1 files changed, 171 insertions, 0 deletions
diff --git a/layout/style/TimelineManager.cpp b/layout/style/TimelineManager.cpp
new file mode 100644
index 0000000000..0d2d98e31c
--- /dev/null
+++ b/layout/style/TimelineManager.cpp
@@ -0,0 +1,171 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "TimelineManager.h"
+
+#include "mozilla/ElementAnimationData.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/ScrollTimeline.h"
+#include "mozilla/dom/ViewTimeline.h"
+#include "nsPresContext.h"
+
+namespace mozilla {
+using dom::Element;
+using dom::ScrollTimeline;
+using dom::ViewTimeline;
+
+template <typename TimelineType>
+void TryDestroyTimeline(Element* aElement, PseudoStyleType aPseudoType) {
+  auto* collection =
+      TimelineCollection<TimelineType>::Get(aElement, aPseudoType);
+  if (!collection) {
+    return;
+  }
+  collection->Destroy();
+}
+
+void TimelineManager::UpdateTimelines(Element* aElement,
+                                      PseudoStyleType aPseudoType,
+                                      const ComputedStyle* aComputedStyle,
+                                      ProgressTimelineType aType) {
+  MOZ_ASSERT(
+      aElement->IsInComposedDoc(),
+      "No need to update timelines that are not attached to the document tree");
+
+  // If we are in a display:none subtree we will have no computed values.
+  // However, if we are on the root of display:none subtree, the computed values
+  // might not have been cleared yet. In either case, since CSS animations
+  // should not run in display:none subtrees, so we don't need timeline, either.
+  const bool shouldDestroyTimelines =
+      !aComputedStyle ||
+      aComputedStyle->StyleDisplay()->mDisplay == StyleDisplay::None;
+
+  switch (aType) {
+    case ProgressTimelineType::Scroll:
+      if (shouldDestroyTimelines) {
+        TryDestroyTimeline<ScrollTimeline>(aElement, aPseudoType);
+        return;
+      }
+      DoUpdateTimelines<StyleScrollTimeline, ScrollTimeline>(
+          mPresContext, aElement, aPseudoType,
+          aComputedStyle->StyleUIReset()->mScrollTimelines,
+          aComputedStyle->StyleUIReset()->mScrollTimelineNameCount);
+      break;
+
+    case ProgressTimelineType::View:
+      if (shouldDestroyTimelines) {
+        TryDestroyTimeline<ViewTimeline>(aElement, aPseudoType);
+        return;
+      }
+      DoUpdateTimelines<StyleViewTimeline, ViewTimeline>(
+          mPresContext, aElement, aPseudoType,
+          aComputedStyle->StyleUIReset()->mViewTimelines,
+          aComputedStyle->StyleUIReset()->mViewTimelineNameCount);
+      break;
+  }
+}
+
+template <typename TimelineType>
+static already_AddRefed<TimelineType> PopExistingTimeline(
+    const nsAtom* aName, TimelineCollection<TimelineType>* aCollection) {
+  if (!aCollection) {
+    return nullptr;
+  }
+  return aCollection->Extract(aName);
+}
+
+template <typename StyleType, typename TimelineType>
+static auto BuildTimelines(nsPresContext* aPresContext, Element* aElement,
+                           PseudoStyleType aPseudoType,
+                           const nsStyleAutoArray<StyleType>& aTimelines,
+                           size_t aTimelineCount,
+                           TimelineCollection<TimelineType>* aCollection) {
+  typename TimelineCollection<TimelineType>::TimelineMap result;
+  // If multiple timelines are attempting to modify the same property, then the
+  // timeline closest to the end of the list of names wins.
+  // The spec doesn't mention this specifically for scroll-timeline-name and
+  // view-timeline-name, so we follow the same rule with animation-name.
+  for (size_t idx = 0; idx < aTimelineCount; ++idx) {
+    const StyleType& timeline = aTimelines[idx];
+    if (timeline.GetName() == nsGkAtoms::_empty) {
+      continue;
+    }
+
+    RefPtr<TimelineType> dest =
+        PopExistingTimeline(timeline.GetName(), aCollection);
+    if (dest) {
+      dest->ReplacePropertiesWith(aElement, aPseudoType, timeline);
+    } else {
+      dest = TimelineType::MakeNamed(aPresContext->Document(), aElement,
+                                     aPseudoType, timeline);
+    }
+    MOZ_ASSERT(dest);
+
+    // Override the previous one if it is duplicated.
+    Unused << result.InsertOrUpdate(timeline.GetName(), dest);
+  }
+  return result;
+}
+
+template <typename TimelineType>
+static TimelineCollection<TimelineType>& EnsureTimelineCollection(
+    Element& aElement, PseudoStyleType aPseudoType);
+
+template <>
+ScrollTimelineCollection& EnsureTimelineCollection<ScrollTimeline>(
+    Element& aElement, PseudoStyleType aPseudoType) {
+  return aElement.EnsureAnimationData().EnsureScrollTimelineCollection(
+      aElement, aPseudoType);
+}
+
+template <>
+ViewTimelineCollection& EnsureTimelineCollection<ViewTimeline>(
+    Element& aElement, PseudoStyleType aPseudoType) {
+  return aElement.EnsureAnimationData().EnsureViewTimelineCollection(
+      aElement, aPseudoType);
+}
+
+template <typename StyleType, typename TimelineType>
+void TimelineManager::DoUpdateTimelines(
+    nsPresContext* aPresContext, Element* aElement, PseudoStyleType aPseudoType,
+    const nsStyleAutoArray<StyleType>& aStyleTimelines, size_t aTimelineCount) {
+  auto* collection =
+      TimelineCollection<TimelineType>::Get(aElement, aPseudoType);
+  if (!collection && aTimelineCount == 1 &&
+      aStyleTimelines[0].GetName() == nsGkAtoms::_empty) {
+    return;
+  }
+
+  // We create a new timeline list based on its computed style and the existing
+  // timelines.
+  auto newTimelines = BuildTimelines<StyleType, TimelineType>(
+      aPresContext, aElement, aPseudoType, aStyleTimelines, aTimelineCount,
+      collection);
+
+  if (newTimelines.IsEmpty()) {
+    if (collection) {
+      collection->Destroy();
+    }
+    return;
+  }
+
+  if (!collection) {
+    collection =
+        &EnsureTimelineCollection<TimelineType>(*aElement, aPseudoType);
+    if (!collection->isInList()) {
+      AddTimelineCollection(collection);
+    }
+  }
+
+  // Replace unused timeline with new ones.
+  collection->Swap(newTimelines);
+
+  // FIXME: Bug 1774060. We may have to restyle the animations which use the
+  // dropped timelines. Or rely on restyling the subtree and the following
+  // siblings when mutating {scroll|view}-timeline-name.
+}
+
+}  // namespace mozilla