Fix current time for inactive timeline

src/proxy-animation.js

@@ -894,7 +894,11 @@ function autoAlignStartTime(details) {
   // 5. Let start offset be the resolved timeline time corresponding to the start of the animation attachment range.
   //    In the case of view timelines, it requires a calculation based on the proportion of the cover range.
   try {
-    startOffset = CSS.percent(fractionalStartDelay(details) * 100);
+    const startDelayFraction = fractionalStartDelay(details);
+    if (startDelayFraction === null)
+      return;
+
+    startOffset = CSS.percent(startDelayFraction * 100);
   } catch {
     // TODO: Validate supported values for range start, to avoid exceptions when resolving the values.
 
@@ -907,7 +911,11 @@ function autoAlignStartTime(details) {
   // 6. Let end offset be the resolved timeline time corresponding to the end of the animation attachment range.
   //    In the case of view timelines, it requires a calculation based on the proportion of the cover range.
   try {
-    endOffset = CSS.percent((1 - fractionalEndDelay(details)) * 100);
+    const endDelayFraction = fractionalEndDelay(details);
+    if (endDelayFraction === null)
+      return;
+
+    endOffset = CSS.percent((1 - endDelayFraction) * 100);
   } catch {
     // TODO: Validate supported values for range end, to avoid exceptions when resolving the values.
 

src/scroll-timeline-base.js

@@ -230,9 +230,9 @@ function updateMeasurements(source) {
     }
   }
 
-  requestAnimationFrame(() => {
-    // Defer ticking timeline to animation frame to prevent
-    // "ResizeObserver loop completed with undelivered notifications"
+  setTimeout(() => {
+    // Schedule a task to update timelines after all measurements are completed
+    // TODO: run task only once if there are multiple calls to updateMeasurements for the same source
     for (const ref of details.timelineRefs) {
       const timeline = ref.deref();
       if (timeline) {
@@ -593,6 +593,9 @@ function range(timeline, phase) {
   if (!(timeline instanceof ViewTimeline))
     return unresolved;
 
+  if (!sourceMeasurements || !subjectMeasurements)
+    return unresolved;
+
   return calculateRange(phase, sourceMeasurements, subjectMeasurements, details.axis, details.inset);
 }
 
@@ -776,7 +779,7 @@ export function relativePosition(timeline, phase, offset) {
 
 export function calculateRelativePosition(phaseRange, offset, coverRange, subject) {
   if (!phaseRange || !coverRange)
-    return 0;
+    return null;
 
   let style = getComputedStyle(subject)
   const info = {

test/expected.txt

@@ -555,7 +555,7 @@ PASS	/scroll-animations/scroll-timelines/cancel-animation.html	The finished prom
 PASS	/scroll-animations/scroll-timelines/cancel-animation.html	The cancel event should NOT be fired if the animation is already idle
 PASS	/scroll-animations/scroll-timelines/cancel-animation.html	Canceling an animation should fire cancel event on orphaned element
 PASS	/scroll-animations/scroll-timelines/cancel-animation.html	Canceling an animation with inactive timeline should cause its start time and hold time to be unresolved
-FAIL	/scroll-animations/scroll-timelines/cancel-animation.html	oncancel event is fired when the timeline is inactive.
+TIMEOUT	/scroll-animations/scroll-timelines/cancel-animation.html	oncancel event is fired when the timeline is inactive.
 PASS	/scroll-animations/scroll-timelines/constructor-no-document.html	The source can be null if the document.scrollingElement does not exist
 PASS	/scroll-animations/scroll-timelines/constructor.html	A ScrollTimeline can be created with a source
 PASS	/scroll-animations/scroll-timelines/constructor.html	A ScrollTimeline can be created with a non-scrolling source
@@ -790,12 +790,12 @@ PASS	/scroll-animations/scroll-timelines/scroll-animation-effect-phases.tentativ
 PASS	/scroll-animations/scroll-timelines/scroll-animation-inactive-timeline.html	Play pending task doesn't run when the timeline is inactive.
 PASS	/scroll-animations/scroll-timelines/scroll-animation-inactive-timeline.html	Animation start and current times are correct if scroll timeline is activated after animation.play call.
 PASS	/scroll-animations/scroll-timelines/scroll-animation-inactive-timeline.html	Animation start and current times are correct if scroll timeline is activated after setting start time.
-FAIL	/scroll-animations/scroll-timelines/scroll-animation-inactive-timeline.html	Animation current time is correct when the timeline becomes newly inactive and then active again.
+PASS	/scroll-animations/scroll-timelines/scroll-animation-inactive-timeline.html	Animation current time is correct when the timeline becomes newly inactive and then active again.
 FAIL	/scroll-animations/scroll-timelines/scroll-animation.html	Animation start and current times are correct for each animation state.
 FAIL	/scroll-animations/scroll-timelines/scroll-animation.html	Animation start and current times are correct for each animation state when the animation starts playing with advanced scroller.
 PASS	/scroll-animations/scroll-timelines/scroll-animation.html	Finished animation plays on reverse scrolling.
 FAIL	/scroll-animations/scroll-timelines/scroll-animation.html	Sending animation finished events by finished animation on reverse scrolling.
-FAIL	/scroll-animations/scroll-timelines/scroll-timeline-invalidation.html	Animation current time and effect local time are updated after scroller content size changes.
+PASS	/scroll-animations/scroll-timelines/scroll-timeline-invalidation.html	Animation current time and effect local time are updated after scroller content size changes.
 PASS	/scroll-animations/scroll-timelines/scroll-timeline-invalidation.html	Animation current time and effect local time are updated after scroller size changes.
 FAIL	/scroll-animations/scroll-timelines/scroll-timeline-invalidation.html	If scroll animation resizes its scroll timeline scroller, layout reruns once per frame.
 FAIL	/scroll-animations/scroll-timelines/scroll-timeline-range.html	Scroll timeline with percentage range [JavaScript API]
@@ -957,4 +957,4 @@ FAIL	/scroll-animations/view-timelines/view-timeline-sticky-block.html	View time
 FAIL	/scroll-animations/view-timelines/view-timeline-sticky-inline.html	View timeline with sticky target, block axis.
 FAIL	/scroll-animations/view-timelines/view-timeline-subject-size-changes.html	View timeline with subject size change after the creation of the animation
 FAIL	/scroll-animations/view-timelines/zero-intrinsic-iteration-duration.tentative.html	Intrinsic iteration duration is non-negative
-Passed 432 of 959 tests.
+Passed 434 of 959 tests.