https://www.flowersgallery.com/scripts/intersection-observer.js?c=943054b67&v=2018088996971

1/**
2 * Copyright 2016 Google Inc. All Rights Reserved.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17(function(window, document) {
18'use strict';
19
20
21// Exits early if all IntersectionObserver and IntersectionObserverEntry
22// features are natively supported.
23if ('IntersectionObserver' in window &&
24    'IntersectionObserverEntry' in window &&
25    'intersectionRatio' in window.IntersectionObserverEntry.prototype) {
26  return;
27}
28
29
30/**
31 * An IntersectionObserver registry. This registry exists to hold a strong
32 * reference to IntersectionObserver instances currently observering a target
33 * element. Without this registry, instances without another reference may be
34 * garbage collected.
35 */
36var registry = [];
37
38
39/**
40 * Creates the global IntersectionObserverEntry constructor.
41 * https://wicg.github.io/IntersectionObserver/#intersection-observer-entry
42 * @param {Object} entry A dictionary of instance properties.
43 * @constructor
44 */
45function IntersectionObserverEntry(entry) {
46  this.time = entry.time;
47  this.target = entry.target;
48  this.rootBounds = entry.rootBounds;
49  this.boundingClientRect = entry.boundingClientRect;
50  this.intersectionRect = entry.intersectionRect || getEmptyRect();
51  this.isIntersecting = !!entry.intersectionRect;
52
53  // Calculates the intersection ratio.
54  var targetRect = this.boundingClientRect;
55  var targetArea = targetRect.width * targetRect.height;
56  var intersectionRect = this.intersectionRect;
57  var intersectionArea = intersectionRect.width * intersectionRect.height;
58
59  // Sets intersection ratio.
60  if (targetArea) {
61    this.intersectionRatio = intersectionArea / targetArea;
62  } else {
63    // If area is zero and is intersecting, sets to 1, otherwise to 0
64    this.intersectionRatio = this.isIntersecting ? 1 : 0;
65  }
66}
67
68
69/**
70 * Creates the global IntersectionObserver constructor.
71 * https://wicg.github.io/IntersectionObserver/#intersection-observer-interface
72 * @param {Function} callback The function to be invoked after intersection
73 *     changes have queued. The function is not invoked if the queue has
74 *     been emptied by calling the `takeRecords` method.
75 * @param {Object=} opt_options Optional configuration options.
76 * @constructor
77 */
78function IntersectionObserver(callback, opt_options) {
79
80  var options = opt_options || {};
81
82  if (typeof callback != 'function') {
83    throw new Error('callback must be a function');
84  }
85
86  if (options.root && options.root.nodeType != 1) {
87    throw new Error('root must be an Element');
88  }
89
90  // Binds and throttles `this._checkForIntersections`.
91  this._checkForIntersections = throttle(
92      this._checkForIntersections.bind(this), this.THROTTLE_TIMEOUT);
93
94  // Private properties.
95  this._callback = callback;
96  this._observationTargets = [];
97  this._queuedEntries = [];
98  this._rootMarginValues = this._parseRootMargin(options.rootMargin);
99
100  // Public properties.
101  this.thresholds = this._initThresholds(options.threshold);
102  this.root = options.root || null;
103  this.rootMargin = this._rootMarginValues.map(function(margin) {
104    return margin.value + margin.unit;
105  }).join(' ');
106}
107
108
109/**
110 * The minimum interval within which the document will be checked for
111 * intersection changes.
112 */
113IntersectionObserver.prototype.THROTTLE_TIMEOUT = 100;
114
115
116/**
117 * The frequency in which the polyfill polls for intersection changes.
118 * this can be updated on a per instance basis and must be set prior to
119 * calling `observe` on the first target.
120 */
121IntersectionObserver.prototype.POLL_INTERVAL = null;
122
123
124/**
125 * Starts observing a target element for intersection changes based on
126 * the thresholds values.
127 * @param {Element} target The DOM element to observe.
128 */
129IntersectionObserver.prototype.observe = function(target) {
130  // If the target is already being observed, do nothing.
131  if (this._observationTargets.some(function(item) {
132    return item.element == target;
133  })) {
134    return;
135  }
136

137  if (!(target && target.nodeType == 1)) {
138    throw new Error('target must be an Element');
139  }
140
141  this._registerInstance();
142  this._observationTargets.push({element: target, entry: null});
143  this._monitorIntersections();
144};
145
146
147/**
148 * Stops observing a target element for intersection changes.
