BitmapData getBitmapData(String name)

Get the BitmapData of the frame with the given name.

The name of a frame is the original file name of the image without it's file extension.

Source 

BitmapData getBitmapData(String name) {
  for(int i = 0; i < frames.length; i++) {
    var frame = frames[i];
    if (frame.name == name) return frame.bitmapData;
  }
  throw new ArgumentError("TextureAtlasFrame not found: '$name'");
}