Caused by: java.lang.IllegalStateException: Immutable bitmap passed to Canvas constructor

            Bitmap bmp =BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);  
            Paint paint = new Paint();
            paint.setColor(Color.BLACK);
            String str = "123";
            Canvas canvas = new Canvas(bmp);　　　　//此句报错
            canvas.drawText(str, 0, 0, paint);

不允许直接修改res里面的图片，只要在后面加上.copy(Bitmap.Config.ARGB_8888, true);

修改后：

Bitmap  originalBitmap = BitmapFactory.decodeResource(getResources(),R.drawable.a).copy(Bitmap.Config.ARGB_8888, true);