Consequently we always want libpng to produce sRGB data. |
|
*/ |
|
data_encoding = P_sRGB; |
|
|
|
/* Is there any transparency or alpha? */ |
|
if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || |
|
png_ptr->num_trans > 0) |
|
{ |
|
/* Is there alpha in the output too? If so all four channels are |
|
* processed into a special RGB cube with alpha support. |
|
*/ |
|
if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) |
|
{ |
|
png_uint_32 r; |
|
|
|
if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) |
|
png_error(png_ptr, "rgb+alpha color-map: too few entries"); |
|
|
|
cmap_entries = (unsigned int)make_rgb_colormap(display); |
|
|
|
/* Add a transparent entry. */ |
|
png_create_colormap_entry(display, cmap_entries, 255, 255, |
|
255, 0, P_sRGB); |
|
|
|
/* This is stored as the background index for the processing |
|
* algorithm. |
|
*/ |
|
background_index = cmap_entries++; |
|
|
|
/* Add 27 r,g,b entries each with alpha 0.5. */ |
|
for (r=0; r<256; r = (r << 1) | 0x7f) |
|
{ |
|
png_uint_32 g; |
|
|
|
for (g=0; g<256; g = (g << 1) | 0x7f) |
|
{ |
|
png_uint_32 b; |
|
|
|
/* This generates components with the values 0, 127 and |
|
* 255 |
|
*/ |
|
for (b=0; b<256; b = (b << 1) | 0x7f) |
|
png_create_colormap_entry(display, cmap_entries++, |
|
r, g, b, 128, P_sRGB); |
|
} |
|
} |
|
|
|
expand_tRNS = 1; |
|
output_processing = PNG_CMAP_RGB_ALPHA; |
|
} |
|
|
|
else |
|
{ |
|
/* Alpha/transparency must be removed. The background must |
|
* exist in the color map (achieved by setting adding it after |
|
* the 666 color-map). If the standard processing code will |
|
* pick up this entry automatically that's all that is |
|
* required; libpng can be called to do the background |
|
* processing. |
|
*/ |
|
unsigned int sample_size = |
|
PNG_IMAGE_SAMPLE_SIZE(output_format); |
|
png_uint_32 r, g, b; /* sRGB background */ |
|
|
|
if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) |
|
png_error(png_ptr, "rgb-alpha color-map: too few entries"); |
|
|
|
cmap_entries = (unsigned int)make_rgb_colormap(display); |
|
|
|
png_create_colormap_entry(display, cmap_entries, back_r, |
|
back_g, back_b, 0/*unused*/, output_encoding); |
|
|
|
if (output_encoding == P_LINEAR) |
|
{ |
|
r = PNG_sRGB_FROM_LINEAR(back_r * 255); |
|
g = PNG_sRGB_FROM_LINEAR(back_g * 255); |
|
b = PNG_sRGB_FROM_LINEAR(back_b * 255); |
|
} |
|
|
|
else |
|
{ |
|
r = back_r; |
|
g = back_g; |
|
b = back_g; |
|
} |
|
|
|
/* Compare the newly-created color-map entry with the one the |
|
* PNG_CMAP_RGB algorithm will use. If the two entries don't |
|
* match, add the new one and set this as the background |
|
* index. |
|
*/ |
|
if (memcmp((png_const_bytep)display->colormap + |
|
sample_size * cmap_entries, |
|
(png_const_bytep)display->colormap + |
|
sample_size * PNG_RGB_INDEX(r,g,b), |
|
sample_size) != 0) |
|
{ |
|
/* The background color must be added. */ |
|
background_index = cmap_entries++; |
|
|
|
/* Add 27 r,g,b entries each with created by composing with |
|
* the background at alpha 0.5. |
|
*/ |
|
for (r=0; r<256; r = (r << 1) | 0x7f) |
|
{ |
|
for (g=0; g<256; g = (g << 1) | 0x7f) |
|
{ |
|
/* This generates components with the values 0, 127 |
|
* and 255 |
|
*/ |
|
for (b=0; b<256; b = (b << 1) | 0x7f) |
|
png_create_colormap_entry(display, cmap_entries++, |
|
png_colormap_compose(display, r, P_sRGB, 128, |
|
back_r, output_encoding), |
|
png_colormap_compose(display, g, P_sRGB, 128, |
|
back_g, output_encoding), |
|
png_colormap_compose(display, b, P_sRGB, 128, |
|
back_b, output_encoding), |
|
0/*unused*/, output_encoding); |
|
} |
|
} |
|
|
|
expand_tRNS = 1; |
|
output_processing = PNG_CMAP_RGB_ALPHA; |
|
} |
|
|
|
else /* background color is in the standard color-map */ |
|
{ |
|
png_color_16 c; |
|
|
|
c.index = 0; /*unused*/ |
|
c.red = (png_uint_16)back_r; |
|
c.gray = c.green = (png_uint_16)back_g; |
|
c.blue = (png_uint_16)back_b; |
|
|
|
png_set_background_fixed(png_ptr, &c, |
|
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, |
|
0/*gamma: not used*/); |
|
|
|
output_processing = PNG_CMAP_RGB; |
|
} |
|
} |
|
} |
|
|
|
else /* no alpha or transparency in the input */ |
|
{ |
|
/* Alpha in the output is irrelevant, simply map the opaque input |
|
* pixels to the 6x6x6 color-map. |
|
*/ |
|
if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries) |
|
png_error(png_ptr, "rgb color-map: too few entries"); |
|
|
|
cmap_entries = (unsigned int)make_rgb_colormap(display); |
|
output_processing = PNG_CMAP_RGB; |
|
} |
|
} |
|
break; |
|
|
|
case PNG_COLOR_TYPE_PALETTE: |
|
/* It's already got a color-map. It may be necessary to eliminate the |
|
* tRNS entries though. |
|
*/ |
|
{ |
|
unsigned int num_trans = png_ptr->num_trans; |
|
png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL; |
|
png_const_colorp colormap = png_ptr->palette; |
|
const int do_background = trans != NULL && |
|
(output_format & PNG_FORMAT_FLAG_ALPHA) == 0; |
|
unsigned int i; |
|
|
|
/* Just in case: */ |
|
if (trans == NULL) |
|
num_trans = 0; |
|
|
|
output_processing = PNG_CMAP_NONE; |
|
data_encoding = P_FILE; /* Don't change from color-map indices */ |
|
cmap_entries = (unsigned int)png_ptr->num_palette; |
|
if (cmap_entries > 256) |
|
cmap_entries = 256; |
|
|
|
if (cmap_entries > (unsigned int)image->colormap_entries) |
|
png_error(png_ptr, "palette color-map: too few entries"); |
|
|
|
for (i=0; i < cmap_entries; ++i) |
|
{ |
|
if (do_background != 0 && i < num_trans && trans[i] < 255) |
|
{ |
|
if (trans[i] == 0) |
|
png_create_colormap_entry(display, i, back_r, back_g, |
|
back_b, 0, output_encoding); |
|
|
|
else |
|
{ |
|
