【报Bug】canvas 触发不了touch事件

示例代码：

<template>  
    <view class="page-container">  
        <canvas class="signature" canvas-id="cvs" type="2d" @touchstart="touchstart"  
         @touchmove="touchmove" @touchend="touchend" @tap="onTap"></canvas>  
    </view>  
</template>  

<script>  
    export default {  
        data() {  
            return {  
                cid: 'cvs',  
                lines: [],  
                line: null,  
            }  
        },  

        onLoad() {  
        },  
        onShow(){  
        },  
        methods: {  
            onTap(){  
                console.log("12312")  
            },  
            touchstart(e) {  
                console.log("===start")  
                console.log(e)  
                let p = this._get_point(e);  
                console.log(p)  
            },  
            touchmove(e) {  
                console.log("===move")  
                console.log(e)  
                let p = this._get_point(e);  
                console.log(p)  
            },  
            touchend(e) {  
                let p = this._get_point(e);  
                console.log("===end")  
                console.log(p)  
            },  
            _get_point(e) {  
                return {  
                    x: e.changedTouches[0].x.toFixed(1),  
                    y: e.changedTouches[0].y.toFixed(1),  
                }  
            },  
        }  
    }  
</script>  

<style lang="scss" scoped>  
    .page-container{  
        .signature{  
            border: 2rpx dotted #000;  
            background:#fff;  
        }  
    }  
</style>  

操作步骤：

微信开发者工具 -> 真机调试 ->自动真机模式(2.0)->启动PC端自动真机调试

预期结果：

touch事件触发打印结果

实际结果：

事件未触发，未打印结果