third_party/libwebp/utils/alpha_processing.h

   1 // Copyright 2013 Google Inc. All Rights Reserved.
   2 //
   3 // Use of this source code is governed by a BSD-style license
   4 // that can be found in the COPYING file in the root of the source
   5 // tree. An additional intellectual property rights grant can be found
   6 // in the file PATENTS. All contributing project authors may
   7 // be found in the AUTHORS file in the root of the source tree.
   8 // -----------------------------------------------------------------------------
   9 //
  10 // Utilities for processing transparent channel.
  11 //
  12 // Author: Skal (pascal.massimino@gmail.com)
  13
  14 #ifndef WEBP_UTILS_ALPHA_PROCESSING_H_
  15 #define WEBP_UTILS_ALPHA_PROCESSING_H_
  16
  17 #include "../webp/types.h"
  18
  19 #ifdef __cplusplus
  20 extern "C" {
  21 #endif
  22
  23 // Pre-Multiply operation transforms x into x * A / 255  (where x=Y,R,G or B).
  24 // Un-Multiply operation transforms x into x * 255 / A.
  25
  26 // Pre-Multiply or Un-Multiply (if 'inverse' is true) argb values in a row.
  27 void WebPMultARGBRow(uint32_t* const ptr, int width, int inverse);
  28
  29 // Same a WebPMultARGBRow(), but for several rows.
  30 void WebPMultARGBRows(uint8_t* ptr, int stride, int width, int num_rows,
  31                       int inverse);
  32
  33 // Same for a row of single values, with side alpha values.
  34 void WebPMultRow(uint8_t* const ptr, const uint8_t* const alpha,
  35                  int width, int inverse);
  36
  37 // Same a WebPMultRow(), but for several 'num_rows' rows.
  38 void WebPMultRows(uint8_t* ptr, int stride,
  39                   const uint8_t* alpha, int alpha_stride,
  40                   int width, int num_rows, int inverse);
  41
  42 #ifdef __cplusplus
  43 }    // extern "C"
  44 #endif
  45
  46 #endif    // WEBP_UTILS_ALPHA_PROCESSING_H_