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575 lines
15 KiB
575 lines
15 KiB
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/* pngwtran.c - transforms the data in a row for PNG writers |
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* |
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* Copyright (c) 2018 Cosmin Truta |
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* Copyright (c) 1998-2002,2004,2006-2016,2018 Glenn Randers-Pehrson |
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* Copyright (c) 1996-1997 Andreas Dilger |
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* 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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#include "pngpriv.h" |
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#ifdef PNG_WRITE_SUPPORTED |
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#ifdef PNG_WRITE_TRANSFORMS_SUPPORTED |
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#ifdef PNG_WRITE_PACK_SUPPORTED |
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/* Pack pixels into bytes. Pass the true bit depth in bit_depth. The |
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* row_info bit depth should be 8 (one pixel per byte). The channels |
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* should be 1 (this only happens on grayscale and paletted images). |
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*/ |
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static void |
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png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth) |
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{ |
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png_debug(1, "in png_do_pack"); |
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if (row_info->bit_depth == 8 && |
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row_info->channels == 1) |
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{ |
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switch ((int)bit_depth) |
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{ |
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case 1: |
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{ |
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png_bytep sp, dp; |
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int mask, v; |
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png_uint_32 i; |
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png_uint_32 row_width = row_info->width; |
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sp = row; |
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dp = row; |
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mask = 0x80; |
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v = 0; |
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for (i = 0; i < row_width; i++) |
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{ |
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if (*sp != 0) |
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v |= mask; |
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sp++; |
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if (mask > 1) |
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mask >>= 1; |
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else |
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{ |
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mask = 0x80; |
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*dp = (png_byte)v; |
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dp++; |
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v = 0; |
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} |
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} |
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if (mask != 0x80) |
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*dp = (png_byte)v; |
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break; |
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} |
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case 2: |
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{ |
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png_bytep sp, dp; |
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unsigned int shift; |
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int v; |
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png_uint_32 i; |
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png_uint_32 row_width = row_info->width; |
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sp = row; |
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dp = row; |
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shift = 6; |
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v = 0; |
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for (i = 0; i < row_width; i++) |
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{ |
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png_byte value; |
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value = (png_byte)(*sp & 0x03); |
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v |= (value << shift); |
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if (shift == 0) |
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{ |
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shift = 6; |
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*dp = (png_byte)v; |
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dp++; |
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v = 0; |
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} |
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else |
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shift -= 2; |
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sp++; |
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} |
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if (shift != 6) |
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*dp = (png_byte)v; |
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break; |
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} |
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case 4: |
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{ |
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png_bytep sp, dp; |
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unsigned int shift; |
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int v; |
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png_uint_32 i; |
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png_uint_32 row_width = row_info->width; |
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sp = row; |
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dp = row; |
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shift = 4; |
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v = 0; |
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for (i = 0; i < row_width; i++) |
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{ |
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png_byte value; |
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value = (png_byte)(*sp & 0x0f); |
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v |= (value << shift); |
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if (shift == 0) |
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{ |
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shift = 4; |
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*dp = (png_byte)v; |
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dp++; |
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v = 0; |
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} |
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else |
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shift -= 4; |
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sp++; |
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} |
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if (shift != 4) |
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*dp = (png_byte)v; |
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break; |
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} |
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default: |
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break; |
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} |
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row_info->bit_depth = (png_byte)bit_depth; |
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row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels); |
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row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, |
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row_info->width); |
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} |
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} |
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#endif |
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#ifdef PNG_WRITE_SHIFT_SUPPORTED |
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/* Shift pixel values to take advantage of whole range. Pass the |
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* true number of bits in bit_depth. The row should be packed |
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* according to row_info->bit_depth. Thus, if you had a row of |
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* bit depth 4, but the pixels only had values from 0 to 7, you |
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* would pass 3 as bit_depth, and this routine would translate the |
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* data to 0 to 15. |
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*/ |
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static void |
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png_do_shift(png_row_infop row_info, png_bytep row, |
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png_const_color_8p bit_depth) |
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{ |
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png_debug(1, "in png_do_shift"); |
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if (row_info->color_type != PNG_COLOR_TYPE_PALETTE) |
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{ |
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int shift_start[4], shift_dec[4]; |
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unsigned int channels = 0; |
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if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0) |
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{ |
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shift_start[channels] = row_info->bit_depth - bit_depth->red; |
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shift_dec[channels] = bit_depth->red; |
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channels++; |
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shift_start[channels] = row_info->bit_depth - bit_depth->green; |
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shift_dec[channels] = bit_depth->green; |
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channels++; |
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shift_start[channels] = row_info->bit_depth - bit_depth->blue; |
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shift_dec[channels] = bit_depth->blue; |
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channels++; |
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} |
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else |
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{ |
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shift_start[channels] = row_info->bit_depth - bit_depth->gray; |
