# all files / ol/ kinetic.js

51.06% Statements 24/47
16.67% Branches 1/6
44.44% Functions 4/9
51.06% Lines 24/47

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82
    83
    84
    85
    86
    87
    88
    89
    90
    91
    92
    93
    94
    95
    96
    97
    98
    99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    149
    150
    151
    152
    153
    154
    155
    156
    157
    158
    159
    1601×

    1×
    1×
    1×

    1×

    119×

    119×

    119×

    119×

    119×

    119×

    1×
    57×
    57×
    57×

    1×
    1×

    1×
    57×

    57×

    1×

    1×

    1×

    1×

     goog.provide('ol.Kinetic');

    goog.require('ol.Coordinate');
    goog.require('ol.PreRenderFunction');
    goog.require('ol.animation');

    /**
     * @classdesc
     * Implementation of inertial deceleration for map movement.
     *
     * @constructor
     * @param {number} decay Rate of decay (must be negative).
     * @param {number} minVelocity Minimum velocity (pixels/millisecond).
     * @param {number} delay Delay to consider to calculate the kinetic
     *     initial values (milliseconds).
     * @struct
     * @api
     */
    ol.Kinetic = function(decay, minVelocity, delay) {

      /**
       * @private
       * @type {number}
       */
      this.decay_ = decay;

      /**
       * @private
       * @type {number}
       */
      this.minVelocity_ = minVelocity;

      /**
       * @private
       * @type {number}
       */
      this.delay_ = delay;

      /**
       * @private
       * @type {Array.<number>}
       */
      this.points_ = [];

      /**
       * @private
       * @type {number}
       */
      this.angle_ = 0;

      /**
       * @private
       * @type {number}
       */
      this.initialVelocity_ = 0;
    };

    /**
     * FIXME empty description for jsdoc
     */
    ol.Kinetic.prototype.begin = function() {
      this.points_.length = 0;
      this.angle_ = 0;
      this.initialVelocity_ = 0;
    };

    /**
     * @param {number} x X.
     * @param {number} y Y.
     */
    ol.Kinetic.prototype.update = function(x, y) {
      this.points_.push(x, y, Date.now());
    };

    /**
     * @return {boolean} Whether we should do kinetic animation.
     */
    ol.Kinetic.prototype.end = function() {
      Eif (this.points_.length < 6) {
        // at least 2 points are required (i.e. there must be at least 6 elements
        // in the array)
        return false;
      }
      var delay = Date.now() - this.delay_;
      var lastIndex = this.points_.length - 3;
      if (this.points_[lastIndex + 2] < delay) {
        // the last tracked point is too old, which means that the user stopped
        // panning before releasing the map
        return false;
      }

      // get the first point which still falls into the delay time
      var firstIndex = lastIndex - 3;
      while (firstIndex > 0 && this.points_[firstIndex + 2] > delay) {
        firstIndex -= 3;
      }
      var duration = this.points_[lastIndex + 2] - this.points_[firstIndex + 2];
      var dx = this.points_[lastIndex] - this.points_[firstIndex];
      var dy = this.points_[lastIndex + 1] - this.points_[firstIndex + 1];
      this.angle_ = Math.atan2(dy, dx);
      this.initialVelocity_ = Math.sqrt(dx * dx + dy * dy) / duration;
      return this.initialVelocity_ > this.minVelocity_;
    };

    /**
     * @param {ol.Coordinate} source Source coordinate for the animation.
     * @return {ol.PreRenderFunction} Pre-render function for kinetic animation.
     */
    ol.Kinetic.prototype.pan = function(source) {
      var decay = this.decay_;
      var initialVelocity = this.initialVelocity_;
      var velocity = this.minVelocity_ - initialVelocity;
      var duration = this.getDuration_();
      var easingFunction = (
          /**
           * @param {number} t T.
           * @return {number} Easing.
           */
          function(t) {
            return initialVelocity * (Math.exp((decay * t) * duration) - 1) /
                velocity;
          });
      return ol.animation.pan({
        source: source,
        duration: duration,
        easing: easingFunction
      });
    };

    /**
     * @private
     * @return {number} Duration of animation (milliseconds).
     */
    ol.Kinetic.prototype.getDuration_ = function() {
      return Math.log(this.minVelocity_ / this.initialVelocity_) / this.decay_;
    };

    /**
     * @return {number} Total distance travelled (pixels).
     */
    ol.Kinetic.prototype.getDistance = function() {
      return (this.minVelocity_ - this.initialVelocity_) / this.decay_;
    };

    /**
     * @return {number} Angle of the kinetic panning animation (radians).
     */
    ol.Kinetic.prototype.getAngle = function() {
      return this.angle_;
    };