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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef ScrollbarActivity_h___
+#define ScrollbarActivity_h___
+
+#include "mozilla/Attributes.h"
+#include "nsCOMPtr.h"
+#include "nsIDOMEventListener.h"
+#include "mozilla/TimeStamp.h"
+#include "nsRefreshDriver.h"
+
+class nsIContent;
+class nsIScrollbarMediator;
+class nsITimer;
+
+namespace mozilla {
+namespace layout {
+
+/**
+ * ScrollbarActivity
+ *
+ * This class manages scrollbar behavior that imitates the native Mac OS X
+ * Lion overlay scrollbar behavior: Scrollbars are only shown while "scrollbar
+ * activity" occurs, and they're hidden with a fade animation after a short
+ * delay.
+ *
+ * Scrollbar activity has these states:
+ * - inactive:
+ * Scrollbars are hidden.
+ * - ongoing activity:
+ * Scrollbars are visible and being operated on in some way, for example
+ * because they're hovered or pressed.
+ * - active, but waiting for fade out
+ * Scrollbars are still completely visible but are about to fade away.
+ * - fading out
+ * Scrollbars are subject to a fade-out animation.
+ *
+ * Initial scrollbar activity needs to be reported by the scrollbar holder that
+ * owns the ScrollbarActivity instance. This needs to happen via a call to
+ * ActivityOccurred(), for example when the current scroll position or the size
+ * of the scroll area changes.
+ *
+ * As soon as scrollbars are visible, the ScrollbarActivity class manages the
+ * rest of the activity behavior: It ensures that mouse motions inside the
+ * scroll area keep the scrollbars visible, and that scrollbars don't fade away
+ * while they're being hovered / dragged. It also sets a sticky hover attribute
+ * on the most recently hovered scrollbar.
+ *
+ * ScrollbarActivity falls into hibernation after the scrollbars have faded
+ * out. It only starts acting after the next call to ActivityOccurred() /
+ * ActivityStarted().
+ */
+
+class ScrollbarActivity final : public nsIDOMEventListener,
+ public nsARefreshObserver
+{
+public:
+ explicit ScrollbarActivity(nsIScrollbarMediator* aScrollableFrame)
+ : mScrollableFrame(aScrollableFrame)
+ , mNestedActivityCounter(0)
+ , mIsActive(false)
+ , mIsFading(false)
+ , mListeningForScrollbarEvents(false)
+ , mListeningForScrollAreaEvents(false)
+ , mHScrollbarHovered(false)
+ , mVScrollbarHovered(false)
+ , mDisplayOnMouseMove(false)
+ , mScrollbarFadeBeginDelay(0)
+ , mScrollbarFadeDuration(0)
+ {
+ QueryLookAndFeelVals();
+ }
+
+ NS_DECL_ISUPPORTS
+ NS_DECL_NSIDOMEVENTLISTENER
+
+ void Destroy();
+
+ void ActivityOccurred();
+ void ActivityStarted();
+ void ActivityStopped();
+
+ virtual void WillRefresh(TimeStamp aTime) override;
+
+ static void FadeBeginTimerFired(nsITimer* aTimer, void* aSelf) {
+ RefPtr<ScrollbarActivity> scrollbarActivity(
+ reinterpret_cast<ScrollbarActivity*>(aSelf));
+ scrollbarActivity->BeginFade();
+ }
+
+protected:
+ virtual ~ScrollbarActivity() {}
+
+ bool IsActivityOngoing()
+ { return mNestedActivityCounter > 0; }
+ bool IsStillFading(TimeStamp aTime);
+ void QueryLookAndFeelVals();
+
+ void HandleEventForScrollbar(const nsAString& aType,
+ nsIContent* aTarget,
+ nsIContent* aScrollbar,
+ bool* aStoredHoverState);
+
+ void SetIsActive(bool aNewActive);
+ bool SetIsFading(bool aNewFading); // returns false if 'this' was destroyed
+
+ void BeginFade();
+ void EndFade();
+
+ void StartFadeBeginTimer();
+ void CancelFadeBeginTimer();
+
+ void StartListeningForScrollbarEvents();
+ void StartListeningForScrollAreaEvents();
+ void StopListeningForScrollbarEvents();
+ void StopListeningForScrollAreaEvents();
+ void AddScrollbarEventListeners(nsIDOMEventTarget* aScrollbar);
+ void RemoveScrollbarEventListeners(nsIDOMEventTarget* aScrollbar);
+
+ void RegisterWithRefreshDriver();
+ void UnregisterFromRefreshDriver();
+
+ bool UpdateOpacity(TimeStamp aTime); // returns false if 'this' was destroyed
+ void HoveredScrollbar(nsIContent* aScrollbar);
+
+ nsRefreshDriver* GetRefreshDriver();
+ nsIContent* GetScrollbarContent(bool aVertical);
+ nsIContent* GetHorizontalScrollbar() { return GetScrollbarContent(false); }
+ nsIContent* GetVerticalScrollbar() { return GetScrollbarContent(true); }
+
+ const TimeDuration FadeDuration() {
+ return TimeDuration::FromMilliseconds(mScrollbarFadeDuration);
+ }
+
+ nsIScrollbarMediator* mScrollableFrame;
+ TimeStamp mFadeBeginTime;
+ nsCOMPtr<nsITimer> mFadeBeginTimer;
+ nsCOMPtr<nsIDOMEventTarget> mHorizontalScrollbar; // null while inactive
+ nsCOMPtr<nsIDOMEventTarget> mVerticalScrollbar; // null while inactive
+ int mNestedActivityCounter;
+ bool mIsActive;
+ bool mIsFading;
+ bool mListeningForScrollbarEvents;
+ bool mListeningForScrollAreaEvents;
+ bool mHScrollbarHovered;
+ bool mVScrollbarHovered;
+
+ // LookAndFeel values we load on creation
+ bool mDisplayOnMouseMove;
+ int mScrollbarFadeBeginDelay;
+ int mScrollbarFadeDuration;
+};
+
+} // namespace layout
+} // namespace mozilla
+
+#endif /* ScrollbarActivity_h___ */