C#生成带二维码的专属微信公众号推广海报实例代码

前言

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*240px
  system.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*100px
  image 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);

总结

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