uniapp电子签名

<template>
    <view>
        <view class="wrapper">
            <view class="handBtn">
                <image @click="selectColorEvent('black','#1A1A1A')" :src="selectColor === 'black' ? '../static/other/color_black_selected.png' : '../static/other/color_black.png'"
                 :class="[selectColor === 'black' ? 'color_select' : '', 'black-select']"></image>
                <image @click="selectColorEvent('red','#ca262a')" :src="selectColor === 'red' ? '../static/other/color_red_selected.png' : '../static/other/color_red.png'"
                 :class="[selectColor === 'red' ? 'color_select' : '', 'black-select']"></image>
                <button @click="retDraw" class="delBtn">重写</button>
                <button @click="saveCanvasAsImg" class="saveBtn">保存</button>
                <button @click="previewCanvasImg" class="previewBtn">预览</button>
                <button @click="uploadCanvasImg" class="uploadBtn">上传</button>
                <button @click="subCanvas" class="subBtn">完成</button>
            </view>
            <view class="handCenter">
                <canvas class="handWriting" :disable-scroll="true" @touchstart="uploadScaleStart" @touchmove="uploadScaleMove"
                 @touchend="uploadScaleEnd" canvas-id="handWriting"></canvas>
            </view>
            <view class="handRight">
                <view class="handTitle">请签名</view>
            </view>
        </view>
    </view>
</template>

<script>
    export default {
        data() {
            return {
                canvasName: 'handWriting',
                ctx: '',
                canvasWidth: 0,
                canvasHeight: 0,
                transparent: 1, // 透明度
                selectColor: 'black',
                lineColor: '#1A1A1A', // 颜色
                lineSize: 1.5, // 笔记倍数
                lineMin: 0.5, // 最小笔画半径
                lineMax: 4, // 最大笔画半径
                pressure: 1, // 默认压力
                smoothness: 60, //顺滑度，用60的距离来计算速度
                currentPoint: {},
                currentLine: [], // 当前线条
                firstTouch: true, // 第一次触发
                radius: 1, //画圆的半径
                cutArea: {
                    top: 0,
                    right: 0,
                    bottom: 0,
                    left: 0
                }, //裁剪区域
                bethelPoint: [], //保存所有线条 生成的贝塞尔点；
                lastPoint: 0,
                chirography: [], //笔迹
                currentChirography: {}, //当前笔迹
                linePrack: [] //划线轨迹 , 生成线条的实际点
            };
        },
        onLoad() {
            let canvasName = this.canvasName;
            let ctx = wx.createCanvasContext(canvasName);

            this.ctx = ctx;
            var query = wx.createSelectorQuery();
            query
                .select('.handCenter')
                .boundingClientRect(rect => {
                    this.canvasWidth = rect.width;
                    this.canvasHeight = rect.height;

                    /* 将canvas背景设置为 白底，不设置  导出的canvas的背景为透明 */
                    this.setCanvasBg('#fff');
                })
                .exec();
        },
        methods: {
            // 笔迹开始
            uploadScaleStart(e) {
                if (e.type != 'touchstart') return false;
                let ctx = this.ctx;
                ctx.setFillStyle(this.lineColor); // 初始线条设置颜色
                ctx.setGlobalAlpha(this.transparent); // 设置半透明
                let currentPoint = {
                    x: e.touches[0].x,
                    y: e.touches[0].y
                };
                let currentLine = this.currentLine;
                currentLine.unshift({
                    time: new Date().getTime(),
                    dis: 0,
                    x: currentPoint.x,
                    y: currentPoint.y
                });
                this.currentPoint = currentPoint;
                // currentLine
                if (this.firstTouch) {
                    this.cutArea = {
                        top: currentPoint.y,
                        right: currentPoint.x,
                        bottom: currentPoint.y,
                        left: currentPoint.x
                    };
                    this.firstTouch = false;
                }
                this.pointToLine(currentLine);
            },
            // 笔迹移动
            uploadScaleMove(e) {
                if (e.type != 'touchmove') return false;
                if (e.cancelable) {
                    // 判断默认行为是否已经被禁用
                    if (!e.defaultPrevented) {
                        e.preventDefault();
                    }
                }
                let point = {
                    x: e.touches[0].x,
                    y: e.touches[0].y
                };

