微信小程序生成分享海报

<canvas id="myCanvas" type="2d" style="border: 1px solid; width: 300px; height: 300px;" />

Page({
  onLoad() {
    this.createPoster();
  },
  createPoster () {
     // 1. 获取 canvas 对象
     this.createSelectorQuery().select('#myCanvas').fields({ node: true }).exec((res) => {
      const canvas = res[0].node
      const cxt = canvas.getContext('2d')

      // 2. 创建图片对象
      const bgImg = canvas.createImage()
      bgImg.src='https://canton-assets.ifanrusercontent.com/canton/kingfisher/dragon-boat-festival-2021/share-card-min.png'
      bgImg.onload = function() {
         // 3. 将图片绘制到 canvas 上
         cxt.drawImage(bgImg, 0, 0, 300, 300)
      }
    })
  },
});