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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.
#include <memory>
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "cc/layers/layer_impl.h"
#include "ui/gfx/geometry/vector2d_f.h"
namespace cc {
class LayerTreeHostImpl;
struct ScrollNode;
// 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 {
// 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 for details.
struct ScrollResult {
gfx::Vector2dF consumed_delta;
gfx::Vector2dF content_scrolled_delta;
static std::unique_ptr<Viewport> Create(LayerTreeHostImpl* host_impl);
// Differs from scrolling in that only the visual viewport is moved, without
// affecting the browser controls or outer viewport.
void Pan(const gfx::Vector2dF& delta);
// Scrolls the viewport, applying the unique bubbling between the inner and
// outer viewport unless the scroll_outer_viewport bit is off. Scrolls can be
// consumed by browser controls.
ScrollResult ScrollBy(const gfx::Vector2dF& delta,
const gfx::Point& viewport_point,
bool is_wheel_scroll,
bool affect_browser_controls,
bool scroll_outer_viewport);
bool CanScroll(const ScrollState& scroll_state) const;
// Scrolls the viewport. Unlike the above method, scrolls the inner before
// the outer viewport. Doesn't affect browser controls or return a result
// since callers don't need it.
void ScrollByInnerFirst(const gfx::Vector2dF& delta);
// Scrolls the viewport, bubbling the delta between the inner and outer
// viewport. Only animates either of the two viewports.
gfx::Vector2dF ScrollAnimated(const gfx::Vector2dF& delta,
base::TimeDelta delayed_by);
gfx::ScrollOffset TotalScrollOffset() const;
void PinchUpdate(float magnify_delta, const gfx::Point& anchor);
void PinchEnd(const gfx::Point& anchor, bool snap_to_min);
// Returns the "representative" viewport layer. That is, the one that's set
// as the currently scrolling layer when the viewport scrolls and the one used
// in the scrolling code to indicate scrolling should happen via this class.
LayerImpl* MainScrollLayer() const;
explicit Viewport(LayerTreeHostImpl* host_impl);
// Returns true if viewport_delta is stricly less than pending_delta.
static bool ShouldAnimateViewport(const gfx::Vector2dF& viewport_delta,
const gfx::Vector2dF& pending_delta);
bool ShouldBrowserControlsConsumeScroll(
const gfx::Vector2dF& scroll_delta) const;
gfx::Vector2dF AdjustOverscroll(const gfx::Vector2dF& delta) const;
// Sends the delta to the browser controls, returns the amount applied.
gfx::Vector2dF ScrollBrowserControls(const gfx::Vector2dF& delta);
gfx::ScrollOffset MaxTotalScrollOffset() const;
ScrollNode* InnerScrollNode() const;
ScrollNode* OuterScrollNode() const;
ScrollTree& scroll_tree() 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_;
FRIEND_TEST_ALL_PREFIXES(ViewportTest, ShouldAnimateViewport);
} // namespace cc