-
Notifications
You must be signed in to change notification settings - Fork 89
/
scroll-timeline-base.js
895 lines (767 loc) · 27.3 KB
/
scroll-timeline-base.js
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
// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
import {installCSSOM} from "./proxy-cssom.js";
import {simplifyCalculation} from "./simplify-calculation";
import {normalizeAxis, splitIntoComponentValues} from './utils.js';
installCSSOM();
const DEFAULT_TIMELINE_AXIS = 'block';
let scrollTimelineOptions = new WeakMap();
let sourceDetails = new WeakMap();
export const ANIMATION_RANGE_NAMES = ['entry', 'exit', 'cover', 'contain', 'entry-crossing', 'exit-crossing'];
function scrollEventSource(source) {
if (source === document.scrollingElement) return document;
return source;
}
/**
* Updates the currentTime for all Web Animation instanced attached to a ScrollTimeline instance
* @param scrollTimelineInstance {ScrollTimeline}
*/
function updateInternal(scrollTimelineInstance) {
validateSource(scrollTimelineInstance);
const details = scrollTimelineOptions.get(scrollTimelineInstance);
let animations = details.animations;
if (animations.length === 0) return;
let timelineTime = scrollTimelineInstance.currentTime;
for (let i = 0; i < animations.length; i++) {
animations[i].tickAnimation(timelineTime);
}
}
/**
* Calculates a scroll offset that corrects for writing modes, text direction
* and a logical axis.
* @param scrollTimeline {ScrollTimeline}
* @param axis {String}
* @returns {Number}
*/
function directionAwareScrollOffset(source, axis) {
if (!source)
return null;
const sourceMeasurements = sourceDetails.get(source).sourceMeasurements;
const style = getComputedStyle(source);
// All writing modes are vertical except for horizontal-tb.
// TODO: sideways-lr should flow bottom to top, but is currently unsupported
// in Chrome.
// http://drafts.csswg.org/css-writing-modes-4/#block-flow
let currentScrollOffset = sourceMeasurements.scrollTop;
if (normalizeAxis(axis, style) === 'x') {
// Negative values are reported for scrollLeft when the inline text
// direction is right to left or for vertical text with a right to left
// block flow. This is a consequence of shifting the scroll origin due to
// changes in the overflow direction.
// http://drafts.csswg.org/cssom-view/#overflow-directions.
currentScrollOffset = Math.abs(sourceMeasurements.scrollLeft);
}
return currentScrollOffset;
}
/**
* Determines target effect end based on animation duration, iterations count and start and end delays
* returned value should always be positive
* @param options {Animation} animation
* @returns {number}
*/
export function calculateTargetEffectEnd(animation) {
return animation.effect.getComputedTiming().activeDuration;
}
/**
* Calculates scroll offset based on axis and source geometry
* @param source {DOMElement}
* @param axis {String}
* @returns {number}
*/
export function calculateMaxScrollOffset(source, axis) {
const sourceMeasurements = sourceDetails.get(source).sourceMeasurements;
// Only one horizontal writing mode: horizontal-tb. All other writing modes
// flow vertically.
const horizontalWritingMode =
getComputedStyle(source).writingMode == 'horizontal-tb';
if (axis === "block")
axis = horizontalWritingMode ? "y" : "x";
else if (axis === "inline")
axis = horizontalWritingMode ? "x" : "y";
if (axis === "y")
return sourceMeasurements.scrollHeight - sourceMeasurements.clientHeight;
else if (axis === "x")
return sourceMeasurements.scrollWidth - sourceMeasurements.clientWidth;
}
function resolvePx(cssValue, info) {
const cssNumericValue = simplifyCalculation(cssValue, info);
if (cssNumericValue instanceof CSSUnitValue) {
if (cssNumericValue.unit === 'px') {
return cssNumericValue.value;
} else {
throw TypeError("Unhandled unit type " + cssNumericValue.unit);
}
} else {
throw TypeError('Unsupported value type: ' + typeof (cssValue));
}
}
// Detects if the cached source is obsolete, and updates if required
// to ensure the new source has a scroll listener.
