C# 實現生成帶二維碼的專屬微信公眾號推廣海報

原文:C# 實現生成帶二維碼的專屬微信公眾號推廣海報

很多微信公眾號中需要生成推廣海報的功能，粉絲獲得專屬海報后可以分享到朋友圈或發給朋友，為公眾號代言邀請好友即可獲取獎勵的。海報自帶渠道二維碼，粉絲長按二維碼即可關注微信公眾號，從而達到吸粉的目的。

效果如下：

代碼實現：

1.獲取臨時二維碼ticket

    /// <summary>/// 獲取臨時二維碼ticket/// </summary>/// <param name="scene_str">場景值ID openid做場景值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), "獲取臨時二維碼ticket失敗" + result);return null;}return ticket;}

使用openid作為場景值的好處是通過掃A推廣的二維碼關注用戶的場景值便是A的openid。

2. 生成帶二維碼的專屬推廣圖片

    /// <summary>/// 生成帶二維碼的專屬推廣圖片/// </summary>/// <param name="user"></param>/// <returns></returns>public string Draw(WxUser user){//背景圖片string path = Server.MapPath("/Content/images/tg.jpg");System.Drawing.Image imgSrc = System.Drawing.Image.FromFile(path);//處理二維碼圖片大小 240*240pxSystem.Drawing.Image qrCodeImage = ReduceImage("https://mp.weixin.qq.com/cgi-bin/showqrcode?ticket="+user.ticket, 240, 240);//處理頭像圖片大小 100*100pxImage titleImage = ReduceImage(user.headimgurl, 100, 100);using (Graphics g = Graphics.FromImage(imgSrc)){//畫專屬推廣二維碼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);//畫頭像g.DrawImage(titleImage, 8, 8, titleImage.Width, titleImage.Height);Font font = new Font("宋體", 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>/// 縮小/放大圖片/// </summary>/// <param name="url">圖片網絡地址</param>/// <param name="toWidth">縮小/放大寬度</param>/// <param name="toHeight">縮小/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.將圖片上傳微信服務器，并發送給用戶

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), "上傳專屬推廣圖片素材失敗" + result);

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