如何获取微信小游戏关系链文档中提到的上屏?

186*****260

要绘制关系链中的图片只能用上屏.如何在编译出来的code.js中获取上屏?
wx.createCanvas 弄出来的都不是上屏.
一直提示 An unsecure canvas can't take an secure canvas as arugment of drawImage When using subcontext

186*****260

使用window.canvas.getContext('2d')
报错:
Cannot set property '__proto__' of null

TypeError: Cannot set property '__proto__' of null
    at HTMLCanvasElement.n.getContext (http://127.0.0.1:51595/game/__dev__/WAGame.js:8:23503)
    at LayaUISample.__proto.drawfriendicon (

cao364893771

186*****260 你好，你解决这个问题了么