                //测试裁剪
                if (point.y < this.cutArea.top) {
                    this.cutArea.top = point.y;
                }
                if (point.y < 0) this.cutArea.top = 0;

                if (point.x > this.cutArea.right) {
                    this.cutArea.right = point.x;
                }
                if (this.canvasWidth - point.x <= 0) {
                    this.cutArea.right = this.canvasWidth;
                }
                if (point.y > this.cutArea.bottom) {
                    this.cutArea.bottom = point.y;
                }
                if (this.canvasHeight - point.y <= 0) {
                    this.cutArea.bottom = this.canvasHeight;
                }
                if (point.x < this.cutArea.left) {
                    this.cutArea.left = point.x;
                }
                if (point.x < 0) this.cutArea.left = 0;

                this.lastPoint = this.currentPoint;
                this.currentPoint = point;

                let currentLine = this.currentLine;
                currentLine.unshift({
                    time: new Date().getTime(),
                    dis: this.distance(this.currentPoint, this.lastPoint),
                    x: point.x,
                    y: point.y
                });

                this.pointToLine(currentLine);
            },
            // 笔迹结束
            uploadScaleEnd(e) {
                if (e.type != 'touchend') return 0;
                let point = {
                    x: e.changedTouches[0].x,
                    y: e.changedTouches[0].y
                };
                this.lastPoint = this.currentPoint;
                this.currentPoint = point;

                let currentLine = this.currentLine;
                currentLine.unshift({
                    time: new Date().getTime(),
                    dis: this.distance(this.currentPoint, this.lastPoint),
                    x: point.x,
                    y: point.y
                });

                if (currentLine.length > 2) {
                    var info = (currentLine[0].time - currentLine[currentLine.length - 1].time) / currentLine.length;
                    //$("#info").text(info.toFixed(2));
                }
                //一笔结束，保存笔迹的坐标点，清空，当前笔迹
                //增加判断是否在手写区域；
                this.pointToLine(currentLine);
                var currentChirography = {
                    lineSize: this.lineSize,
                    lineColor: this.lineColor
                };
                var chirography = this.chirography;
                chirography.unshift(currentChirography);
                this.chirography = chirography;

                var linePrack = this.linePrack;
                linePrack.unshift(this.currentLine);
                this.linePrack = linePrack;
                this.currentLine = [];
            },
            retDraw() {
                this.ctx.clearRect(0, 0, 700, 730);
                this.ctx.draw();

                //设置canvas背景
                this.setCanvasBg('#fff');
            },
            //画两点之间的线条；参数为:line，会绘制最近的开始的两个点；
            pointToLine(line) {
                this.calcBethelLine(line);
                return;
            },
            //计算插值的方式；
            calcBethelLine(line) {
                if (line.length <= 1) {
                    line[0].r = this.radius;
                    return;
                }
                let x0,
                    x1,
                    x2,
                    y0,
                    y1,
                    y2,
                    r0,
                    r1,
                    r2,
                    len,
                    lastRadius,
                    dis = 0,
                    time = 0,
                    curveValue = 0.5;
                if (line.length <= 2) {
                    x0 = line[1].x;
                    y0 = line[1].y;
                    x2 = line[1].x + (line[0].x - line[1].x) * curveValue;
                    y2 = line[1].y + (line[0].y - line[1].y) * curveValue;
                    //x2 = line[1].x;
                    //y2 = line[1].y;
                    x1 = x0 + (x2 - x0) * curveValue;
                    y1 = y0 + (y2 - y0) * curveValue;
                } else {
                    x0 = line[2].x + (line[1].x - line[2].x) * curveValue;
                    y0 = line[2].y + (line[1].y - line[2].y) * curveValue;
                    x1 = line[1].x;
                    y1 = line[1].y;
                    x2 = x1 + (line[0].x - x1) * curveValue;
                    y2 = y1 + (line[0].y - y1) * curveValue;
                }
                //从计算公式看，三个点分别是(x0,y0),(x1,y1),(x2,y2) ；(x1,y1)这个是控制点，控制点不会落在曲线上；实际上，这个点还会手写获取的实际点，却落在曲线上
                len = this.distance({
                    x: x2,
                    y: y2
                }, {
                    x: x0,
                    y: y0
                });
                lastRadius = this.radius;
                for (let n = 0; n < line.length - 1; n++) {
                    dis += line[n].dis;
                    time += line[n].time - line[n + 1].time;
                    if (dis > this.smoothness) break;
                }

