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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CC_ANIMATION_SCROLL_TIMELINE_H_
#define CC_ANIMATION_SCROLL_TIMELINE_H_
#include "base/optional.h"
#include "base/time/time.h"
#include "cc/animation/animation_export.h"
#include "cc/animation/animation_timeline.h"
#include "cc/animation/keyframe_model.h"
#include "cc/paint/element_id.h"
namespace cc {
class ScrollTree;
// A ScrollTimeline is an animation timeline that bases its current time on the
// progress of scrolling in some scroll container.
//
// This is the compositor-side representation of the web concept expressed in
// https://wicg.github.io/scroll-animations/#scrolltimeline-interface.
class CC_ANIMATION_EXPORT ScrollTimeline : public AnimationTimeline {
public:
// cc does not know about writing modes. The ScrollDirection below is
// converted using blink::scroll_timeline_util::ConvertOrientation which takes
// the spec-compliant ScrollDirection enumeration.
// https://drafts.csswg.org/scroll-animations/#scrolldirection-enumeration
enum ScrollDirection {
ScrollUp,
ScrollDown,
ScrollLeft,
ScrollRight,
};
ScrollTimeline(base::Optional<ElementId> scroller_id,
ScrollDirection direction,
base::Optional<double> start_scroll_offset,
base::Optional<double> end_scroll_offset,
double time_range,
int animation_timeline_id);
static scoped_refptr<ScrollTimeline> Create(
base::Optional<ElementId> scroller_id,
ScrollDirection direction,
base::Optional<double> start_scroll_offset,
base::Optional<double> end_scroll_offset,
double time_range);
// Create a copy of this ScrollTimeline intended for the impl thread in the
// compositor.
scoped_refptr<AnimationTimeline> CreateImplInstance() const override;
// ScrollTimeline is active if the scroll node exists in active or pending
// scroll tree.
virtual bool IsActive(const ScrollTree& scroll_tree,
bool is_active_tree) const;
// Calculate the current time of the ScrollTimeline. This is either a
// base::TimeTicks value or base::nullopt if the current time is unresolved.
// The internal calculations are performed using doubles and the result is
// converted to base::TimeTicks. This limits the precision to 1us.
virtual base::Optional<base::TimeTicks> CurrentTime(
const ScrollTree& scroll_tree,
bool is_active_tree) const;
void UpdateScrollerIdAndScrollOffsets(
base::Optional<ElementId> scroller_id,
base::Optional<double> start_scroll_offset,
base::Optional<double> end_scroll_offset);
void PushPropertiesTo(AnimationTimeline* impl_timeline) override;
void ActivateTimeline() override;
base::Optional<ElementId> GetActiveIdForTest() const { return active_id_; }
base::Optional<ElementId> GetPendingIdForTest() const { return pending_id_; }
ScrollDirection GetDirectionForTest() const { return direction_; }
base::Optional<double> GetStartScrollOffsetForTest() const {
return start_scroll_offset_;
}
base::Optional<double> GetEndScrollOffsetForTest() const {
return end_scroll_offset_;
}
double GetTimeRangeForTest() const { return time_range_; }
bool IsScrollTimeline() const override;
protected:
~ScrollTimeline() override;
private:
// The scroller which this ScrollTimeline is based on. The same underlying
// scroll source may have different ids in the pending and active tree (see
// http://crbug.com/847588).
base::Optional<ElementId> active_id_;
base::Optional<ElementId> pending_id_;
// The direction of the ScrollTimeline indicates which axis of the scroller
// it should base its current time on, and where the origin point is.
ScrollDirection direction_;
// These define the total range of the scroller that the ScrollTimeline is
// active within. If not set they default to the beginning/end of the scroller
// respectively, respecting the current |direction_|.
base::Optional<double> start_scroll_offset_;
base::Optional<double> end_scroll_offset_;
// A ScrollTimeline maps from the scroll offset in the scroller to a time
// value based on a 'time range'. See the implementation of CurrentTime or the
// spec for details.
double time_range_;
};
inline ScrollTimeline* ToScrollTimeline(AnimationTimeline* timeline) {
DCHECK(timeline->IsScrollTimeline());
return static_cast<ScrollTimeline*>(timeline);
}
} // namespace cc
#endif // CC_ANIMATION_SCROLL_TIMELINE_H_
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