/* Must compose the PNG file color in the color-map entry |
|
* on the sRGB color in 'back'. |
|
*/ |
|
png_create_colormap_entry(display, i, |
|
png_colormap_compose(display, colormap[i].red, |
|
P_FILE, trans[i], back_r, output_encoding), |
|
png_colormap_compose(display, colormap[i].green, |
|
P_FILE, trans[i], back_g, output_encoding), |
|
png_colormap_compose(display, colormap[i].blue, |
|
P_FILE, trans[i], back_b, output_encoding), |
|
output_encoding == P_LINEAR ? trans[i] * 257U : |
|
trans[i], |
|
output_encoding); |
|
} |
|
} |
|
|
|
else |
|
png_create_colormap_entry(display, i, colormap[i].red, |
|
colormap[i].green, colormap[i].blue, |
|
i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/); |
|
} |
|
|
|
/* The PNG data may have indices packed in fewer than 8 bits, it |
|
* must be expanded if so. |
|
*/ |
|
if (png_ptr->bit_depth < 8) |
|
png_set_packing(png_ptr); |
|
} |
|
break; |
|
|
|
default: |
|
png_error(png_ptr, "invalid PNG color type"); |
|
/*NOT REACHED*/ |
|
} |
|
|
|
/* Now deal with the output processing */ |
|
if (expand_tRNS != 0 && png_ptr->num_trans > 0 && |
|
(png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0) |
|
png_set_tRNS_to_alpha(png_ptr); |
|
|
|
switch (data_encoding) |
|
{ |
|
case P_sRGB: |
|
/* Change to 8-bit sRGB */ |
|
png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB); |
|
/* FALLTHROUGH */ |
|
|
|
case P_FILE: |
|
if (png_ptr->bit_depth > 8) |
|
png_set_scale_16(png_ptr); |
|
break; |
|
|
|
#ifdef __GNUC__ |
|
default: |
|
png_error(png_ptr, "bad data option (internal error)"); |
|
#endif |
|
} |
|
|
|
if (cmap_entries > 256 || cmap_entries > image->colormap_entries) |
|
png_error(png_ptr, "color map overflow (BAD internal error)"); |
|
|
|
image->colormap_entries = cmap_entries; |
|
|
|
/* Double check using the recorded background index */ |
|
switch (output_processing) |
|
{ |
|
case PNG_CMAP_NONE: |
|
if (background_index != PNG_CMAP_NONE_BACKGROUND) |
|
goto bad_background; |
|
break; |
|
|
|
case PNG_CMAP_GA: |
|
if (background_index != PNG_CMAP_GA_BACKGROUND) |
|
goto bad_background; |
|
break; |
|
|
|
case PNG_CMAP_TRANS: |
|
if (background_index >= cmap_entries || |
|
background_index != PNG_CMAP_TRANS_BACKGROUND) |
|
goto bad_background; |
|
break; |
|
|
|
case PNG_CMAP_RGB: |
|
if (background_index != PNG_CMAP_RGB_BACKGROUND) |
|
goto bad_background; |
|
break; |
|
|
|
case PNG_CMAP_RGB_ALPHA: |
|
if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND) |
|
goto bad_background; |
|
break; |
|
|
|
default: |
|
png_error(png_ptr, "bad processing option (internal error)"); |
|
|
|
bad_background: |
|
png_error(png_ptr, "bad background index (internal error)"); |
|
} |
|
|
|
display->colormap_processing = (int)output_processing; |
|
|
|
return 1/*ok*/; |
|
} |
|
|
|
/* The final part of the color-map read called from png_image_finish_read. */ |
|
static int |
|
png_image_read_and_map(png_voidp argument) |
|
{ |
|
png_image_read_control *display = png_voidcast(png_image_read_control*, |
|
argument); |
|
png_imagep image = display->image; |
|
png_structrp png_ptr = image->opaque->png_ptr; |
|
int passes; |
|
|
|
/* Called when the libpng data must be transformed into the color-mapped |
|
* form. There is a local row buffer in display->local and this routine must |
|
* do the interlace handling. |
|
*/ |
|
switch (png_ptr->interlaced) |
|
{ |
|
case PNG_INTERLACE_NONE: |
|
passes = 1; |
|
break; |
|
|
|
case PNG_INTERLACE_ADAM7: |
|
passes = PNG_INTERLACE_ADAM7_PASSES; |
|
break; |
|
|
|
default: |
|
png_error(png_ptr, "unknown interlace type"); |
|
} |
|
|
|
{ |
|
png_uint_32 height = image->height; |
|
png_uint_32 width = image->width; |
|
int proc = display->colormap_processing; |
|
png_bytep first_row = png_voidcast(png_bytep, display->first_row); |
|
ptrdiff_t step_row = display->row_bytes; |
|
int pass; |
|
|
|
for (pass = 0; pass < passes; ++pass) |
|
{ |
|
unsigned int startx, stepx, stepy; |
|
png_uint_32 y; |
|
|
|
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) |
|
{ |
|
/* The row may be empty for a short image: */ |
|
if (PNG_PASS_COLS(width, pass) == 0) |
|
continue; |
|
|
|
startx = PNG_PASS_START_COL(pass); |
|
stepx = PNG_PASS_COL_OFFSET(pass); |
|
y = PNG_PASS_START_ROW(pass); |
|
stepy = PNG_PASS_ROW_OFFSET(pass); |
|
} |
|
|
|
else |
|
{ |
|
y = 0; |
|
startx = 0; |
|
stepx = stepy = 1; |
|
} |
|
|
|
for (; y<height; y += stepy) |
|
{ |
|
png_bytep inrow = png_voidcast(png_bytep, display->local_row); |
|
png_bytep outrow = first_row + y * step_row; |
|
png_const_bytep end_row = outrow + width; |
|
|
|
/* Read read the libpng data into the temporary buffer. */ |
|
png_read_row(png_ptr, inrow, NULL); |
|
|
|
/* Now process the row according to the processing option, note |
|
* that the caller verifies that the format of the libpng output |
|
* data is as required. |
|
*/ |
|
outrow += startx; |
|
switch (proc) |
|
{ |
|
case PNG_CMAP_GA: |
|
for (; outrow < end_row; outrow += stepx) |
|
{ |
|
/* The data is always in the PNG order */ |
|
unsigned int gray = *inrow++; |
|
unsigned int alpha = *inrow++; |
|
unsigned int entry; |
|
|
|
/* NOTE: this code is copied as a comment in |
|
* make_ga_colormap above. Please update the |
|
* comment if you change this code! |
|
*/ |
|
if (alpha > 229) /* opaque */ |
|
{ |
|
entry = (231 * gray + 128) >> 8; |
|
} |
|
else if (alpha < 26) /* transparent */ |
|
{ |
|
entry = 231; |
|
} |
|
else /* partially opaque */ |
|
{ |
|
entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray); |
|
} |
|
|
|
*outrow = (png_byte)entry; |
|
} |
|
break; |
|
|
|
case PNG_CMAP_TRANS: |
|
for (; outrow < end_row; outrow += stepx) |
