method drawAtlas

Source

void drawAtlas(Image atlas,
               List<RSTransform> transforms,
               List<Rect> rects,
               List<Color> colors,
               TransferMode transferMode,
               Rect cullRect,
               Paint paint) {
  final int rectCount = rects.length;

  if (transforms.length != rectCount)
    throw new ArgumentError("[transforms] and [rects] lengths must match");
  if (colors.isNotEmpty && colors.length != rectCount)
    throw new ArgumentError("if supplied, [colors] length must match that of [transforms] and [rects]");

  final Float32List rstTransformBuffer = new Float32List(rectCount * 4);
  final Float32List rectBuffer = new Float32List(rectCount * 4);

  for (int i = 0; i < rectCount; ++i) {
    final int index0 = i * 4;
    final int index1 = index0 + 1;
    final int index2 = index0 + 2;
    final int index3 = index0 + 3;
    final RSTransform rstTransform = transforms[i];
    final Rect rect = rects[i];
    rstTransformBuffer[index0] = rstTransform.scos;
    rstTransformBuffer[index1] = rstTransform.ssin;
    rstTransformBuffer[index2] = rstTransform.tx;
    rstTransformBuffer[index3] = rstTransform.ty;
    rectBuffer[index0] = rect.left;
    rectBuffer[index1] = rect.top;
    rectBuffer[index2] = rect.right;
    rectBuffer[index3] = rect.bottom;
  }

  final Int32List colorBuffer = colors.isEmpty ? null : _encodeColorList(colors);
  final Float32List cullRectBuffer = cullRect?._value;

  _drawAtlas(
    paint._objects, paint._data, atlas, rstTransformBuffer, rectBuffer,
    colorBuffer, transferMode.index, cullRectBuffer
  );
}