149 * @param {Element} target The DOM element to observe.
150 */
151IntersectionObserver.prototype.unobserve = function(target) {
152  this._observationTargets =
153      this._observationTargets.filter(function(item) {
154
155    return item.element != target;
156  });
157  if (!this._observationTargets.length) {
158    this._unmonitorIntersections();
159    this._unregisterInstance();
160  }
161};
162
163
164/**
165 * Stops observing all target elements for intersection changes.
166 */
167IntersectionObserver.prototype.disconnect = function() {
168  this._observationTargets = [];
169  this._unmonitorIntersections();
170  this._unregisterInstance();
171};
172
173
174/**
175 * Returns any queue entries that have not yet been reported to the
176 * callback and clears the queue. This can be used in conjunction with the
177 * callback to obtain the absolute most up-to-date intersection information.
178 * @return {Array} The currently queued entries.
179 */
180IntersectionObserver.prototype.takeRecords = function() {
181  var records = this._queuedEntries.slice();
182  this._queuedEntries = [];
183  return records;
184};
185
186
187/**
188 * Accepts the threshold value from the user configuration object and
189 * returns a sorted array of unique threshold values. If a value is not
190 * between 0 and 1 and error is thrown.
191 * @private
192 * @param {Array|number=} opt_threshold An optional threshold value or
193 *     a list of threshold values, defaulting to [0].
194 * @return {Array} A sorted list of unique and valid threshold values.
195 */
196IntersectionObserver.prototype._initThresholds = function(opt_threshold) {
197  var threshold = opt_threshold || [0];
198  if (!Array.isArray(threshold)) threshold = [threshold];
199
200  return threshold.sort().filter(function(t, i, a) {
201    if (typeof t != 'number' || isNaN(t) || t < 0 || t > 1) {
202      throw new Error('threshold must be a number between 0 and 1 inclusively');
203    }
204    return t !== a[i - 1];
205  });
206};
207
208
209/**
210 * Accepts the rootMargin value from the user configuration object
211 * and returns an array of the four margin values as an object c

211ontaining
212 * the value and unit properties. If any of the values are not properly
213 * formatted or use a unit other than px or %, and error is thrown.
214 * @private
215 * @param {string=} opt_rootMargin An optional rootMargin value,
216 *     defaulting to '0px'.
217 * @return {Array<Object>} An array of margin objects with the keys
218 *     value and unit.
219 */
220IntersectionObserver.prototype._parseRootMargin = function(opt_rootMargin) {
221  var marginString = opt_rootMargin || '0px';
222  var margins = marginString.split(/\s+/).map(function(margin) {
223    var parts = /^(-?\d*\.?\d+)(px|%)$/.exec(margin);
224    if (!parts) {
225      throw new Error('rootMargin must be specified in pixels or percent');
226    }
227    return {value: parseFloat(parts[1]), unit: parts[2]};
228  });
229
230  // Handles shorthand.
231  margins[1] = margins[1] || margins[0];
232  margins[2] = margins[2] || margins[0];
233  margins[3] = margins[3] || margins[1];
234
235  return margins;
236};
237
238
239/**
240 * Starts polling for intersection changes if the polling is not already
241 * happening, and if the page's visibilty state is visible.
242 * @private
243 */
244IntersectionObserver.prototype._monitorIntersections = function() {
245  if (!this._monitoringIntersections) {
246    this._monitoringIntersections = true;
247
248    this._checkForIntersections();
249
250    // If a poll interval is set, use polling instead of listening to
251    // resize and scroll events or DOM mutations.
252    if (this.POLL_INTERVAL) {
253      this._monitoringInterval = setInterval(
254          this._checkForIntersections, this.POLL_INTERVAL);
255    }
256    else {
257      addEvent(window, 'resize', this._checkForIntersections, true);
258      addEvent(document, 'scroll', this._checkForIntersections, true);
259
260      if ('MutationObserver' in window) {
261        this._domObserver = new MutationObserver(this._checkForIntersections);
262        this._domObserver.observe(document, {
263          attributes: true,
264          childList: true,
265          characterData: true,
266          subtree: true
267        });
268      }
269    }
270  }
271};
272
273
274/**
275 * Stops polling for intersection changes.
