aboutsummaryrefslogtreecommitdiff
path: root/ext/js/dom/document-util.js
blob: ed0a98e7c7d1751c6bc47a001b83bff2ccc75d40 (plain)
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
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
/*
 * Copyright (C) 2016-2022  Yomichan Authors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

/* global
 * DOMTextScanner
 * TextSourceElement
 * TextSourceRange
 */

/**
 * This class contains utility functions related to the HTML document.
 */
class DocumentUtil {
    /**
     * Options to configure how element detection is performed.
     * @typedef {object} GetRangeFromPointOptions
     * @property {boolean} deepContentScan Whether or deep content scanning should be performed. When deep content scanning is enabled,
     *   some transparent overlay elements will be ignored when looking for the element at the input position.
     * @property {boolean} normalizeCssZoom Whether or not zoom coordinates should be normalized.
     */

    /**
     * Scans the document for text or elements with text information at the given coordinate.
     * Coordinates are provided in [client space](https://developer.mozilla.org/en-US/docs/Web/CSS/CSSOM_View/Coordinate_systems).
     * @callback GetRangeFromPointHandler
     * @param {number} x The x coordinate to search at.
     * @param {number} y The y coordinate to search at.
     * @param {GetRangeFromPointOptions} options Options to configure how element detection is performed.
     * @returns {?TextSourceRange|TextSourceElement} A range for the hovered text or element, or `null` if no applicable content was found.
     */

    /**
     * Scans the document for text or elements with text information at the given coordinate.
     * Coordinates are provided in [client space](https://developer.mozilla.org/en-US/docs/Web/CSS/CSSOM_View/Coordinate_systems).
     * @param {number} x The x coordinate to search at.
     * @param {number} y The y coordinate to search at.
     * @param {GetRangeFromPointOptions} options Options to configure how element detection is performed.
     * @returns {?TextSourceRange|TextSourceElement} A range for the hovered text or element, or `null` if no applicable content was found.
     */
    static getRangeFromPoint(x, y, options) {
        for (const handler of this._getRangeFromPointHandlers) {
            const r = handler(x, y, options);
            if (r !== null) { return r; }
        }

        const {deepContentScan, normalizeCssZoom} = options;

        const elements = this._getElementsFromPoint(x, y, deepContentScan);
        let imposter = null;
        let imposterContainer = null;
        let imposterSourceElement = null;
        if (elements.length > 0) {
            const element = elements[0];
            switch (element.nodeName.toUpperCase()) {
                case 'IMG':
                case 'BUTTON':
                case 'SELECT':
                    return TextSourceElement.create(element);
                case 'INPUT':
                    if (element.type === 'text') {
                        imposterSourceElement = element;
                        [imposter, imposterContainer] = this._createImposter(element, false);
                    }
                    break;
                case 'TEXTAREA':
                    imposterSourceElement = element;
                    [imposter, imposterContainer] = this._createImposter(element, true);
                    break;
            }
        }

        const range = this._caretRangeFromPointExt(x, y, deepContentScan ? elements : [], normalizeCssZoom);
        if (range !== null) {
            if (imposter !== null) {
                this._setImposterStyle(imposterContainer.style, 'z-index', '-2147483646');
                this._setImposterStyle(imposter.style, 'pointer-events', 'none');
                return TextSourceRange.createFromImposter(range, imposterContainer, imposterSourceElement);
            }
            return TextSourceRange.create(range);
        } else {
            if (imposterContainer !== null) {
                imposterContainer.parentNode.removeChild(imposterContainer);
            }
            return null;
        }
    }

    /**
     * Registers a custom handler for scanning for text or elements at the input position.
     * @param {GetRangeFromPointHandler} handler The handler callback which will be invoked when calling `getRangeFromPoint`.
     */
    static registerGetRangeFromPointHandler(handler) {
        this._getRangeFromPointHandlers.push(handler);
    }

