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// Copyright 2016 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 ScrollManager_h
#define ScrollManager_h
#include <deque>
#include "base/macros.h"
#include "core/CoreExport.h"
#include "core/page/EventWithHitTestResults.h"
#include "platform/geometry/LayoutSize.h"
#include "platform/heap/Handle.h"
#include "platform/heap/Visitor.h"
#include "platform/scroll/ScrollTypes.h"
#include "platform/wtf/Allocator.h"
#include "public/platform/WebInputEventResult.h"
namespace blink {
class AutoscrollController;
class LayoutBox;
class LayoutObject;
class LocalFrame;
class PaintLayer;
class PaintLayerScrollableArea;
class Page;
class Scrollbar;
class ScrollState;
class WebGestureEvent;
// This class takes care of scrolling and resizing and the related states. The
// user action that causes scrolling or resizing is determined in other *Manager
// classes and they call into this class for doing the work.
class CORE_EXPORT ScrollManager
: public GarbageCollectedFinalized<ScrollManager> {
explicit ScrollManager(LocalFrame&);
void Trace(blink::Visitor*);
void Clear();
bool MiddleClickAutoscrollInProgress() const;
void StopMiddleClickAutoscroll();
AutoscrollController* GetAutoscrollController() const;
void StopAutoscroll();
// Performs a chaining logical scroll, within a *single* frame, starting
// from either a provided starting node or a default based on the focused or
// most recently clicked node, falling back to the frame.
// Returns true if the scroll was consumed.
// direction - The logical direction to scroll in. This will be converted to
// a physical direction for each LayoutBox we try to scroll
// based on that box's writing mode.
// granularity - The units that the scroll delta parameter is in.
// startNode - Optional. If provided, start chaining from the given node.
// If not, use the current focus or last clicked node.
bool LogicalScroll(ScrollDirection,
Node* start_node,
Node* mouse_press_node);
// Performs a logical scroll that chains, crossing frames, starting from
// the given node or a reasonable default (focus/last clicked).
bool BubblingScroll(ScrollDirection,
Node* starting_node,
Node* mouse_press_node);
// TODO( Consider moving all gesture related functions to
// another class.
// Handle the provided scroll gesture event, propagating down to child frames
// as necessary.
WebInputEventResult HandleGestureScrollEvent(const WebGestureEvent&);
WebInputEventResult HandleGestureScrollEnd(const WebGestureEvent&);
bool IsScrollbarHandlingGestures() const;
// Returns true if the gesture event should be handled in ScrollManager.
bool CanHandleGestureEvent(const GestureEventWithHitTestResults&);
// These functions are related to |m_resizeScrollableArea|.
bool InResizeMode() const;
void Resize(const WebMouseEvent&);
// Clears |m_resizeScrollableArea|. if |shouldNotBeNull| is true this
// function DCHECKs to make sure that variable is indeed not null.
void ClearResizeScrollableArea(bool should_not_be_null);
void SetResizeScrollableArea(PaintLayer*, IntPoint);
WebInputEventResult HandleGestureScrollUpdate(const WebGestureEvent&);
WebInputEventResult HandleGestureScrollBegin(const WebGestureEvent&);
WebInputEventResult PassScrollGestureEvent(const WebGestureEvent&,
void ClearGestureScrollState();
void CustomizedScroll(ScrollState&);
Page* GetPage() const;
bool IsViewportScrollingElement(const Element&) const;
bool HandleScrollGestureOnResizer(Node*, const WebGestureEvent&);
void RecomputeScrollChain(const Node& start_node,
const ScrollState&,
std::deque<int>& scroll_chain);
bool CanScroll(const ScrollState&, const Element& current_element);
// scroller_size is set only when scrolling non root scroller.
void ComputeScrollRelatedMetrics(
uint32_t* non_composited_main_thread_scrolling_reasons);
void RecordScrollRelatedMetrics(const WebGestureDevice);
WebGestureEvent SynthesizeGestureScrollBegin(
const WebGestureEvent& update_event);
void SnapAtGestureScrollEnd();
// NOTE: If adding a new field to this class please ensure that it is
// cleared in |ScrollManager::clear()|.
const Member<LocalFrame> frame_;
// Only used with the ScrollCustomization runtime enabled feature.
std::deque<int> current_scroll_chain_;
Member<Node> scroll_gesture_handling_node_;
bool last_gesture_scroll_over_embedded_content_view_;
// The most recent element to scroll natively during this scroll
// sequence. Null if no native element has scrolled this scroll
// sequence, or if the most recent element to scroll used scroll
// customization.
Member<Element> previous_gesture_scrolled_element_;
// True iff some of the delta has been consumed for the current
// scroll sequence in this frame, or any child frames. Only used
// with ScrollCustomization. If some delta has been consumed, a
// scroll which shouldn't propagate can't cause any element to
// scroll other than the |m_previousGestureScrolledNode|.
bool delta_consumed_for_scroll_sequence_;
// True iff some of the delta has been consumed for the current
// scroll sequence on the specific axis.
bool did_scroll_x_for_scroll_gesture_;
bool did_scroll_y_for_scroll_gesture_;
Member<Scrollbar> scrollbar_handling_scroll_gesture_;
Member<PaintLayerScrollableArea> resize_scrollable_area_;
offset_from_resize_corner_; // In the coords of m_resizeScrollableArea.
} // namespace blink
#endif // ScrollManager_h