|
{ |
|
png_byte gray = *inrow++; |
|
png_byte alpha = *inrow++; |
|
|
|
if (alpha == 0) |
|
*outrow = PNG_CMAP_TRANS_BACKGROUND; |
|
|
|
else if (gray != PNG_CMAP_TRANS_BACKGROUND) |
|
*outrow = gray; |
|
|
|
else |
|
*outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1); |
|
} |
|
break; |
|
|
|
case PNG_CMAP_RGB: |
|
for (; outrow < end_row; outrow += stepx) |
|
{ |
|
*outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]); |
|
inrow += 3; |
|
} |
|
break; |
|
|
|
case PNG_CMAP_RGB_ALPHA: |
|
for (; outrow < end_row; outrow += stepx) |
|
{ |
|
unsigned int alpha = inrow[3]; |
|
|
|
/* Because the alpha entries only hold alpha==0.5 values |
|
* split the processing at alpha==0.25 (64) and 0.75 |
|
* (196). |
|
*/ |
|
|
|
if (alpha >= 196) |
|
*outrow = PNG_RGB_INDEX(inrow[0], inrow[1], |
|
inrow[2]); |
|
|
|
else if (alpha < 64) |
|
*outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND; |
|
|
|
else |
|
{ |
|
/* Likewise there are three entries for each of r, g |
|
* and b. We could select the entry by popcount on |
|
* the top two bits on those architectures that |
|
* support it, this is what the code below does, |
|
* crudely. |
|
*/ |
|
unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1; |
|
|
|
/* Here are how the values map: |
|
* |
|
* 0x00 .. 0x3f -> 0 |
|
* 0x40 .. 0xbf -> 1 |
|
* 0xc0 .. 0xff -> 2 |
|
* |
|
* So, as above with the explicit alpha checks, the |
|
* breakpoints are at 64 and 196. |
|
*/ |
|
if (inrow[0] & 0x80) back_i += 9; /* red */ |
|
if (inrow[0] & 0x40) back_i += 9; |
|
if (inrow[0] & 0x80) back_i += 3; /* green */ |
|
if (inrow[0] & 0x40) back_i += 3; |
|
if (inrow[0] & 0x80) back_i += 1; /* blue */ |
|
if (inrow[0] & 0x40) back_i += 1; |
|
|
|
*outrow = (png_byte)back_i; |
|
} |
|
|
|
inrow += 4; |
|
} |
|
break; |
|
|
|
default: |
|
break; |
|
} |
|
} |
|
} |
|
} |
|
|
|
return 1; |
|
} |
|
|
|
static int |
|
png_image_read_colormapped(png_voidp argument) |
|
{ |
|
png_image_read_control *display = png_voidcast(png_image_read_control*, |
|
argument); |
|
png_imagep image = display->image; |
|
png_controlp control = image->opaque; |
|
png_structrp png_ptr = control->png_ptr; |
|
png_inforp info_ptr = control->info_ptr; |
|
|
|
int passes = 0; /* As a flag */ |
|
|
|
PNG_SKIP_CHUNKS(png_ptr); |
|
|
|
/* Update the 'info' structure and make sure the result is as required; first |
|
* make sure to turn on the interlace handling if it will be required |
|
* (because it can't be turned on *after* the call to png_read_update_info!) |
|
*/ |
|
if (display->colormap_processing == PNG_CMAP_NONE) |
|
passes = png_set_interlace_handling(png_ptr); |
|
|
|
png_read_update_info(png_ptr, info_ptr); |
|
|
|
/* The expected output can be deduced from the colormap_processing option. */ |
|
switch (display->colormap_processing) |
|
{ |
|
case PNG_CMAP_NONE: |
|
/* Output must be one channel and one byte per pixel, the output |
|
* encoding can be anything. |
|
*/ |
|
if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE || |
|
info_ptr->color_type == PNG_COLOR_TYPE_GRAY) && |
|
info_ptr->bit_depth == 8) |
|
break; |
|
|
|
goto bad_output; |
|
|
|
case PNG_CMAP_TRANS: |
|
case PNG_CMAP_GA: |
|
/* Output must be two channels and the 'G' one must be sRGB, the latter |
|
* can be checked with an exact number because it should have been set |
|
* to this number above! |
|
*/ |
|
if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA && |
|
info_ptr->bit_depth == 8 && |
|
png_ptr->screen_gamma == PNG_GAMMA_sRGB && |
|
image->colormap_entries == 256) |
|
break; |
|
|
|
goto bad_output; |
|
|
|
case PNG_CMAP_RGB: |
|
/* Output must be 8-bit sRGB encoded RGB */ |
|
if (info_ptr->color_type == PNG_COLOR_TYPE_RGB && |
|
info_ptr->bit_depth == 8 && |
|
png_ptr->screen_gamma == PNG_GAMMA_sRGB && |
|
image->colormap_entries == 216) |
|
break; |
|
|
|
goto bad_output; |
|
|
|
case PNG_CMAP_RGB_ALPHA: |
|
/* Output must be 8-bit sRGB encoded RGBA */ |
|
if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA && |
|
info_ptr->bit_depth == 8 && |
|
png_ptr->screen_gamma == PNG_GAMMA_sRGB && |
|
image->colormap_entries == 244 /* 216 + 1 + 27 */) |
|
break; |
|
|
|
goto bad_output; |
|
|
|
default: |
|
bad_output: |
|
png_error(png_ptr, "bad color-map processing (internal error)"); |
|
} |
|
|
|
/* Now read the rows. Do this here if it is possible to read directly into |
|
* the output buffer, otherwise allocate a local row buffer of the maximum |
|
* size libpng requires and call the relevant processing routine safely. |
|
*/ |
|
{ |
|
png_voidp first_row = display->buffer; |
|
ptrdiff_t row_bytes = display->row_stride; |
|
|
|
/* The following expression is designed to work correctly whether it gives |
|
* a signed or an unsigned result. |
|
*/ |
|
if (row_bytes < 0) |
|
{ |
|
char *ptr = png_voidcast(char*, first_row); |
|
ptr += (image->height-1) * (-row_bytes); |
|
first_row = png_voidcast(png_voidp, ptr); |
|
} |
|
|
|
display->first_row = first_row; |
|
display->row_bytes = row_bytes; |
|
} |
|
|
|
if (passes == 0) |
|
{ |
|
int result; |
|
png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); |
|
|
|
display->local_row = row; |
|
result = png_safe_execute(image, png_image_read_and_map, display); |
|
display->local_row = NULL; |
|
png_free(png_ptr, row); |
|
|
|
return result; |
|
} |
|
|
|
else |
|
{ |
|
png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes; |
|
|
|
while (--passes >= 0) |
|
{ |
|
png_uint_32 y = image->height; |
|
png_bytep row = png_voidcast(png_bytep, display->first_row); |
|
|
|
for (; y > 0; --y) |
|
{ |
|
png_read_row(png_ptr, row, NULL); |
|
