依次点击链接请查看以下步骤
选择图片：
https://mp.weixin.qq.com/debug/wxadoc/dev/api/media-picture.html#wxchooseimageobject
查看图片信息：
https://mp.weixin.qq.com/debug/wxadoc/dev/api/media-picture.html#wxgetimageinfoobject
浏览图片:
https://mp.weixin.qq.com/debug/wxadoc/dev/api/media-picture.html#wxpreviewimageobject
图片上传:(需要后台接口把选取的图片路径转换成后台存储图片的路径)
https://mp.weixin.qq.com/debug/wxadoc/dev/api/network-file.html#wxuploadfileobject