PDF二维码去除边框

用上篇的方法生成的二维码有个小问题，边框太大，网上说构造函数里的”Margin”指定为1就可以，试过后没用，查到别人写的去除边框的代码，就是手动操作去除周边的空白，不过是Java版的，这里给出c#版的
======================继续给自己new对象的分割线============
修改上篇文章里的CreateQRbmp()函数，并添加DeleteWhite()函数

        /// <summary>
        /// 生成二维码
        /// </summary>
        /// <param name="content">需要生成二维码的内容</param>
        /// <param name="size">二维码图片长宽大小</param>
        /// <returns></returns>
        public static Bitmap CreateQRbmp(string content, int size)
        {
            try
            {
                var options = new QrCodeEncodingOptions
                {
                    DisableECI = true,
                    CharacterSet = "UTF-8",
                    Width = size,
                    Height = size,
                    Margin = 1,
                    ErrorCorrection = ZXing.QrCode.Internal.ErrorCorrectionLevel.H
                };
                var writer = new BarcodeWriter();
                writer.Format = BarcodeFormat.QR_CODE;
                writer.Options = options;
                BitMatrix matrix = writer.Encode(content);
                matrix = DeleteWhite(matrix);//删除白边
                int width = matrix.Width;
                int height = matrix.Height;
                Bitmap bitmap = new Bitmap(width, height, PixelFormat.Format32bppRgb);
                for (int y = 0; y < height; y++)
                {
                    for (int x = 0; x < width; x++)
                    {
                        if (matrix[x, y])
                        {
                            bitmap.SetPixel(x, y, Color.Black);
                        }
                        else
                        {
                            bitmap.SetPixel(x, y, Color.White);
                        }
                    }
                }
                //bitmap.Save("qr.png");                
                return bitmap;
            }
            catch (Exception ex)
            {
                return null;
            }
        }

        private static BitMatrix DeleteWhite(BitMatrix matrix)
        {
            int[] rec = matrix.getEnclosingRectangle();
            int resWidth = rec[2] + 1;
            int resHeight = rec[3] + 1;

            BitMatrix resMatrix = new BitMatrix(resWidth, resHeight);
            resMatrix.clear();
            for (int i = 0; i < resWidth; i++)
            {
                for (int j = 0; j < resHeight; j++)
                {
                    if (matrix[i + rec[0], j + rec[1]])
                        resMatrix[i, j] = true;
                }
            }
            return resMatrix;
        }