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// Copyright 2015 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_LAYERS_VIEWPORT_H_
#define CC_LAYERS_VIEWPORT_H_
#include "base/memory/scoped_ptr.h"
#include "cc/layers/layer_impl.h"
#include "ui/gfx/geometry/vector2d_f.h"
namespace cc {
class LayerTreeHostImpl;
// Encapsulates gesture handling logic on the viewport layers. The "viewport"
// is made up of two scrolling layers, the inner viewport (visual) and the
// outer viewport (layout) scroll layers. These layers have different scroll
// bubbling behavior from the rest of the layer tree which is encoded in this
// class.
class CC_EXPORT Viewport {
public:
struct ScrollResult {
gfx::Vector2dF applied_delta;
gfx::Vector2dF unused_scroll_delta;
gfx::Vector2dF top_controls_applied_delta;
};
static scoped_ptr<Viewport> Create(LayerTreeHostImpl* host_impl);
// Scrolls the viewport, applying the unique bubbling between the inner and
// outer viewport. Scrolls can be consumed by top controls.
ScrollResult ScrollBy(const gfx::Vector2dF& delta,
const gfx::Point& viewport_point,
bool is_wheel_scroll);
private:
explicit Viewport(LayerTreeHostImpl* host_impl);
bool ShouldTopControlsConsumeScroll(const gfx::Vector2dF& scroll_delta) const;
gfx::Vector2dF AdjustOverscroll(const gfx::Vector2dF& delta) const;
// Sends the delta to the top controls, returns the amount applied.
gfx::Vector2dF ScrollTopControls(const gfx::Vector2dF& delta);
gfx::ScrollOffset MaxTotalScrollOffset() const;
gfx::ScrollOffset TotalScrollOffset() const;
LayerImpl* InnerScrollLayer() const;
LayerImpl* OuterScrollLayer() const;
LayerTreeHostImpl* host_impl_;
DISALLOW_COPY_AND_ASSIGN(Viewport);
};
} // namespace cc
#endif // CC_LAYERS_VIEWPORT_H_
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