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569c22f86c
I thought this was the root cause of bug 1925564, but turns out it's not. Still, mousedown doesn't guarantee a mouseup if you move the mouse out of the element, so seems wise not to use it. It only sorta works because thumb dragging captures the scrollbar... Use the hover state and the drag state instead, which simplifies the code anyways. Differential Revision: https://phabricator.services.mozilla.com/D226905
107 lines
3.4 KiB
C++
107 lines
3.4 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 StartListeningForScrollAreaEvents();
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void StopListeningForScrollAreaEvents();
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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<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 mListeningForScrollAreaEvents = 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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