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 || #39;#C5C5C3 #39;; 
 this.checkColor = opt opt.checkColor || #39;#5AA9EC #39;;
 this.errorColor = opt opt.errorColor || #39;#e19984 #39;;
 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 i++) {
 for (let j = 0; j 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 === #39;uncheck #39;) {
 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 === #39;function #39; this.onEnd(this.checkPoints, false);
 onTouchCancel(e) {
 typeof this.onEnd === #39;function #39; 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 = #39;uncheck #39;;
 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( #39;over #39;);
 s.lock.gestureError();
 setTimeout(function() {
 s.lock.reset();
 }, 1000);
 }, {width:300, height:300})
 this.lock.drawGestureLock();
 console.log( #39;onLoad #39;)
 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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