其他机型无任何问题 [图片]

canvas组件下，有一段示例代码，如下： <!-- canvas.wxml --> <canvas type="2d" id="myCanvas"></canvas> // canvas.js Page({ onReady() { const query = wx.createSelectorQuery() query.select('#myCanvas') .fields({ node: true, size: true }) .exec((res) => { const canvas = res[0].node const ctx = canvas.getContext('2d') const dpr = wx.getSystemInfoSync().pixelRatio canvas.width = res[0].width * dpr canvas.height = res[0].height * dpr ctx.scale(dpr, dpr) ctx.fillRect(0, 0, 100, 100) }) } }) 不太理解长宽为什么要乘以dpr，并且画布缩放同样的倍数。我把这些去掉后预览看起来和上面一样： canvas.width = res[0].width canvas.height = res[0].height // ctx.scale(dpr, dpr)

[图片] [图片]

VM21:2 (in promise) MiniProgramError Cannot read property 'createView' of undefined TypeError: Cannot read property 'createView' of undefined     at n.value (eval at n.call.document (http://127.0.0.1:51844/remote-debug/runtime.js?devtools_ignore=true:1:11339), <anonymous>:2:1064980)     at n.value (eval at n.call.document (http://127.0.0.1:51844/remote-debug/runtime.js?devtools_ignore=true:1:11339), <anonymous>:2:757375)     at t (eval at n.call.document (http://127.0.0.1:51844/remote-debug/runtime.js?devtools_ignore=true:1:11339), <anonymous>:2:757542)     at n.value (eval at n.call.document (http://127.0.0.1:51844/remote-debug/runtime.js?devtools_ignore=true:1:11339), <anonymous>:2:757631)     at eval (eval at n.call.document (http://127.0.0.1:51844/remote-debug/runtime.js?devtools_ignore=true:1:11339), <anonymous>:2:1300784)     at new Promise (<anonymous>)     at pu (eval at n.call.document (http://127.0.0.1:51844/remote-debug/runtime.js?devtools_ignore=true:1:11339), <anonymous>:2:1300746)     at eval (eval at n.call.document (http://127.0.0.1:51844/remote-debug/runtime.js?devtools_ignore=true:1:11339), <anonymous>:2:1302216)     at Array.forEach (<anonymous>)     at r (eval at n.call.document (http://127.0.0.1:51844/remote-debug/runtime.js?devtools_ignore=true:1:11339), <anonymous>:2:1302194)