зеркало из https://github.com/mozilla/gecko-dev.git
121 строка
4.1 KiB
C++
121 строка
4.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef ScrollbarActivity_h___
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#define ScrollbarActivity_h___
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#include "mozilla/Assertions.h"
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#include "nsCOMPtr.h"
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#include "nsIDOMEventListener.h"
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class nsIContent;
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class nsIScrollbarMediator;
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class nsITimer;
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namespace mozilla {
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namespace dom {
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class Element;
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class EventTarget;
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} // namespace dom
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namespace layout {
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/**
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* ScrollbarActivity
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*
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* This class manages scrollbar behavior that imitates the native Mac OS X
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* Lion overlay scrollbar behavior: Scrollbars are only shown while "scrollbar
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* activity" occurs, and they're hidden with a fade animation after a short
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* delay.
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*
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* Scrollbar activity has these states:
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* - inactive:
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* Scrollbars are hidden.
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* - ongoing activity:
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* Scrollbars are visible and being operated on in some way, for example
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* because they're hovered or pressed.
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* - active, but waiting for fade out
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* Scrollbars are still completely visible but are about to fade away.
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* - fading out
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* Scrollbars are subject to a fade-out animation.
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*
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* Initial scrollbar activity needs to be reported by the scrollbar holder that
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* owns the ScrollbarActivity instance. This needs to happen via a call to
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* ActivityOccurred(), for example when the current scroll position or the size
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* of the scroll area changes.
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*
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* As soon as scrollbars are visible, the ScrollbarActivity class manages the
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* rest of the activity behavior: It ensures that mouse motions inside the
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* scroll area keep the scrollbars visible, and that scrollbars don't fade away
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* while they're being hovered / dragged. It also sets a sticky hover attribute
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* on the most recently hovered scrollbar.
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*
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* ScrollbarActivity falls into hibernation after the scrollbars have faded
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* out. It only starts acting after the next call to ActivityOccurred() /
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* ActivityStarted().
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*/
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class ScrollbarActivity final : public nsIDOMEventListener {
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public:
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explicit ScrollbarActivity(nsIScrollbarMediator* aScrollableFrame)
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: mScrollableFrame(aScrollableFrame) {
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MOZ_ASSERT(mScrollableFrame);
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}
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NS_DECL_ISUPPORTS
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NS_DECL_NSIDOMEVENTLISTENER
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void Destroy();
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void ActivityOccurred();
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void ActivityStarted();
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void ActivityStopped();
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bool IsActive() const { return mNestedActivityCounter; }
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protected:
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virtual ~ScrollbarActivity() = default;
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void StartFadeTimer();
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void CancelFadeTimer();
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void BeginFade();
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void HandleEventForScrollbar(const nsAString& aType, nsIContent* aTarget,
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dom::Element* aScrollbar,
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bool* aStoredHoverState);
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void StartListeningForScrollbarEvents();
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void StartListeningForScrollAreaEvents();
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void StopListeningForScrollbarEvents();
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void StopListeningForScrollAreaEvents();
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void AddScrollbarEventListeners(dom::EventTarget* aScrollbar);
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void RemoveScrollbarEventListeners(dom::EventTarget* aScrollbar);
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void HoveredScrollbar(dom::Element* aScrollbar);
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dom::Element* GetScrollbarContent(bool aVertical);
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dom::Element* GetHorizontalScrollbar() { return GetScrollbarContent(false); }
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dom::Element* GetVerticalScrollbar() { return GetScrollbarContent(true); }
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nsIScrollbarMediator* const mScrollableFrame;
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nsCOMPtr<dom::EventTarget> mHorizontalScrollbar; // null while inactive
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nsCOMPtr<dom::EventTarget> mVerticalScrollbar; // null while inactive
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nsCOMPtr<nsITimer> mFadeTimer;
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uint32_t mNestedActivityCounter = 0;
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// This boolean is true from the point activity starts to the point BeginFade
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// runs, and effectively reflects the "active" attribute of the scrollbar.
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bool mScrollbarEffectivelyVisible = false;
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bool mListeningForScrollbarEvents = false;
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bool mListeningForScrollAreaEvents = false;
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bool mHScrollbarHovered = false;
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bool mVScrollbarHovered = false;
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};
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} // namespace layout
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} // namespace mozilla
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#endif /* ScrollbarActivity_h___ */
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