    /**
     * Extract a sentence from a document.
     * @param {TextSourceRange|TextSourceElement} source The text source object, either `TextSourceRange` or `TextSourceElement`.
     * @param {boolean} layoutAwareScan Whether or not layout-aware scan mode should be used.
     * @param {number} extent The length of the sentence to extract.
     * @param {boolean} terminateAtNewlines Whether or not a sentence should be terminated at newline characters.
     * @param {Map<string, *[]>} terminatorMap A mapping of characters that terminate a sentence.
     *   Format:
     *   ```js
     *   new Map([ [character: string, [includeCharacterAtStart: boolean, includeCharacterAtEnd: boolean]], ... ])
     *   ```
     * @param {Map<string, *[]>} forwardQuoteMap A mapping of quote characters that delimit a sentence.
     *   Format:
     *   ```js
     *   new Map([ [character: string, [otherCharacter: string, includeCharacterAtStart: boolean]], ... ])
     *   ```
     * @param {Map<string, *[]>} backwardQuoteMap A mapping of quote characters that delimit a sentence,
     *   which is the inverse of forwardQuoteMap.
     *   Format:
     *   ```js
     *   new Map([ [character: string, [otherCharacter: string, includeCharacterAtEnd: boolean]], ... ])
     *   ```
     * @returns {{sentence: string, offset: number}} The sentence and the offset to the original source.
     */
    static extractSentence(source, layoutAwareScan, extent, terminateAtNewlines, terminatorMap, forwardQuoteMap, backwardQuoteMap) {
        // Scan text
        source = source.clone();
        const startLength = source.setStartOffset(extent, layoutAwareScan);
        const endLength = source.setEndOffset(extent * 2 - startLength, true, layoutAwareScan);
        const text = source.text();
        const textLength = text.length;
        const textEndAnchor = textLength - endLength;
        let pos1 = startLength;
        let pos2 = textEndAnchor;

        // Move backward
        let quoteStack = [];
        for (; pos1 > 0; --pos1) {
            const c = text[pos1 - 1];
            if (c === '\n' && terminateAtNewlines) { break; }

            if (quoteStack.length === 0) {
                const terminatorInfo = terminatorMap.get(c);
                if (typeof terminatorInfo !== 'undefined') {
                    if (terminatorInfo[0]) { --pos1; }
                    break;
                }
            }

            let quoteInfo = forwardQuoteMap.get(c);
            if (typeof quoteInfo !== 'undefined') {
                if (quoteStack.length === 0) {
                    if (quoteInfo[1]) { --pos1; }
                    break;
                } else if (quoteStack[0] === c) {
                    quoteStack.pop();
                    continue;
                }
            }

            quoteInfo = backwardQuoteMap.get(c);
            if (typeof quoteInfo !== 'undefined') {
                quoteStack.unshift(quoteInfo[0]);
            }
        }

        // Move forward
        quoteStack = [];
        for (; pos2 < textLength; ++pos2) {
            const c = text[pos2];
            if (c === '\n' && terminateAtNewlines) { break; }

            if (quoteStack.length === 0) {
                const terminatorInfo = terminatorMap.get(c);
                if (typeof terminatorInfo !== 'undefined') {
                    if (terminatorInfo[1]) { ++pos2; }
                    break;
                }
            }

            let quoteInfo = backwardQuoteMap.get(c);
            if (typeof quoteInfo !== 'undefined') {
                if (quoteStack.length === 0) {
                    if (quoteInfo[1]) { ++pos2; }
                    break;
                } else if (quoteStack[0] === c) {
                    quoteStack.pop();
                    continue;
                }
            }

            quoteInfo = forwardQuoteMap.get(c);
            if (typeof quoteInfo !== 'undefined') {
                quoteStack.unshift(quoteInfo[0]);
            }
        }

        // Trim whitespace
        for (; pos1 < startLength && this._isWhitespace(text[pos1]); ++pos1) { /* NOP */ }
        for (; pos2 > textEndAnchor && this._isWhitespace(text[pos2 - 1]); --pos2) { /* NOP */ }

        // Result
        return {
            text: text.substring(pos1, pos2),
            offset: startLength - pos1
        };
    }