function validateSource(timeline) {
if (!(timeline instanceof ViewTimeline)) {
validateAnonymousSource(timeline);
return;
}
const node = timeline.subject;
if (!node) {
updateSource(timeline, null);
return;
}
const display = getComputedStyle(node).display;
if (display == 'none') {
updateSource(timeline, null);
return;
}
const source = getScrollParent(node);
updateSource(timeline, source);
}
function validateAnonymousSource(timeline) {
const details = scrollTimelineOptions.get(timeline);
if(!details.anonymousSource)
return;
const source = getAnonymousSourceElement(details.anonymousSource, details.anonymousTarget);
updateSource(timeline, source);
}
function isValidAxis(axis) {
return ["block", "inline", "x", "y"].includes(axis);
}
/**
* Read measurements of source element
* @param {HTMLElement} source
* @return {{clientWidth: *, scrollHeight: *, scrollLeft, clientHeight: *, scrollTop, scrollWidth: *}}
*/
export function measureSource (source) {
const style = getComputedStyle(source);
return {
scrollLeft: source.scrollLeft,
scrollTop: source.scrollTop,
scrollWidth: source.scrollWidth,
scrollHeight: source.scrollHeight,
clientWidth: source.clientWidth,
clientHeight: source.clientHeight,
writingMode: style.writingMode,
direction: style.direction,
scrollPaddingTop: style.scrollPaddingTop,
scrollPaddingBottom: style.scrollPaddingBottom,
scrollPaddingLeft: style.scrollPaddingLeft,
scrollPaddingRight: style.scrollPaddingRight
};
}
/**
* Measure subject element relative to source
* @param {HTMLElement} source
* @param {HTMLElement|undefined} subject
* @param subject
*/
export function measureSubject(source, subject) {
if (!source || !subject) {
return
}
let top = 0;
let left = 0;
let node = subject;
const ancestor = source.offsetParent;
while (node && node != ancestor) {
left += node.offsetLeft;
top += node.offsetTop;
node = node.offsetParent;
}
left -= source.offsetLeft + source.clientLeft;
top -= source.offsetTop + source.clientTop;
const style = getComputedStyle(subject);
return {
top,
left,
offsetWidth: subject.offsetWidth,
offsetHeight: subject.offsetHeight,
fontSize: style.fontSize,
};
}
/**
* Update measurements of source, and update timelines
* @param {HTMLElement} source
*/
function updateMeasurements(source) {
let details = sourceDetails.get(source);
details.sourceMeasurements = measureSource(source);
// Update measurements of the subject of connected view timelines
for (const ref of details.timelineRefs) {
const timeline = ref.deref();
if ((timeline instanceof ViewTimeline)) {
const timelineDetails = scrollTimelineOptions.get(timeline)
timelineDetails.subjectMeasurements = measureSubject(source, timeline.subject)
}
}
if (details.updateScheduled)
return;
setTimeout(() => {
// Schedule a task to update timelines after all measurements are completed
for (const ref of details.timelineRefs) {
const timeline = ref.deref();
if (timeline) {
updateInternal(timeline);
}
}
details.updateScheduled = false;
});
details.updateScheduled = true;
}
function updateSource(timeline, source) {
const timelineDetails = scrollTimelineOptions.get(timeline);
const oldSource = timelineDetails.source;
if (oldSource == source)
return;
if (oldSource) {
const details = sourceDetails.get(oldSource);
if (details) {
// Remove timeline reference from old source
details.timelineRefs.delete(timeline);
// Clean up timeline refs that have been garbage-collected
const undefinedRefs = Array.from(details.timelineRefs).filter(ref => typeof ref.deref() === 'undefined');
for (const ref of undefinedRefs) {
details.timelineRefs.delete(ref);
}
if (details.timelineRefs.size === 0) {
// All timelines have been disconnected from the source
// Clean up
details.disconnect();
sourceDetails.delete(oldSource);
}
}
}
timelineDetails.source = source;
if (source) {
let details = sourceDetails.get(source);
if (!details) {
// This is the first timeline for this source
// Store a set of weak refs to connected timelines and current measurements
details = {
timelineRefs: new Set(),
sourceMeasurements: measureSource(source)
};
sourceDetails.set(source, details);
// Use resize observer to detect changes to source size
const resizeObserver = new ResizeObserver((entries) => {
for (const entry of entries) {
updateMeasurements(timelineDetails.source)
}
});
resizeObserver.observe(source);
for (const child of source.children) {
resizeObserver.observe(child)
}
// Use mutation observer to detect updated style attributes on source element
const mutationObserver = new MutationObserver((records) => {
for (const record of records) {
updateMeasurements(record.target);
}
});
