橫屏

wxml

<view class="container"><canvas canvas-id="firstCanvas" id="firstCanvas" bindtouchstart="bindtouchstart" bindtouchmove="bindtouchmove"></canvas><view class="btn"><button type="warn" bindtap="clear">清除</button><button type="primary" bindtap="export">確定</button></view> </view>

wxss

#firstCanvas{width: 750rpx;height: 600rpx;background-color: #fff; }

js

const app = getApp() Page({data: {context: null,index: 0,height: 0,width: 0},/**記錄開始點 */bindtouchstart: function(e) {this.data.context.moveTo(e.changedTouches[0].x, e.changedTouches[0].y)},/**記錄移動點，刷新繪制 */bindtouchmove: function(e) {this.data.context.lineTo(e.changedTouches[0].x, e.changedTouches[0].y);this.data.context.stroke();this.data.context.draw(true);this.data.context.moveTo(e.changedTouches[0].x, e.changedTouches[0].y);},/**清空畫布 */clear: function() {this.data.context.clearRect(0, 0, this.data.width, this.data.height);this.data.context.draw();this.data.context.setStrokeStyle('#00ff00')this.data.context.setLineWidth(2)this.data.context.setFontSize(20)let str = "簽名區域";this.data.context.fillText(str, Math.ceil((this.data.width - this.data.context.measureText(str).width) / 2), Math.ceil(this.data.height / 2) - 20)this.data.context.draw()},base64(url, type) {return new Promise((resolve, reject) => {wx.getFileSystemManager().readFile({filePath: url,encoding: 'base64',success(res){resolve('data:img/'+type.toLocaleLowerCase()+':base64,'+res.data)},fail(){reject()}})})},/**導出圖片 */export: function() {const that=this;this.data.context.draw(false, wx.canvasToTempFilePath({x: 0,y: 0,width: that.data.width,height: that.data.height,destWidth: that.data.width,destHeight: that.data.height,fileType: 'jpg',canvasId: 'firstCanvas',success(res) {let url = res.tempFilePaththat.base64(url, 'jpg').then(res => {console.log('base64數據流',res);var pages = getCurrentPages();var prevPage = pages[pages.length - 2]; //上一個頁面//直接調用上一個頁面的setData()方法，把數據存到上一個頁面中去prevPage.setData({sign: {sign:res,}})wx.navigateBack({//返回delta: 1})})},fail() {wx.showToast({title: '導出失敗',icon: 'none',duration: 2000})}}))},onShow: function() {let query = wx.createSelectorQuery();const that = this;query.select('#firstCanvas').boundingClientRect();query.exec((rect) => {let width = rect[0].width;let height = rect[0].height;that.setData({width,height});const context = wx.createCanvasContext('firstCanvas')that.setData({context: context})that.data.context.setLineWidth(2)that.data.context.setLineCap('round')});}, })

效果

橫屏

<view class="wrapper"><view class="handBtn"><image catchtap="selectColorEvent" src="{{ selectColor === 'black' ? '../../public/image/index/sign/color_black_selected.png' : '../../public/image/index/sign/color_black.png' }}" class="{{ selectColor === 'black' ? 'color_select' : '' }} black-select" data-color="black"data-color-value="#1A1A1A"></image><image catchtap="selectColorEvent" src="{{ selectColor === 'red' ? '../../public/image/index/sign/color_red_selected.png' : '../../public/image/index/sign/color_red.png' }}" class="{{ selectColor === 'red' ? 'color_select' : '' }} red-select" data-color="red"data-color-value="#ca262a"></image><button catchtap="retDraw" class="delBtn">重寫</button><button catchtap="saveCanvasAsImg" class="saveBtn">保存</button><button catchtap="previewCanvasImg" class="previewBtn">預覽</button><button catchtap="uploadCanvasImg" class="uploadBtn">上傳</button><button catchtap="subCanvas" class="subBtn">完成</button></view><view class="handCenter"><canvas class="handWriting" disable-scroll="true" bindtouchstart="uploadScaleStart" bindtouchmove="uploadScaleMove"bindtouchend="uploadScaleEnd" bindtap="mouseDown" canvas-id="handWriting"></canvas></view><view class="handRight"><view class="handTitle">手寫板</view></view> </view>

wxss

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;align-items: center;flex: 1; }.delBtn, .saveBtn, .previewBtn, .uploadBtn, .subBtn{width: 160rpx !important;height: 70rpx;border: 2rpx solid #eeeeee;transform: rotate(90deg);color: #666; }.delBtn{position: absolute;bottom: 850rpx; }.saveBtn{position: absolute;bottom: 660rpx; } .previewBtn{position: absolute;bottom: 470rpx; } .uploadBtn{position: absolute;bottom: 280rpx; } .subBtn {position: absolute;bottom: 52rpx;display: inline-flex;transform: rotate(90deg);background: #218FFC;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; }