                this.radius = Math.min((time / len) * this.pressure + this.lineMin, this.lineMax) * this.lineSize;
                line[0].r = this.radius;
                //计算笔迹半径；
                if (line.length <= 2) {
                    r0 = (lastRadius + this.radius) / 2;
                    r1 = r0;
                    r2 = r1;
                    //return;
                } else {
                    r0 = (line[2].r + line[1].r) / 2;
                    r1 = line[1].r;
                    r2 = (line[1].r + line[0].r) / 2;
                }
                let n = 5;
                let point = [];
                for (let i = 0; i < n; i++) {
                    let t = i / (n - 1);
                    let x = (1 - t) * (1 - t) * x0 + 2 * t * (1 - t) * x1 + t * t * x2;
                    let y = (1 - t) * (1 - t) * y0 + 2 * t * (1 - t) * y1 + t * t * y2;
                    let r = lastRadius + ((this.radius - lastRadius) / n) * i;
                    point.push({
                        x: x,
                        y: y,
                        r: r
                    });
                    if (point.length == 3) {
                        let a = this.ctaCalc(point[0].x, point[0].y, point[0].r, point[1].x, point[1].y, point[1].r, point[2].x, point[2]
                            .y, point[2].r);
                        a[0].color = this.lineColor;
                        // let bethelPoint = this.bethelPoint;
                        // bethelPoint = bethelPoint.push(a);
                        this.bethelDraw(a, 1);
                        point = [{
                            x: x,
                            y: y,
                            r: r
                        }];
                    }
                }
                this.currentLine = line;
            },
            //求两点之间距离
            distance(a, b) {
                let x = b.x - a.x;
                let y = b.y - a.y;
                return Math.sqrt(x * x + y * y);
            },
            ctaCalc(x0, y0, r0, x1, y1, r1, x2, y2, r2) {
                let a = [],
                    vx01,
                    vy01,
                    norm,
                    n_x0,
                    n_y0,
                    vx21,
                    vy21,
                    n_x2,
                    n_y2;
                vx01 = x1 - x0;
                vy01 = y1 - y0;
                norm = Math.sqrt(vx01 * vx01 + vy01 * vy01 + 0.0001) * 2;
                vx01 = (vx01 / norm) * r0;
                vy01 = (vy01 / norm) * r0;
                n_x0 = vy01;
                n_y0 = -vx01;
                vx21 = x1 - x2;
                vy21 = y1 - y2;
                norm = Math.sqrt(vx21 * vx21 + vy21 * vy21 + 0.0001) * 2;
                vx21 = (vx21 / norm) * r2;
                vy21 = (vy21 / norm) * r2;
                n_x2 = -vy21;
                n_y2 = vx21;
                a.push({
                    mx: x0 + n_x0,
                    my: y0 + n_y0,
                    color: '#1A1A1A'
                });
                a.push({
                    c1x: x1 + n_x0,
                    c1y: y1 + n_y0,
                    c2x: x1 + n_x2,
                    c2y: y1 + n_y2,
                    ex: x2 + n_x2,
                    ey: y2 + n_y2
                });
                a.push({
                    c1x: x2 + n_x2 - vx21,
                    c1y: y2 + n_y2 - vy21,
                    c2x: x2 - n_x2 - vx21,
                    c2y: y2 - n_y2 - vy21,
                    ex: x2 - n_x2,
                    ey: y2 - n_y2
                });
                a.push({
                    c1x: x1 - n_x2,
                    c1y: y1 - n_y2,
                    c2x: x1 - n_x0,
                    c2y: y1 - n_y0,
                    ex: x0 - n_x0,
                    ey: y0 - n_y0
                });
                a.push({
                    c1x: x0 - n_x0 - vx01,
                    c1y: y0 - n_y0 - vy01,
                    c2x: x0 + n_x0 - vx01,
                    c2y: y0 + n_y0 - vy01,
                    ex: x0 + n_x0,
                    ey: y0 + n_y0
                });
                a[0].mx = a[0].mx.toFixed(1);
                a[0].mx = parseFloat(a[0].mx);
                a[0].my = a[0].my.toFixed(1);
                a[0].my = parseFloat(a[0].my);
                for (let i = 1; i < a.length; i++) {
                    a[i].c1x = a[i].c1x.toFixed(1);
                    a[i].c1x = parseFloat(a[i].c1x);
                    a[i].c1y = a[i].c1y.toFixed(1);
                    a[i].c1y = parseFloat(a[i].c1y);
                    a[i].c2x = a[i].c2x.toFixed(1);
                    a[i].c2x = parseFloat(a[i].c2x);
                    a[i].c2y = a[i].c2y.toFixed(1);
                    a[i].c2y = parseFloat(a[i].c2y);
                    a[i].ex = a[i].ex.toFixed(1);
                    a[i].ex = parseFloat(a[i].ex);
                    a[i].ey = a[i].ey.toFixed(1);
                    a[i].ey = parseFloat(a[i].ey);
                }
                return a;
            },
            bethelDraw(point, is_fill, color) {
                let ctx = this.ctx;
                ctx.beginPath();
                ctx.moveTo(point[0].mx, point[0].my);
                if (undefined != color) {
                    ctx.setFillStyle(color);
                    ctx.setStrokeStyle(color);
                } else {
                    ctx.setFillStyle(point[0].color);
                    ctx.setStrokeStyle(point[0].color);
                }
                for (let i = 1; i < point.length; i++) {
                    ctx.bezierCurveTo(point[i].c1x, point[i].c1y, point[i].c2x, point[i].c2y, point[i].ex, point[i].ey);
                }
                ctx.stroke();
                if (undefined != is_fill) {
                    ctx.fill(); //填充图形 ( 后绘制的图形会覆盖前面的图形, 绘制时注意先后顺序 )
                }
                ctx.draw(true);
            },
            selectColorEvent(str, color) {
                this.selectColor = str;
                this.lineColor = color;
            },
            //将Canvas内容转成 临时图片 --> cb 为回调函数 形参 tempImgPath 为 生成的图片临时路径
            canvasToImg(cb) {
                //这种写法移动端 出不来