    /**
     * Computes the scaling adjustment that is necessary for client space coordinates based on the
     * CSS zoom level.
     * @param {Node} node A node in the document.
     * @returns {number} The scaling factor.
     */
    static computeZoomScale(node) {
        if (this._cssZoomSupported === null) {
            this._cssZoomSupported = (typeof document.createElement('div').style.zoom === 'string');
        }
        if (!this._cssZoomSupported) { return 1; }
        // documentElement must be excluded because the computer style of its zoom property is inconsistent.
        // * If CSS `:root{zoom:X;}` is specified, the computed zoom will always report `X`.
        // * If CSS `:root{zoom:X;}` is not specified, the computed zoom report the browser's zoom level.
        // Therefor, if CSS root zoom is specified as a value other than 1, the adjusted {x, y} values
        // would be incorrect, which is not new behaviour.
        let scale = 1;
        const {ELEMENT_NODE, DOCUMENT_FRAGMENT_NODE} = Node;
        const {documentElement} = document;
        for (; node !== null && node !== documentElement; node = node.parentNode) {
            const {nodeType} = node;
            if (nodeType === DOCUMENT_FRAGMENT_NODE) {
                const {host} = node;
                if (typeof host !== 'undefined') {
                    node = host;
                }
                continue;
            } else if (nodeType !== ELEMENT_NODE) {
                continue;
            }
            let {zoom} = getComputedStyle(node);
            if (typeof zoom !== 'string') { continue; }
            zoom = Number.parseFloat(zoom);
            if (!Number.isFinite(zoom) || zoom === 0) { continue; }
            scale *= zoom;
        }
        return scale;
    }

    /**
     * Converts a rect based on the CSS zoom scaling for a given node.
     * @param {DOMRect} rect The rect to convert.
     * @param {Node} node The node to compute the zoom from.
     * @returns {DOMRect} The updated rect, or the same rect if no change is needed.
     */
    static convertRectZoomCoordinates(rect, node) {
        const scale = this.computeZoomScale(node);
        return (scale === 1 ? rect : new DOMRect(rect.left * scale, rect.top * scale, rect.width * scale, rect.height * scale));
    }

    /**
     * Converts multiple rects based on the CSS zoom scaling for a given node.
     * @param {DOMRect[]} rects The rects to convert.
     * @param {Node} node The node to compute the zoom from.
     * @returns {DOMRect[]} The updated rects, or the same rects array if no change is needed.
     */
    static convertMultipleRectZoomCoordinates(rects, node) {
        const scale = this.computeZoomScale(node);
        if (scale === 1) { return rects; }
        const results = [];
        for (const rect of rects) {
            results.push(new DOMRect(rect.left * scale, rect.top * scale, rect.width * scale, rect.height * scale));
        }
        return results;
    }

    /**
     * Checks whether a given point is contained within a rect.
     * @param {number} x The horizontal coordinate.
     * @param {number} y The vertical coordinate.
     * @param {DOMRect} rect The rect to check.
     * @returns {boolean} `true` if the point is inside the rect, `false` otherwise.
     */
    static isPointInRect(x, y, rect) {
        return (
            x >= rect.left && x < rect.right &&
            y >= rect.top && y < rect.bottom
        );
    }

    /**
     * Checks whether a given point is contained within any rect in a list.
     * @param {number} x The horizontal coordinate.
     * @param {number} y The vertical coordinate.
     * @param {DOMRect[]} rects The rect to check.
     * @returns {boolean} `true` if the point is inside any of the rects, `false` otherwise.
     */
    static isPointInAnyRect(x, y, rects) {
        for (const rect of rects) {
            if (this.isPointInRect(x, y, rect)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Checks whether a given point is contained within a selection range.
     * @param {number} x The horizontal coordinate.
     * @param {number} y The vertical coordinate.
     * @param {Selection} selection The selection to check.
     * @returns {boolean} `true` if the point is inside the selection, `false` otherwise.
     */
    static isPointInSelection(x, y, selection) {
        for (let i = 0; i < selection.rangeCount; ++i) {
            const range = selection.getRangeAt(i);
            if (this.isPointInAnyRect(x, y, range.getClientRects())) {
                return true;
            }
        }
        return false;
    }

    static isMouseButtonPressed(mouseEvent, button) {
        const mouseEventButton = mouseEvent.button;
        switch (button) {
            case 'primary': return mouseEventButton === 0;
            case 'secondary': return mouseEventButton === 2;
            case 'auxiliary': return mouseEventButton === 1;
            default: return false;
        }
    }

    /**
     * Gets an array of the active modifier keys.
     * @param {KeyboardEvent|MouseEvent|TouchEvent} event The event to check.
     * @returns {string[]} An array of modifiers.
     */
    static getActiveModifiers(event) {
        const modifiers = [];
        if (event.altKey) { modifiers.push('alt'); }
        if (event.ctrlKey) { modifiers.push('ctrl'); }
        if (event.metaKey) { modifiers.push('meta'); }
        if (event.shiftKey) { modifiers.push('shift'); }
        return modifiers;
    }