row += row_bytes; |
|
} |
|
} |
|
|
|
return 1; |
|
} |
|
} |
|
|
|
/* Just the row reading part of png_image_read. */ |
|
static int |
|
png_image_read_composite(png_voidp argument) |
|
{ |
|
png_image_read_control *display = png_voidcast(png_image_read_control*, |
|
argument); |
|
png_imagep image = display->image; |
|
png_structrp png_ptr = image->opaque->png_ptr; |
|
int passes; |
|
|
|
switch (png_ptr->interlaced) |
|
{ |
|
case PNG_INTERLACE_NONE: |
|
passes = 1; |
|
break; |
|
|
|
case PNG_INTERLACE_ADAM7: |
|
passes = PNG_INTERLACE_ADAM7_PASSES; |
|
break; |
|
|
|
default: |
|
png_error(png_ptr, "unknown interlace type"); |
|
} |
|
|
|
{ |
|
png_uint_32 height = image->height; |
|
png_uint_32 width = image->width; |
|
ptrdiff_t step_row = display->row_bytes; |
|
unsigned int channels = |
|
(image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1; |
|
int pass; |
|
|
|
for (pass = 0; pass < passes; ++pass) |
|
{ |
|
unsigned int startx, stepx, stepy; |
|
png_uint_32 y; |
|
|
|
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) |
|
{ |
|
/* The row may be empty for a short image: */ |
|
if (PNG_PASS_COLS(width, pass) == 0) |
|
continue; |
|
|
|
startx = PNG_PASS_START_COL(pass) * channels; |
|
stepx = PNG_PASS_COL_OFFSET(pass) * channels; |
|
y = PNG_PASS_START_ROW(pass); |
|
stepy = PNG_PASS_ROW_OFFSET(pass); |
|
} |
|
|
|
else |
|
{ |
|
y = 0; |
|
startx = 0; |
|
stepx = channels; |
|
stepy = 1; |
|
} |
|
|
|
for (; y<height; y += stepy) |
|
{ |
|
png_bytep inrow = png_voidcast(png_bytep, display->local_row); |
|
png_bytep outrow; |
|
png_const_bytep end_row; |
|
|
|
/* Read the row, which is packed: */ |
|
png_read_row(png_ptr, inrow, NULL); |
|
|
|
outrow = png_voidcast(png_bytep, display->first_row); |
|
outrow += y * step_row; |
|
end_row = outrow + width * channels; |
|
|
|
/* Now do the composition on each pixel in this row. */ |
|
outrow += startx; |
|
for (; outrow < end_row; outrow += stepx) |
|
{ |
|
png_byte alpha = inrow[channels]; |
|
|
|
if (alpha > 0) /* else no change to the output */ |
|
{ |
|
unsigned int c; |
|
|
|
for (c=0; c<channels; ++c) |
|
{ |
|
png_uint_32 component = inrow[c]; |
|
|
|
if (alpha < 255) /* else just use component */ |
|
{ |
|
/* This is PNG_OPTIMIZED_ALPHA, the component value |
|
* is a linear 8-bit value. Combine this with the |
|
* current outrow[c] value which is sRGB encoded. |
|
* Arithmetic here is 16-bits to preserve the output |
|
* values correctly. |
|
*/ |
|
component *= 257*255; /* =65535 */ |
|
component += (255-alpha)*png_sRGB_table[outrow[c]]; |
|
|
|
/* So 'component' is scaled by 255*65535 and is |
|
* therefore appropriate for the sRGB to linear |
|
* conversion table. |
|
*/ |
|
component = PNG_sRGB_FROM_LINEAR(component); |
|
} |
|
|
|
outrow[c] = (png_byte)component; |
|
} |
|
} |
|
|
|
inrow += channels+1; /* components and alpha channel */ |
|
} |
|
} |
|
} |
|
} |
|
|
|
return 1; |
|
} |
|
|
|
/* The do_local_background case; called when all the following transforms are to |
|
* be done: |
|
* |
|
* PNG_RGB_TO_GRAY |
|
* PNG_COMPOSITE |
|
* PNG_GAMMA |
|
* |
|
* This is a work-around for the fact that both the PNG_RGB_TO_GRAY and |
|
* PNG_COMPOSITE code performs gamma correction, so we get double gamma |
|
* correction. The fix-up is to prevent the PNG_COMPOSITE operation from |
|
* happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha |
|
* row and handles the removal or pre-multiplication of the alpha channel. |
|
*/ |
|
static int |
|
png_image_read_background(png_voidp argument) |
|
{ |
|
png_image_read_control *display = png_voidcast(png_image_read_control*, |
|
argument); |
|
png_imagep image = display->image; |
|
png_structrp png_ptr = image->opaque->png_ptr; |
|
png_inforp info_ptr = image->opaque->info_ptr; |
|
png_uint_32 height = image->height; |
|
png_uint_32 width = image->width; |
|
int pass, passes; |
|
|
|
/* Double check the convoluted logic below. We expect to get here with |
|
* libpng doing rgb to gray and gamma correction but background processing |
|
* left to the png_image_read_background function. The rows libpng produce |
|
* might be 8 or 16-bit but should always have two channels; gray plus alpha. |
|
*/ |
|
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0) |
|
png_error(png_ptr, "lost rgb to gray"); |
|
|
|
if ((png_ptr->transformations & PNG_COMPOSE) != 0) |
|
png_error(png_ptr, "unexpected compose"); |
|
|
|
if (png_get_channels(png_ptr, info_ptr) != 2) |
|
png_error(png_ptr, "lost/gained channels"); |
|
|
|
/* Expect the 8-bit case to always remove the alpha channel */ |
|
if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 && |
|
(image->format & PNG_FORMAT_FLAG_ALPHA) != 0) |
|
png_error(png_ptr, "unexpected 8-bit transformation"); |
|
|
|
switch (png_ptr->interlaced) |
|
{ |
|
case PNG_INTERLACE_NONE: |
|
passes = 1; |
|
break; |
|
|
|
case PNG_INTERLACE_ADAM7: |
|
passes = PNG_INTERLACE_ADAM7_PASSES; |
|
break; |
|
|
|
default: |
|
png_error(png_ptr, "unknown interlace type"); |
|
} |
|
|
|
/* Use direct access to info_ptr here because otherwise the simplified API |
|
* would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is |
|
* checking the value after libpng expansions, not the original value in the |
|
* PNG. |
|
*/ |
|
switch (info_ptr->bit_depth) |
|
{ |
|
case 8: |
|
/* 8-bit sRGB gray values with an alpha channel; the alpha channel is |
|
* to be removed by composing on a background: either the row if |
|
* display->background is NULL or display->background->green if not. |
|
* Unlike the code above ALPHA_OPTIMIZED has *not* been done. |
|
*/ |
|
{ |
|
png_bytep first_row = png_voidcast(png_bytep, display->first_row); |
