Android Bitmap 与 Drawable之间的转换

BitmapDrawable bitmapDrawable = (BitmapDrawable)bitmap;
Drawable drawable = (Drawable)bitmapDrawable;

Bitmap bitmap = new Bitmap (...);
Drawable drawable = new BitmapDrawable(bitmap);

Drawable mydDrawable = getBackground();
Bitmap image = ((BitmapDrawable)mydDrawable).getBitmap();