微信小程序如何实现横竖屏切换的签名功能？

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原文：本文实例为大家分享了微信小程序实现横屏和竖屏签名的具体代码，供大家参考。具体内容如下+wxml+view class=container canvas canvas-id=firstCanvas id=firstCanvas bindtouchstart=bindtouchstart bin

改写后：“本文提供微信小程序实现横竖屏签名功能的代码示例，供开发者参考。代码片段如下：+wxml+view class=container canvas canvas-id=firstCanvas id=firstCanvas bindtouchstart=bindtouchstart+

本文实例为大家分享了微信小程序实现横屏和竖屏签名的具体代码，供大家参考，具体内容如下

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">       确定     </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   },   /**记录开始点 */   bindtouchstart: function(e) {          this.data.context.moveTo(e.changedTouches[0].x, e.changedTouches[0].y)   },   /**记录移动点，刷新绘制 */   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);   },      /**清空画布 */   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 = "签名区域";     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()         }       })     })   },   /**导出图片 */   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.tempFilePath         that.base64(url, 'jpg').then(res => {           console.log('base64数据流',res);           var pages = getCurrentPages();           var prevPage = pages[pages.length - 2]; //上一个页面            //直接调用上一个页面的setData()方法，把数据存到上一个页面中去           prevPage.setData({             sign: {               sign:res,             }           })           wx.navigateBack({//返回             delta: 1           })         })       },       fail() {         wx.showToast({           title: '导出失败',           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

横屏

<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">重写</button>     <button catchtap="saveCanvasAsImg" class="saveBtn">保存</button>     <button catchtap="previewCanvasImg" class="previewBtn">预览</button>     <button catchtap="uploadCanvasImg" class="uploadBtn">上传</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">手写板</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', // 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     signImg: 'signImg',     linePrack: [] //划线轨迹 , 生成线条的实际点   },   onLoad (options) {     this.setData({       signImg: options.names,     })     let canvasName = this.data.canvasName     let 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       })       /* 将canvas背景设置为 白底，不设置  导出的canvas的背景为透明 */       // console.log(this, 'hahah');       this.setCanvasBg('#fff');     }).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.currentLine     currentLine.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.currentLine     currentLine.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.chirography     chirography.unshift(currentChirography);     this.setData({       chirography     })     var linePrack = this.data.linePrack     linePrack.unshift(this.data.currentLine);     this.setData({       linePrack,       currentLine: []     })   },   retDraw() {     this.data.ctx.clearRect(0, 0, 700, 730)     this.data.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.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].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.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     })   },   // 设置背景函数   //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.data.ctx.rect(0, 0, this.data.canvasWidth, this.data.canvasHeight - 4);       // ctx.setFillStyle('red')     this.data.ctx.setFillStyle( color )     this.data.ctx.fill()  //设置填充     this.data.ctx.draw()    //开画   },   //保存到相册   saveCanvasAsImg(){     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             })         }     })   },   //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: '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                 }             })         }     })   },   // 完成  导出图片   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, //图片质量       success(res) {         let url = res.tempFilePath         that.base64(url, 'jpg').then(res => {           var pages = getCurrentPages();           var prevPage = pages[pages.length - 2]; //上一个页面            //直接调用上一个页面的setData()方法，把数据存到上一个页面中去           prevPage.setSign(res)           wx.navigateBack({//返回             delta: 1           })         })       },       fail() {         wx.showToast({           title: '导出失败',           icon: 'none',           duration: 2000         })       }     })     )   } })

调用页面引入

wxml

<view class="sign" bindtap="signName">       <view class="sign-title">检查员签名：       </view>       <view class="sign-img">         <image src="{{base64ImgUrl}}"></image>       </view>     </view>

js

// 跳签名板页面   setSign(value) {     wx.setStorageSync('signImg2', value)     this.setData({       base64ImgUrl: value     })   },   signName() {     wx.navigateTo({       url: '../sign_name/index?names=signImg2',     })   },

效果

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自由互联。