Bug 1355548 - Using cached perference values in WheelTransaction. r=masayuki

EventStateManager uses preferences of WheelTransaction frequently. Caches them to reduce overheads.

MozReview-Commit-ID: HhuCKu5QVsh

dom/events/EventStateManager.cpp

@@ -331,6 +331,7 @@ EventStateManager::EventStateManager()
                                  "dom.w3c_pointer_events.enabled", false);
     sAddedPointerEventEnabled = true;
   }
+  WheelTransaction::InitializeStatics();
 }
 
 nsresult

dom/events/WheelHandlingHelper.cpp

@@ -281,7 +281,7 @@ WheelTransaction::OnFailToScrollTarget()
 {
   NS_PRECONDITION(sTargetFrame, "We don't have mouse scrolling transaction");
 
-  if (Preferences::GetBool("test.mousescroll", false)) {
+  if (Prefs::sTestMouseScroll) {
     // This event is used for automated tests, see bug 442774.
     nsContentUtils::DispatchTrustedEvent(
                       sTargetFrame->GetContent()->OwnerDoc(),
@@ -310,7 +310,7 @@ WheelTransaction::OnTimeout(nsITimer* aTimer, void* aClosure)
   // the next DOM event might create strange situation for us.
   MayEndTransaction();
 
-  if (Preferences::GetBool("test.mousescroll", false)) {
+  if (Prefs::sTestMouseScroll) {
     // This event is used for automated tests, see bug 442774.
     nsContentUtils::DispatchTrustedEvent(
                       frame->GetContent()->OwnerDoc(),
@@ -346,18 +346,6 @@ WheelTransaction::GetScreenPoint(WidgetGUIEvent* aEvent)
   return aEvent->mRefPoint + aEvent->mWidget->WidgetToScreenOffset();
 }
 
-/* static */ uint32_t
-WheelTransaction::GetTimeoutTime()
-{
-  return Preferences::GetUint("mousewheel.transaction.timeout", 1500);
-}
-
-/* static */ uint32_t
-WheelTransaction::GetIgnoreMoveDelayTime()
-{
-  return Preferences::GetUint("mousewheel.transaction.ignoremovedelay", 100);
-}
-
 /* static */ DeltaValues
 WheelTransaction::AccelerateWheelDelta(WidgetWheelEvent* aEvent,
                                        bool aAllowScrollSpeedOverride)
@@ -392,18 +380,6 @@ WheelTransaction::ComputeAcceleratedWheelDelta(double aDelta, int32_t aFactor)
   return mozilla::ComputeAcceleratedWheelDelta(aDelta, sScrollSeriesCounter, aFactor);
 }
 
-/* static */ int32_t
-WheelTransaction::GetAccelerationStart()
-{
-  return Preferences::GetInt("mousewheel.acceleration.start", -1);
-}
-
-/* static */ int32_t
-WheelTransaction::GetAccelerationFactor()
-{
-  return Preferences::GetInt("mousewheel.acceleration.factor", -1);
-}
-
 /* static */ DeltaValues
 WheelTransaction::OverrideSystemScrollSpeed(WidgetWheelEvent* aEvent)
 {
@@ -550,4 +526,31 @@ ScrollbarsForWheel::DeactivateAllTemporarilyActivatedScrollTargets()
   }
 }
 
+/******************************************************************/
+/* mozilla::WheelTransaction                                      */
+/******************************************************************/
+int32_t WheelTransaction::Prefs::sMouseWheelAccelerationStart = -1;
+int32_t WheelTransaction::Prefs::sMouseWheelAccelerationFactor = -1;
+uint32_t WheelTransaction::Prefs::sMouseWheelTransactionTimeout = 1500;
+uint32_t WheelTransaction::Prefs::sMouseWheelTransactionIgnoreMoveDelay = 100;
+bool WheelTransaction::Prefs::sTestMouseScroll = false;
+
+/* static */ void
+WheelTransaction::Prefs::InitializeStatics()
+{
+  static bool sIsInitialized = false;
+  if (!sIsInitialized) {
+    Preferences::AddIntVarCache(&sMouseWheelAccelerationStart,
+                                "mousewheel.acceleration.start", -1);
+    Preferences::AddIntVarCache(&sMouseWheelAccelerationFactor,
+                                "mousewheel.acceleration.factor", -1);
+    Preferences::AddUintVarCache(&sMouseWheelTransactionTimeout,
+                                 "mousewheel.transaction.timeout", 1500);
+    Preferences::AddUintVarCache(&sMouseWheelTransactionIgnoreMoveDelay,
+                                 "mousewheel.transaction.ignoremovedelay", 100);
+    Preferences::AddBoolVarCache(&sTestMouseScroll, "test.mousescroll", false);
+    sIsInitialized = true;
+  }
+}
+
 } // namespace mozilla

dom/events/WheelHandlingHelper.h

@@ -143,12 +143,19 @@ public:
   }
   static void OnEvent(WidgetEvent* aEvent);
   static void Shutdown();
-  static uint32_t GetTimeoutTime();
+  static uint32_t GetTimeoutTime()
+  {
+    return Prefs::sMouseWheelTransactionTimeout;
+  }
 
   static void OwnScrollbars(bool aOwn);
 
   static DeltaValues AccelerateWheelDelta(WidgetWheelEvent* aEvent,
                                           bool aAllowScrollSpeedOverride);
+  static void InitializeStatics()
+  {
+    Prefs::InitializeStatics();
+  }
 
 protected:
   static void BeginTransaction(nsIFrame* aTargetFrame,
@@ -162,9 +169,18 @@ protected:
   static void OnFailToScrollTarget();
   static void OnTimeout(nsITimer* aTimer, void* aClosure);
   static void SetTimeout();
-  static uint32_t GetIgnoreMoveDelayTime();
-  static int32_t GetAccelerationStart();
-  static int32_t GetAccelerationFactor();
+  static uint32_t GetIgnoreMoveDelayTime()
+  {
+    return Prefs::sMouseWheelTransactionIgnoreMoveDelay;
+  }
+  static int32_t GetAccelerationStart()
+  {
+    return Prefs::sMouseWheelAccelerationStart;
+  }
+  static int32_t GetAccelerationFactor()
+  {
+    return Prefs::sMouseWheelAccelerationFactor;
+  }
   static DeltaValues OverrideSystemScrollSpeed(WidgetWheelEvent* aEvent);
   static double ComputeAcceleratedWheelDelta(double aDelta, int32_t aFactor);
   static bool OutOfTime(uint32_t aBaseTime, uint32_t aThreshold);
@@ -175,6 +191,17 @@ protected:
   static nsITimer* sTimer;
   static int32_t sScrollSeriesCounter;
   static bool sOwnScrollbars;
+
+  class Prefs
+  {
+  public:
+    static void InitializeStatics();
+    static int32_t sMouseWheelAccelerationStart;
+    static int32_t sMouseWheelAccelerationFactor;
+    static uint32_t sMouseWheelTransactionTimeout;
+    static uint32_t sMouseWheelTransactionIgnoreMoveDelay;
+    static bool sTestMouseScroll;
+  };
 };
 
 } // namespace mozilla