276 * @private
277 */
278IntersectionObserver.prototype._unmonitorIntersections = function() {
279  if (this._monitoringIntersections) {
280    this._monitoringIntersections = false;
281
282    clearInterval(this._monitoringInterval);
283    this._monitoringInterval = null;
284
285    removeEvent(window, 'resize', this._checkForIntersections, true);
286    removeEvent(document, 'scroll', this._checkForIntersections, true);
287
288    if (this._domObserver) {
289      this._domObserver.disconnect();
290      this._domObserver = null;
291    }
292  }
293};
294
295
296/**
297 * Scans each observation target for intersection changes and adds them
298 * to the internal entries queue. If new entries are found, it
299 * schedules the callback to be invoked.
300 * @private
301 */
302IntersectionObserver.prototype._checkForIntersections = function() {
303  var rootIsInDom = this._rootIsInDom();
304  var rootRect = rootIsInDom ? this._getRootRect() : getEmptyRect();
305
306  this._observationTargets.forEach(function(item) {
307    var target = item.element;
308    var targetRect = getBoundingClientRect(target);
309    var rootContainsTarget = this._rootContainsTarget(target);
310    var oldEntry = item.entry;
311    var intersectionRect = rootIsInDom && rootContainsTarget &&
312        this._computeTargetAndRootIntersection(target, rootRect);
313
314    var newEntry = item.entry = new IntersectionObserverEntry({
315      time: now(),
316      target: target,
317      boundingClientRect: targetRect,
318      rootBounds: rootRect,
319      intersectionRect: intersectionRect
320    });
321
322    if (!oldEntry) {
323      this._queuedEntries.push(newEntry);
324    } else if (rootIsInDom && rootContainsTarget) {
325      // If the new entry intersection ratio has crossed any of the
326      // thresholds, add a new entry.
327      if (this._hasCrossedThreshold(oldEntry, newEntry)) {
328        this._queuedEntries.push(newEntry);
329      }
330    } else {
331      // If the root is not in the DOM or target is not contained within
332      // root but the previous entry for this target had an intersection,
333      // add a new record indicating removal.
334      if (oldEntry && oldEntry.isIntersecting) {
335        this._queuedEntries.push(newEntry);
336      }
337    }
338  }, this);
339
340  if (this._queuedEntries.length) {
341    this._callback(this.takeRecords(), this);
342  }
343};
344
345
346/**
347 * Accepts a target and root rect computes the intersection between then
348 * following the algorithm in the spec.
349 * TODO(philipwalton): at this time clip-path is not considered.
350 * https://wicg.github.io/IntersectionObserver/#calculate-intersection-rect-algo
351 * @param {Element} target The target DOM element
352 * @param {Object} rootRect The bounding rect of the root after being
353 *     expanded by the rootMargin value.
354 * @return {?Object} The final intersection rect object or undefined if no
355 *     intersection is found.
356 * @private
357 */
358IntersectionObserver.prototype._computeTargetAndRootIntersection =
359    function(target, rootRect) {
360
361  // If the element isn't displayed, an intersection can't happen.
362  if (window.getComputedStyle(target).display == 'none') return;
363
364  var targetRect = getBoundingClientRect(target);
365  var intersectionRect = targetRect;
366  var parent = target.parentNode;
367  var atRoot = false;

368
369  while (!atRoot) {
370    var parentRect = null;
371
372    // If we're at the root element, set parentRect to the already
373    // calculated rootRect. And since <body> and <html> cannot be clipped
374    // to a rect that's not also the document rect, consider them root too.
375    if (parent == this.root ||
376        parent == document.body ||
377        parent == document.documentElement ||
378        parent.nodeType != 1) {
379      atRoot = true;
380      parentRect = rootRect;
381    }
382    // Otherwise check to see if the parent element hides overflow,
383    // and if so update parentRect.
384    else {
385      if (window.getComputedStyle(parent).overflow != 'visible') {
386        parentRect = getBoundingClientRect(parent);
387      }
388    }
389    // If either of the above conditionals set a new parentRect,
390    // calculate new intersection data.
391    if (parentRect) {
392      intersectionRect = computeRectIntersection(parentRect, intersectionRect);
393
394      if (!intersectionRect) break;
395    }
396    parent = parent.parentNode;
397  }
398  return intersectionRect;
399};
400
401
402/**
403 * Returns the root rect after being expanded by the rootMargin value.
404 * @return {Object} The expanded root rect.
405 * @private
406 */
407IntersectionObserver.prototype._getRootRect = function() {
408  var rootRect;
409  if (this.root) {
410    rootRect = getBoundingClientRect(this.root);
411  } else {
412    // Use <html>/<body> instead of window since scroll bars affect size.
