.wxml

<canvas class="canvas" type="2d" id="myCanvas" bindtouchstart="update_edit_position" bindtouchmove="brush"/>

.wxss

定义画布显示样式

.canvas{background-color: white;height: 65vh;width: 100%;margin-top: 5px;margin-bottom: 5px;  
}

.js

data:{edit_brush:{},
}，
onReady() {const query = wx.createSelectorQuery()query.select('#myCanvas').fields({ node: true, size: true }).exec((res) => {const canvas = res[0].nodeconst ctx = canvas.getContext('2d')canvas.width = res[0].width * dprcanvas.height = res[0].height * dprthis.setData({canvas: canvasctx: ctx})})
},//触摸开始更新初始位置
get_edit_position(e){va