C#在二维码中添加圆角logo

 public class QRCodeHelper
    {

        #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));
            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));
            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;
        }
        #endregion
    }
效果图如下