|
ptrdiff_t step_row = display->row_bytes; |
|
|
|
for (pass = 0; pass < passes; ++pass) |
|
{ |
|
png_bytep row = png_voidcast(png_bytep, display->first_row); |
|
unsigned int startx, stepx, stepy; |
|
png_uint_32 y; |
|
|
|
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) |
|
{ |
|
/* The row may be empty for a short image: */ |
|
if (PNG_PASS_COLS(width, pass) == 0) |
|
continue; |
|
|
|
startx = PNG_PASS_START_COL(pass); |
|
stepx = PNG_PASS_COL_OFFSET(pass); |
|
y = PNG_PASS_START_ROW(pass); |
|
stepy = PNG_PASS_ROW_OFFSET(pass); |
|
} |
|
|
|
else |
|
{ |
|
y = 0; |
|
startx = 0; |
|
stepx = stepy = 1; |
|
} |
|
|
|
if (display->background == NULL) |
|
{ |
|
for (; y<height; y += stepy) |
|
{ |
|
png_bytep inrow = png_voidcast(png_bytep, |
|
display->local_row); |
|
png_bytep outrow = first_row + y * step_row; |
|
png_const_bytep end_row = outrow + width; |
|
|
|
/* Read the row, which is packed: */ |
|
png_read_row(png_ptr, inrow, NULL); |
|
|
|
/* Now do the composition on each pixel in this row. */ |
|
outrow += startx; |
|
for (; outrow < end_row; outrow += stepx) |
|
{ |
|
png_byte alpha = inrow[1]; |
|
|
|
if (alpha > 0) /* else no change to the output */ |
|
{ |
|
png_uint_32 component = inrow[0]; |
|
|
|
if (alpha < 255) /* else just use component */ |
|
{ |
|
/* Since PNG_OPTIMIZED_ALPHA was not set it is |
|
* necessary to invert the sRGB transfer |
|
* function and multiply the alpha out. |
|
*/ |
|
component = png_sRGB_table[component] * alpha; |
|
component += png_sRGB_table[outrow[0]] * |
|
(255-alpha); |
|
component = PNG_sRGB_FROM_LINEAR(component); |
|
} |
|
|
|
outrow[0] = (png_byte)component; |
|
} |
|
|
|
inrow += 2; /* gray and alpha channel */ |
|
} |
|
} |
|
} |
|
|
|
else /* constant background value */ |
|
{ |
|
png_byte background8 = display->background->green; |
|
png_uint_16 background = png_sRGB_table[background8]; |
|
|
|
for (; y<height; y += stepy) |
|
{ |
|
png_bytep inrow = png_voidcast(png_bytep, |
|
display->local_row); |
|
png_bytep outrow = first_row + y * step_row; |
|
png_const_bytep end_row = outrow + width; |
|
|
|
/* Read the row, which is packed: */ |
|
png_read_row(png_ptr, inrow, NULL); |
|
|
|
/* Now do the composition on each pixel in this row. */ |
|
outrow += startx; |
|
for (; outrow < end_row; outrow += stepx) |
|
{ |
|
png_byte alpha = inrow[1]; |
|
|
|
if (alpha > 0) /* else use background */ |
|
{ |
|
png_uint_32 component = inrow[0]; |
|
|
|
if (alpha < 255) /* else just use component */ |
|
{ |
|
component = png_sRGB_table[component] * alpha; |
|
component += background * (255-alpha); |
|
component = PNG_sRGB_FROM_LINEAR(component); |
|
} |
|
|
|
outrow[0] = (png_byte)component; |
|
} |
|
|
|
else |
|
outrow[0] = background8; |
|
|
|
inrow += 2; /* gray and alpha channel */ |
|
} |
|
|
|
row += display->row_bytes; |
|
} |
|
} |
|
} |
|
} |
|
break; |
|
|
|
case 16: |
|
/* 16-bit linear with pre-multiplied alpha; the pre-multiplication must |
|
* still be done and, maybe, the alpha channel removed. This code also |
|
* handles the alpha-first option. |
|
*/ |
|
{ |
|
png_uint_16p first_row = png_voidcast(png_uint_16p, |
|
display->first_row); |
|
/* The division by two is safe because the caller passed in a |
|
* stride which was multiplied by 2 (below) to get row_bytes. |
|
*/ |
|
ptrdiff_t step_row = display->row_bytes / 2; |
|
unsigned int preserve_alpha = (image->format & |
|
PNG_FORMAT_FLAG_ALPHA) != 0; |
|
unsigned int outchannels = 1U+preserve_alpha; |
|
int swap_alpha = 0; |
|
|
|
# ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED |
|
if (preserve_alpha != 0 && |
|
(image->format & PNG_FORMAT_FLAG_AFIRST) != 0) |
|
swap_alpha = 1; |
|
# endif |
|
|
|
for (pass = 0; pass < passes; ++pass) |
|
{ |
|
unsigned int startx, stepx, stepy; |
|
png_uint_32 y; |
|
|
|
/* The 'x' start and step are adjusted to output components here. |
|
*/ |
|
if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) |
|
{ |
|
/* The row may be empty for a short image: */ |
|
if (PNG_PASS_COLS(width, pass) == 0) |
|
continue; |
|
|
|
startx = PNG_PASS_START_COL(pass) * outchannels; |
|
stepx = PNG_PASS_COL_OFFSET(pass) * outchannels; |
|
y = PNG_PASS_START_ROW(pass); |
|
stepy = PNG_PASS_ROW_OFFSET(pass); |
|
} |
|
|
|
else |
|
{ |
|
y = 0; |
|
startx = 0; |
|
stepx = outchannels; |
|
stepy = 1; |
|
} |
|
|
|
for (; y<height; y += stepy) |
|
{ |
|
png_const_uint_16p inrow; |
|
png_uint_16p outrow = first_row + y*step_row; |
|
png_uint_16p end_row = outrow + width * outchannels; |
|
|
|
/* Read the row, which is packed: */ |
|
png_read_row(png_ptr, png_voidcast(png_bytep, |
|
display->local_row), NULL); |
|
inrow = png_voidcast(png_const_uint_16p, display->local_row); |
|
|
|
/* Now do the pre-multiplication on each pixel in this row. |
|
*/ |
|
outrow += startx; |
|
for (; outrow < end_row; outrow += stepx) |
|
{ |
|
png_uint_32 component = inrow[0]; |
|
png_uint_16 alpha = inrow[1]; |
|
|
|
if (alpha > 0) /* else 0 */ |
|
{ |
|
if (alpha < 65535) /* else just use component */ |
|
{ |
|
component *= alpha; |
|
component += 32767; |
|
component /= 65535; |
|
} |
|
} |
|
|
|
else |
|
component = 0; |
|
|
|
outrow[swap_alpha] = (png_uint_16)component; |
|
if (preserve_alpha != 0) |
|
outrow[1 ^ swap_alpha] = alpha; |
|
|
|
inrow += 2; /* components and alpha channel */ |
|
} |
|
} |
|
} |
|
} |
|
break; |
|
|
|
#ifdef __GNUC__ |
|
default: |
|
png_error(png_ptr, "unexpected bit depth"); |
|
#endif |
|
} |
|
|
|
return 1; |
|
} |
|
|
|
/* The guts of png_image_finish_read as a png_safe_execute callback. */ |
|
static int |
|