mutationObserver.observe(source, {attributes: true, attributeFilter: ['style', 'class']});
const scrollListener = () => {
// Sample and store scroll pos
details.sourceMeasurements.scrollLeft = source.scrollLeft;
details.sourceMeasurements.scrollTop = source.scrollTop;
for (const ref of details.timelineRefs) {
const timeline = ref.deref();
if (timeline) {
updateInternal(timeline);
}
}
};
scrollEventSource(source).addEventListener("scroll", scrollListener);
details.disconnect = () => {
resizeObserver.disconnect();
mutationObserver.disconnect();
scrollEventSource(source).removeEventListener("scroll", scrollListener);
};
}
// Add a weak ref to the timeline so that we can update it when the source changes
details.timelineRefs.add(new WeakRef(timeline));
}
}
/**
* Removes a Web Animation instance from ScrollTimeline
* @param scrollTimeline {ScrollTimeline}
* @param animation {Animation}
* @param options {Object}
*/
export function removeAnimation(scrollTimeline, animation) {
let animations = scrollTimelineOptions.get(scrollTimeline).animations;
for (let i = 0; i < animations.length; i++) {
if (animations[i].animation == animation) {
animations.splice(i, 1);
}
}
}
/**
* Attaches a Web Animation instance to ScrollTimeline.
* @param scrollTimeline {ScrollTimeline}
* @param animation {Animation}
* @param tickAnimation {function(number)}
*/
export function addAnimation(scrollTimeline, animation, tickAnimation) {
let animations = scrollTimelineOptions.get(scrollTimeline).animations;
for (let i = 0; i < animations.length; i++) {
// @TODO: This early return causes issues when a page with the polyfill
// is loaded from the BFCache. Ideally, this code gets fixed instead of
// the workaround which clears the proxyAnimations cache on pagehide.
// See https://github.com/flackr/scroll-timeline/issues/146#issuecomment-1698159183
// for details.
if (animations[i].animation == animation)
return;
}
animations.push({
animation: animation,
tickAnimation: tickAnimation
});
queueMicrotask(() => {
updateInternal(scrollTimeline);
});
}
// TODO: this is a private function used for unit testing add function
export function _getStlOptions(scrollTimeline) {
return scrollTimelineOptions.get(scrollTimeline);
}
export class ScrollTimeline {
constructor(options) {
scrollTimelineOptions.set(this, {
source: null,
axis: DEFAULT_TIMELINE_AXIS,
anonymousSource: (options ? options.anonymousSource : null),
anonymousTarget: (options ? options.anonymousTarget : null),
// View timeline
subject: null,
inset: null,
// Internal members
animations: [],
subjectMeasurements: null
});
const source =
options && options.source !== undefined ? options.source
: document.scrollingElement;
updateSource(this, source);
if ((options && options.axis !== undefined) &&
(options.axis != DEFAULT_TIMELINE_AXIS)) {
if (!isValidAxis(options.axis)) {
throw TypeError("Invalid axis");
}
scrollTimelineOptions.get(this).axis = options.axis;
}
updateInternal(this);
}
set source(element) {
updateSource(this, element);
updateInternal(this);
}
get source() {
return scrollTimelineOptions.get(this).source;
}
set axis(axis) {
if (!isValidAxis(axis)) {
throw TypeError("Invalid axis");
}
scrollTimelineOptions.get(this).axis = axis;
updateInternal(this);
}
get axis() {
return scrollTimelineOptions.get(this).axis;
}
get duration() {
return CSS.percent(100);
}
get phase() {
// Per https://drafts.csswg.org/scroll-animations-1/#phase-algorithm
// Step 1
const unresolved = null;
// if source is null
const container = this.source;
if (!container) return "inactive";
let scrollerStyle = getComputedStyle(container);
// if source does not currently have a CSS layout box
if (scrollerStyle.display == "none")
return "inactive";
// if source's layout box is not a scroll container"
if (container != document.scrollingElement &&
(scrollerStyle.overflow == 'visible' ||
scrollerStyle.overflow == "clip")) {
return "inactive";
}
return "active"
}
get currentTime() {
const unresolved = null;
const container = this.source;
if (!container || !container.isConnected) return unresolved;
if (this.phase == 'inactive')
return unresolved;
const scrollerStyle = getComputedStyle(container);
if (
scrollerStyle.display === "inline" ||
scrollerStyle.display === "none"
) {
return unresolved;
}
const axis = this.axis;
const scrollPos = directionAwareScrollOffset(container, axis);
const maxScrollPos = calculateMaxScrollOffset(container, axis);
return maxScrollPos > 0 ? CSS.percent(100 * scrollPos / maxScrollPos)
: CSS.percent(100);
}
get __polyfill() {
return true;
}
}
// Methods for calculation of the containing block.
