Bug 782175 Support slower scroll settings with mousewheel.*.delta_multiplier_* r=smaug

content/events/src/nsEventStateManager.cpp

@@ -1118,6 +1118,11 @@ nsEventStateManager::PreHandleEvent(nsPresContext* aPresContext,
       widget::WheelEvent* wheelEvent = static_cast<widget::WheelEvent*>(aEvent);
       WheelPrefs::GetInstance()->ApplyUserPrefsToDelta(wheelEvent);
 
+      // If we won't dispatch a DOM event for this event, nothing to do anymore.
+      if (!NS_IsAllowedToDispatchDOMEvent(wheelEvent)) {
+        break;
+      }
+
       // Init lineOrPageDelta values for line scroll events for some devices
       // on some platforms which might dispatch wheel events which don't have
       // lineOrPageDelta values.  And also, if delta values are customized by
@@ -5315,25 +5320,16 @@ nsEventStateManager::WheelPrefs::Init(
   prefNameX.AppendLiteral("delta_multiplier_x");
   mMultiplierX[aIndex] =
     static_cast<double>(Preferences::GetInt(prefNameX.get(), 100)) / 100;
-  if (mMultiplierX[aIndex] < 1.0 && mMultiplierX[aIndex] > -1.0) {
-    mMultiplierX[aIndex] = mMultiplierX[aIndex] < 0.0 ? -1.0 : 1.0;
-  }
 
   nsCAutoString prefNameY(basePrefName);
   prefNameY.AppendLiteral("delta_multiplier_y");
   mMultiplierY[aIndex] =
     static_cast<double>(Preferences::GetInt(prefNameY.get(), 100)) / 100;
-  if (mMultiplierY[aIndex] < 1.0 && mMultiplierY[aIndex] > -1.0) {
-    mMultiplierY[aIndex] = mMultiplierY[aIndex] < 0.0 ? -1.0 : 1.0;
-  }
 
   nsCAutoString prefNameZ(basePrefName);
   prefNameZ.AppendLiteral("delta_multiplier_z");
   mMultiplierZ[aIndex] =
     static_cast<double>(Preferences::GetInt(prefNameZ.get(), 100)) / 100;
-  if (mMultiplierZ[aIndex] < 1.0 && mMultiplierZ[aIndex] > -1.0) {
-    mMultiplierZ[aIndex] = mMultiplierZ[aIndex] < 0.0 ? -1.0 : 1.0;
-  }
 
   nsCAutoString prefNameAction(basePrefName);
   prefNameAction.AppendLiteral("action");
@@ -5380,10 +5376,12 @@ nsEventStateManager::WheelPrefs::CancelApplyingUserPrefsFromOverflowDelta(
   Index index = GetIndexFor(aEvent);
   Init(index);
 
-  NS_ASSERTION(mMultiplierX[index] && mMultiplierY[index],
+  if (mMultiplierX[index]) {
-               "The absolute values of both multipliers must be 1 or larger");
+    aEvent->overflowDeltaX /= mMultiplierX[index];
-  aEvent->overflowDeltaX /= mMultiplierX[index];
+  }
-  aEvent->overflowDeltaY /= mMultiplierY[index];
+  if (mMultiplierY[index]) {
+    aEvent->overflowDeltaY /= mMultiplierY[index];
+  }
 }
 
 nsEventStateManager::WheelPrefs::Action

content/events/test/test_dom_wheel_event.html

@@ -301,9 +301,6 @@ function testDeltaMultiplierPrefs()
 
       for (var j = 0; j < kPrefValues.length; j++) {
         currentMultiplier = kPrefValues[j] / 100;
-        if (currentMultiplier > -1.0 && currentMultiplier < 1.0) {
-          currentMultiplier = currentMultiplier < 0 ? -1.0 : 1.0;
-        }
         for (var k = 0; k < kDeltaMultiplierPrefs.length; k++) {
           currentPref = "mousewheel." + currentTest.name + "." + kDeltaMultiplierPrefs[k];
 
@@ -318,15 +315,29 @@ function testDeltaMultiplierPrefs()
             ", deltaMode: " + currentEvent.deltaMode + ", modifiers: \"" + modifierList + "\", (trusted event): ";
           synthesizeWheel(gScrollableElement, 10, 10, currentEvent);
 
