draw() {
    const dpr = wx.getSystemInfoSync().pixelRatio
    wx.createSelectorQuery().select('#video').context(res => {
      console.log('select video', res)
      const video = this.video = res.context


      wx.createSelectorQuery().selectAll('#cvs1').node(res => {
        console.log('select canvas', res)
        const ctx1 = res[0].node.getContext('2d')
        res[0].node.width = 300 * dpr
        res[0].node.height = 200 * dpr


        setInterval(() => {
          ctx1.drawImage(video, 0, 0, 300 * dpr, 200 * dpr);
        }, 1000 / 24)
      }).exec()
    }).exec()
  },
})



//https://developers.weixin.qq.com/miniprogram/dev/api/canvas/RenderingContext.html

转载于：https://developers.weixin.qq.com/community/develop/doc/0000868e4f00007f2e7b3e2f35b800