https://www.esker.com/themes/custom/sndev/js/flickity-fade.js?v=1.0.2

1/**
2 * Flickity fade v1.0.0
3 * Fade between Flickity slides
4 */
5
6/* jshint browser: true, undef: true, unused: true */
7
8(function (window, factory) {
9  // universal module definition
10  /*globals define, module, require */
11  if (typeof define == 'function' && define.amd) {
12    // AMD
13    define([
14      'flickity/js/index',
15      'fizzy-ui-utils/utils',
16    ], factory);
17  } else if (typeof module == 'object' && module.exports) {
18    // CommonJS
19    module.exports = factory(
20      require('flickity'),
21      require('fizzy-ui-utils')
22    );
23  } else {
24    // browser global
25    factory(
26      window.Flickity,
27      window.fizzyUIUtils
28    );
29  }
30
31}(this, function factory(Flickity, utils) {
32
33  // ---- Slide ---- //
34
35  var Slide = Flickity.Slide;
36
37  var slideUpdateTarget = Slide.prototype.updateTarget;
38  Slide.prototype.updateTarget = function () {
39    slideUpdateTarget.apply(this, arguments);
40    if (!this.parent.options.fade) {
41      return;
42    }
43    // position cells at selected target
44    var slideTargetX = this.target - this.x;
45    var firstCellX = this.cells[0].x;
46    this.cells.forEach(function (cell) {
47      var targetX = cell.x - firstCellX - slideTargetX;
48      cell.renderPosition(targetX);
49    });
50  };
51
52  Slide.prototype.setOpacity = function (alpha) {
53    this.cells.forEach(function (cell) {
54      cell.element.style.opacity = alpha;
55    });
56  };
57
58  // ---- Flickity ---- //
59
60  var proto = Flickity.prototype;
61
62  Flickity.createMethods.push('_createFade');
63
64  proto._createFade = function () {
65    this.fadeIndex = this.selectedIndex;
66    this.prevSelectedIndex = this.selectedIndex;
67    this.on('select', this.onSelectFade);
68    this.on('dragEnd', this.onDragEndFade);
69    this.on('settle', this.onSettleFade);
70    this.on('activate', this.onActivateFade);
71    this.on('deactivate', this.onDeactivateFade);
72  };
73
74  var updateSlides = proto.updateSlides;
75  proto.updateSlides = function () {
76    updateSlides.apply(this, arguments);
77    if (!this.options.fade) {
78      return;
79    }
80    // set initial opacity
81    this.slides.forEach(function (slide, i) {
82      var alpha = i == this.selectedIndex ? 1 : 0;
83      slide.setOpacity(alpha);
84    }, this);
85  };
86
87  /* ---- events ---- */
88
89  proto.onSelectFade = function () {
90    // in case of resize, keep fadeIndex within current count
91    this.fadeIndex = Math.min(this.prevSelectedIndex, this.slides.length - 1);
92    this.prevSelectedIndex = this.selectedIndex;
93  };
94
95  proto.onSettleFade = function () {
96    delete this.didDragEnd;
97    if (!this.options.fade) {
98      return;
99    }
100    // set full and 0 opacity on selected & faded slides
101    this.selectedSlide.setOpacity(1);
102    var fadedSlide = this.slides[this.fadeIndex];
103    if (fadedSlide && this.fadeIndex != this.selectedIndex) {
104      this.slides[this.fadeIndex].setOpacity(0);
105    }
106  };
107
108  proto.onDragEndFade = function () {
109    // set flag
110    this.didDragEnd = true;
111  };
112
113  proto.onActivateFade = function () {
114    if (this.options.fade) {
115      this.element.classList.add('is-fade');
116    }
117  };
118
119  proto.onDeactivateFade = function () {
120    if (!this.options.fade) {
121      return;
122    }
123    this.element.classList.remove('is-fade');
124    // reset opacity
125    this.slides.forEach(function (slide) {
126      slide.setOpacity('');
127    });
128  };
129
130  /* ---- position & fading ---- */
131
132  var positionSlider = proto.positionSlider;
133  proto.positionSlider = function () {
134    if (!this.options.fade) {
135      positionSlider.apply(this, arguments);
136      return;
137    }
