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// Copyright 2014 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 UI_ANDROID_EDGE_EFFECT_BASE_H_
#define UI_ANDROID_EDGE_EFFECT_BASE_H_
#include "base/time/time.h"
#include "ui/gfx/geometry/size_f.h"
#include "ui/gfx/transform.h"
namespace cc {
class Layer;
}
namespace ui {
// A base class for overscroll-related Android effects.
class EdgeEffectBase {
public:
enum State {
STATE_IDLE = 0,
STATE_PULL,
STATE_ABSORB,
STATE_RECEDE,
STATE_PULL_DECAY
};
enum Edge { EDGE_TOP, EDGE_LEFT, EDGE_BOTTOM, EDGE_RIGHT, EDGE_COUNT };
virtual ~EdgeEffectBase() {}
virtual void Pull(base::TimeTicks current_time,
float delta_distance,
float displacement) = 0;
virtual void Absorb(base::TimeTicks current_time, float velocity) = 0;
virtual bool Update(base::TimeTicks current_time) = 0;
virtual void Release(base::TimeTicks current_time) = 0;
virtual void Finish() = 0;
virtual bool IsFinished() const = 0;
virtual float GetAlpha() const = 0;
virtual void ApplyToLayers(Edge edge,
const gfx::SizeF& viewport_size,
float offset) = 0;
virtual void SetParent(cc::Layer* parent) = 0;
protected:
// Computes the transform for an edge effect given the |edge|, |viewport_size|
// and edge |offset|. This assumes the the effect transform anchor is at the
// centered edge of the effect.
static gfx::Transform ComputeTransform(Edge edge,
const gfx::SizeF& viewport_size,
float offset);
// Computes the maximum effect size relative to the screen |edge|. For
// top/bottom edges, thsi is simply |viewport_size|, while for left/right
// edges this is |viewport_size| with coordinates swapped.
static gfx::SizeF ComputeOrientedSize(Edge edge,
const gfx::SizeF& viewport_size);
};
} // namespace ui
#endif // UI_ANDROID_EDGE_EFFECT_BASE_H_
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