// See https://developer.mozilla.org/en-US/docs/Web/CSS/Containing_block.
function findClosestAncestor(element, matcher) {
let candidate = element.parentElement;
while(candidate != null) {
if (matcher(candidate))
return candidate;
candidate = candidate.parentElement;
}
}
export function getAnonymousSourceElement(sourceType, node) {
switch (sourceType) {
case 'root':
return document.scrollingElement;
case 'nearest':
return getScrollParent(node);
case 'self':
return node;
default:
throw new TypeError('Invalid ScrollTimeline Source Type.');
}
}
function isBlockContainer(element) {
const style = getComputedStyle(element);
switch (style.display) {
case 'block':
case 'inline-block':
case 'list-item':
case 'table':
case 'table-caption':
case 'flow-root':
case 'flex':
case 'grid':
return true;
}
return false;
}
function isFixedElementContainer(element) {
const style = getComputedStyle(element);
if (style.transform != 'none' || style.perspective != 'none')
return true;
if (style.willChange == 'transform' || style.willChange == 'perspective')
return true;
if (style.filter != 'none' || style.willChange == 'filter')
return true;
if (style.backdropFilter != 'none')
return true;
return false;
}
function isAbsoluteElementContainer(element) {
const style = getComputedStyle(element);
if (style.position != 'static')
return true;
return isFixedElementContainer(element);
}
function getContainingBlock(element) {
switch (getComputedStyle(element).position) {
case 'static':
case 'relative':
case 'sticky':
return findClosestAncestor(element, isBlockContainer);
case 'absolute':
return findClosestAncestor(element, isAbsoluteElementContainer);
case 'fixed':
return findClosestAncestor(element, isFixedElementContainer);
}
}
export function getScrollParent(node) {
if (!node || !node.isConnected)
return undefined;
while (node = getContainingBlock(node)) {
const style = getComputedStyle(node);
switch(style['overflow-x']) {
case 'auto':
case 'scroll':
case 'hidden':
// https://drafts.csswg.org/css-overflow-3/#overflow-propagation
// The UA must apply the overflow from the root element to the viewport;
// however, if the overflow is visible in both axis, then the overflow
// of the first visible child body is applied instead.
if (node == document.body &&
getComputedStyle(document.scrollingElement).overflow == "visible")
return document.scrollingElement;
return node;
}
}
return document.scrollingElement;
}
// ---- View timelines -----
// Computes the scroll offsets corresponding to the [0, 100]% range for a
// specific phase on a view timeline.
// TODO: Track changes to determine when associated animations require their
// timing to be renormalized.
export function range(timeline, phase) {
const details = scrollTimelineOptions.get(timeline);
const subjectMeasurements = details.subjectMeasurements
const sourceMeasurements = sourceDetails.get(details.source).sourceMeasurements
const unresolved = null;
if (timeline.phase === 'inactive')
return unresolved;
if (!(timeline instanceof ViewTimeline))
return unresolved;
return calculateRange(phase, sourceMeasurements, subjectMeasurements, details.axis, details.inset);
}
export function calculateRange(phase, sourceMeasurements, subjectMeasurements, axis, optionsInset) {
// TODO: handle position sticky
// Determine the view and container size based on the scroll direction.
