手勢解鎖是app上常見的解鎖方式，相比輸入密碼方式操作起來要方便許多。這篇文章主要介紹了微信小程序開發(fā)教程-手勢解鎖實例，有興趣的可以了解一下。

手勢解鎖是app上常見的解鎖方式，相比輸入密碼方式操作起來要方便許多。下面展示如何基于微信小程序?qū)崿F(xiàn)手機(jī)解鎖。最終實現(xiàn)效果如下圖:

整個功能基于canvas實現(xiàn)，首先添加畫布組件，并設(shè)定樣式

<!--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;
}

手勢解鎖實現(xiàn)代碼在gesture_lock.js中(完整源碼地址見末尾)。

初始化

  constructor(canvasid, context, cb, opt){
    this.touchPoints = [];
    this.checkPoints = [];
    this.canvasid = canvasid;
    this.ctx = context;
    this.width = opt && opt.width || 300; //畫布長度
    this.height = opt && opt.height || 300; //畫布寬度
    this.cycleNum = opt && opt.cycleNum || 3;
    this.radius = 0; //觸摸點(diǎn)半徑
    this.isParamOk = false;
    this.marge = this.margeCircle = 25; //觸摸點(diǎn)及觸摸點(diǎn)和畫布邊界間隔
    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) {
      // 計算觸摸點(diǎn)的半徑長度
      this.radius = (this.width - this.marge * 2 - (this.margeCircle * (this.cycleNum - 1))) / (this.cycleNum * 2)
      this.radius = Math.floor(this.radius);
      // 計算每個觸摸點(diǎn)的圓心位置
      this.calCircleParams();
    }
    this.onEnd = cb; //滑動手勢結(jié)束時的回調(diào)函數(shù)
  }

主要設(shè)置一些參數(shù)，如canvas的長寬，canvas的context，手勢鎖的個數(shù)(3乘3, 4乘4)，手勢鎖的顏色，手勢滑動結(jié)束時的回調(diào)函數(shù)等。并計算出手勢鎖的半徑。

計算每個手勢鎖的圓心位置

  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)
      }
    }
  }

繪制手勢鎖

   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);

接下來就是識別用戶的滑動行為，判斷用戶劃過了哪些圓圈，進(jìn)而識別出用戶的手勢。

在touchstart和touchmove事件中檢測觸發(fā)并更新畫布

  onTouchStart(e) {
    // 不識別多點(diǎn)觸控
    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);
  }

檢測用戶是否劃過某個圓圈

  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;
      }
    }
  }

更新畫布

   drawCanvas(color, point) {
    //每次更新之前先清空畫布
    this.ctx.clearRect(0, 0, this.width, this.height);
    //使用不同顏色和形式繪制已觸發(fā)和未觸發(fā)的鎖
    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)
      }
    }
    //繪制已識別鎖之間的線段
    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];
       }
    }
    //繪制最后一個識別鎖和當(dāng)前觸摸點(diǎn)之間的線段
    if (this.lastCheckPoint && point) {
      this.drawLine(this.lastCheckPoint, point, color);
    }
    this.ctx.draw(true);
  }

當(dāng)用戶滑動結(jié)束時調(diào)用回調(diào)函數(shù)并傳遞識別出的手勢

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

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

重置和顯示手勢錯誤

  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);
  }

如何調(diào)用

在onload方法中創(chuàng)建lock對象并在用戶觸摸事件中調(diào)用相應(yīng)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
  //調(diào)用應(yīng)用實例的方法獲取全局?jǐn)?shù)據(jù)
  app.getUserInfo(function(userInfo){
   //更新數(shù)據(jù)
   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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