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/* -*- 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 */
#ifndef mozilla_dom_ViewTimeline_h
#define mozilla_dom_ViewTimeline_h
#include "mozilla/dom/ScrollTimeline.h"
namespace mozilla {
class ScrollContainerFrame;
} // namespace mozilla
namespace mozilla::dom {
* A view progress timeline is a segment of a scroll progress timeline that are
* scoped to the scroll positions in which any part of the associated element’s
* principal box intersects its nearest ancestor scrollport. So ViewTimeline
* is a special case of ScrollTimeline.
class ViewTimeline final : public ScrollTimeline {
template <typename T, typename... Args>
friend already_AddRefed<T> mozilla::MakeAndAddRef(Args&&... aArgs);
ViewTimeline() = delete;
// Note: |aSubject| is used as the subject which specifies view-timeline-name
// property, and we use this subject to look up its nearest scroll container.
static already_AddRefed<ViewTimeline> MakeNamed(
Document* aDocument, Element* aSubject, PseudoStyleType aPseudoType,
const StyleViewTimeline& aStyleTimeline);
static already_AddRefed<ViewTimeline> MakeAnonymous(
Document* aDocument, const NonOwningAnimationTarget& aTarget,
StyleScrollAxis aAxis, const StyleViewTimelineInset& aInset);
JSObject* WrapObject(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto) override {
return nullptr;
bool IsViewTimeline() const override { return true; }
void ReplacePropertiesWith(Element* aSubjectElement,
PseudoStyleType aPseudoType,
const StyleViewTimeline& aNew);
~ViewTimeline() = default;
ViewTimeline(Document* aDocument, const Scroller& aScroller,
StyleScrollAxis aAxis, Element* aSubject,
PseudoStyleType aSubjectPseudoType,
const StyleViewTimelineInset& aInset)
: ScrollTimeline(aDocument, aScroller, aAxis),
mInset(aInset) {}
Maybe<ScrollOffsets> ComputeOffsets(
const ScrollContainerFrame* aScrollContainerFrame,
layers::ScrollDirection aOrientation) const override;
ScrollOffsets ComputeInsets(const ScrollContainerFrame* aScrollContainerFrame,
layers::ScrollDirection aOrientation) const;
// The subject element.
// 1. For view(), the subject element is the animation target.
// 2. For view-timeline property, the subject element is the element who
// defines this property.
RefPtr<Element> mSubject;
PseudoStyleType mSubjectPseudoType;
// FIXME: Bug 1817073. view-timeline-inset is an animatable property. However,
// the inset from view() is not animatable, so for named view timeline, this
// value depends on the animation style. Therefore, we have to check its style
// value when using it. For now, in order to simplify the implementation, we
// make |mInset| be fixed.
StyleViewTimelineInset mInset;
} // namespace mozilla::dom
#endif // mozilla_dom_ViewTimeline_h