Drawable to Bitmap

public static Bitmap drawableToBitmap (Drawable drawable) {
    if (drawable instanceof BitmapDrawable) {
        return ((BitmapDrawable)drawable).getBitmap();
    }

    Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());//这个不加看不到。。。
    drawable.draw(canvas);

    return bitmap;
}