C# 实现生成带二维码的专属微信公众号推广海报

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

///

/// 获取临时二维码ticket
///

/// 场景值ID openid做场景值ID
///
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

///

/// 生成带二维码的专属推广图片
///

///
///
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;
}

///

/// 缩小/放大图片
///

/// 图片网络地址
/// 缩小/放大宽度
/// 缩小/放大高度
///
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 = "" + nowtime + "";
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