    /**
     * Gets an array of the active modifier keys and buttons.
     * @param {KeyboardEvent|MouseEvent|TouchEvent} event The event to check.
     * @returns {string[]} An array of modifiers and buttons.
     */
    static getActiveModifiersAndButtons(event) {
        const modifiers = this.getActiveModifiers(event);
        this._getActiveButtons(event, modifiers);
        return modifiers;
    }

    /**
     * Gets an array of the active buttons.
     * @param {KeyboardEvent|MouseEvent|TouchEvent} event The event to check.
     * @returns {string[]} An array of modifiers and buttons.
     */
    static getActiveButtons(event) {
        const buttons = [];
        this._getActiveButtons(event, buttons);
        return buttons;
    }

    /**
     * Adds a fullscreen change event listener. This function handles all of the browser-specific variants.
     * @param {Function} onFullscreenChanged The event callback.
     * @param {?EventListenerCollection} eventListenerCollection An optional `EventListenerCollection` to add the registration to.
     */
    static addFullscreenChangeEventListener(onFullscreenChanged, eventListenerCollection=null) {
        const target = document;
        const options = false;
        const fullscreenEventNames = [
            'fullscreenchange',
            'MSFullscreenChange',
            'mozfullscreenchange',
            'webkitfullscreenchange'
        ];
        for (const eventName of fullscreenEventNames) {
            if (eventListenerCollection === null) {
                target.addEventListener(eventName, onFullscreenChanged, options);
            } else {
                eventListenerCollection.addEventListener(target, eventName, onFullscreenChanged, options);
            }
        }
    }

    /**
     * Returns the current fullscreen element. This function handles all of the browser-specific variants.
     * @returns {?Element} The current fullscreen element, or `null` if the window is not fullscreen.
     */
    static getFullscreenElement() {
        return (
            document.fullscreenElement ||
            document.msFullscreenElement ||
            document.mozFullScreenElement ||
            document.webkitFullscreenElement ||
            null
        );
    }

    /**
     * Gets all of the nodes within a `Range`.
     * @param {Range} range The range to check.
     * @returns {Node[]} The list of nodes.
     */
    static getNodesInRange(range) {
        const end = range.endContainer;
        const nodes = [];
        for (let node = range.startContainer; node !== null; node = this.getNextNode(node)) {
            nodes.push(node);
            if (node === end) { break; }
        }
        return nodes;
    }

    /**
     * Gets the next node after a specified node. This traverses the DOM in its logical order.
     * @param {Node} node The node to start at.
     * @returns {?Node} The next node, or `null` if there is no next node.
     */
    static getNextNode(node) {
        let next = node.firstChild;
        if (next === null) {
            while (true) {
                next = node.nextSibling;
                if (next !== null) { break; }

                next = node.parentNode;
                if (next === null) { break; }

                node = next;
            }
        }
        return next;
    }

    /**
     * Checks whether any node in a list of nodes matches a selector.
     * @param {Node[]} nodes The list of ndoes to check.
     * @param {string} selector The selector to test.
     * @returns {boolean} `true` if any element node matches the selector, `false` otherwise.
     */
    static anyNodeMatchesSelector(nodes, selector) {
        const ELEMENT_NODE = Node.ELEMENT_NODE;
        for (let node of nodes) {
            for (; node !== null; node = node.parentNode) {
                if (node.nodeType !== ELEMENT_NODE) { continue; }
                if (node.matches(selector)) { return true; }
                break;
            }
        }
        return false;
    }

    /**
     * Checks whether every node in a list of nodes matches a selector.
     * @param {Node[]} nodes The list of ndoes to check.
     * @param {string} selector The selector to test.
     * @returns {boolean} `true` if every element node matches the selector, `false` otherwise.
     */
    static everyNodeMatchesSelector(nodes, selector) {
        const ELEMENT_NODE = Node.ELEMENT_NODE;
        for (let node of nodes) {
            while (true) {
                if (node === null) { return false; }
                if (node.nodeType === ELEMENT_NODE && node.matches(selector)) { break; }
                node = node.parentNode;
            }
        }
        return true;
    }

    /**
     * Checks whether the meta key is supported in the browser on the specified operating system.
     * @param {string} os The operating system to check.
     * @param {string} browser The browser to check.
     * @returns {boolean} `true` if supported, `false` otherwise.
     */
    static isMetaKeySupported(os, browser) {
        return !(browser === 'firefox' || browser === 'firefox-mobile') || os === 'mac';
    }

