libwebp/src/enc/alpha.c

// Copyright 2011 Google Inc.
//
// 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/
// -----------------------------------------------------------------------------
//
// Alpha-plane compression.
//
// Author: Skal (pascal.massimino@gmail.com)

#include <assert.h>
#include <stdlib.h>

#include "./vp8enci.h"
#include "../utils/alpha.h"

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

//------------------------------------------------------------------------------

void VP8EncInitAlpha(VP8Encoder* enc) {
  enc->has_alpha_ = (enc->pic_->a != NULL);
  enc->alpha_data_ = NULL;
  enc->alpha_data_size_ = 0;
}

int VP8EncFinishAlpha(VP8Encoder* enc) {
  if (enc->has_alpha_) {
    const WebPConfig* config = enc->config_;
    const WebPPicture* pic = enc->pic_;
    uint8_t* tmp_data = NULL;
    size_t tmp_size = 0;
    assert(pic->a);
    if (!EncodeAlpha(pic->a, pic->width, pic->height, pic->a_stride,
                     config->alpha_quality, config->alpha_compression,
                     &tmp_data, &tmp_size)) {
      return 0;
    }
    if (tmp_size != (uint32_t)tmp_size) {  // Sanity check.
      free(tmp_data);
      return 0;
    }
    enc->alpha_data_size_ = (uint32_t)tmp_size;
    enc->alpha_data_ = tmp_data;
  }
  return 1;
}

void VP8EncDeleteAlpha(VP8Encoder* enc) {
  free(enc->alpha_data_);
  enc->alpha_data_ = NULL;
  enc->alpha_data_size_ = 0;
  enc->has_alpha_ = 0;
}

#if defined(__cplusplus) || defined(c_plusplus)
}    // extern "C"
#endif