                this.ctx.draw(true, () => {
                    wx.canvasToTempFilePath({
                        canvasId: 'handWriting',
                        fileType: 'png',
                        quality: 1, //图片质量
                        success(res) {
                            // console.log(res.tempFilePath, 'canvas生成图片地址');

                            wx.showToast({
                                title: '执行了吗？'
                            });

                            cb(res.tempFilePath);
                        }
                    });
                });
            },
            //完成
            subCanvas() {
                this.ctx.draw(true, () => {
                    wx.canvasToTempFilePath({
                        canvasId: 'handWriting',
                        fileType: 'png',
                        quality: 1, //图片质量
                        success(res) {
                            // console.log(res.tempFilePath, 'canvas生成图片地址');
                            wx.showToast({
                                title: '以保存'
                            });
                            //保存到系统相册
                            wx.saveImageToPhotosAlbum({
                                filePath: res.tempFilePath,
                                success(res) {
                                    wx.showToast({
                                        title: '已成功保存到相册',
                                        duration: 2000
                                    });
                                }
                            });
                        }
                    });
                });
            },
            //保存到相册
            saveCanvasAsImg() {

                /*
                this.canvasToImg( tempImgPath=>{
                    // console.log(tempImgPath, '临时路径');
                    wx.saveImageToPhotosAlbum({
                        filePath: tempImgPath,
                        success(res) {
                            wx.showToast({
                                title: '已保存到相册',
                                duration: 2000
                            });
                        }
                    })
                } );
        */

                wx.canvasToTempFilePath({
                    canvasId: 'handWriting',
                    fileType: 'png',
                    quality: 1, //图片质量
                    success(res) {
                        // console.log(res.tempFilePath, 'canvas生成图片地址');
                        wx.saveImageToPhotosAlbum({
                            filePath: res.tempFilePath,
                            success(res) {
                                wx.showToast({
                                    title: '已保存到相册',
                                    duration: 2000
                                });
                            }
                        });
                    }
                });
            },
            //预览
            previewCanvasImg() {
                wx.canvasToTempFilePath({
                    canvasId: 'handWriting',
                    fileType: 'jpg',
                    quality: 1, //图片质量
                    success(res) {
                        // console.log(res.tempFilePath, 'canvas生成图片地址');

                        wx.previewImage({
                            urls: [res.tempFilePath] //预览图片 数组
                        });
                    }
                });