-          ok(calledHandlers.wheel, description + "wheel event was not fired");
+          var expectedProps = {
-          ok(calledHandlers.DOMMouseScroll.horizontal,
+            deltaX: currentEvent.deltaX * currentMultiplier,
-             description + "Horizontal DOMMouseScroll event was not fired");
+            deltaY: currentEvent.deltaY * currentMultiplier,
-          ok(calledHandlers.DOMMouseScroll.vertical,
+            dletaZ: currentEvent.deltaZ * currentMultiplier,
-             description + "Vertical DOMMouseScroll event was not fired");
+            lineOrPageDeltaX: currentEvent.lineOrPageDeltaX * currentMultiplier,
-          ok(calledHandlers.MozMousePixelScroll.horizontal,
+            lineOrPageDeltaY: currentEvent.lineOrPageDeltaY * currentMultiplier,
-             description + "Horizontal MozMousePixelScroll event was not fired");
+          };
-          ok(calledHandlers.MozMousePixelScroll.vertical,
+
-             description + "Vertical MozMousePixelScroll event was not fired");
+          is(calledHandlers.wheel,
+             expectedProps.deltaX != 0 || expectedProps.deltaY != 0 || expectedProps.deltaZ != 0,
+             description + "wheel event was (not) fired");
+          is(calledHandlers.DOMMouseScroll.horizontal,
+             expectedProps.lineOrPageDeltaX >= 1 || expectedProps.lineOrPageDeltaX <= -1,
+             description + "Horizontal DOMMouseScroll event was (not) fired");
+          is(calledHandlers.DOMMouseScroll.vertical,
+             expectedProps.lineOrPageDeltaY >= 1 || expectedProps.lineOrPageDeltaY <= -1,
+             description + "Vertical DOMMouseScroll event was (not) fired");
+          is(calledHandlers.MozMousePixelScroll.horizontal,
+             expectedProps.deltaY >= 1 || expectedProps.deltaY <= -1,
+             description + "Horizontal MozMousePixelScroll event was (not) fired");
+          is(calledHandlers.MozMousePixelScroll.vertical,
+             expectedProps.deltaY >= 1 || expectedProps.deltaY <= -1,
+             description + "Vertical MozMousePixelScroll event was (not) fired");
 
           calledHandlers = { wheel: false,
                              DOMMouseScroll: { horizontal: false, vertical: false },

layout/base/nsPresShell.cpp

@@ -6230,13 +6230,6 @@ PresShell::HandleEventWithTarget(nsEvent* aEvent, nsIFrame* aFrame,
   return rv;
 }
 
-static inline bool
-IsSynthesizedMouseEvent(nsEvent* aEvent)
-{
-  return aEvent->eventStructType == NS_MOUSE_EVENT &&
-         static_cast<nsMouseEvent*>(aEvent)->reason != nsMouseEvent::eReal;
-}
-
 static bool CanHandleContextMenuEvent(nsMouseEvent* aMouseEvent,
                                         nsIFrame* aFrame)
 {
@@ -6442,11 +6435,7 @@ PresShell::HandleEventInternal(nsEvent* aEvent, nsEventStatus* aStatus)
       if (aEvent->eventStructType == NS_KEY_EVENT) {
         nsContentUtils::SetIsHandlingKeyBoardEvent(true);
       }
-      // We want synthesized mouse moves to cause mouseover and mouseout
+      if (NS_IsAllowedToDispatchDOMEvent(aEvent)) {
-      // DOM events (PreHandleEvent above), but not mousemove DOM events.
-      // Synthesized button up events also do not cause DOM events
-      // because they do not have a reliable refPoint.
-      if (!IsSynthesizedMouseEvent(aEvent)) {
         nsPresShellEventCB eventCB(this);
         if (aEvent->eventStructType == NS_TOUCH_EVENT) {
           DispatchTouchEvent(aEvent, aStatus, &eventCB, touchIsNew);

widget/nsGUIEvent.h

@@ -1821,4 +1821,32 @@ inline bool NS_IsEventTargetedAtFocusedContent(nsEvent* aEvent)
          NS_IS_RETARGETED_PLUGIN_EVENT(aEvent);
 }
 
+/**
+ * Whether the event should cause a DOM event.
+ */
+inline bool NS_IsAllowedToDispatchDOMEvent(nsEvent* aEvent)
+{
+  switch (aEvent->eventStructType) {
+    case NS_MOUSE_EVENT:
+      // We want synthesized mouse moves to cause mouseover and mouseout
+      // DOM events (nsEventStateManager::PreHandleEvent), but not mousemove
+      // DOM events.
+      // Synthesized button up events also do not cause DOM events because they
+      // do not have a reliable refPoint.
+      return static_cast<nsMouseEvent*>(aEvent)->reason == nsMouseEvent::eReal;
+
+    case NS_WHEEL_EVENT: {
+      // wheel event whose all delta values are zero by user pref applied, it
+      // shouldn't cause a DOM event.
+      mozilla::widget::WheelEvent* wheelEvent =
+        static_cast<mozilla::widget::WheelEvent*>(aEvent);
+      return wheelEvent->deltaX != 0.0 || wheelEvent->deltaY != 0.0 ||
+             wheelEvent->deltaZ != 0.0;
+    }
+
+    default:
+      return true;
+  }
+}
+
 #endif // nsGUIEvent_h__