js

Page({data: {canvasName: 'handWriting',ctx: '',canvasWidth: 0,canvasHeight: 0,transparent: 1, // 透明度selectColor: 'black',lineColor: '#1A1A1A', // 顏色lineSize: 1.5, // 筆記倍數lineMin: 0.5, // 最小筆畫半徑lineMax: 4, // 最大筆畫半徑pressure: 1, // 默認壓力smoothness: 60, //順滑度，用60的距離來計算速度currentPoint: {},currentLine: [], // 當前線條firstTouch: true, // 第一次觸發radius: 1, //畫圓的半徑cutArea: { top: 0, right: 0, bottom: 0, left: 0 }, //裁剪區域bethelPoint: [], //保存所有線條 生成的貝塞爾點；lastPoint: 0,chirography: [], //筆跡currentChirography: {}, //當前筆跡signImg: 'signImg',linePrack: [] //劃線軌跡 , 生成線條的實際點},onLoad (options) {this.setData({signImg: options.names,})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})/* 將canvas背景設置為 白底，不設置 導出的canvas的背景為透明 */// console.log(this, 'hahah');this.setCanvasBg('#fff');}).exec();},// 筆跡開始uploadScaleStart (e) {if (e.type != 'touchstart') return false;let ctx = this.data.ctx;ctx.setFillStyle(this.data.lineColor); // 初始線條設置顏色ctx.setGlobalAlpha(this.data.transparent); // 設置半透明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);},// 筆跡移動uploadScaleMove (e) {if (e.type != 'touchmove') return false;if (e.cancelable) {// 判斷默認行為是否已經被禁用if (!e.defaultPrevented) {e.preventDefault();}}let point = {x: e.touches[0].x,y: e.touches[0].y}//測試裁剪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);},// 筆跡結束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));}//一筆結束，保存筆跡的坐標點，清空，當前筆跡//增加判斷是否在手寫區域；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();//設置canvas背景this.setCanvasBg("#fff");},//畫兩點之間的線條；參數為:line，會繪制最近的開始的兩個點；pointToLine (line) {this.calcBethelLine(line);return;},//計算插值的方式；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 = 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;}//從計算公式看，三個點分別是(x0,y0),(x1,y1),(x2,y2) ；(x1,y1)這個是控制點，控制點不會落在曲線上；實際上，這個點還會手寫獲取的實際點，卻落在曲線上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;//計算筆跡半徑；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})},//求兩點之間距離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(); //填充圖形 ( 后繪制的圖形會覆蓋前面的圖形, 繪制時注意先后順序 )}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})},// 設置背景函數//設置canvas背景色 不設置 導出的canvas的背景為透明 //@params：字符串 colorsetCanvasBg(color){/* 將canvas背景設置為 白底，不設置 導出的canvas的背景為透明 *///rect() 參數說明 矩形路徑左上角的橫坐標，左上角的縱坐標, 矩形路徑的寬度, 矩形路徑的高度//這里是 canvasHeight - 4 是因為下邊蓋住邊框了，所以手動減了寫this.data.ctx.rect(0, 0, this.data.canvasWidth, this.data.canvasHeight - 4); // ctx.setFillStyle('red')this.data.ctx.setFillStyle( color )this.data.ctx.fill() //設置填充this.data.ctx.draw() //開畫},//保存到相冊saveCanvasAsImg(){wx.canvasToTempFilePath({canvasId: 'handWriting',fileType: 'png',quality: 1, //圖片質量success(res) {// console.log(res.tempFilePath, 'canvas生成圖片地址');wx.saveImageToPhotosAlbum({filePath: res.tempFilePath,success(res) {wx.showToast({title: '已保存到相冊',duration: 2000});}})}})},//預覽previewCanvasImg(){wx.canvasToTempFilePath({canvasId: 'handWriting',fileType: 'jpg',quality: 1, //圖片質量success(res) {// console.log(res.tempFilePath, 'canvas生成圖片地址');wx.previewImage({urls: [res.tempFilePath], //預覽圖片 數組})}})},//上傳uploadCanvasImg() {wx.canvasToTempFilePath({canvasId: 'handWriting',fileType: 'png',quality: 1, //圖片質量success(res) {// console.log(res.tempFilePath, 'canvas生成圖片地址');//上傳wx.uploadFile({url: 'https://example.weixin.qq.com/upload', // 僅為示例，非真實的接口地址filePath: res.tempFilePath,name: 'file_signature',formData: {user: 'test'},success(res) {const data = res.data// do something}})}})},// 完成 導出圖片base64(url, type) {return new Promise((resolve, reject) => {wx.getFileSystemManager().readFile({filePath: url,encoding: 'base64',success(res){resolve('data:image/'+type.toLocaleLowerCase()+';base64,'+res.data)},fail(){reject()}})})},subCanvas(){const that=this;this.data.ctx.draw(false, wx.canvasToTempFilePath({canvasId: 'handWriting',fileType: 'jpg',quality: 1, //圖片質量success(res) {let url = res.tempFilePaththat.base64(url, 'jpg').then(res => {var pages = getCurrentPages();var prevPage = pages[pages.length - 2]; //上一個頁面//直接調用上一個頁面的setData()方法，把數據存到上一個頁面中去prevPage.setSign(res)wx.navigateBack({//返回delta: 1})})},fail() {wx.showToast({title: '導出失敗',icon: 'none',duration: 2000})}}))} })

調用頁面引入
wxml

<view class="sign" bindtap="signName"><view class="sign-title">檢查員簽名：</view><view class="sign-img"><image src="{{base64ImgUrl}}"></image></view></view>

js

// 跳簽名板頁面setSign(value) {wx.setStorageSync('signImg2', value)this.setData({base64ImgUrl: value})},signName() {wx.navigateTo({url: '../sign_name/index?names=signImg2',})},

效果

總結

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