Method drawPathWithFilter

src/pdf/PDFExportContext.cpp:1241–1309

}  // namespace

void PDFExportContext::drawPathWithFilter(const MCState& state, const Path& originPath,
                                          const Matrix& matrix, const Fill& originPaint) {
  DEBUG_ASSERT(originPaint.maskFilter);

  Path path(originPath);
  path.transform(matrix);
  auto maskBound = path.getBounds();

  Fill paint(originPaint);

  if (Types::Get(originPaint.maskFilter.get()) != Types::MaskFilterType::Shader) {
    return;
  }
  const auto shaderMaskFilter = static_cast<const ShaderMaskFilter*>(originPaint.maskFilter.get());
  auto [picture, pictureMatrix] = MaskFilterToPicture(shaderMaskFilter);

  auto maskContext = makeCongruentDevice();
  if (!picture) {  //mask as image
    auto surface = Surface::Make(document->context(), static_cast<int>(maskBound.width()),
                                 static_cast<int>(maskBound.height()));
    Canvas* maskCanvas = surface->getCanvas();
    Paint maskPaint;
    maskPaint.setShader(shaderMaskFilter->getShader());
    maskCanvas->drawPaint(maskPaint);

    auto grayscaleInfo = ImageInfo::Make(surface->width(), surface->height(), ColorType::ALPHA_8);
    auto byteSize = grayscaleInfo.byteSize();
    void* pixels = malloc(byteSize);
    if (!surface->readPixels(grayscaleInfo, pixels)) {
      free(pixels);
      return;
    }
    auto pixelData = Data::MakeAdopted(pixels, byteSize, Data::FreeProc);
    // Convert alpha-8 to a grayscale image
    grayscaleInfo = ImageInfo::Make(surface->width(), surface->height(), ColorType::Gray_8);
    auto maskImage = Image::MakeFrom(grayscaleInfo, pixelData);

    // PDF doesn't seem to allow masking vector graphics with an Image XObject.
    // Must mask with a Form XObject.
    {
      Canvas canvas(maskContext.get());
      canvas.drawImage(maskImage, maskBound.x(), maskBound.y());
    }
  } else {
    Canvas canvas(maskContext.get());
    canvas.concat(pictureMatrix);
    canvas.drawPicture(picture);
  }

  if (!state.matrix.isIdentity() && paint.shader) {
    paint.shader = paint.shader->makeWithMatrix(matrix);
  }
  ScopedContentEntry contentEntry(this, state, Matrix::I(), paint);
  if (!contentEntry) {
    return;
  }

  setGraphicState(