Method readScaledPixels

src/core/codecs/jpeg/JpegCodec.cpp:199–300

}

bool JpegCodec::readScaledPixels(ColorType colorType, AlphaType alphaType, size_t dstRowBytes,
                                 void* dstPixels, uint32_t scaleNum) const {
  if (dstPixels == nullptr) {
    return false;
  }
  if (colorType == ColorType::ALPHA_8) {
    memset(dstPixels, 255, dstRowBytes * static_cast<size_t>(height()));
    return true;
  }
  auto dstInfo = ImageInfo::Make(width(), height(), colorType, alphaType, dstRowBytes);
  Bitmap bitmap = {};
  auto outPixels = dstPixels;
  auto outRowBytes = dstRowBytes;
  J_COLOR_SPACE out_color_space;
  switch (colorType) {
    case ColorType::RGBA_8888:
      out_color_space = JCS_EXT_RGBA;
      break;
    case ColorType::BGRA_8888:
      out_color_space = JCS_EXT_BGRA;
      break;
    case ColorType::Gray_8:
      out_color_space = JCS_GRAYSCALE;
      break;
    case ColorType::RGB_565:
      out_color_space = JCS_RGB565;
      break;
    default:
      auto success = bitmap.allocPixels(width(), height(), false, false);
      if (!success) {
        return false;
      }
      out_color_space = JCS_EXT_RGBA;
      break;
  }
  Pixmap pixmap(bitmap);
  if (!pixmap.isEmpty()) {
    outPixels = pixmap.writablePixels();
    outRowBytes = pixmap.rowBytes();
  }
  FILE* infile = nullptr;
  if (fileData == nullptr && (infile = fopen(filePath.c_str(), "rb")) == nullptr) {
    return false;
  }
  jpeg_decompress_struct cinfo = {};
  my_error_mgr jerr = {};
  cinfo.err = jpeg_std_error(&jerr.pub);
  bool result = false;
  do {
    if (setjmp(jerr.setjmp_buffer)) break;
    jpeg_create_decompress(&cinfo);
    if (infile) {
      jpeg_stdio_src(&cinfo, infile);
    } else {
      jpeg_mem_src(&cinfo, fileData->bytes(), fileData->size());
    }
    jpeg_save_markers(&cinfo, JPEG_APP0 + 1, 0xFFFF);
    jpeg_save_markers(&cinfo, JPEG_APP0 + 2, 0xFFFF);