當設定了QRCodeVersion=0之後，二維碼的大小會根據文字內容改變，但是更多時候希望二維碼的大小由引數指定，通過設定QRCodeScale也可以一定程度上改變大小，不過有個精度問題，我測試了下每降一級大概減少49px，而需求是自定義大小。解決辦法，自己寫Graphics來渲染

 /// <summary>
 /// 生成二維碼
 /// </summary>
 /// <param name="Content">內容文字</param>
 /// <param name="size">圖片尺寸（畫素）</param>
 /// <param name="margin">
 
圖片白邊（畫素）</param>
 /// <returns></returns>
 public static Bitmap CreateQRCode(string Content, int size, int margin = 5)
 {
     QRCodeEncoder qrCodeEncoder = new QRCodeEncoder();
     qrCodeEncoder.QRCodeEncodeMode = QRCodeEncoder.ENCODE_MODE.BYTE;
     qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.M;
     qrCodeEncoder.QRCodeScale = 5
 
;
     qrCodeEncoder.QRCodeVersion = 0;

     try
     {
         System.Drawing.Image image = qrCodeEncoder.Encode(Content);
         int resWidth = size + 2 * margin;
         int resHeight = size + 2 * margin;
         // 核心就是這裡新建一個bitmap物件然後將image在這裡渲染
         Bitmap newBit = new Bitmap(resWidth, resHeight, PixelFormat.Format32bppRgb);
         Graphics gg = Graphics.FromImage(newBit);

         // 設定背景白色
 

         for (int y = 0; y < resWidth; y++)
         {
             for (int x = 0; x < resHeight; x++)
             {
                 newBit.SetPixel(x, y, Color.White);
             }
         }

         // 設定黑色邊框
         for (int i = 0; i < resWidth; i++)
         {
             newBit.SetPixel(i, 0, Color.Black);
             newBit.SetPixel(i, resWidth - 1, Color.Black);

         }

         for (int j = 0; j < resHeight; j++)
         {
             newBit.SetPixel(0, j, Color.Black);
             newBit.SetPixel(resHeight - 1, j, Color.Black);

         }
         gg.DrawImage(image, margin, margin, size, size);
         //newBit.Save(size.ToString() + ".png");
         return newBit;
     }
     catch(Exception ex)
     {
         return null;
     }
 }