layout/generic/ScrollbarActivity.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef ScrollbarActivity_h___
   7 #define ScrollbarActivity_h___
   8
   9 #include "mozilla/Attributes.h"
  10 #include "nsCOMPtr.h"
  11 #include "nsIDOMEventListener.h"
  12 #include "mozilla/TimeStamp.h"
  13 #include "nsRefreshDriver.h"
  14
  15 class nsIContent;
  16 class nsIScrollbarMediator;
  17 class nsITimer;
  18 class nsIAtom;
  19
  20 namespace mozilla {
  21 namespace layout {
  22
  23 /**
  24  * ScrollbarActivity
  25  *
  26  * This class manages scrollbar behavior that imitates the native Mac OS X
  27  * Lion overlay scrollbar behavior: Scrollbars are only shown while "scrollbar
  28  * activity" occurs, and they're hidden with a fade animation after a short
  29  * delay.
  30  *
  31  * Scrollbar activity has these states:
  32  *  - inactive:
  33  *      Scrollbars are hidden.
  34  *  - ongoing activity:
  35  *      Scrollbars are visible and being operated on in some way, for example
  36  *      because they're hovered or pressed.
  37  *  - active, but waiting for fade out
  38  *      Scrollbars are still completely visible but are about to fade away.
  39  *  - fading out
  40  *      Scrollbars are subject to a fade-out animation.
  41  *
  42  * Initial scrollbar activity needs to be reported by the scrollbar holder that
  43  * owns the ScrollbarActivity instance. This needs to happen via a call to
  44  * ActivityOccurred(), for example when the current scroll position or the size
  45  * of the scroll area changes.
  46  *
  47  * As soon as scrollbars are visible, the ScrollbarActivity class manages the
  48  * rest of the activity behavior: It ensures that mouse motions inside the
  49  * scroll area keep the scrollbars visible, and that scrollbars don't fade away
  50  * while they're being hovered / dragged. It also sets a sticky hover attribute
  51  * on the most recently hovered scrollbar.
  52  *
  53  * ScrollbarActivity falls into hibernation after the scrollbars have faded
  54  * out. It only starts acting after the next call to ActivityOccurred() /
  55  * ActivityStarted().
  56  */
  57
  58 class ScrollbarActivity MOZ_FINAL : public nsIDOMEventListener,
  59                                     public nsARefreshObserver {
  60 public:
  61   explicit ScrollbarActivity(nsIScrollbarMediator* aScrollableFrame)
  62    : mScrollableFrame(aScrollableFrame)
  63    , mNestedActivityCounter(0)
  64    , mIsActive(false)
  65    , mIsFading(false)
  66    , mListeningForScrollbarEvents(false)
  67    , mListeningForScrollAreaEvents(false)
  68    , mHScrollbarHovered(false)
  69    , mVScrollbarHovered(false)
  70    , mDisplayOnMouseMove(false)
  71    , mScrollbarFadeBeginDelay(0)
  72    , mScrollbarFadeDuration(0)
  73   {
  74     QueryLookAndFeelVals();
  75   }
  76
  77   NS_DECL_ISUPPORTS
  78   NS_DECL_NSIDOMEVENTLISTENER
  79
  80   void Destroy();
  81
  82   void ActivityOccurred();
  83   void ActivityStarted();
  84   void ActivityStopped();
  85
  86   virtual void WillRefresh(TimeStamp aTime) MOZ_OVERRIDE;
  87
  88   static void FadeBeginTimerFired(nsITimer* aTimer, void* aSelf) {
  89     nsRefPtr<ScrollbarActivity> scrollbarActivity(
  90       reinterpret_cast<ScrollbarActivity*>(aSelf));
  91     scrollbarActivity->BeginFade();
  92   }
  93
  94 protected:
  95   virtual ~ScrollbarActivity() {}
  96
  97   bool IsActivityOngoing()
  98   { return mNestedActivityCounter > 0; }
  99   bool IsStillFading(TimeStamp aTime);
 100   void QueryLookAndFeelVals();
 101
 102   void HandleEventForScrollbar(const nsAString& aType,
 103                                nsIContent* aTarget,
 104                                nsIContent* aScrollbar,
 105                                bool* aStoredHoverState);
 106
 107   void SetIsActive(bool aNewActive);
 108   bool SetIsFading(bool aNewFading); // returns false if 'this' was destroyed
 109
 110   void BeginFade();
 111   void EndFade();
 112
 113   void StartFadeBeginTimer();
 114   void CancelFadeBeginTimer();
 115
 116   void StartListeningForScrollbarEvents();
 117   void StartListeningForScrollAreaEvents();
 118   void StopListeningForScrollbarEvents();
 119   void StopListeningForScrollAreaEvents();
 120   void AddScrollbarEventListeners(nsIDOMEventTarget* aScrollbar);
 121   void RemoveScrollbarEventListeners(nsIDOMEventTarget* aScrollbar);
 122
 123   void RegisterWithRefreshDriver();
 124   void UnregisterFromRefreshDriver();
 125
 126   bool UpdateOpacity(TimeStamp aTime); // returns false if 'this' was destroyed
 127   void HoveredScrollbar(nsIContent* aScrollbar);
 128
 129   nsRefreshDriver* GetRefreshDriver();
 130   nsIContent* GetScrollbarContent(bool aVertical);
 131   nsIContent* GetHorizontalScrollbar() { return GetScrollbarContent(false); }
 132   nsIContent* GetVerticalScrollbar() { return GetScrollbarContent(true); }
 133
 134   const TimeDuration FadeDuration() {
 135     return TimeDuration::FromMilliseconds(mScrollbarFadeDuration);
 136   }
 137
 138   nsIScrollbarMediator* mScrollableFrame;
 139   TimeStamp mFadeBeginTime;
 140   nsCOMPtr<nsITimer> mFadeBeginTimer;
 141   nsCOMPtr<nsIDOMEventTarget> mHorizontalScrollbar; // null while inactive
 142   nsCOMPtr<nsIDOMEventTarget> mVerticalScrollbar;   // null while inactive
 143   int mNestedActivityCounter;
 144   bool mIsActive;
 145   bool mIsFading;
 146   bool mListeningForScrollbarEvents;
 147   bool mListeningForScrollAreaEvents;
 148   bool mHScrollbarHovered;
 149   bool mVScrollbarHovered;
 150
 151   // LookAndFeel values we load on creation
 152   bool mDisplayOnMouseMove;
 153   int mScrollbarFadeBeginDelay;
 154   int mScrollbarFadeDuration;
 155 };
 156
 157 } // namespace layout
 158 } // namespace mozilla
 159
 160 #endif /* ScrollbarActivity_h___ */