android convert drawable to bitmap

glide에서 사용되는 것을 bitmap으로 변환함

public static Bitmap getBitmapFromDrawable(ImageView iv){
    Logger.log("#688 iv->"+iv.getDrawable());
    Bitmap bitmap = null;
    Drawable drawable = iv.getDrawable();
    if(drawable == null){
        return bitmap;
    }
    if (drawable instanceof GlideBitmapDrawable) {
        bitmap = ((GlideBitmapDrawable) drawable).getBitmap();
    } else if (drawable instanceof TransitionDrawable) {
        TransitionDrawable transitionDrawable = (TransitionDrawable) drawable;
        int length = transitionDrawable.getNumberOfLayers();
        for (int i = 0; i < length; ++i) {
            Drawable child = transitionDrawable.getDrawable(i);
            if (child instanceof GlideBitmapDrawable) {
                bitmap = ((GlideBitmapDrawable) child).getBitmap();
                break;
            } else if (child instanceof SquaringDrawable
                    && child.getCurrent() instanceof GlideBitmapDrawable) {
                bitmap = ((GlideBitmapDrawable) child.getCurrent()).getBitmap();
                break;
            }
        }
    } else if (drawable instanceof SquaringDrawable) {
        bitmap = ((GlideBitmapDrawable) drawable.getCurrent()).getBitmap();
    }

    return bitmap;
}