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shift_dec[channels] = bit_depth->gray; |
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channels++; |
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} |
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if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0) |
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{ |
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shift_start[channels] = row_info->bit_depth - bit_depth->alpha; |
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shift_dec[channels] = bit_depth->alpha; |
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channels++; |
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} |
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/* With low row depths, could only be grayscale, so one channel */ |
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if (row_info->bit_depth < 8) |
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{ |
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png_bytep bp = row; |
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size_t i; |
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unsigned int mask; |
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size_t row_bytes = row_info->rowbytes; |
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if (bit_depth->gray == 1 && row_info->bit_depth == 2) |
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mask = 0x55; |
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else if (row_info->bit_depth == 4 && bit_depth->gray == 3) |
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mask = 0x11; |
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else |
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mask = 0xff; |
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for (i = 0; i < row_bytes; i++, bp++) |
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{ |
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int j; |
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unsigned int v, out; |
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v = *bp; |
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out = 0; |
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for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0]) |
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{ |
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if (j > 0) |
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out |= v << j; |
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else |
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out |= (v >> (-j)) & mask; |
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} |
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*bp = (png_byte)(out & 0xff); |
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} |
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} |
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else if (row_info->bit_depth == 8) |
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{ |
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png_bytep bp = row; |
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png_uint_32 i; |
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png_uint_32 istop = channels * row_info->width; |
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for (i = 0; i < istop; i++, bp++) |
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{ |
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unsigned int c = i%channels; |
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int j; |
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unsigned int v, out; |
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v = *bp; |
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out = 0; |
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for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c]) |
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{ |
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if (j > 0) |
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out |= v << j; |
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else |
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out |= v >> (-j); |
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} |
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*bp = (png_byte)(out & 0xff); |
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} |
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} |
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else |
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{ |
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png_bytep bp; |
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png_uint_32 i; |
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png_uint_32 istop = channels * row_info->width; |
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for (bp = row, i = 0; i < istop; i++) |
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{ |
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unsigned int c = i%channels; |
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int j; |
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unsigned int value, v; |
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v = png_get_uint_16(bp); |
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value = 0; |
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for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c]) |
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{ |
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if (j > 0) |
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value |= v << j; |
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else |
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value |= v >> (-j); |
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} |
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*bp++ = (png_byte)((value >> 8) & 0xff); |
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*bp++ = (png_byte)(value & 0xff); |
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} |
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} |
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} |
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} |
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#endif |
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#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED |
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static void |
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png_do_write_swap_alpha(png_row_infop row_info, png_bytep row) |
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{ |
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png_debug(1, "in png_do_write_swap_alpha"); |
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{ |
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if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) |
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{ |
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if (row_info->bit_depth == 8) |
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{ |
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/* This converts from ARGB to RGBA */ |
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png_bytep sp, dp; |
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png_uint_32 i; |
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png_uint_32 row_width = row_info->width; |
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for (i = 0, sp = dp = row; i < row_width; i++) |
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{ |
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png_byte save = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = save; |
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} |
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} |
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#ifdef PNG_WRITE_16BIT_SUPPORTED |
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else |
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{ |
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/* This converts from AARRGGBB to RRGGBBAA */ |
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png_bytep sp, dp; |
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png_uint_32 i; |
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png_uint_32 row_width = row_info->width; |
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for (i = 0, sp = dp = row; i < row_width; i++) |
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{ |
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png_byte save[2]; |
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save[0] = *(sp++); |
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save[1] = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = save[0]; |
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*(dp++) = save[1]; |
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} |
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} |
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#endif /* WRITE_16BIT */ |
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} |
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else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) |
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{ |
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if (row_info->bit_depth == 8) |
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{ |
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/* This converts from AG to GA */ |
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png_bytep sp, dp; |
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png_uint_32 i; |
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png_uint_32 row_width = row_info->width; |
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for (i = 0, sp = dp = row; i < row_width; i++) |
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{ |
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png_byte save = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = save; |
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} |
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} |
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#ifdef PNG_WRITE_16BIT_SUPPORTED |
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else |
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{ |
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/* This converts from AAGG to GGAA */ |
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png_bytep sp, dp; |
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png_uint_32 i; |
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png_uint_32 row_width = row_info->width; |
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for (i = 0, sp = dp = row; i < row_width; i++) |
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{ |
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png_byte save[2]; |
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save[0] = *(sp++); |
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save[1] = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = save[0]; |
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*(dp++) = save[1]; |
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} |
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} |
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#endif /* WRITE_16BIT */ |
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} |
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} |
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} |
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#endif |
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#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED |
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static void |
