void copyPixels(BitmapData source, Rectangle<num> sourceRect, Point<num> destPoint)

See BitmapData.copyPixels

Source 

void copyPixels(BitmapData source, Rectangle<num> sourceRect, Point<num> destPoint) {
  var sourceQuad = source.renderTextureQuad.cut(sourceRect);
  var renderState = new RenderState(_renderContext, _drawMatrix);
  renderState.globalMatrix.prependTranslation(destPoint.x, destPoint.y);
  _renderContext.setTransform(renderState.globalMatrix);
  _renderContext.rawContext.clearRect(0, 0, sourceRect.width, sourceRect.height);
  _renderContext.renderTextureQuad(renderState, sourceQuad);
}