解决canvas微信头像跨域问题

只需在nginx配置微信图片转发处理就好，加上如下代码：

location ^~ /wechat_image/ {
    add_header 'Access-Control-Allow-Origin' "$http_origin" always;
    add_header 'Access-Control-Allow-Credentials' 'true' always;
    add_header 'Access-Control-Allow-Methods' 'GET, OPTIONS' always;
    add_header 'Access-Control-Allow-Headers' 'Accept,Authorization,Cache-Control,Content-Type,DNT,If-Mod    ified-  Since,Keep-Alive,Origin,User-Agent,X-Requested-With' always;
    proxy_pass http://wx.qlogo.cn/;
 }