    /**
     * Checks whether an element on the page that can accept input is focused.
     * @returns {boolean} `true` if an input element is focused, `false` otherwise.
     */
    static isInputElementFocused() {
        const element = document.activeElement;
        if (element === null) { return false; }
        const type = element.nodeName.toUpperCase();
        switch (type) {
            case 'INPUT':
            case 'TEXTAREA':
            case 'SELECT':
                return true;
            default:
                return element.isContentEditable;
        }
    }

    /**
     * Offsets an array of DOMRects by a given amount.
     * @param {DOMRect[]} rects The DOMRects to offset.
     * @param {number} x The horizontal offset amount.
     * @param {number} y The vertical offset amount.
     * @returns {DOMRect} The DOMRects with the offset applied.
     */
    static offsetDOMRects(rects, x, y) {
        const results = [];
        for (const rect of rects) {
            results.push(new DOMRect(rect.left + x, rect.top + y, rect.width, rect.height));
        }
        return results;
    }

    /**
     * Gets the parent writing mode of an element.
     * See: https://developer.mozilla.org/en-US/docs/Web/CSS/writing-mode.
     * @param {Element} element The HTML element to check.
     * @returns {string} The writing mode.
     */
    static getElementWritingMode(element) {
        if (element !== null) {
            const {writingMode} = getComputedStyle(element);
            if (typeof writingMode === 'string') {
                return this.normalizeWritingMode(writingMode);
            }
        }
        return 'horizontal-tb';
    }

    /**
     * Normalizes a CSS writing mode value by converting non-standard and deprecated values
     * into their corresponding standard vaules.
     * @param {string} writingMode The writing mode to normalize.
     * @returns {string} The normalized writing mode.
     */
    static normalizeWritingMode(writingMode) {
        switch (writingMode) {
            case 'lr':
            case 'lr-tb':
            case 'rl':
                return 'horizontal-tb';
            case 'tb':
                return 'vertical-lr';
            case 'tb-rl':
                return 'vertical-rl';
            default:
                return writingMode;
        }
    }

    // Private

    static _getActiveButtons(event, array) {
        let {buttons} = event;
        if (typeof buttons === 'number' && buttons > 0) {
            for (let i = 0; i < 6; ++i) {
                const buttonFlag = (1 << i);
                if ((buttons & buttonFlag) !== 0) {
                    array.push(`mouse${i}`);
                    buttons &= ~buttonFlag;
                    if (buttons === 0) { break; }
                }
            }
        }
    }

    static _setImposterStyle(style, propertyName, value) {
        style.setProperty(propertyName, value, 'important');
    }

    static _createImposter(element, isTextarea) {
        const body = document.body;
        if (body === null) { return [null, null]; }

        const elementStyle = window.getComputedStyle(element);
        const elementRect = element.getBoundingClientRect();
        const documentRect = document.documentElement.getBoundingClientRect();
        let left = elementRect.left - documentRect.left;
        let top = elementRect.top - documentRect.top;

        // Container
        const container = document.createElement('div');
        const containerStyle = container.style;
        this._setImposterStyle(containerStyle, 'all', 'initial');
        this._setImposterStyle(containerStyle, 'position', 'absolute');
        this._setImposterStyle(containerStyle, 'left', '0');
        this._setImposterStyle(containerStyle, 'top', '0');
        this._setImposterStyle(containerStyle, 'width', `${documentRect.width}px`);
        this._setImposterStyle(containerStyle, 'height', `${documentRect.height}px`);
        this._setImposterStyle(containerStyle, 'overflow', 'hidden');
        this._setImposterStyle(containerStyle, 'opacity', '0');
        this._setImposterStyle(containerStyle, 'pointer-events', 'none');
        this._setImposterStyle(containerStyle, 'z-index', '2147483646');

