微信小程序获取普通二维码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.IO;
using System.Web.Script.Serialization;
using LitJson;
using System.Drawing;
using System.Drawing.Imaging;

namespace WetChat
{
public  class Chat
{
public string Path;

public string Width;

public string Savepath;

public string Codes;
public Chat(string savepath,string codes)
{
this.Path = "pages/index/index?codes="+ codes;
this.Savepath = savepath+"qr_"+codes+".png";
this.Codes = codes;
}
/// <summary>
/// 获取acesstoken
/// </summary>
/// <returns></returns>
public string GetAccess_Token()
{
string urls = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=&secret=";
HttpWebRequest request = (System.Net.HttpWebRequest)WebRequest.Create(urls);  //请求api
HttpWebResponse response = (System.Net.HttpWebResponse)request.GetResponse();
string respText = "";
using (Stream resStream = response.GetResponseStream())
{
StreamReader reader = new StreamReader(resStream, Encoding.Default);
respText = reader.ReadToEnd();
resStream.Close();
}
JavaScriptSerializer Jss = new JavaScriptSerializer();
Dictionary<string, object> respDic = (Dictionary<string, object>)Jss.DeserializeObject(respText);
//通过键access_token获取值
return respDic["access_token"].ToString();
}
/// <summary>
///
/// </summary>
/// <param name="path"></param>
/// <param name="width"></param>
/// <param name="savepath"></param>
public void GetWxCode()
{
string url = "https://api.weixin.qq.com/cgi-bin/wxaapp/createwxaqrcode?access_token=" + GetAccess_Token();
HttpWebRequest request = (System.Net.HttpWebRequest)WebRequest.Create(url);  //创建url
request.Method = "POST";
request.ContentType = "application/json;charset=UTF-8";
JsonData data = new JsonData();
data["path"] = this.Path;
data["width"] = this.Width;

string json = data.ToJson();
byte[] load = Encoding.UTF8.GetBytes(json);
request.ContentLength = load.Length;
Stream writer = request.GetRequestStream();
writer.Write(load, 0, load.Length);

HttpWebResponse response = (System.Net.HttpWebResponse)request.GetResponse();
Stream s = response.GetResponseStream();
byte[] mg = StreamToBytes(s);
Image imgs = CaptureImage(mg);
byte[] mgs = PhotoImageInsert(imgs);
if (File.Exists(this.Savepath))
{
File.Delete(this.Savepath);
File.WriteAllBytes(this.Savepath, mgs);

}
else
{

File.WriteAllBytes(this.Savepath, mgs);

}

}

public static byte[] StreamToBytes(Stream stream)
{

List<byte> bytes = new List<byte>();
int temp = stream.ReadByte();
while (temp != -1)
{
bytes.Add((byte)temp);
temp = stream.ReadByte();
}
return bytes.ToArray();

}

/// <summary>
/// 第二部截取：图片转换为文件流
/// </summary>
/// <param name="bytes"></param>
public System.Drawing.Image CaptureImage(byte[] bytes)
{
Image formimage = ReturnPhoto(bytes);
Bitmap bitmap = new Bitmap(440, 440);
Point p = new Point(0, 0);

Size s = new Size(455, 455);
Graphics gra = Graphics.FromImage(bitmap);
gra.DrawImage(formimage, -15, -15, new Rectangle(p,s), GraphicsUnit.Pixel);
Image saveimage = Image.FromHbitmap(bitmap.GetHbitmap());

return saveimage;

}

/// <summary>
/// 第三部：图片转换文件流
/// </summary>
/// <param name="imgPhoto"></param>
/// <returns></returns>
public byte[] PhotoImageInsert(System.Drawing.Image imgPhoto)
{
MemoryStream mstream = new MemoryStream();
imgPhoto.Save(mstream, System.Drawing.Imaging.ImageFormat.Bmp);
byte[] byData = new Byte[mstream.Length];
mstream.Position = 0;
mstream.Read(byData, 0, byData.Length); mstream.Close();
return byData;
}
/// <summary>
/// 第一步：将文件流转换为image
/// </summary>
/// <param name="streamByte"></param>
/// <returns></returns>
public System.Drawing.Image ReturnPhoto(byte[] streamByte)
{
System.IO.MemoryStream ms = new System.IO.MemoryStream(streamByte);
System.Drawing.Image img = System.Drawing.Image.FromStream(ms);
return img;
}

}
}

　　普通二维码有下面的微信的logo 所以截取

　　分了三部：

　　第一：将文件流转换为image

　　第二：将image截取

　　第三：将image转换为文件流

　　

　　生成100个编码总共用时40s（着实有点多，转换哪里太浪费了）