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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/macros.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:
// If the pinch zoom anchor on the first PinchUpdate is within this length
// of the screen edge, "snap" the zoom to that edge. Experimentally
// determined.
static const int kPinchZoomSnapMarginDips = 100;
// TODO(tdresser): eventually |consumed_delta| should equal
// |content_scrolled_delta|. See crbug.com/510045 for details.
struct ScrollResult {
gfx::Vector2dF consumed_delta;
gfx::Vector2dF content_scrolled_delta;
};
static scoped_ptr<Viewport> Create(LayerTreeHostImpl* host_impl);
// Differs from scrolling in that only the visual viewport is moved, without
// affecting the top controls or outer viewport.
void Pan(const gfx::Vector2dF& delta);
// 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,
bool affect_top_controls);
void PinchUpdate(float magnify_delta, const gfx::Point& anchor);
void PinchEnd();
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;
void SnapPinchAnchorIfWithinMargin(const gfx::Point& anchor);
LayerTreeHostImpl* host_impl_;
bool pinch_zoom_active_;
// The pinch zoom anchor point is adjusted by this amount during a pinch. This
// is used to "snap" a pinch-zoom to the edge of the screen.
gfx::Vector2d pinch_anchor_adjustment_;
DISALLOW_COPY_AND_ASSIGN(Viewport);
};
} // namespace cc
#endif // CC_LAYERS_VIEWPORT_H_
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