很多微信公众号中需要生成推广海报的功能，粉丝获得专属海报后可以分享到朋友圈或发给朋友，为公众号代言邀请好友即可获取奖励的。海报自带渠道二维码，粉丝长按二维码即可关注微信公众号，从而达到吸粉的目的。
效果如下：
代码实现：
1.获取临时二维码ticket
/// <summary>/// 获取临时二维码ticket/// </summary>/// <param name="scene_str">场景值ID openid做场景值ID</param>/// <returns></returns>public static string CreateTempQRCode(string scene_str,string access_token){var result = HttpUtility.SendPostHttpRequest($"https://api.weixin.qq.com/cgi-bin/qrcode/create?access_token={access_token}", "application/json", "{\"expire_seconds\": 2592000, \"action_name\": \"QR_STR_SCENE\", \"action_info\": {\"scene\": {\"scene_str\": \"" + scene_str + "\"}}}");JObject jobect = (JObject)JsonConvert.DeserializeObject(result);string ticket = (string)jobect["ticket"];if (string.IsNullOrEmpty(ticket)){LogHelper.WriteLog(typeof(WeixinHelper), "获取临时二维码ticket失败" + result);return null;}return ticket;}使用openid作为场景值的好处是通过扫A推广的二维码关注用户的场景值便是A的openid。
2. 生成带二维码的专属推广图片
/// <summary>/// 生成带二维码的专属推广图片/// </summary>/// <param name="user"></param>/// <returns></returns>public string Draw(WxUser user){//背景图片string path = Server.MapPath("/Content/images/tg.jpg");System.Drawing.Image imgSrc = System.Drawing.Image.FromFile(path);//处理二维码图片大小 240*240pxSystem.Drawing.Image qrCodeImage = ReduceImage("https://mp.weixin.qq.com/cgi-bin/showqrcode?ticket="+user.ticket, 240, 240);//处理头像图片大小 100*100pxImage titleImage = ReduceImage(user.headimgurl, 100, 100);using (Graphics g = Graphics.FromImage(imgSrc)){//画专属推广二维码g.DrawImage(qrCodeImage, new Rectangle(imgSrc.Width - qrCodeImage.Width - 200,imgSrc.Height - qrCodeImage.Height - 200,qrCodeImage.Width,qrCodeImage.Height),0, 0, qrCodeImage.Width, qrCodeImage.Height, GraphicsUnit.Pixel);//画头像g.DrawImage(titleImage, 8, 8, titleImage.Width, titleImage.Height);Font font = new Font("宋体", 30, FontStyle.Bold);g.DrawString(user.nickname, font, new SolidBrush(Color.Red), 110, 10);}string newpath = Server.MapPath(@"/Content/images/newtg_" + Guid.NewGuid().ToString() + ".jpg");imgSrc.Save(newpath, System.Drawing.Imaging.ImageFormat.Jpeg);return newpath;}/// <summary>/// 缩小/放大图片/// </summary>/// <param name="url">图片网络地址</param>/// <param name="toWidth">缩小/放大宽度</param>/// <param name="toHeight">缩小/放大高度</param>/// <returns></returns>public Image ReduceImage(string url, int toWidth, int toHeight){WebRequest request = WebRequest.Create(url);WebResponse response = request.GetResponse();Stream responseStream = response.GetResponseStream();Image originalImage = Image.FromStream(responseStream);if (toWidth <= 0 && toHeight <= 0){return originalImage;}else if (toWidth > 0 && toHeight > 0){if (originalImage.Width < toWidth && originalImage.Height < toHeight)return originalImage;}else if (toWidth <= 0 && toHeight > 0){if (originalImage.Height < toHeight)return originalImage;toWidth = originalImage.Width * toHeight / originalImage.Height;}else if (toHeight <= 0 && toWidth > 0){if (originalImage.Width < toWidth)return originalImage;toHeight = originalImage.Height * toWidth / originalImage.Width;}Image toBitmap = new Bitmap(toWidth, toHeight);using (Graphics g = Graphics.FromImage(toBitmap)){g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;g.Clear(Color.Transparent);g.DrawImage(originalImage,new Rectangle(0, 0, toWidth, toHeight),new Rectangle(0, 0, originalImage.Width, originalImage.Height),GraphicsUnit.Pixel);originalImage.Dispose();return toBitmap;}}3.将图片上传微信服务器，并发送给用户
string imagePath = Draw(user);string result = HttpUtility.UploadFile($"https://api.weixin.qq.com/cgi-bin/material/add_material?access_token={access_token}&type=image", imagePath);JObject jObject = (JObject)JsonConvert.DeserializeObject(result);string media_id = (string)jObject["media_id"];
if (!string.IsNullOrEmpty(media_id))
{string resxml = "<xml><ToUserName><![CDATA[" + xmlMsg.FromUserName + "]]></ToUserName><FromUserName><![CDATA[" + xmlMsg.ToUserName + "]]></FromUserName><CreateTime>" + nowtime + "</CreateTime><MsgType><![CDATA[image]]></MsgType><Image><MediaId><![CDATA[" + media_id + "]]></MediaId></Image></xml>";return resxml;}
LogHelper.WriteLog(typeof(WechatController), "上传专属推广图片素材失败" + result);
详细请查看 http://blog.yshizi.cn/50.html
