<template>
    <view class="container">
        <button @tap="createCanvas">签名</button>
        <view class="signature" v-show="showCanvas">
            <canvas class="mycanvas" canvas-id="mycanvas" @touchstart="touchstart" @touchmove="touchmove" @touchend="touchend"></canvas>
            <view class="footer">
                <view class="left" @click="finish">保存</view>
                <view class="right" @click="clear">清除</view>
                <view class="close" @click="close">关闭</view>
            </view>
        </view>
    </view>
</template>

<script>
    export default {
        data() {
            return {
                showCanvas:false,
                ctx:‘‘,         //绘图图像
                points:[],       //路径点集合 
                signature:‘‘
            }
        },
        methods: {
            //关闭并清空画布
            close:function(){
                this.showCanvas = false;
                this.clear();
            },
            //创建并显示画布
            createCanvas:function(){
                this.showCanvas = true;
                
                this.ctx = uni.createCanvasContext("mycanvas",this);   //创建绘图对象
                
                //设置画笔样式
                this.ctx.lineWidth = 4;
                this.ctx.lineCap = "round"
                this.ctx.lineJoin = "round"
            },
            //触摸开始，获取到起点
            touchstart:function(e){
                let startX = e.changedTouches[0].x;
                let startY = e.changedTouches[0].y;
                let startPoint = {X:startX,Y:startY};
                this.points.push(startPoint);
                //每次触摸开始，开启新的路径
                this.ctx.beginPath();
            },
            
            //触摸移动，获取到路径点
            touchmove:function(e){
                console.log("触发")
                let moveX = e.changedTouches[0].x;
                let moveY = e.changedTouches[0].y;
                let movePoint = {X:moveX,Y:moveY};
                this.points.push(movePoint);       //存点
                console.log("points1",this.points[0])
                console.log("points2",this.points[1])
                console.log("len",this.points.length)
                let len = this.points.length;
                if(len>=2){
                    this.draw();                   //绘制路径
                }
                
            },
            
            // 触摸结束，将未绘制的点清空防止对后续路径产生干扰
            touchend:function(){                   
                this.points=[];
            },
            
            /* ***********************************************
            #   绘制笔迹
            #    1.为保证笔迹实时显示，必须在移动的同时绘制笔迹
            #    2.为保证笔迹连续，每次从路径集合中区两个点作为起点（moveTo）和终点(lineTo)
            #    3.将上一次的终点作为下一次绘制的起点（即清除第一个点）
            ************************************************ */
            draw: function() {
                let point1 = this.points[0]
                let point2 = this.points[1]
                this.points.shift()
                this.ctx.moveTo(point1.X, point1.Y)
                this.ctx.lineTo(point2.X, point2.Y)
                this.ctx.stroke()
                this.ctx.draw(true)
            },
            
            //清空画布
            clear:function(){
                let that = this;
                uni.getSystemInfo({
                    success: function(res) {
                        let canvasw = res.windowWidth;
                        let canvash = res.windowHeight;
                        that.ctx.clearRect(0, 0, canvasw, canvash);
                        that.ctx.draw(true);
                    },
                })
            },
            //完成绘画并保存到本地
            finish:function(){
                let that = this;
                uni.canvasToTempFilePath({
                  canvasId: ‘mycanvas‘,
                  success: function(res) {
                      console.log(res)
                        
                    //上传到服务器
                    that.api.uploadFile({
                        url: ‘user/upload/one‘,
                        filePath: res.tempFilePath,
                        name: ‘file‘,
                        success: (uploadFileRes) => {
                            console.log(uploadFileRes)
                            that.signature = uploadFileRes.data.url;
                            that.clear();
                            that.showCanvas = false;
                        }
                    })
                    //保存到本地
                    /* 
                    
                    let path = res.tempFilePath;
                    uni.saveImageToPhotosAlbum({
                        filePath:path,
                    }) */
                  } 
                })
            },
        }
    }
</script>

<style lang="less">
    .signature {position: fixed;top: 10px;left: 2%;z-index: 999;width:96%;}
        page{
            background: #fff;
        }
        .container {
            padding: 20rpx 0 120rpx 0;
            box-sizing: border-box;
        }
        .title{
            height:50upx;
            line-height: 50upx;
            font-size: 16px;
        }
        .mycanvas{
            width: 100%;
            height: calc(100vh - 200upx);
            background-color: #ECECEC;
        }
        .footer{
            font-size: 14px;
            height: 150upx;
            display: flex;
            justify-content: space-around;
            align-items: center;
        }
        .left,.right,.close{
            line-height: 100upx;
            height: 100upx;
            width: 220upx;
            text-align: center;
            font-weight: bold;
            color: white;
            border-radius: 5upx;
        }
        .left{
            background: #007AFF;
        }
        .right{
            background:orange;
        }
        .close {
            background:#A3A3A3;
        }
</style>