png_image_read_direct(png_voidp argument) |
|
{ |
|
png_image_read_control *display = png_voidcast(png_image_read_control*, |
|
argument); |
|
png_imagep image = display->image; |
|
png_structrp png_ptr = image->opaque->png_ptr; |
|
png_inforp info_ptr = image->opaque->info_ptr; |
|
|
|
png_uint_32 format = image->format; |
|
int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0; |
|
int do_local_compose = 0; |
|
int do_local_background = 0; /* to avoid double gamma correction bug */ |
|
int passes = 0; |
|
|
|
/* Add transforms to ensure the correct output format is produced then check |
|
* that the required implementation support is there. Always expand; always |
|
* need 8 bits minimum, no palette and expanded tRNS. |
|
*/ |
|
png_set_expand(png_ptr); |
|
|
|
/* Now check the format to see if it was modified. */ |
|
{ |
|
png_uint_32 base_format = png_image_format(png_ptr) & |
|
~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */; |
|
png_uint_32 change = format ^ base_format; |
|
png_fixed_point output_gamma; |
|
int mode; /* alpha mode */ |
|
|
|
/* Do this first so that we have a record if rgb to gray is happening. */ |
|
if ((change & PNG_FORMAT_FLAG_COLOR) != 0) |
|
{ |
|
/* gray<->color transformation required. */ |
|
if ((format & PNG_FORMAT_FLAG_COLOR) != 0) |
|
png_set_gray_to_rgb(png_ptr); |
|
|
|
else |
|
{ |
|
/* libpng can't do both rgb to gray and |
|
* background/pre-multiplication if there is also significant gamma |
|
* correction, because both operations require linear colors and |
|
* the code only supports one transform doing the gamma correction. |
|
* Handle this by doing the pre-multiplication or background |
|
* operation in this code, if necessary. |
|
* |
|
* TODO: fix this by rewriting pngrtran.c (!) |
|
* |
|
* For the moment (given that fixing this in pngrtran.c is an |
|
* enormous change) 'do_local_background' is used to indicate that |
|
* the problem exists. |
|
*/ |
|
if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) |
|
do_local_background = 1/*maybe*/; |
|
|
|
png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, |
|
PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT); |
|
} |
|
|
|
change &= ~PNG_FORMAT_FLAG_COLOR; |
|
} |
|
|
|
/* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise. |
|
*/ |
|
{ |
|
png_fixed_point input_gamma_default; |
|
|
|
if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 && |
|
(image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) |
|
input_gamma_default = PNG_GAMMA_LINEAR; |
|
else |
|
input_gamma_default = PNG_DEFAULT_sRGB; |
|
|
|
/* Call png_set_alpha_mode to set the default for the input gamma; the |
|
* output gamma is set by a second call below. |
|
*/ |
|
png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default); |
|
} |
|
|
|
if (linear != 0) |
|
{ |
|
/* If there *is* an alpha channel in the input it must be multiplied |
|
* out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG. |
|
*/ |
|
if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) |
|
mode = PNG_ALPHA_STANDARD; /* associated alpha */ |
|
|
|
else |
|
mode = PNG_ALPHA_PNG; |
|
|
|
output_gamma = PNG_GAMMA_LINEAR; |
|
} |
|
|
|
else |
|
{ |
|
mode = PNG_ALPHA_PNG; |
|
output_gamma = PNG_DEFAULT_sRGB; |
|
} |
|
|
|
if ((change & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0) |
|
{ |
|
mode = PNG_ALPHA_OPTIMIZED; |
|
change &= ~PNG_FORMAT_FLAG_ASSOCIATED_ALPHA; |
|
} |
|
|
|
/* If 'do_local_background' is set check for the presence of gamma |
|
* correction; this is part of the work-round for the libpng bug |
|
* described above. |
|
* |
|
* TODO: fix libpng and remove this. |
|
*/ |
|
if (do_local_background != 0) |
|
{ |
|
png_fixed_point gtest; |
|
|
|
/* This is 'png_gamma_threshold' from pngrtran.c; the test used for |
|
* gamma correction, the screen gamma hasn't been set on png_struct |
|
* yet; it's set below. png_struct::gamma, however, is set to the |
|
* final value. |
|
*/ |
|
if (png_muldiv(>est, output_gamma, png_ptr->colorspace.gamma, |
|
PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0) |
|
do_local_background = 0; |
|
|
|
else if (mode == PNG_ALPHA_STANDARD) |
|
{ |
|
do_local_background = 2/*required*/; |
|
mode = PNG_ALPHA_PNG; /* prevent libpng doing it */ |
|
} |
|
|
|
/* else leave as 1 for the checks below */ |
|
} |
|
|
|
/* If the bit-depth changes then handle that here. */ |
|
if ((change & PNG_FORMAT_FLAG_LINEAR) != 0) |
|
{ |
|
if (linear != 0 /*16-bit output*/) |
|
png_set_expand_16(png_ptr); |
|
|
|
else /* 8-bit output */ |
|
png_set_scale_16(png_ptr); |
|
|
|
change &= ~PNG_FORMAT_FLAG_LINEAR; |
|
} |
|
|
|
/* Now the background/alpha channel changes. */ |
|
if ((change & PNG_FORMAT_FLAG_ALPHA) != 0) |
|
{ |
|
/* Removing an alpha channel requires composition for the 8-bit |
|
* formats; for the 16-bit it is already done, above, by the |
|
* pre-multiplication and the channel just needs to be stripped. |
|
*/ |
|
if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) |
|
{ |
|
/* If RGB->gray is happening the alpha channel must be left and the |
|
* operation completed locally. |
|
* |
|
* TODO: fix libpng and remove this. |
|
*/ |
|
if (do_local_background != 0) |
|
do_local_background = 2/*required*/; |
|
|
|
/* 16-bit output: just remove the channel */ |
|
else if (linear != 0) /* compose on black (well, pre-multiply) */ |
|
png_set_strip_alpha(png_ptr); |
|
|
|
/* 8-bit output: do an appropriate compose */ |
|
else if (display->background != NULL) |
|
{ |
|
png_color_16 c; |
|
|
|
c.index = 0; /*unused*/ |
|
c.red = display->background->red; |
|
c.green = display->background->green; |
|
c.blue = display->background->blue; |