                /*    //移动端出不来  ^~^！！
                        this.canvasToImg( tempImgPath=>{
                            wx.previewImage({
                                urls: [tempImgPath], //预览图片 数组
                            })
                        } );
                */
            },
            //上传
            uploadCanvasImg() {

                wx.canvasToTempFilePath({
                    canvasId: 'handWriting',
                    fileType: 'png',
                    quality: 1, //图片质量
                    success(res) {
                        // console.log(res.tempFilePath, 'canvas生成图片地址');

                        //上传
                        wx.uploadFile({
                            url: 'https://example.weixin.qq.com/upload', // 仅为示例，非真实的接口地址
                            filePath: res.tempFilePath,
                            name: 'file_signature',
                            formData: {
                                user: 'test'
                            },
                            success(res) {
                                const data = res.data;
                                // do something
                            }
                        });
                    }
                });
            },
            //设置canvas背景色  不设置  导出的canvas的背景为透明
            //@params：字符串  color
            setCanvasBg(color) {

                /* 将canvas背景设置为 白底，不设置  导出的canvas的背景为透明 */
                //rect() 参数说明  矩形路径左上角的横坐标，左上角的纵坐标, 矩形路径的宽度, 矩形路径的高度
                //这里是 canvasHeight - 4 是因为下边盖住边框了，所以手动减了写
                this.ctx.rect(0, 0, this.canvasWidth, this.canvasHeight - 4);
                // ctx.setFillStyle('red')
                this.ctx.setFillStyle(color);
                this.ctx.fill(); //设置填充
                this.ctx.draw(); //开画
            }
        }
    };
</script>

<style>
    page {
        background: #fbfbfb;
        height: auto;
        overflow: hidden;
    }

    .wrapper {
        width: 100%;
        height: 95vh;
        margin: 30rpx 0;
        overflow: hidden;
        display: flex;
        align-content: center;
        flex-direction: row;
        justify-content: center;
        font-size: 28rpx;
    }

    .handWriting {
        background: #fff;
        width: 100%;
        height: 95vh;
    }

    .handRight {
        display: inline-flex;
        align-items: center;
    }

    .handCenter {
        border: 4rpx dashed #e9e9e9;
        flex: 5;
        overflow: hidden;
        box-sizing: border-box;
    }

    .handTitle {
        transform: rotate(90deg);
        flex: 1;
        color: #666;
    }

    .handBtn button {
        font-size: 28rpx;
    }

    .handBtn {
        height: 95vh;
        display: inline-flex;
        flex-direction: column;
        justify-content: space-between;
        align-content: space-between;
        flex: 1;
    }

    .delBtn {
        position: absolute;
        top: 250rpx;
        left: 0rpx;
        transform: rotate(90deg);
        color: #666;
    }

    .delBtn image {
        position: absolute;
        top: 13rpx;
        left: 25rpx;
    }

    .subBtn {
        position: absolute;
        bottom: 52rpx;
        left: -3rpx;
        display: inline-flex;
        transform: rotate(90deg);
        background: #008ef6;
        color: #fff;
        margin-bottom: 30rpx;
        text-align: center;
        justify-content: center;
    }

    /*Peach - 新增 - 保存*/

    .saveBtn {
        position: absolute;
        top: 375rpx;
        left: 0rpx;
        transform: rotate(90deg);
        color: #666;
    }

    .previewBtn {
        position: absolute;
        top: 500rpx;
        left: 0rpx;
        transform: rotate(90deg);
        color: #666;
    }

    .uploadBtn {
        position: absolute;
        top: 625rpx;
        left: 0rpx;
        transform: rotate(90deg);
        color: #666;
    }

    /*Peach - 新增 - 保存*/

    .black-select {
        width: 60rpx;
        height: 60rpx;
        position: absolute;
        top: 30rpx;
        left: 25rpx;
    }

    .black-select.color_select {
        width: 90rpx;
        height: 90rpx;
        top: 100rpx;
        left: 10rpx;
    }

    .red-select {
        width: 60rpx;
        height: 60rpx;
        position: absolute;
        top: 140rpx;
        left: 25rpx;
    }

    .red-select.color_select {
        width: 90rpx;
        height: 90rpx;
        top: 120rpx;
        left: 10rpx;
    }
</style>