138
139    this.fadeSlides();
140    this.dispatchScrollEvent();
141  };
142
143  var positionSliderAtSelected = proto.positionSliderAtSelected;
144  proto.positionSliderAtSelected = function () {
145    if (this.options.fade) {
146      // position fade slider at origin
147      this.setTranslateX(0);
148    }
149    positionSliderAtSelected.apply(this, arguments);
150  };
151
152  proto.fadeSlides = function () {
153    if (this.slides.length < 2) {
154      return;
155    }
156    // get slides to fade-in & fade-out
157    var indexes = this.getFadeIndexes();
158    var fadeSlideA = this.slides[indexes.a];
159    var fadeSlideB = this.slides[indexes.b];
160    var distance = this.wrapDifference(fadeSlideA.target, fadeSlideB.target);
161    var progress = this.wrapDifference(fadeSlideA.target, -this.x);
162    progress = progress / distance;
163
164    fadeSlideA.setOpacity(1 - progress);
165    fadeSlideB.setOpacity(progress);
166
167    // hide previous slide
168    var fadeHideIndex = indexes.a;
169    if (this.isDragging) {
170      fadeHideIndex = progress > 0.5 ? indexes.a : indexes.b;
171    }
172    var isNewHideIndex = this.fadeHideIndex != undefined &&
173      this.fadeHideIndex != fadeHideIndex &&
174      this.fadeHideIndex != indexes.a &&
175      this.fadeHideIndex != indexes.b;
176    if (isNewHideIndex) {
177      // new fadeHideSlide set, hide previous
178      this.slides[this.fadeHideIndex].setOpacity(0);
179    }
180    this.fadeHideIndex = fadeHideIndex;
181  };
182
183  proto.getFadeIndexes = function () {
184    if (!this.isDragging && !this.didDragEnd) {
185      return {
186        a: this.fadeIndex,
187        b: this.selectedIndex,
188      };
189    }
190    if (this.options.wrapAround) {
191      return this.getFadeDragWrapIndexes();
192    } else {
193      return this.getFadeDragLimitIndexes();
194    }
195  };
196
197  proto.getFadeDragWrapIndexes = function () {
198    var distances = this.slides.map(function (slide, i) {

199      return this.getSlideDistance(-this.x, i);
200    }, this);
201    var absDistances = distances.map(function (distance) {
202      return Math.abs(distance);
203    });
204    var minDistance = Math.min.apply(Math, absDistances);
205    var closestIndex = absDistances.indexOf(minDistance);
206    var distance = distances[closestIndex];
207    var len = this.slides.length;
208
209    var delta = distance >= 0 ? 1 : -1;
210    return {
211      a: closestIndex,
212      b: utils.modulo(closestIndex + delta, len),
213    };
214  };
215
216  proto.getFadeDragLimitIndexes = function () {
217    // calculate closest previous slide
218    var dragIndex = 0;
219    for (var i = 0; i < this.slides.length - 1; i++) {
220      var slide = this.slides[i];
221      if (-this.x < slide.target) {
222        break;
223      }
224      dragIndex = i;
225    }
226    return {
227      a: dragIndex,
228      b: dragIndex + 1,
229    };
230  };
231
232  proto.wrapDifference = function (a, b) {
233    var diff = b - a;
234
235    if (!this.options.wrapAround) {
236      return diff;
237    }
238
239    var diffPlus = diff + this.slideableWidth;
240    var diffMinus = diff - this.slideableWidth;
241    if (Math.abs(diffPlus) < Math.abs(diff)) {
242      diff = diffPlus;
243    }
244    if (Math.abs(diffMinus) < Math.abs(diff)) {
245      diff = diffMinus;
246    }
247    return diff;
248  };
249
250  // ---- wrapAround ---- //
251
252  var _getWrapShiftCells = proto._getWrapShiftCells;
253  proto._getWrapShiftCells = function () {
254    if (!this.options.fade) {
255      _getWrapShiftCells.apply(this, arguments);
256    }
257  };
258
259  var shiftWrapCells = proto.shiftWrapCells;
260  proto.shiftWrapCells = function () {
261    if (!this.options.fade) {
262      shiftWrapCells.apply(this, arguments);
263    }
264  };
265
266  return Flickity;
267
268}));