Method readPixels

src/core/ImageCodec.cpp:153–201

}

bool ImageCodec::readPixels(const ImageInfo& dstInfo, void* dstPixels) const {
  if (dstInfo.width() > width() || dstInfo.height() > height()) {
    return false;
  }
  if (dstInfo.width() == width() && dstInfo.height() == height()) {
    return onReadPixels(dstInfo.colorType(), dstInfo.alphaType(), dstInfo.rowBytes(), dstPixels);
  }

  Buffer buffer = {};
  Buffer dstTempBuffer = {};
  auto dstData = dstPixels;
  auto dstImageInfo = dstInfo;
  auto colorType = dstInfo.colorType();
  auto srcRowBytes = dstInfo.bytesPerPixel() * static_cast<size_t>(width());
  if (dstInfo.colorType() != ColorType::RGBA_8888 && dstInfo.colorType() != ColorType::BGRA_8888 &&
      dstInfo.colorType() != ColorType::ALPHA_8 && dstInfo.colorType() != ColorType::Gray_8) {
    colorType = ColorType::RGBA_8888;
    srcRowBytes = ImageInfo::GetBytesPerPixel(colorType) * static_cast<size_t>(width());
    dstImageInfo = dstInfo.makeColorType(colorType);
    auto dstRowBytes = dstImageInfo.rowBytes();
    if (dstRowBytes % 16) {
      dstRowBytes = dstImageInfo.rowBytes() + GetPaddingAlignment16(dstImageInfo.rowBytes());
      dstImageInfo = ImageInfo::Make(dstInfo.width(), dstInfo.height(), colorType,
                                     dstInfo.alphaType(), dstRowBytes);
    }
    if (!dstTempBuffer.alloc(dstImageInfo.byteSize())) {
      return false;
    }
    dstData = dstTempBuffer.bytes();
  }
  srcRowBytes = srcRowBytes + GetPaddingAlignment16(srcRowBytes);
  if (!buffer.alloc(srcRowBytes * static_cast<size_t>(height()))) {
    return false;
  }
  auto result = onReadPixels(colorType, dstInfo.alphaType(), srcRowBytes, buffer.data());
  if (!result) {
    return false;
  }
  auto isOneComponent = dstImageInfo.colorType() == ColorType::Gray_8 ||
                        dstImageInfo.colorType() == ColorType::ALPHA_8;
  auto inputLayout = PixelLayout{width(), height(), static_cast<int>(srcRowBytes)};
  auto outputLayout = PixelLayout{dstImageInfo.width(), dstImageInfo.height(),
                                  static_cast<int>(dstImageInfo.rowBytes())};
  BoxFilterDownsample(buffer.data(), inputLayout, dstData, outputLayout, isOneComponent);
  if (!dstTempBuffer.isEmpty()) {
    Pixmap(dstImageInfo, dstData).readPixels(dstInfo, dstPixels);
  }
  return true;
}

std::shared_ptr<ImageBuffer> ImageCodec::onMakeBuffer(bool tryHardware) const {
  auto pixelBuffer = PixelBuffer::Make(width(), height(), isAlphaOnly(), tryHardware);