以下代码在仅在基础库2.6版本无法正常运行，其他版本暂未测出问

1.横版JSON配置

详细配置项

2.效果预览

3.代码实现

3.1 HTML

<view class="container">
    <canvas 
        type="2d" 
        id="myCanvas"
        style="width:100vw;height:90vh;border-bottom:1px solid grey"
        capture-bind:touchstart="touchStart" 
        capture-bind:touchmove="touchMove"
    >
    </canvas>
    <view class="optionBtn">
        <view class="btnStyle">
            <view class="rotateText" bindtap="reset">重置</view>
        </view>
        <view class="line"></view>
        <view class="btnStyle">
            <view class="rotateText" bindtap="sure">确定</view>
        </view>
    </view>
</view>

3.2 CSS

.container{
    width: 100vw;
    height: 100vh;
}
.optionBtn{
    width: 100vw;
    height:10vh;
    display: flex;
    align-items: center;
    justify-content: center;
}
.line{
    width: 1rpx;
    height: 10vh;
    background: black;
}
.btnStyle{
    width:50vw;
    height:10vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

3.3 JSON

{
    "usingComponents": {},
    "pageOrientation": "landscape",
    "disableScroll": true
}

3.4 JS

Page({
    data:{
        signPath:[]
    },
    //初始化画布
    init(data){

        const width = data[0].width;
        const height=data[0].height;
        const canvas = data[0].node;
        const ctx = canvas.getContext('2d');
        const dpr = wx.getSystemInfoSync().pixelRatio

        canvas.width = width * dpr
        canvas.height = height * dpr
        ctx.scale(dpr,dpr)

        this._dpr = dpr
        this._ctx = ctx
        this._canvas = canvas
    },
    //获取初始点位置
    touchStart(e){
        console.log(e)
        const { _ctx:ctx } = this
        const { clientX:x ,clientY:y } = e.touches[0]
        ctx.beginPath()
    },  
    //绘制路径
    touchMove(e){
        const { _ctx:ctx } = this
        const { clientX:x ,clientY:y } = e.touches[0]

        this.data.signPath.push([x,y])
        this.setData({
            signPath:this.data.signPath
        })

        ctx.lineTo(x, y)
        ctx.stroke()
    },
    //重绘
    reset(){
        const { _ctx:ctx,_canvas:canvas } = this
         //初始化绘制路径
        this.setData({
            signPath:[]
        })
        ctx.clearRect(10, 10, canvas.width, canvas.height)
    },
    //提交签名图片
    sure(){
        
        if(this.data.signPath.length <= 0){
            wx.showToast({
              title: '签名不能为空',
              icon:'none'
            })
            return 
        }

        //导出图片
        this.outImage()
    },
    //导出图片
    outImage(){
        const { _canvas:canvas,_dpr:dpr } = this
        
        wx.canvasToTempFilePath({
            x: 0,
            y: 0,
            width:canvas.width / dpr,
            height:canvas.height / dpr,
            destWidth:canvas.width,
            destHeight:canvas.height,
            canvas:canvas,
            success(res) {
                console.log(res.tempFilePath)
            },
            complete(e){
                console.log(e)
            }
        },this)
    },
    onLoad(){
        wx.createSelectorQuery()
        .select('#myCanvas')
        .fields({node: true,size: true})
        .exec(this.init.bind(this))
    }
})