// The view position is the scroll position of the logical starting edge
// of the view.
const rtl = sourceMeasurements.direction == 'rtl' || sourceMeasurements.writingMode == 'vertical-rl';
let viewSize = undefined;
let viewPos = undefined;
let sizes = {
fontSize: subjectMeasurements.fontSize
};
if (normalizeAxis(axis, sourceMeasurements) === 'x') {
viewSize = subjectMeasurements.offsetWidth;
viewPos = subjectMeasurements.left;
sizes.scrollPadding = [sourceMeasurements.scrollPaddingLeft, sourceMeasurements.scrollPaddingRight];
if (rtl) {
viewPos += sourceMeasurements.scrollWidth - sourceMeasurements.clientWidth;
sizes.scrollPadding = [sourceMeasurements.scrollPaddingRight, sourceMeasurements.scrollPaddingLeft];
}
sizes.containerSize = sourceMeasurements.clientWidth;
} else {
// TODO: support sideways-lr
viewSize = subjectMeasurements.offsetHeight;
viewPos = subjectMeasurements.top;
sizes.scrollPadding = [sourceMeasurements.scrollPaddingTop, sourceMeasurements.scrollPaddingBottom];
sizes.containerSize = sourceMeasurements.clientHeight;
}
const inset = calculateInset(optionsInset, sizes);
// Cover:
// 0% progress represents the position at which the start border edge of the
// element’s principal box coincides with the end edge of its view progress
// visibility range.
// 100% progress represents the position at which the end border edge of the
// element’s principal box coincides with the start edge of its view progress
// visibility range.
const coverStartOffset = viewPos - sizes.containerSize + inset.end;
const coverEndOffset = viewPos + viewSize - inset.start;
// Contain:
// The 0% progress represents the earlier of the following positions:
// 1. The start border edge of the element’s principal box coincides with
// the start edge of its view progress visibility range.
// 2. The end border edge of the element’s principal box coincides with
// the end edge of its view progress visibility range.
// The 100% progress represents the greater of the following positions:
// 1. The start border edge of the element’s principal box coincides with
// the start edge of its view progress visibility range.
// 2. The end border edge of the element’s principal box coincides with
// the end edge of its view progress visibility range.
const alignStartOffset = coverStartOffset + viewSize;
const alignEndOffset = coverEndOffset - viewSize;
const containStartOffset = Math.min(alignStartOffset, alignEndOffset);
const containEndOffset = Math.max(alignStartOffset, alignEndOffset);
// Entry and Exit bounds align with cover and contains bounds.
let startOffset = undefined;
let endOffset = undefined;
// Take inset into account when determining the scrollport size
const adjustedScrollportSize = sizes.containerSize - inset.start - inset.end;
const subjectIsLargerThanScrollport = viewSize > adjustedScrollportSize;
switch(phase) {
case 'cover':
startOffset = coverStartOffset;
endOffset = coverEndOffset;
break;
case 'contain':
startOffset = containStartOffset;
endOffset = containEndOffset;
break;
case 'entry':
startOffset = coverStartOffset;
endOffset = containStartOffset;
break;
case 'exit':
startOffset = containEndOffset;
endOffset = coverEndOffset;
break;
case 'entry-crossing':
startOffset = coverStartOffset;
endOffset = subjectIsLargerThanScrollport ? containEndOffset : containStartOffset;
break;
case 'exit-crossing':
startOffset = subjectIsLargerThanScrollport ? containStartOffset : containEndOffset;
endOffset = coverEndOffset;
break;
}
return { start: startOffset, end: endOffset };
}
function parseInset(value) {
const inset = { start: 0, end: 0 };
if (!value) return inset;
let parts;
// Parse string parts to
if (typeof value === 'string') {
parts = splitIntoComponentValues(value).map(str => {
if (str === 'auto') {
return 'auto';
}
try {
return CSSNumericValue.parse(str);
} catch (e) {
throw TypeError(`Could not parse inset "${value}"`);
}
});
} else if (Array.isArray(value)) {
parts = value;
} else {
parts = [value];
}
if (parts.length === 0 || parts.length > 2) {
throw TypeError('Invalid inset');
}
// Validate that the parts are 'auto' or <length-percentage>
for (const part of parts) {
if (part === 'auto') {
continue;
}
const type = part.type();
if (!(type.length === 1 || type.percent === 1)) {
throw TypeError('Invalid inset');
}
}
return {
start: parts[0],
end: parts[1] ?? parts[0]
};
}
function calculateInset(value, sizes) {
const inset = { start: 0, end: 0 };
if (!value) return inset;
const [start, end] = [value.start, value.end].map((part, i) => {
if (part === 'auto') {
return sizes.scrollPadding[i] === 'auto' ? 0 : parseFloat(sizes.scrollPadding[i]);
}
return resolvePx(part, {
percentageReference: CSS.px(sizes.containerSize),
fontSize: CSS.px(parseFloat(sizes.fontSize))
})
});
return { start, end };
}
// Calculate the fractional offset of a range value relative to the normal range.
