xamarin android 实现二维码带logo生成效果

            MultiFormatWriter writer = new MultiFormatWriter();
            Dictionary<EncodeHintType, object> hint = new Dictionary<EncodeHintType, object>();
            hint.Add(EncodeHintType.CHARACTER_SET, "UTF-8");
            hint.Add(EncodeHintType.ERROR_CORRECTION, ZXing.QrCode.Internal.ErrorCorrectionLevel.H);
            BarcodeWriter barcodeWriter = new BarcodeWriter();
            var bm = writer.encode("123123123", BarcodeFormat.QR_CODE, 700, 700, hint);
            var bmp = barcodeWriter.Write(bm);
            //获取二维码实际尺寸（去掉二维码两边空白后的实际尺寸）
            int[] rectangle = bm.getEnclosingRectangle();

            Bitmap logo = BitmapFactory.DecodeResource(this.Resources, Resource.Mipmap.timg);
            //计算插入图片的大小和位置

            int width = Math.Min((int)(rectangle[2] / 3.5), logo.Width);
            int height = Math.Min((int)(rectangle[3] / 3.5), logo.Height);
            int left = (bmp.Width - width) / 2;
            int top = (bmp.Height - height) / 2;
            int right = left + width;
            int bottom = top + height;
            //将img转换成bmp格式，否则后面无法创建Graphics对象 
            using (Android.Graphics.Canvas g = new Canvas(bmp))
            {
                //先填充个白色背景
              //  g.DrawRect(new Rect(left-1, top-1, right+1, bottom+1), new Paint() { Color = Color.White });
                g.DrawBitmap(logo, new Rect(0, 0, logo.Width, logo.Height), new Rect(left, top, right, bottom), new Paint());
            } 
            ImageView view = new ImageView(this);
            view.SetImageBitmap(bmp);
            this.AddContentView(view, new Android.Views.ViewGroup.LayoutParams(700, 700));