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png_do_write_invert_alpha(png_row_infop row_info, png_bytep row) |
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{ |
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png_debug(1, "in png_do_write_invert_alpha"); |
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{ |
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if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) |
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{ |
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if (row_info->bit_depth == 8) |
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{ |
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/* This inverts the alpha channel in RGBA */ |
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png_bytep sp, dp; |
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png_uint_32 i; |
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png_uint_32 row_width = row_info->width; |
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for (i = 0, sp = dp = row; i < row_width; i++) |
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{ |
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/* Does nothing |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*/ |
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sp+=3; dp = sp; |
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*dp = (png_byte)(255 - *(sp++)); |
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} |
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} |
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#ifdef PNG_WRITE_16BIT_SUPPORTED |
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else |
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{ |
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/* This inverts the alpha channel in RRGGBBAA */ |
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png_bytep sp, dp; |
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png_uint_32 i; |
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png_uint_32 row_width = row_info->width; |
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for (i = 0, sp = dp = row; i < row_width; i++) |
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{ |
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/* Does nothing |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*/ |
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sp+=6; dp = sp; |
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*(dp++) = (png_byte)(255 - *(sp++)); |
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*dp = (png_byte)(255 - *(sp++)); |
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} |
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} |
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#endif /* WRITE_16BIT */ |
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} |
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else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) |
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{ |
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if (row_info->bit_depth == 8) |
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{ |
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/* This inverts the alpha channel in GA */ |
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png_bytep sp, dp; |
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png_uint_32 i; |
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png_uint_32 row_width = row_info->width; |
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for (i = 0, sp = dp = row; i < row_width; i++) |
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{ |
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*(dp++) = *(sp++); |
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*(dp++) = (png_byte)(255 - *(sp++)); |
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} |
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} |
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#ifdef PNG_WRITE_16BIT_SUPPORTED |
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else |
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{ |
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/* This inverts the alpha channel in GGAA */ |
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png_bytep sp, dp; |
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png_uint_32 i; |
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png_uint_32 row_width = row_info->width; |
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for (i = 0, sp = dp = row; i < row_width; i++) |
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{ |
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/* Does nothing |
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*(dp++) = *(sp++); |
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*(dp++) = *(sp++); |
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*/ |
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sp+=2; dp = sp; |
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*(dp++) = (png_byte)(255 - *(sp++)); |
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*dp = (png_byte)(255 - *(sp++)); |
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} |
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} |
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#endif /* WRITE_16BIT */ |
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} |
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} |
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} |
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#endif |
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/* Transform the data according to the user's wishes. The order of |
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* transformations is significant. |
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*/ |
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void /* PRIVATE */ |
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png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info) |
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{ |
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png_debug(1, "in png_do_write_transformations"); |
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if (png_ptr == NULL) |
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return; |
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#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED |
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if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0) |
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if (png_ptr->write_user_transform_fn != NULL) |
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(*(png_ptr->write_user_transform_fn)) /* User write transform |
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function */ |
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(png_ptr, /* png_ptr */ |
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row_info, /* row_info: */ |
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/* png_uint_32 width; width of row */ |
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/* size_t rowbytes; number of bytes in row */ |
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/* png_byte color_type; color type of pixels */ |
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/* png_byte bit_depth; bit depth of samples */ |
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/* png_byte channels; number of channels (1-4) */ |
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/* png_byte pixel_depth; bits per pixel (depth*channels) */ |
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png_ptr->row_buf + 1); /* start of pixel data for row */ |
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#endif |
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#ifdef PNG_WRITE_FILLER_SUPPORTED |
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if ((png_ptr->transformations & PNG_FILLER) != 0) |
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png_do_strip_channel(row_info, png_ptr->row_buf + 1, |
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!(png_ptr->flags & PNG_FLAG_FILLER_AFTER)); |
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#endif |
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#ifdef PNG_WRITE_PACKSWAP_SUPPORTED |
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if ((png_ptr->transformations & PNG_PACKSWAP) != 0) |
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png_do_packswap(row_info, png_ptr->row_buf + 1); |
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#endif |
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#ifdef PNG_WRITE_PACK_SUPPORTED |
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if ((png_ptr->transformations & PNG_PACK) != 0) |
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png_do_pack(row_info, png_ptr->row_buf + 1, |
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(png_uint_32)png_ptr->bit_depth); |
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#endif |
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#ifdef PNG_WRITE_SWAP_SUPPORTED |
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# ifdef PNG_16BIT_SUPPORTED |
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if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0) |
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png_do_swap(row_info, png_ptr->row_buf + 1); |
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# endif |
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#endif |
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#ifdef PNG_WRITE_SHIFT_SUPPORTED |
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if ((png_ptr->transformations & PNG_SHIFT) != 0) |
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png_do_shift(row_info, png_ptr->row_buf + 1, |
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&(png_ptr->shift)); |
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#endif |
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#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED |
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if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0) |
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png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1); |
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#endif |
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#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED |
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if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0) |
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png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1); |
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#endif |
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#ifdef PNG_WRITE_BGR_SUPPORTED |
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if ((png_ptr->transformations & PNG_BGR) != 0) |
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png_do_bgr(row_info, png_ptr->row_buf + 1); |
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#endif |
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#ifdef PNG_WRITE_INVERT_SUPPORTED |
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if ((png_ptr->transformations & PNG_INVERT_MONO) != 0) |
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png_do_invert(row_info, png_ptr->row_buf + 1); |
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#endif |
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} |
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#endif /* WRITE_TRANSFORMS */ |
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#endif /* WRITE */
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