微信创建带参数二维码，并加上logo

现在需要创建一个场景二维码，除了基础的微信接口创建外，需要加上小logo，思路如下：

1、 首先根据微信的开发文档创建二维码，获取二维码的url，没啥可说的，按照文档来就好了

获取到的二维码就是这么素净~

2、得到了下载地址，我们就已文件流的方式，将二维码的流，转换为图像对象，并将指定的图片转换为图像对象（注意：地址必须是绝对路径

　　　　　　/// <summary>        
　　　　　　/// 下载二维码图片
        /// </summary>
        /// <param name="dirName">文件路径</param>
        /// <param name="fileName">文件名</param>
        /// <param name="downloadUrl">下载地址</param>
        /// <param name="url">最终图片存放地址</param>
        /// <returns></returns>
        private string LoadImg(string dirName,string fileName,string downloadUrl, out string url)
        {
                //设置文件保存的地址，格式，文件夹的判断和创建
                string urlPath =CreateUrl(dirName,fileName, out url);// out 文件路径

                HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(downloadUrl);
                req.Method = "GET";
                using (WebResponse wr = req.GetResponse())
                {
                    HttpWebResponse myResponse = (HttpWebResponse)req.GetResponse();
                    string strpath = myResponse.ResponseUri.ToString();
                    WebClient mywebclient = new WebClient();

　　　　　　　　　　　　//开始了
　　　　　　　　　　　　//素净的二维码
                    byte[] bytelist = mywebclient.DownloadData(strpath);

                    MemoryStream ms1 = new MemoryStream(bytelist);
                    Bitmap b1 = (Bitmap)Image.FromStream(ms1);
                    ms1.Close();

　　　　　　　　　　　　//logo图片
                    Bitmap b2 = new Bitmap(AppDomain.CurrentDomain.BaseDirectory + @"logo\logo3.png");

　　　　　　　　　　　　//合并
                    var ret = new ImageUtility().MergeQrImg(b1, b2, );
                    Image img = ret;
                    img.Save(AppDomain.CurrentDomain.BaseDirectory + urlPath);
                    string path = urlPath;
　　　　　　　　　　　　//返回最终路径
                    return path;
                }
            }

这个是合并图片使用到的帮助类，自己领悟

logo大小的调整、边框颜色的调整在帮助类中可以自行设置。

 public static Bitmap GetThumbnail(Bitmap b, int destHeight, int destWidth)
         {
             System.Drawing.Image imgSource = b;
             System.Drawing.Imaging.ImageFormat thisFormat = imgSource.RawFormat;
             int sW = , sH = ;
             // 按比例缩放
             int sWidth = imgSource.Width;
             int sHeight = imgSource.Height;
             if (sHeight > destHeight || sWidth > destWidth)
             {
                 if ((sWidth * destHeight) > (sHeight * destWidth))
                 {
                     sW = destWidth;
                     sH = (destWidth * sHeight) / sWidth;
                 }
                 else
                 {
                     sH = destHeight;
                     sW = (sWidth * destHeight) / sHeight;
                 }
             }
             else
             {
                 sW = sWidth;
                 sH = sHeight;
             }
             Bitmap outBmp = new Bitmap(destWidth, destHeight);
             Graphics g = Graphics.FromImage(outBmp);
             g.Clear(Color.Transparent);
             // 设置画布的描绘质量
             g.CompositingQuality = CompositingQuality.HighQuality;
             g.SmoothingMode = SmoothingMode.HighQuality;
             g.InterpolationMode = InterpolationMode.HighQualityBicubic;
             g.DrawImage(imgSource, new Rectangle((destWidth - sW) / , (destHeight - sH) / , sW, sH), , , imgSource.Width, imgSource.Height, GraphicsUnit.Pixel);
             g.Dispose();
             // 以下代码为保存图片时，设置压缩质量
             EncoderParameters encoderParams = new EncoderParameters();
             long[] quality = new long[];
             quality[] = ;
             EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
             encoderParams.Param[] = encoderParam;
             imgSource.Dispose();
             return outBmp;
         }
     }