export function fractionalOffset(timeline, value) {
if (timeline instanceof ViewTimeline) {
const { rangeName, offset } = value;
const phaseRange = range(timeline, rangeName);
const coverRange = range(timeline, 'cover');
return calculateRelativePosition(phaseRange, offset, coverRange, timeline.subject);
}
if (timeline instanceof ScrollTimeline) {
const { axis, source } = timeline;
const { sourceMeasurements } = sourceDetails.get(source);
let sourceScrollDistance = undefined;
if (normalizeAxis(axis, sourceMeasurements) === 'x') {
sourceScrollDistance = sourceMeasurements.scrollWidth - sourceMeasurements.clientWidth;
} else {
sourceScrollDistance = sourceMeasurements.scrollHeight - sourceMeasurements.clientHeight;
}
// TODO: pass relative measurements (viewport, font-size, root font-size, etc. ) to resolvePx() to resolve relative units
const position = resolvePx(value, {percentageReference: CSS.px(sourceScrollDistance)});
const fractionalOffset = position / sourceScrollDistance;
return fractionalOffset;
}
unsupportedTimeline(timeline);
}
export function calculateRelativePosition(phaseRange, offset, coverRange, subject) {
if (!phaseRange || !coverRange)
return 0;
let style = getComputedStyle(subject)
const info = {
percentageReference: CSS.px(phaseRange.end - phaseRange.start),
fontSize: CSS.px(parseFloat(style.fontSize))
};
const offsetPX = resolvePx(offset, info) + phaseRange.start;
return (offsetPX - coverRange.start) / (coverRange.end - coverRange.start);
}
// https://drafts.csswg.org/scroll-animations-1/#view-progress-timelines
export class ViewTimeline extends ScrollTimeline {
// As specced, ViewTimeline has a subject and a source, but
// ViewTimelineOptions only has source. Furthermore, there is a strict
// relationship between subject and source (source is nearest scrollable
// ancestor of subject).
// Proceeding under the assumption that subject will be added to
// ViewTimelineOptions. Inferring the source from the subject if not
// explicitly set.
constructor(options) {
super(options);
const details = scrollTimelineOptions.get(this);
details.subject = options && options.subject ? options.subject : undefined;
// TODO: Handle insets.
if (options && options.inset) {
details.inset = parseInset(options.inset);
}
if (details.subject) {
const resizeObserver = new ResizeObserver(() => {
updateMeasurements(details.source)
})
resizeObserver.observe(details.subject)
const mutationObserver = new MutationObserver(() => {
updateMeasurements(details.source);
});
mutationObserver.observe(details.subject, {attributes: true, attributeFilter: ['class', 'style']});
}
validateSource(this);
details.subjectMeasurements = measureSubject(details.source, details.subject);
updateInternal(this);
}
get source() {
validateSource(this);
return scrollTimelineOptions.get(this).source;
}
set source(source) {
throw new Error("Cannot set the source of a view timeline");
}
get subject() {
return scrollTimelineOptions.get(this).subject;
}
// The axis is called "axis" for a view timeline.
// Internally we still call it axis.
get axis() {
return scrollTimelineOptions.get(this).axis;
}
get currentTime() {
const unresolved = null;
const scrollPos = directionAwareScrollOffset(this.source, this.axis);
if (scrollPos == unresolved)
return unresolved;
const offsets = range(this, 'cover');
if (!offsets)
return unresolved;
const progress =
(scrollPos - offsets.start) / (offsets.end - offsets.start);
return CSS.percent(100 * progress);
}
get startOffset() {
return CSS.px(range(this,'cover').start);
}
get endOffset() {
return CSS.px(range(this,'cover').end);
}
}