413    var html = document.documentElement;
414    var body = document.body;
415    rootRect = {
416      top: 0,
417      left: 0,
418      right: html.clientWidth || body.clientWidth,
419      width: html.clientWidth || body.clientWidth,
420      bottom: html.clientHeight || body.clientHeight,
421      height: html.clientHeight || body.clientHeight
422    };
423  }
424  return this._expandRectByRootMargin(rootRect);
425};
426
427
428/**
429 * Accepts a rect and expands it by the rootMargin value.
430 * @param {Object} rect The rect object to expand.
431 * @return {Object} The expanded rect.
432 * @private
433 */
434IntersectionObserver.prototype._expandRectByRootMargin = function(rect) {
435  var margins = this._rootMarginValues.map(function(margin, i) {
436    return margin.unit == 'px' ? margin.value :
437        margin.value * (i % 2 ? rect.width : rect.height) / 100;
438  });
439  var newRect = {
440    top: rect.top - margins[0],
441    right: rect.right + margins[1],
442    bottom: rect.bottom + margins[2],
443    left: rect.left - margins[3]
444  };
445  newRect.width = newRect.right - newRect.left;
446  newRect.height = newRect.bottom - newRect.top;
447
448  return newRect;
449};
450
451
452/**
453 * Accepts an old and new entry and returns true if at least one of the
454 * threshold values has been crossed.
455 * @param {?IntersectionObserverEntry} oldEntry The previous entry for a
456 *    particular target element or null if no previous entry exists.
457 * @param {IntersectionObserverEntry} newEntry The current entry for a
458 *    particular target element.
459 * @return {boolean} Returns true if a any threshold has been crossed.
460 * @private
461 */
462IntersectionObserver.prototype._hasCrossedThreshold =
463    function(oldEntry, newEntry) {
464
465  // To make comparing easier, an entry that has a ratio of 0
466  // but does not actually intersect is given a value of -1
467  var oldRatio = oldEntry && oldEntry.isIntersecting ?
468      oldEntry.intersectionRatio || 0 : -1;
469  var newRatio = newEntry.isIntersecting ?
470      newEntry.intersectionRatio || 0 : -1;
471
472  // Ignore unchanged ratios
473  if (oldRatio === newRatio) return;
474
475  for (var i = 0; i < this.thresholds.length; i++) {
476    var threshold = this.thresholds[i];
477
478    // Return true if an entry matches a threshold or if the new ratio
479    // and the old ratio are on the opposite sides of a threshold.
480    if (threshold == oldRatio || threshold == newRatio ||
481        threshold < oldRatio !== threshold < newRatio) {
482      return true;
483    }
484  }
485};
486
487
488/**
489 * Returns whether or not the root element is an element and is in the DOM.
490 * @return {boolean} True if the root element is an element and is in the DOM.
491 * @private
492 */
493IntersectionObserver.prototype._rootIsInDom = function() {
494  return !this.root || containsDeep(document, this.root);
495};
496
497
498/**
499 * Returns whether or not the target element is a child of root.
500 * @param {Element} target The target element to check.
501 * @return {boolean} True if the target element is a child of root.
502 * @private
503 */
504IntersectionObserver.prototype._rootContainsTarget = function(target) {
505  return containsDeep(this.root || document, target);
506};
507
508
509/**
510 * Adds the instance to the global IntersectionObserver registry if it isn't
511 * already present.
512 * @private
513 */
514IntersectionObserver.prototype._registerInstance = function() {
515  if (registry.indexOf(this) < 0) {
516    registry.push(this);
517  }
518};
519
520
521/**
522 * Removes the instance from the global IntersectionObserver registry.
523 * @private
524 */
525IntersectionObserver.prototype._unregisterInstance = function() {
526  var index = registry.indexOf(this);
527  if (index != -1) registry.splice(index, 1);
528};
529
530
531/**
532 * Returns the result of the performance.now() method or null in browsers
533 * that don't support the API.
534 * @return {number} The elapsed time since the page was requested.
535 */
536function now() {
537  return window.performance && performance.now && performance.now();
538}
539
540
541/**
542 * Throttles a function and delays its executiong, so it's only called at most
543 * once within a given time period.
544 * @param {Function} fn The function to throttle.
545 * @param {number} timeout The amount of time that must pass before the
546 *     function can be called again.
