app.js

//app.js
App({
  onLaunch: function () {
    //调用API从本地缓存中获取数据
    var logs = wx.getStorageSync('logs') || []
    logs.unshift(Date.now())
    wx.setStorageSync('logs', logs);
    this.screenSize();
  },

  getUserInfo: function (cb) {
    var that = this
    if (this.globalData.userInfo) {
      typeof cb == "function" && cb(this.globalData.userInfo)
    } else {
      //调用登录接口
      wx.getUserInfo({
        withCredentials: false,
        success: function (res) {
          that.globalData.userInfo = res.userInfo
          typeof cb == "function" && cb(that.globalData.userInfo)
        }
      })
    }
  },

  screenSize: function () {
    var that = this;
    wx.getSystemInfo({
      success: function (res) {
        var ww = res.windowWidth;
        var hh = res.windowHeight;
        that.globalData.ww = ww;
        that.globalData.hh = hh;
      }
    })
  },

  bezier: function (points, times) {
    // 0、以3个控制点为例，点A,B,C,AB上设置点D,BC上设置点E,DE连线上设置点F,则最终的贝塞尔曲线是点F的坐标轨迹。
    // 1、计算相邻控制点间距。
    // 2、根据完成时间,计算每次执行时D在AB方向上移动的距离，E在BC方向上移动的距离。
    // 3、时间每递增100ms，则D,E在指定方向上发生位移, F在DE上的位移则可通过AD/AB = DF/DE得出。
    // 4、根据DE的正余弦值和DE的值计算出F的坐标。
    // 邻控制AB点间距
    var bezier_points = [];
    var points_D = [];
    var points_E = [];
    const DIST_AB = Math.sqrt(Math.pow(points[1]['x'] - points[0]['x'], 2) + Math.pow(points[1]['y'] - points[0]['y'], 2));
    // 邻控制BC点间距
    const DIST_BC = Math.sqrt(Math.pow(points[2]['x'] - points[1]['x'], 2) + Math.pow(points[2]['y'] - points[1]['y'], 2));
    // D每次在AB方向上移动的距离
    const EACH_MOVE_AD = DIST_AB / times;
    // E每次在BC方向上移动的距离 
    const EACH_MOVE_BE = DIST_BC / times;
    // 点AB的正切
    const TAN_AB = (points[1]['y'] - points[0]['y']) / (points[1]['x'] - points[0]['x']);
    // 点BC的正切
    const TAN_BC = (points[2]['y'] - points[1]['y']) / (points[2]['x'] - points[1]['x']);
    // 点AB的弧度值
    const RADIUS_AB = Math.atan(TAN_AB);
    // 点BC的弧度值
    const RADIUS_BC = Math.atan(TAN_BC);
    // 每次执行
    for (var i = 1; i <= times; i++) {
      // AD的距离
      var dist_AD = EACH_MOVE_AD * i;
      // BE的距离
      var dist_BE = EACH_MOVE_BE * i;
      // D点的坐标
      var point_D = {};
      point_D['x'] = dist_AD * Math.cos(RADIUS_AB) + points[0]['x'];
      point_D['y'] = dist_AD * Math.sin(RADIUS_AB) + points[0]['y'];
      points_D.push(point_D);
      // E点的坐标
      var point_E = {};
      point_E['x'] = dist_BE * Math.cos(RADIUS_BC) + points[1]['x'];
      point_E['y'] = dist_BE * Math.sin(RADIUS_BC) + points[1]['y'];
      points_E.push(point_E);
      // 此时线段DE的正切值
      var tan_DE = (point_E['y'] - point_D['y']) / (point_E['x'] - point_D['x']);
      // tan_DE的弧度值
      var radius_DE = Math.atan(tan_DE);
      // 地市DE的间距
      var dist_DE = Math.sqrt(Math.pow((point_E['x'] - point_D['x']), 2) + Math.pow((point_E['y'] - point_D['y']), 2));
      // 此时DF的距离
      var dist_DF = (dist_AD / DIST_AB) * dist_DE;
      // 此时DF点的坐标
      var point_F = {};
      point_F['x'] = dist_DF * Math.cos(radius_DE) + point_D['x'];
      point_F['y'] = dist_DF * Math.sin(radius_DE) + point_D['y'];
      bezier_points.push(point_F);
    }
    return {
      'bezier_points': bezier_points
    };
  },

  globalData: {
    userInfo: null
  }
})