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89 lines
2.7 KiB
C
89 lines
2.7 KiB
C
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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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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 "nsCOMPtr.h"
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#include "mozilla/TimeStamp.h"
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class nsIContent;
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class nsITimer;
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class nsIAtom;
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class nsIScrollableFrame;
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namespace mozilla {
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/**
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* ScrollbarActivity
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*
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* This class manages scrollbar active state. When some activity occured
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* the 'active' attribute of the both the horizontal scrollbar and vertical
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* scrollbar is set.
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* After a small amount of time of inactivity this attribute is unset from
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* both scrollbars.
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* Some css specific rules can affect the scrollbar, like showing/hiding it
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* with a fade transition.
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*
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* Initial scrollbar activity needs to be reported by the scrollbar frame 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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* ScrollbarActivity then wait until a timeout has expired or a new call to
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* ActivityOccured() has been made. When the timeout expires ActivityFinished()
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* is call and reset the active state.
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*/
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class ScrollbarActivity {
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public:
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ScrollbarActivity(nsIScrollableFrame* aScrollableFrame)
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: mIsActive(false)
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, mScrollableFrame(aScrollableFrame)
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{}
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void ActivityOccurred();
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void ActivityFinished();
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~ScrollbarActivity();
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protected:
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/*
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* mIsActive is true once any type of activity occurent on the scrollable
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* frame and until kScrollbarActivityFinishedDelay has expired.
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* This does not reflect the value of the 'active' attributes on scrollbars.
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*/
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bool mIsActive;
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/*
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* Hold a reference to the scrollable frame in order to retrieve the
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* horizontal and vertical scrollbar boxes where to set the 'active'
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* attribute.
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*/
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nsIScrollableFrame* mScrollableFrame;
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nsCOMPtr<nsITimer> mActivityFinishedTimer;
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void SetIsActive(bool aNewActive);
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enum { kScrollbarActivityFinishedDelay = 450 }; // milliseconds
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static void ActivityFinishedTimerFired(nsITimer* aTimer, void* aSelf) {
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reinterpret_cast<ScrollbarActivity*>(aSelf)->ActivityFinished();
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}
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void StartActivityFinishedTimer();
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void CancelActivityFinishedTimer();
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nsIContent* GetScrollbarContent(bool aVertical);
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nsIContent* GetHorizontalScrollbar() {
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return GetScrollbarContent(false);
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}
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nsIContent* GetVerticalScrollbar() {
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return GetScrollbarContent(true);
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}
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};
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} // namespace mozilla
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#endif /* ScrollbarActivity_h___ */
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