//公共域发送数据

let openDataContext = wx.getOpenDataContext()

let sharedCanvas = openDataContext.canvas

sharedCanvas.width = 400

sharedCanvas.height = 200

setTimeout(() => {

  let canvas = wx.createCanvas()

  let context = canvas.getContext('2d')

  context.drawImage(sharedCanvas, 0, 0)

}, 2000);