开放数据域

var sharedCanvas = wx.getSharedCanvas();
var context= sharedCanvas.getContext('2d');

context.width = data[1].avatarUrl;

主域

var openDataContext = wx.getOpenDataContext();
var sharedCanvas = openDataContext.canvas;

var context = sharedCanvas.getContext('2d');

console.log("宽度:"+context.width);

这样就可以将头像链接传递到主域了，另外请问下我怎么在开放数据域设置

sharedCanvas 

的大小？