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- // Copyright 2018 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_INPUT_SNAP_FLING_CURVE_H_
- #define CC_INPUT_SNAP_FLING_CURVE_H_
- #include "base/time/time.h"
- #include "cc/cc_export.h"
- #include "ui/gfx/geometry/rect_f.h"
- #include "ui/gfx/geometry/vector2d_f.h"
- namespace cc {
- // The curve for the snap fling animation. The curve would generate a geometric
- // sequence of deltas to be scrolled at each frame.
- class CC_EXPORT SnapFlingCurve {
- public:
- // Creates the curve based on the start offset, target offset, and the first
- // inertial GSU's time_stamp.
- SnapFlingCurve(const gfx::PointF& start_offset,
- const gfx::PointF& target_offset,
- base::TimeTicks first_gsu_time);
- virtual ~SnapFlingCurve();
- // Estimate the total distance that will be scrolled given the first GSU's
- // delta
- static gfx::Vector2dF EstimateDisplacement(const gfx::Vector2dF& first_delta);
- // Returns the delta that should be scrolled at |time|.
- virtual gfx::Vector2dF GetScrollDelta(base::TimeTicks time);
- // Updates |current_displacement_|. This sync is necessary because the node
- // might be scrolled by other calls and the scrolls might be clamped.
- void UpdateCurrentOffset(const gfx::PointF& current_offset);
- // Returns true if the scroll has arrived at the snap destination.
- virtual bool IsFinished() const;
- base::TimeDelta duration() const { return duration_; }
- private:
- // Returns the curve's current distance at |current_time|.
- double GetCurrentCurveDistance(base::TimeDelta current_time);
- // The initial scroll offset of the scroller.
- const gfx::PointF start_offset_;
- // The total displacement to the snap position.
- const gfx::Vector2dF total_displacement_;
- // 1D representation of |total_displacement_|.
- const double total_distance_;
- // The current displacement that has been scrolled.
- gfx::Vector2dF current_displacement_;
- // The timestamp of the first GSU.
- const base::TimeTicks start_time_;
- // The number of deltas in the curve's geometric sequence.
- const double total_frames_;
- // The first delta that defines the curve's geometric sequence.
- const double first_delta_;
- // The total milliseconds needed to finish the curve.
- const base::TimeDelta duration_;
- bool is_finished_ = false;
- // |total_displacement_.x| / |total_distance_|
- double ratio_x_;
- // |total_displacement_.y| / |total_distance_|
- double ratio_y_;
- };
- } // namespace cc
- #endif // CC_INPUT_SNAP_FLING_CURVE_H_
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