将PNG徽标叠加到Camera的图像上

Question

我正在尝试从相机捕获图片并将徽标徽标覆盖在该图片的左上角。我尝试了使用Canvas进行叠加的方法，但是它不起作用。这是我的代码：

此方法用于将图片保存到存储器中

 public void saveBitmapToGallery(Bitmap bm, String picturename) {
        String root = Environment.getExternalStorageDirectory().toString();
        File mydir = new File(picturepath);
        DisplayMetrics dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);
        displayheight = dm.heightPixels;
        displaywidth = dm.widthPixels;
        File file = new File(mydir, picturename + ".JPG");
        try {
            FileOutputStream fos = new FileOutputStream(file);
            Bitmap.createScaledBitmap(bm, displaywidth, displayheight, true);
            bm.compress(Bitmap.CompressFormat.JPEG, 100, fos);
            fos.flush();
            fos.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

这是我写的在图片上叠加位图的方法：

public Bitmap embedBitmap(Bitmap src){ // This method receives the bitmap from the OnActivityResult method
        int bitmapwidth = src.getWidth();
        int bitmapheight = src.getHeight();
        int logowidth = logo.getWidth();
        int logoheight = logo.getHeight();

        float marginLeft = (float) (bitmapwidth * 0.5 - logowidth * 0.5);
        float marginTop = (float) (bitmapheight * 0.5 - logoheight * 0.5);

        //Bitmap dest =  Bitmap.createBitmap(bitmapwidth,bitmapheight,src.getConfig());
        Canvas cv = new Canvas(src);
        //cv.drawBitmap(src,new Matrix(),null);
        cv.drawBitmap(logo, 0,0,new Paint());
        saveBitmapToGallery(src, picturename);
        return src;
    }

}

让我知道需要做什么。谢谢。