生成二维矩阵，编码时指定大小，怎么添加LOGO还在琢磨

public static Bitmap Create2DCode(String str) throws WriterException {    //生成二维矩阵,编码时指定大小,不要生成了图片以后再进行缩放,这样会模糊导致识别失败    BitMatrix matrix = new MultiFormatWriter().encode(str, BarcodeFormat.QR_CODE, 300, 300);    int width = matrix.getWidth();    int height = matrix.getHeight();    //二维矩阵转为一维像素数组,也就是一直横着排了    int[] pixels = new int[width * height];    for (int y = 0; y < height; y++) {        for (int x = 0; x < width; x++) {            if (matrix.get(x, y)) {                pixels[y * width + x] = 0xff000000;            }        }    }    Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);    //通过像素数组生成bitmap,具体参考api    bitmap.setPixels(pixels, 0, width, 0, 0, width, height);    return bitmap;}