        // Imposter
        const imposter = document.createElement('div');
        const imposterStyle = imposter.style;

        let value = element.value;
        if (value.endsWith('\n')) { value += '\n'; }
        imposter.textContent = value;

        for (let i = 0, ii = elementStyle.length; i < ii; ++i) {
            const property = elementStyle[i];
            this._setImposterStyle(imposterStyle, property, elementStyle.getPropertyValue(property));
        }
        this._setImposterStyle(imposterStyle, 'position', 'absolute');
        this._setImposterStyle(imposterStyle, 'top', `${top}px`);
        this._setImposterStyle(imposterStyle, 'left', `${left}px`);
        this._setImposterStyle(imposterStyle, 'margin', '0');
        this._setImposterStyle(imposterStyle, 'pointer-events', 'auto');

        if (isTextarea) {
            if (elementStyle.overflow === 'visible') {
                this._setImposterStyle(imposterStyle, 'overflow', 'auto');
            }
        } else {
            this._setImposterStyle(imposterStyle, 'overflow', 'hidden');
            this._setImposterStyle(imposterStyle, 'white-space', 'nowrap');
            this._setImposterStyle(imposterStyle, 'line-height', elementStyle.height);
        }

        container.appendChild(imposter);
        body.appendChild(container);

        // Adjust size
        const imposterRect = imposter.getBoundingClientRect();
        if (imposterRect.width !== elementRect.width || imposterRect.height !== elementRect.height) {
            const width = parseFloat(elementStyle.width) + (elementRect.width - imposterRect.width);
            const height = parseFloat(elementStyle.height) + (elementRect.height - imposterRect.height);
            this._setImposterStyle(imposterStyle, 'width', `${width}px`);
            this._setImposterStyle(imposterStyle, 'height', `${height}px`);
        }
        if (imposterRect.left !== elementRect.left || imposterRect.top !== elementRect.top) {
            left += (elementRect.left - imposterRect.left);
            top += (elementRect.top - imposterRect.top);
            this._setImposterStyle(imposterStyle, 'left', `${left}px`);
            this._setImposterStyle(imposterStyle, 'top', `${top}px`);
        }

        imposter.scrollTop = element.scrollTop;
        imposter.scrollLeft = element.scrollLeft;

        return [imposter, container];
    }

    static _getElementsFromPoint(x, y, all) {
        if (all) {
            // document.elementsFromPoint can return duplicates which must be removed.
            const elements = document.elementsFromPoint(x, y);
            return elements.filter((e, i) => elements.indexOf(e) === i);
        }

        const e = document.elementFromPoint(x, y);
        return e !== null ? [e] : [];
    }

    static _isPointInRange(x, y, range, normalizeCssZoom) {
        // Require a text node to start
        const {startContainer} = range;
        if (startContainer.nodeType !== Node.TEXT_NODE) {
            return false;
        }

        // Convert CSS zoom coordinates
        if (normalizeCssZoom) {
            const scale = this.computeZoomScale(startContainer);
            x /= scale;
            y /= scale;
        }

        // Scan forward
        const nodePre = range.endContainer;
        const offsetPre = range.endOffset;
        try {
            const {node, offset, content} = new DOMTextScanner(nodePre, offsetPre, true, false).seek(1);
            range.setEnd(node, offset);

            if (!this._isWhitespace(content) && this.isPointInAnyRect(x, y, range.getClientRects())) {
                return true;
            }
        } finally {
            range.setEnd(nodePre, offsetPre);
        }

        // Scan backward
        const {node, offset, content} = new DOMTextScanner(startContainer, range.startOffset, true, false).seek(-1);
        range.setStart(node, offset);

        if (!this._isWhitespace(content) && this.isPointInAnyRect(x, y, range.getClientRects())) {
            // This purposefully leaves the starting offset as modified and sets the range length to 0.
            range.setEnd(node, offset);
            return true;
        }

        // No match
        return false;
    }

    static _isWhitespace(string) {
        return string.trim().length === 0;
    }

    static _caretRangeFromPoint(x, y) {
        if (typeof document.caretRangeFromPoint === 'function') {
            // Chrome, Edge
            return document.caretRangeFromPoint(x, y);
        }

        if (typeof document.caretPositionFromPoint === 'function') {
            // Firefox
            return this._caretPositionFromPoint(x, y);
        }