|
c.gray = display->background->green; |
|
|
|
/* This is always an 8-bit sRGB value, using the 'green' channel |
|
* for gray is much better than calculating the luminance here; |
|
* we can get off-by-one errors in that calculation relative to |
|
* the app expectations and that will show up in transparent |
|
* pixels. |
|
*/ |
|
png_set_background_fixed(png_ptr, &c, |
|
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, |
|
0/*gamma: not used*/); |
|
} |
|
|
|
else /* compose on row: implemented below. */ |
|
{ |
|
do_local_compose = 1; |
|
/* This leaves the alpha channel in the output, so it has to be |
|
* removed by the code below. Set the encoding to the 'OPTIMIZE' |
|
* one so the code only has to hack on the pixels that require |
|
* composition. |
|
*/ |
|
mode = PNG_ALPHA_OPTIMIZED; |
|
} |
|
} |
|
|
|
else /* output needs an alpha channel */ |
|
{ |
|
/* This is tricky because it happens before the swap operation has |
|
* been accomplished; however, the swap does *not* swap the added |
|
* alpha channel (weird API), so it must be added in the correct |
|
* place. |
|
*/ |
|
png_uint_32 filler; /* opaque filler */ |
|
int where; |
|
|
|
if (linear != 0) |
|
filler = 65535; |
|
|
|
else |
|
filler = 255; |
|
|
|
#ifdef PNG_FORMAT_AFIRST_SUPPORTED |
|
if ((format & PNG_FORMAT_FLAG_AFIRST) != 0) |
|
{ |
|
where = PNG_FILLER_BEFORE; |
|
change &= ~PNG_FORMAT_FLAG_AFIRST; |
|
} |
|
|
|
else |
|
#endif |
|
where = PNG_FILLER_AFTER; |
|
|
|
png_set_add_alpha(png_ptr, filler, where); |
|
} |
|
|
|
/* This stops the (irrelevant) call to swap_alpha below. */ |
|
change &= ~PNG_FORMAT_FLAG_ALPHA; |
|
} |
|
|
|
/* Now set the alpha mode correctly; this is always done, even if there is |
|
* no alpha channel in either the input or the output because it correctly |
|
* sets the output gamma. |
|
*/ |
|
png_set_alpha_mode_fixed(png_ptr, mode, output_gamma); |
|
|
|
# ifdef PNG_FORMAT_BGR_SUPPORTED |
|
if ((change & PNG_FORMAT_FLAG_BGR) != 0) |
|
{ |
|
/* Check only the output format; PNG is never BGR; don't do this if |
|
* the output is gray, but fix up the 'format' value in that case. |
|
*/ |
|
if ((format & PNG_FORMAT_FLAG_COLOR) != 0) |
|
png_set_bgr(png_ptr); |
|
|
|
else |
|
format &= ~PNG_FORMAT_FLAG_BGR; |
|
|
|
change &= ~PNG_FORMAT_FLAG_BGR; |
|
} |
|
# endif |
|
|
|
# ifdef PNG_FORMAT_AFIRST_SUPPORTED |
|
if ((change & PNG_FORMAT_FLAG_AFIRST) != 0) |
|
{ |
|
/* Only relevant if there is an alpha channel - it's particularly |
|
* important to handle this correctly because do_local_compose may |
|
* be set above and then libpng will keep the alpha channel for this |
|
* code to remove. |
|
*/ |
|
if ((format & PNG_FORMAT_FLAG_ALPHA) != 0) |
|
{ |
|
/* Disable this if doing a local background, |
|
* TODO: remove this when local background is no longer required. |
|
*/ |
|
if (do_local_background != 2) |
|
png_set_swap_alpha(png_ptr); |
|
} |
|
|
|
else |
|
format &= ~PNG_FORMAT_FLAG_AFIRST; |
|
|
|
change &= ~PNG_FORMAT_FLAG_AFIRST; |
|
} |
|
# endif |
|
|
|
/* If the *output* is 16-bit then we need to check for a byte-swap on this |
|
* architecture. |
|
*/ |
|
if (linear != 0) |
|
{ |
|
PNG_CONST png_uint_16 le = 0x0001; |
|
|
|
if ((*(png_const_bytep) & le) != 0) |
|
png_set_swap(png_ptr); |
|
} |
|
|
|
/* If change is not now 0 some transformation is missing - error out. */ |
|
if (change != 0) |
|
png_error(png_ptr, "png_read_image: unsupported transformation"); |
|
} |
|
|
|
PNG_SKIP_CHUNKS(png_ptr); |
|
|
|
/* Update the 'info' structure and make sure the result is as required; first |
|
* make sure to turn on the interlace handling if it will be required |
|
* (because it can't be turned on *after* the call to png_read_update_info!) |
|
* |
|
* TODO: remove the do_local_background fixup below. |
|
*/ |
|
if (do_local_compose == 0 && do_local_background != 2) |
|
passes = png_set_interlace_handling(png_ptr); |
|
|
|
png_read_update_info(png_ptr, info_ptr); |
|
|
|
{ |
|
png_uint_32 info_format = 0; |
|
|
|
if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) |
|
info_format |= PNG_FORMAT_FLAG_COLOR; |
|
|
|
if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0) |
|
{ |
|
/* do_local_compose removes this channel below. */ |
|
if (do_local_compose == 0) |
|
{ |
|
/* do_local_background does the same if required. */ |
|
if (do_local_background != 2 || |
|
(format & PNG_FORMAT_FLAG_ALPHA) != 0) |
|
info_format |= PNG_FORMAT_FLAG_ALPHA; |
|
} |
|
} |
|
|
|
else if (do_local_compose != 0) /* internal error */ |
|
png_error(png_ptr, "png_image_read: alpha channel lost"); |
|
|
|
if ((format & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0) { |
|
info_format |= PNG_FORMAT_FLAG_ASSOCIATED_ALPHA; |
|
} |
|
|
|
if (info_ptr->bit_depth == 16) |
|
info_format |= PNG_FORMAT_FLAG_LINEAR; |
|
|
|
#ifdef PNG_FORMAT_BGR_SUPPORTED |
|
if ((png_ptr->transformations & PNG_BGR) != 0) |
|
info_format |= PNG_FORMAT_FLAG_BGR; |
|
#endif |
|
|
|
#ifdef PNG_FORMAT_AFIRST_SUPPORTED |
|
if (do_local_background == 2) |
|
{ |
|
if ((format & PNG_FORMAT_FLAG_AFIRST) != 0) |
|
info_format |= PNG_FORMAT_FLAG_AFIRST; |
|
} |
|
|
|
if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 || |
|
((png_ptr->transformations & PNG_ADD_ALPHA) != 0 && |
|
(png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0)) |
|
{ |
|
if (do_local_background == 2) |
|
png_error(png_ptr, "unexpected alpha swap transformation"); |
|
|
|
info_format |= PNG_FORMAT_FLAG_AFIRST; |
|
} |
|
# endif |
|
|
|
/* This is actually an internal error. */ |
|
if (info_format != format) |
|
png_error(png_ptr, "png_read_image: invalid transformations"); |
