mirror of https://github.com/opencv/opencv.git
Open Source Computer Vision Library
https://opencv.org/
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
76 lines
2.9 KiB
76 lines
2.9 KiB
// Copyright 2012 Google Inc. All Rights Reserved. |
|
// |
|
// This code is licensed under the same terms as WebM: |
|
// Software License Agreement: http://www.webmproject.org/license/software/ |
|
// Additional IP Rights Grant: http://www.webmproject.org/license/additional/ |
|
// ----------------------------------------------------------------------------- |
|
// |
|
// Rescaling functions |
|
// |
|
// Author: Skal (pascal.massimino@gmail.com) |
|
|
|
#ifndef WEBP_UTILS_RESCALER_H_ |
|
#define WEBP_UTILS_RESCALER_H_ |
|
|
|
#if defined(__cplusplus) || defined(c_plusplus) |
|
extern "C" { |
|
#endif |
|
|
|
#include "../webp/types.h" |
|
|
|
// Structure used for on-the-fly rescaling |
|
typedef struct { |
|
int x_expand; // true if we're expanding in the x direction |
|
int num_channels; // bytes to jump between pixels |
|
int fy_scale, fx_scale; // fixed-point scaling factor |
|
int64_t fxy_scale; // '' |
|
// we need hpel-precise add/sub increments, for the downsampled U/V planes. |
|
int y_accum; // vertical accumulator |
|
int y_add, y_sub; // vertical increments (add ~= src, sub ~= dst) |
|
int x_add, x_sub; // horizontal increments (add ~= src, sub ~= dst) |
|
int src_width, src_height; // source dimensions |
|
int dst_width, dst_height; // destination dimensions |
|
uint8_t* dst; |
|
int dst_stride; |
|
int32_t* irow, *frow; // work buffer |
|
} WebPRescaler; |
|
|
|
// Initialize a rescaler given scratch area 'work' and dimensions of src & dst. |
|
void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height, |
|
uint8_t* const dst, |
|
int dst_width, int dst_height, int dst_stride, |
|
int num_channels, |
|
int x_add, int x_sub, |
|
int y_add, int y_sub, |
|
int32_t* const work); |
|
|
|
// Import a row of data and save its contribution in the rescaler. |
|
// 'channel' denotes the channel number to be imported. |
|
void WebPRescalerImportRow(WebPRescaler* const rescaler, |
|
const uint8_t* const src, int channel); |
|
|
|
// Import multiple rows over all channels, until at least one row is ready to |
|
// be exported. Returns the actual number of lines that were imported. |
|
int WebPRescalerImport(WebPRescaler* const rescaler, int num_rows, |
|
const uint8_t* src, int src_stride); |
|
|
|
// Return true if there is pending output rows ready. |
|
static WEBP_INLINE |
|
int WebPRescalerHasPendingOutput(const WebPRescaler* const rescaler) { |
|
return (rescaler->y_accum <= 0); |
|
} |
|
|
|
// Export one row from rescaler. Returns the pointer where output was written, |
|
// or NULL if no row was pending. |
|
uint8_t* WebPRescalerExportRow(WebPRescaler* const wrk); |
|
|
|
// Export as many rows as possible. Return the numbers of rows written. |
|
int WebPRescalerExport(WebPRescaler* const wrk); |
|
|
|
//------------------------------------------------------------------------------ |
|
|
|
#if defined(__cplusplus) || defined(c_plusplus) |
|
} // extern "C" |
|
#endif |
|
|
|
#endif /* WEBP_UTILS_RESCALER_H_ */
|
|
|