        // No support
        return null;
    }

    static _caretPositionFromPoint(x, y) {
        const position = document.caretPositionFromPoint(x, y);
        if (position === null) {
            return null;
        }
        const node = position.offsetNode;
        if (node === null) {
            return null;
        }

        let offset = 0;
        const {nodeType} = node;
        switch (nodeType) {
            case Node.TEXT_NODE:
                offset = position.offset;
                break;
            case Node.ELEMENT_NODE:
                // Elements with user-select: all will return the element
                // instead of a text point inside the element.
                if (this._isElementUserSelectAll(node)) {
                    return this._caretPositionFromPointNormalizeStyles(x, y, node);
                }
                break;
        }

        try {
            const range = document.createRange();
            range.setStart(node, offset);
            range.setEnd(node, offset);
            return range;
        } catch (e) {
            // Firefox throws new DOMException("The operation is insecure.")
            // when trying to select a node from within a ShadowRoot.
            return null;
        }
    }

    static _caretPositionFromPointNormalizeStyles(x, y, nextElement) {
        const previousStyles = new Map();
        try {
            while (true) {
                this._recordPreviousStyle(previousStyles, nextElement);
                nextElement.style.setProperty('user-select', 'text', 'important');

                const position = document.caretPositionFromPoint(x, y);
                if (position === null) {
                    return null;
                }
                const node = position.offsetNode;
                if (node === null) {
                    return null;
                }

                let offset = 0;
                const {nodeType} = node;
                switch (nodeType) {
                    case Node.TEXT_NODE:
                        offset = position.offset;
                        break;
                    case Node.ELEMENT_NODE:
                        // Elements with user-select: all will return the element
                        // instead of a text point inside the element.
                        if (this._isElementUserSelectAll(node)) {
                            if (previousStyles.has(node)) {
                                // Recursive
                                return null;
                            }
                            nextElement = node;
                            continue;
                        }
                        break;
                }

                try {
                    const range = document.createRange();
                    range.setStart(node, offset);
                    range.setEnd(node, offset);
                    return range;
                } catch (e) {
                    // Firefox throws new DOMException("The operation is insecure.")
                    // when trying to select a node from within a ShadowRoot.
                    return null;
                }
            }
        } finally {
            this._revertStyles(previousStyles);
        }
    }

    static _caretRangeFromPointExt(x, y, elements, normalizeCssZoom) {
        let previousStyles = null;
        try {
            let i = 0;
            let startContinerPre = null;
            while (true) {
                const range = this._caretRangeFromPoint(x, y);
                if (range === null) {
                    return null;
                }

                const startContainer = range.startContainer;
                if (startContinerPre !== startContainer) {
                    if (this._isPointInRange(x, y, range, normalizeCssZoom)) {
                        return range;
                    }
                    startContinerPre = startContainer;
                }

                if (previousStyles === null) { previousStyles = new Map(); }
                i = this._disableTransparentElement(elements, i, previousStyles);
                if (i < 0) {
                    return null;
                }
            }
        } finally {
            if (previousStyles !== null && previousStyles.size > 0) {
                this._revertStyles(previousStyles);
            }
        }
    }

    static _disableTransparentElement(elements, i, previousStyles) {
        while (true) {
            if (i >= elements.length) {
                return -1;
            }

            const element = elements[i++];
            if (this._isElementTransparent(element)) {
                this._recordPreviousStyle(previousStyles, element);
                element.style.setProperty('pointer-events', 'none', 'important');
                return i;
            }
        }
    }

    static _recordPreviousStyle(previousStyles, element) {
        if (previousStyles.has(element)) { return; }
        const style = element.hasAttribute('style') ? element.getAttribute('style') : null;
        previousStyles.set(element, style);
    }

    static _revertStyles(previousStyles) {
        for (const [element, style] of previousStyles.entries()) {
            if (style === null) {
                element.removeAttribute('style');
            } else {
                element.setAttribute('style', style);
            }
        }
    }

    static _isElementTransparent(element) {
        if (
            element === document.body ||
            element === document.documentElement
        ) {
            return false;
        }
        const style = window.getComputedStyle(element);
        return (
            parseFloat(style.opacity) <= 0 ||
            style.visibility === 'hidden' ||
            (style.backgroundImage === 'none' && this._isColorTransparent(style.backgroundColor))
        );
    }

    static _isColorTransparent(cssColor) {
        return this._transparentColorPattern.test(cssColor);
    }

    static _isElementUserSelectAll(element) {
        return getComputedStyle(element).userSelect === 'all';
    }
}
// eslint-disable-next-line no-underscore-dangle
DocumentUtil._transparentColorPattern = /rgba\s*\([^)]*,\s*0(?:\.0+)?\s*\)/;
// eslint-disable-next-line no-underscore-dangle
DocumentUtil._cssZoomSupported = null;
// eslint-disable-next-line no-underscore-dangle
DocumentUtil._getRangeFromPointHandlers = [];