贴上代码

<canvas id="canvas" type="2d" style="background-color: blueviolet;width: {{canvasWidth}}rpx;height: {{canvasHeight}}rpx;"></canvas>

Page({
  data: {
    canvasWidth:750,
    canvasHeight:800,
    src:"https://hbimg.huabanimg.com/56a2edad23c576a631f2f1fb52939763d2f9910a37f4-wKjMvn"
  },
  onLoad: function (options) {
    wx.createSelectorQuery().select("#canvas").fields({
      node:true,
      size:true,
      id:true
    }).exec(res=>{
      let canvas=res[0].node
      let ctx=canvas.getContext('2d')


      let dpr=wx.getSystemInfoSync().pixelRatio
      canvas.width=res[0].width*dpr
      canvas.height=res[0].height*dpr


      //createPattern()重复图像
      imgObject.onload=()=>{
        ctx.drawImage(imgObject,420,420,300,300)
      const pattern = ctx.createPattern(imgObject, 'repeat')
      ctx.fillStyle = pattern
      ctx.fillRect(0, 0, canvas.width, canvas.height)
    })
  },
})

预览如图所示

开发工具里

手机上（大的猫咪是加载的一张照片，和createPattern无关）

望官方看到尽快解决