     public class ImageUtility
     {
         #region 合并用户QR图片和用户头像
         /// <summary>
         /// 合并用户QR图片和用户头像
         /// </summary>
         /// <param name="qrImg">QR图片</param>
         /// <param name="headerImg">用户头像</param>
         /// <param name="n">缩放比例</param>
         /// <returns></returns>
         public Bitmap   MergeQrImg(Bitmap qrImg, Bitmap headerImg, double n = 0.23)
         {
             int margin = ;
             float dpix = qrImg.HorizontalResolution;
             float dpiy = qrImg.VerticalResolution;
             var _newWidth = ( * qrImg.Width -  * margin) * 1.0f / ;
             var _headerImg = ZoomPic(headerImg, _newWidth / headerImg.Width);
             //处理头像
             int newImgWidth = _headerImg.Width + margin;
             Bitmap headerBgImg = new Bitmap(newImgWidth, newImgWidth);
             headerBgImg.MakeTransparent();
             Graphics g = Graphics.FromImage(headerBgImg);
             g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
             g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
             g.Clear(Color.Transparent);
             Pen p = new Pen(new SolidBrush(Color.White));
             //位置和大小
             Rectangle rect = new Rectangle(, , newImgWidth - , newImgWidth - );
             using (GraphicsPath path = CreateRoundedRectanglePath(rect, ))
             {
                 g.DrawPath(p, path);
                 g.FillPath(new SolidBrush(Color.White), path);
             }
             //画头像
             Bitmap img1 = new Bitmap(_headerImg.Width, _headerImg.Width);
             Graphics g1 = Graphics.FromImage(img1);
             g1.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
             g1.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
             g1.Clear(Color.Transparent);
             //Pen p1 = new Pen(new SolidBrush(Color.Gray));
             Pen p1 = new Pen(new SolidBrush(Color.White));
             Rectangle rect1 = new Rectangle(, , _headerImg.Width - , _headerImg.Width - );
             using (GraphicsPath path1 = CreateRoundedRectanglePath(rect1, ))
             {
                 g1.DrawPath(p1, path1);
                 TextureBrush brush = new TextureBrush(_headerImg);
                 g1.FillPath(brush, path1);
             }
             g1.Dispose();
             PointF center = new PointF((newImgWidth - _headerImg.Width) / , (newImgWidth - _headerImg.Height) / );
             g.DrawImage(img1, center.X, center.Y, _headerImg.Width, _headerImg.Height);
             g.Dispose();
             Bitmap backgroudImg = new Bitmap(qrImg.Width, qrImg.Height);
             backgroudImg.MakeTransparent();
             backgroudImg.SetResolution(dpix, dpiy);
             headerBgImg.SetResolution(dpix, dpiy);
             Graphics g2 = Graphics.FromImage(backgroudImg);
             g2.Clear(Color.Transparent);
             g2.DrawImage(qrImg, , );
             PointF center2 = new PointF((qrImg.Width - headerBgImg.Width) / , (qrImg.Height - headerBgImg.Height) / );
             g2.DrawImage(headerBgImg, center2);
             g2.Dispose();
             return backgroudImg;
         }
         #endregion

         #region 图形处理
         /// <summary>
         /// 创建圆角矩形
         /// </summary>
         /// <param name="rect">区域</param>
         /// <param name="cornerRadius">圆角角度</param>
         /// <returns></returns>
         private GraphicsPath CreateRoundedRectanglePath(Rectangle rect, int cornerRadius)
         {
             //下午重新整理下，圆角矩形
             GraphicsPath roundedRect = new GraphicsPath();
             roundedRect.AddArc(rect.X, rect.Y, cornerRadius * , cornerRadius * , , );
             roundedRect.AddLine(rect.X + cornerRadius, rect.Y, rect.Right - cornerRadius * , rect.Y);
             roundedRect.AddArc(rect.X + rect.Width - cornerRadius * , rect.Y, cornerRadius * , cornerRadius * , , );
             roundedRect.AddLine(rect.Right, rect.Y + cornerRadius * , rect.Right, rect.Y + rect.Height - cornerRadius * );
             roundedRect.AddArc(rect.X + rect.Width - cornerRadius * , rect.Y + rect.Height - cornerRadius * , cornerRadius * , cornerRadius * , , );
             roundedRect.AddLine(rect.Right - cornerRadius * , rect.Bottom, rect.X + cornerRadius * , rect.Bottom);
             roundedRect.AddArc(rect.X, rect.Bottom - cornerRadius * , cornerRadius * , cornerRadius * , , );
             roundedRect.AddLine(rect.X, rect.Bottom - cornerRadius * , rect.X, rect.Y + cornerRadius * );
             roundedRect.CloseFigure();
             return roundedRect;
         }
         /// <summary>
         /// 图片按比例缩放
         /// </summary>
         private Image ZoomPic(Image initImage, double n)
         {
             //缩略图宽、高计算
             double newWidth = initImage.Width;
             double newHeight = initImage.Height;
             newWidth = n * initImage.Width;
             newHeight = n * initImage.Height;
             //生成新图
             //新建一个bmp图片
             System.Drawing.Image newImage = new System.Drawing.Bitmap((int)newWidth, (int)newHeight);
             //新建一个画板
             System.Drawing.Graphics newG = System.Drawing.Graphics.FromImage(newImage);
             //设置质量
             newG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
             newG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
             //置背景色
             newG.Clear(Color.Transparent);
             //画图
             newG.DrawImage(initImage, new System.Drawing.Rectangle(, , newImage.Width, newImage.Height), new System.Drawing.Rectangle(, , initImage.Width, initImage.Height), System.Drawing.GraphicsUnit.Pixel);
             newG.Dispose();
             return newImage;
         }

最后生成的图片类似这样：

微信开发文档：https://mp.weixin.qq.com/wiki