微信小程序开发之手势解锁的介绍

手势解锁是app上常见的解锁方式，相比输入密码方式操作起来要方便许多。这篇文章主要介绍了微信小程序开发教程-手势解锁实例，有兴趣的可以了解一下。

手势解锁是app上常见的解锁方式，相比输入密码方式操作起来要方便许多。下面展示如何基于微信小程序实现手机解锁。最终实现效果如下图:

整个功能基于canvas实现，首先添加画布组件，并设定样式

<!--index.wxml--><view>.gesture-lock {margin: 100rpx auto;width: 300px;height: 300px;background-color: #ffffff;}

手势解锁实现代码在gesture_lock.js中(完整源码地址见末尾)。

初始化

constructor(canvasid, context, cb, opt){this.touchPoints = [];this.checkPoints = [];this.canvasid = canvasid;this.ctx = context;this.width = opt && opt.width || 300; //画布长度this.height = opt && opt.height || 300; //画布宽度this.cycleNum = opt && opt.cycleNum || 3;this.radius = 0; //触摸点半径this.isParamOk = false;this.marge = this.margeCircle = 25; //触摸点及触摸点和画布边界间隔this.initColor = opt && opt.initColor || '#C5C5C3';this.checkColor = opt && opt.checkColor || '#5AA9EC';this.errorColor = opt && opt.errorColor || '#e19984';this.touchState = "unTouch";this.checkParam();this.lastCheckPoint = null;if (this.isParamOk) {// 计算触摸点的半径长度this.radius = (this.width - this.marge * 2 - (this.margeCircle * (this.cycleNum - 1))) / (this.cycleNum * 2)this.radius = Math.floor(this.radius);// 计算每个触摸点的圆心位置this.calCircleParams();}this.onEnd = cb; //滑动手势结束时的回调函数}

主要设置一些参数，如canvas的长宽，canvas的context，手势锁的个数(3乘3, 4乘4)，手势锁的颜色，手势滑动结束时的回调函数等。并计算出手势锁的半径。

计算每个手势锁的圆心位置

calCircleParams() {let n = this.cycleNum;let count = 0;for (let i = 0; i < n; i++) {for (let j = 0; j < n; j++){count++;let touchPoint = {x: this.marge + i * (this.radius * 2 + this.margeCircle) + this.radius,y: this.marge + j * (this.radius * 2 + this.margeCircle) + this.radius,index: count,check: "uncheck",}this.touchPoints.push(touchPoint)}}}

绘制手势锁

for (let i = 0; i < this.touchPoints.length; i++){this.drawCircle(this.touchPoints[i].x, this.touchPoints[i].y, this.radius, this.initColor)}this.ctx.draw(true);

接下来就是识别用户的滑动行为，判断用户划过了哪些圆圈，进而识别出用户的手势。

在touchstart和touchmove事件中检测触发并更新画布

onTouchStart(e) {// 不识别多点触控if (e.touches.length > 1){this.touchState = "unTouch";return;}this.touchState = "startTouch";this.checkTouch(e);let point = {x:e.touches[0].x, y:e.touches[0].y};this.drawCanvas(this.checkColor, point);}onTouchMove(e) {if (e.touchState === "unTouch") {return;}if (e.touches.length > 1){this.touchState = "unTouch";return;}this.checkTouch(e);let point = {x:e.touches[0].x, y:e.touches[0].y};this.drawCanvas(this.checkColor, point);}

检测用户是否划过某个圆圈

checkTouch(e) {for (let i = 0; i < this.touchPoints.length; i++){let point = this.touchPoints[i];if (isPointInCycle(e.touches[0].x, e.touches[0].y, point.x, point.y, this.radius)) {if (point.check === 'uncheck') {this.checkPoints.push(point);this.lastCheckPoint = point;}point.check = "check"return;}}}

更新画布

drawCanvas(color, point) {//每次更新之前先清空画布this.ctx.clearRect(0, 0, this.width, this.height);//使用不同颜色和形式绘制已触发和未触发的锁for (let i = 0; i < this.touchPoints.length; i++){let point = this.touchPoints[i];if (point.check === "check") {this.drawCircle(point.x, point.y, this.radius, color);this.drawCircleCentre(point.x, point.y, color);}else {this.drawCircle(this.touchPoints[i].x, this.touchPoints[i].y, this.radius, this.initColor)}}//绘制已识别锁之间的线段if (this.checkPoints.length > 1) {let lastPoint = this.checkPoints[0];for (let i = 1; i < this.checkPoints.length; i++) {this.drawLine(lastPoint, this.checkPoints[i], color);lastPoint = this.checkPoints[i];}}//绘制最后一个识别锁和当前触摸点之间的线段if (this.lastCheckPoint && point) {this.drawLine(this.lastCheckPoint, point, color);}this.ctx.draw(true);}

当用户滑动结束时调用回调函数并传递识别出的手势

onTouchEnd(e) {typeof this.onEnd === 'function' && this.onEnd(this.checkPoints, false);}onTouchCancel(e) {typeof this.onEnd === 'function' && this.onEnd(this.checkPoints, true);}

重置和显示手势错误

gestureError() {this.drawCanvas(this.errorColor)}reset() {for (let i = 0; i < this.touchPoints.length; i++) {this.touchPoints[i].check = 'uncheck';}this.checkPoints = [];this.lastCheckPoint = null;this.drawCanvas(this.initColor);}

如何调用

在onload方法中创建lock对象并在用户触摸事件中调用相应方法

onLoad: function () {var s = this;this.lock = new Lock("id-gesture-lock", wx.createCanvasContext("id-gesture-lock"), function(checkPoints, isCancel) {console.log('over');s.lock.gestureError();setTimeout(function() {s.lock.reset();}, 1000);}, {width:300, height:300})this.lock.drawGestureLock();console.log('onLoad')var that = this//调用应用实例的方法获取全局数据app.getUserInfo(function(userInfo){//更新数据that.setData({userInfo:userInfo})that.update()}) }, onTouchStart: function (e) {this.lock.onTouchStart(e); }, onTouchMove: function (e) {this.lock.onTouchMove(e); }, onTouchEnd: function (e) {this.lock.onTouchEnd(e); }

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