|
} |
|
|
|
/* Now read the rows. If do_local_compose is set then it is necessary to use |
|
* a local row buffer. The output will be GA, RGBA or BGRA and must be |
|
* converted to G, RGB or BGR as appropriate. The 'local_row' member of the |
|
* display acts as a flag. |
|
*/ |
|
{ |
|
png_voidp first_row = display->buffer; |
|
ptrdiff_t row_bytes = display->row_stride; |
|
|
|
if (linear != 0) |
|
row_bytes *= 2; |
|
|
|
/* The following expression is designed to work correctly whether it gives |
|
* a signed or an unsigned result. |
|
*/ |
|
if (row_bytes < 0) |
|
{ |
|
char *ptr = png_voidcast(char*, first_row); |
|
ptr += (image->height-1) * (-row_bytes); |
|
first_row = png_voidcast(png_voidp, ptr); |
|
} |
|
|
|
display->first_row = first_row; |
|
display->row_bytes = row_bytes; |
|
} |
|
|
|
if (do_local_compose != 0) |
|
{ |
|
int result; |
|
png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); |
|
|
|
display->local_row = row; |
|
result = png_safe_execute(image, png_image_read_composite, display); |
|
display->local_row = NULL; |
|
png_free(png_ptr, row); |
|
|
|
return result; |
|
} |
|
|
|
else if (do_local_background == 2) |
|
{ |
|
int result; |
|
png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); |
|
|
|
display->local_row = row; |
|
result = png_safe_execute(image, png_image_read_background, display); |
|
display->local_row = NULL; |
|
png_free(png_ptr, row); |
|
|
|
return result; |
|
} |
|
|
|
else |
|
{ |
|
png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes; |
|
|
|
while (--passes >= 0) |
|
{ |
|
png_uint_32 y = image->height; |
|
png_bytep row = png_voidcast(png_bytep, display->first_row); |
|
|
|
for (; y > 0; --y) |
|
{ |
|
png_read_row(png_ptr, row, NULL); |
|
row += row_bytes; |
|
} |
|
} |
|
|
|
return 1; |
|
} |
|
} |
|
|
|
int PNGAPI |
|
png_image_finish_read(png_imagep image, png_const_colorp background, |
|
void *buffer, png_int_32 row_stride, void *colormap) |
|
{ |
|
if (image != NULL && image->version == PNG_IMAGE_VERSION) |
|
{ |
|
/* Check for row_stride overflow. This check is not performed on the |
|
* original PNG format because it may not occur in the output PNG format |
|
* and libpng deals with the issues of reading the original. |
|
*/ |
|
const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format); |
|
|
|
/* The following checks just the 'row_stride' calculation to ensure it |
|
* fits in a signed 32-bit value. Because channels/components can be |
|
* either 1 or 2 bytes in size the length of a row can still overflow 32 |
|
* bits; this is just to verify that the 'row_stride' argument can be |
|
* represented. |
|
*/ |
|
if (image->width <= 0x7fffffffU/channels) /* no overflow */ |
|
{ |
|
png_uint_32 check; |
|
const png_uint_32 png_row_stride = image->width * channels; |
|
|
|
if (row_stride == 0) |
|
row_stride = (png_int_32)/*SAFE*/png_row_stride; |
|
|
|
if (row_stride < 0) |
|
check = (png_uint_32)(-row_stride); |
|
|
|
else |
|
check = (png_uint_32)row_stride; |
|
|
|
/* This verifies 'check', the absolute value of the actual stride |
|
* passed in and detects overflow in the application calculation (i.e. |
|
* if the app did actually pass in a non-zero 'row_stride'. |
|
*/ |
|
if (image->opaque != NULL && buffer != NULL && check >= png_row_stride) |
|
{ |
|
/* Now check for overflow of the image buffer calculation; this |
|
* limits the whole image size to 32 bits for API compatibility with |
|
* the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro. |
|
* |
|
* The PNG_IMAGE_BUFFER_SIZE macro is: |
|
* |
|
* (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride)) |
|
* |
|
* And the component size is always 1 or 2, so make sure that the |
|
* number of *bytes* that the application is saying are available |
|
* does actually fit into a 32-bit number. |
|
* |
|
* NOTE: this will be changed in 1.7 because PNG_IMAGE_BUFFER_SIZE |
|
* will be changed to use png_alloc_size_t; bigger images can be |
|
* accommodated on 64-bit systems. |
|
*/ |
|
if (image->height <= |
|
0xffffffffU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check) |
|
{ |
|
if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 || |
|
(image->colormap_entries > 0 && colormap != NULL)) |
|
{ |
|
int result; |
|
png_image_read_control display; |
|
|
|
memset(&display, 0, (sizeof display)); |
|
display.image = image; |
|
display.buffer = buffer; |
|
display.row_stride = row_stride; |
|
display.colormap = colormap; |
|
display.background = background; |
|
display.local_row = NULL; |
|
|
|
/* Choose the correct 'end' routine; for the color-map case |
|
* all the setup has already been done. |
|
*/ |
|
if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0) |
|
result = |
|
png_safe_execute(image, |
|
png_image_read_colormap, &display) && |
|
png_safe_execute(image, |
|
png_image_read_colormapped, &display); |
|
|
|
else |
|
result = |
|
png_safe_execute(image, |
|
png_image_read_direct, &display); |
|
|
|
png_image_free(image); |
|
return result; |
|
} |
|
|
|
else |
|
return png_image_error(image, |
|
"png_image_finish_read[color-map]: no color-map"); |
|
} |
|
|
|
else |
|
return png_image_error(image, |
|
"png_image_finish_read: image too large"); |
|
} |
|
|
|
else |
|
return png_image_error(image, |
|
"png_image_finish_read: invalid argument"); |
|
} |
|
|
|
else |
|
return png_image_error(image, |
|
"png_image_finish_read: row_stride too large"); |
|
} |
|
|
|
else if (image != NULL) |
|
return png_image_error(image, |
|
"png_image_finish_read: damaged PNG_IMAGE_VERSION"); |
|
|
|
return 0; |
|
} |
|
|
|
#endif /* SIMPLIFIED_READ */ |
|
#endif /* READ */
|
|
|