547 * @return {Function} The throttled function.
548 */
549function throttle(fn, timeout) {
550  var timer = null;
551  return function () {
552    if (!timer) {
553      timer = setTimeout(function() {
554        fn();
555        timer = null;
556      }, timeout);
557    }
558  };
559}
560
561
562/**
563 * Adds an event handler to a DOM node ensuring cross-browser compatibility.
564 * @param {Node} node The DOM node to add the event handler to.
565 * @param {string} event The event name.
566 * @param {Function} fn The event handler to add.
567 * @param {boolean} opt_useCapture Optionally adds the even to the capture
568 *     phase. Note: this only works in modern browsers.
569 */
570function addEvent(node, event, fn, opt_useCapture) {
571  if (typeof node.addEventListener == 'function') {
572    node.addEventListener(event, fn, opt_useCapture || false);
573  }
574  else if (typeof node.attachEvent == 'function') {
575    node.attachEvent('on' + event, fn);
576  }
577}
578
579
580/**
581 * Removes a previously added event handler from a DOM node.
582 * @param {Node} node The DOM node to remove the event handler from.
583 * @param {string} event The event name.
584 * @param {Function} fn The event handler to remove.
585 * @param {boolean} opt_useCapture If the event handler was added with this
586 *     flag set to true, it should be set to true here in order to remove it.
587 */
588function removeEvent(node, event, fn, opt_useCapture) {
589  if (typeof node.removeEventListener == 'function') {
590    node.removeEventListener(event, fn, opt_useCapture || false);
591  }
592  else if (typeof node.detatchEvent == 'function') {
593    node.detatchEvent('on' + event, fn);
594  }
595}
596
597
598/**
599 * Returns the intersection between two rect objects.
600 * @param {Object} rect1 The first rect.
601 * @param {Object} rect2 The second rect.
602 * @return {?Object} The intersection rect or undefined if no intersection
603 *     is found.
604 */
605function computeRectIntersection(rect1, rect2) {
606  var top = Math.max(rect1.top, rect2.top);
607  var bottom = Math.min(rect1.bottom, rect2.bottom);
608  var left = Math.max(rect1.left, rect2.left);
609  var right = Math.min(rect1.right, rect2.right);
610  var width = right - left;
611  var height = bottom - top;
612
613  return (width >= 0 && height >= 0) && {
614    top: top,
615    bottom: bottom,
616    left: left,
617    right: right,
618    width: width,
619    height: height
620  };
621}
622
623
624/**
625 * Shims the native getBoundingClientRect for compatibility with older IE.
626 * @param {Element} el The element whose bounding rect to get.
627 * @return {Object} The (possibly shimmed) rect of the element.
628 */
629function getBoundingClientRect(el) {
630  var rect;
631
632  try {
633      rect = el.getBoundingClientRect();
634  } catch (e) {/* ignore Windows 7 IE11 "Unspecified error" */}
635
636  if (!rect) {
637      return getEmptyRect();
638  }
639
640  // Older IE
641  if (!rect.width || !rect.height) {
642    rect = {
643      top: rect.top,
644      right: rect.right,
645      bottom: rect.bottom,
646      left: rect.left,
647      width: rect.right - rect.left,
648      height: rect.bottom - rect.top
649    };
650  }
651  return rect;
652}
653
654
655/**
656 * Returns an empty rect object. An empty rect is returned when an element
657 * is not in the DOM.
658 * @return {Object} The empty rect.
659 */
660function getEmptyRect() {
661  return {
662    top: 0,
663    bottom: 0,
664    left: 0,
665    right: 0,
666    width: 0,
667    height: 0
668  };
669}
670
671/**
672 * Checks to see if a parent element contains a child elemnt (including inside
673 * shadow DOM).
674 * @param {Node} parent The parent element.
675 * @param {Node} child The child element.
676 * @return {boolean} True if the parent node contains the child node.
677 */
678function containsDeep(parent, child) {
679  var node = child;
680  while (node) {
681    // Check if the node is a shadow root, if it is get the host.
682    if (node.nodeType == 11 && node.host) {
683      node = node.host;
684    }
685
686    if (node == parent) return true;
687
688    // Traverse upwards in the DOM.
689    node = node.parentNode;
690  }
691  return false;

692}
693
694
695// Exposes the constructors globally.
696window.IntersectionObserver = IntersectionObserver;
697window.IntersectionObserverEntry = IntersectionObserverEntry;
698
699}(window, document));