微信小程序开发之手势解锁代码实例

手势解锁

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 class="container">  <canvas canvas-id="id-gesture-lock" class="gesture-lock" bindtouchstart="onTouchStart"    bindtouchmove="onTouchMove" bindtouchend="onTouchEnd"></canvas></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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