private Bitmap loadBitmapFromView(View v) {
        int w = v.getWidth();
        int h = v.getHeight();
        Bitmap bmp = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        Canvas c = new Canvas(bmp);
//        c.drawColor(Color.WHITE);//如果不设置canvas画布为白色，则生成透明
        v.layout(0, 0, w, h);
        v.draw(c);
        return bmp;
    }