微信小程序实现手写板微信小程序实现手写板

本文实例为大家分享了微信小程序实现手写板的具体代码，供大家参考，具体内容如下

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js:

// index.jsvar QQMapWX = require('../../utils/qqmap-wx-jssdk.js'); var qqmapsdk = new QQMapWX({key: 'H2RBZ-MGCC3-N4G3I-YCX6A-IKB5J-WIBTW' // 必填}); Page({data: {show: false,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.data.canvasNamelet ctx = wx.createCanvasContext(canvasName)this.setData({ctx: ctx})var query = wx.createSelectorQuery(); query.select('.handCenter').boundingClientRect(rect => {this.setData({canvasWidth: rect.width,canvasHeight: rect.height})}).exec(); },// 笔迹开始uploadScaleStart(e) {if (e.type != 'touchstart') return false; let ctx = this.data.ctx; ctx.setFillStyle(this.data.lineColor); // 初始线条设置颜色ctx.setGlobalAlpha(this.data.transparent); // 设置半透明let currentPoint = {x: e.touches[0].x,y: e.touches[0].y}let currentLine = this.data.currentLine; currentLine.unshift({time: new Date().getTime(),dis: 0,x: currentPoint.x,y: currentPoint.y})this.setData({currentPoint,// currentLine})if (this.data.firstTouch) {this.setData({cutArea: { top: currentPoint.y, right: currentPoint.x, bottom: currentPoint.y, left: currentPoint.x },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.data.cutArea.top) {this.data.cutArea.top = point.y; }if (point.y < 0) this.data.cutArea.top = 0; if (point.x > this.data.cutArea.right) {this.data.cutArea.right = point.x; }if (this.data.canvasWidth - point.x <= 0) {this.data.cutArea.right = this.data.canvasWidth; }if (point.y > this.data.cutArea.bottom) {this.data.cutArea.bottom = point.y; }if (this.data.canvasHeight - point.y <= 0) {this.data.cutArea.bottom = this.data.canvasHeight; }if (point.x < this.data.cutArea.left) {this.data.cutArea.left = point.x; }if (point.x < 0) this.data.cutArea.left = 0; this.setData({lastPoint: this.data.currentPoint,currentPoint: point})let currentLine = this.data.currentLinecurrentLine.unshift({time: new Date().getTime(),dis: this.distance(this.data.currentPoint, this.data.lastPoint),x: point.x,y: point.y})// this.setData({//currentLine// })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.setData({lastPoint: this.data.currentPoint,currentPoint: point})let currentLine = this.data.currentLinecurrentLine.unshift({time: new Date().getTime(),dis: this.distance(this.data.currentPoint, this.data.lastPoint),x: point.x,y: point.y})// this.setData({//currentLine// })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.data.lineSize,lineColor: this.data.lineColor}; var chirography = this.data.chirographychirography.unshift(currentChirography); this.setData({chirography})var linePrack = this.data.linePracklinePrack.unshift(this.data.currentLine); this.setData({linePrack,currentLine: []})}, retDraw() {this.data.ctx.clearRect(0, 0, 700, 730)this.data.ctx.draw()},//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.data.radius; return; }let x0, x1, x2, y0, y1, y2, r0, r1, r2, len, lastRadius, dis = 0, time = 0, curveValue = https://www.it610.com/article/0.5; if (line.length <= 2) {x0 = line[1].xy0 = line[1].yx2 = 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.data.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.data.smoothness) break; }this.setData({radius: Math.min(time / len * this.data.pressure + this.data.lineMin, this.data.lineMax) * this.data.lineSize}); line[0].r = this.data.radius; //计算笔迹半径；if (line.length <= 2) {r0 = (lastRadius + this.data.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.data.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.data.lineColor; // let bethelPoint = this.data.bethelPoint; // console.log(a)// console.log(this.data.bethelPoint)// bethelPoint = bethelPoint.push(a); this.bethelDraw(a, 1); point = [{ x: x, y: y, r: r }]; }}this.setData({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.data.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(event) {console.log(event)var color = event.currentTarget.dataset.colorValue; var colorSelected = event.currentTarget.dataset.color; this.setData({selectColor: colorSelected,lineColor: color})},//保存到相册saveCanvasAsImg() {var _this = this; wx.canvasToTempFilePath({canvasId: 'handWriting',fileType: 'png',destWidth: 600,destHeight: 300,quality: 1, //图片质量success(res) {console.log(res.tempFilePath, 'canvas生成图片地址'); _this.setData({ show: false,tempFilePath: res.tempFilePath}); }})},, autograph: function (e) {this.setData({ show: true })}, closeSheet: function (e) {this.setData({ show: false })}})

/*wxss*/.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; }.black-select {width: 60rpx; height: 60rpx; position: absolute; top: 30rpx; left: 25rpx; }.black-select.color_select {width: 90rpx; height: 90rpx; top: 30rpx; 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; }

【微信小程序实现手写板】以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。