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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