C++ (Cpp) png_get_next_frame_height示例

示例#1

文件： nsPNGDecoder.cpp 项目： hobinjk/gecko-dev

// got the header of a new frame that's coming
void
nsPNGDecoder::frame_info_callback(png_structp png_ptr, png_uint_32 frame_num)
{
  png_uint_32 x_offset, y_offset;
  int32_t width, height;

  nsPNGDecoder* decoder =
               static_cast<nsPNGDecoder*>(png_get_progressive_ptr(png_ptr));

  // old frame is done
  decoder->EndImageFrame();

  // Only the first frame can be hidden, so unhide unconditionally here.
  decoder->mFrameIsHidden = false;

  x_offset = png_get_next_frame_x_offset(png_ptr, decoder->mInfo);
  y_offset = png_get_next_frame_y_offset(png_ptr, decoder->mInfo);
  width = png_get_next_frame_width(png_ptr, decoder->mInfo);
  height = png_get_next_frame_height(png_ptr, decoder->mInfo);

  decoder->CreateFrame(x_offset, y_offset, width, height, decoder->format);

  if (decoder->NeedsNewFrame()) {
    // We know that we need a new frame, so pause input so the decoder
    // infrastructure can give it to us.
    png_process_data_pause(png_ptr, /* save = */ 1);
  }
}

示例#2

// got the header of a new frame that's coming
void
nsPNGDecoder::frame_info_callback(png_structp png_ptr, png_uint_32 frame_num)
{
#ifdef PNG_APNG_SUPPORTED
  png_uint_32 x_offset, y_offset;
  PRInt32 width, height;

  nsPNGDecoder *decoder =
               static_cast<nsPNGDecoder*>(png_get_progressive_ptr(png_ptr));

  // old frame is done
  decoder->EndImageFrame();

  // Only the first frame can be hidden, so unhide unconditionally here.
  decoder->mFrameIsHidden = PR_FALSE;

  x_offset = png_get_next_frame_x_offset(png_ptr, decoder->mInfo);
  y_offset = png_get_next_frame_y_offset(png_ptr, decoder->mInfo);
  width = png_get_next_frame_width(png_ptr, decoder->mInfo);
  height = png_get_next_frame_height(png_ptr, decoder->mInfo);

  decoder->CreateFrame(x_offset, y_offset, width, height, decoder->format);
#endif
}