3 files changed, 28 insertions, 14 deletions

diff --git a/src/gui/kernel/qapplication.cpp b/src/gui/kernel/qapplication.cpp
index df5097b..1332545 100644
--- a/src/gui/kernel/qapplication.cpp
+++ b/src/gui/kernel/qapplication.cpp
@@ -925,7 +925,7 @@ void QApplicationPrivate::initialize()
     graphics_system = QGraphicsSystemFactory::create(graphics_system_name);
 #endif
 #ifndef QT_NO_WHEELEVENT
-#ifdef QT_MAC_USE_COCOA
+#ifdef Q_OS_MAC 
     QApplicationPrivate::wheel_scroll_lines = 1;
 #else
     QApplicationPrivate::wheel_scroll_lines = 3;
diff --git a/src/gui/kernel/qapplication_mac.mm b/src/gui/kernel/qapplication_mac.mm
index c294e62..a95ae9d 100644
--- a/src/gui/kernel/qapplication_mac.mm
+++ b/src/gui/kernel/qapplication_mac.mm
@@ -1686,13 +1686,15 @@ QApplicationPrivate::globalEventProcessor(EventHandlerCallRef er, EventRef event
             // (actually two events; one for horizontal and one for vertical).
             // As a results of this, and to make sure we dont't receive duplicate events,
             // we try to detect when this happend by checking the 'compatibilityEvent'. 
+            const int scrollFactor = 4 * 8;
             SInt32 mdelt = 0;
             GetEventParameter(event, kEventParamMouseWheelSmoothHorizontalDelta, typeSInt32, 0,
                               sizeof(mdelt), 0, &mdelt);
-            wheel_deltaX = mdelt;
+            wheel_deltaX = mdelt * scrollFactor;
+            mdelt = 0;
             GetEventParameter(event, kEventParamMouseWheelSmoothVerticalDelta, typeSInt32, 0,
                               sizeof(mdelt), 0, &mdelt);
-            wheel_deltaY = mdelt;
+            wheel_deltaY = mdelt * scrollFactor;
             GetEventParameter(event, kEventParamEventRef, typeEventRef, 0,
                               sizeof(compatibilityEvent), 0, &compatibilityEvent);
         } else if (ekind == kEventMouseWheelMoved) {
@@ -1704,10 +1706,14 @@ QApplicationPrivate::globalEventProcessor(EventHandlerCallRef er, EventRef event
                 EventMouseWheelAxis axis;
                 GetEventParameter(event, kEventParamMouseWheelAxis, typeMouseWheelAxis, 0,
                         sizeof(axis), 0, &axis);
+
+                // The 'new' event has acceleration applied by the OS, while the old (on
+                // Carbon only), has not. So we introduce acceleration here to be consistent:
+                int scrollFactor = 120 * qMin(5, qAbs(mdelt));
                 if (axis == kEventMouseWheelAxisX)
-                    wheel_deltaX = mdelt * 120;
+                    wheel_deltaX = mdelt * scrollFactor;
                 else
-                    wheel_deltaY = mdelt * 120;
+                    wheel_deltaY = mdelt * scrollFactor;
             }
         }
 
@@ -2660,7 +2666,11 @@ int QApplication::keyboardInputInterval()
 
 void QApplication::setWheelScrollLines(int n)
 {
-    QApplicationPrivate::wheel_scroll_lines = n;
+    Q_UNUSED(n);
+    // On Mac, acceleration is handled by the OS. Multiplying wheel scroll
+    // deltas with n will not be as cross platform as one might think! So
+    // we choose to go native in this case (and let wheel_scroll_lines == 1).
+    //    QApplicationPrivate::wheel_scroll_lines = n;
 }
 
 int QApplication::wheelScrollLines()
diff --git a/src/gui/kernel/qcocoaview_mac.mm b/src/gui/kernel/qcocoaview_mac.mm
index f482d1c..b1c5fc5 100644
--- a/src/gui/kernel/qcocoaview_mac.mm
+++ b/src/gui/kernel/qcocoaview_mac.mm
@@ -789,18 +789,22 @@ extern "C" {
     const EventRef carbonEvent = (EventRef)[theEvent eventRef];
     const UInt32 carbonEventKind = carbonEvent ? ::GetEventKind(carbonEvent) : 0;
     if (carbonEventKind == kEventMouseScroll) {
-        // The mouse device containts pixel scroll
-        // wheel support (Mighty Mouse, Trackpad)
-        deltaX = (int)[theEvent deviceDeltaX] * 120;
-        deltaY = (int)[theEvent deviceDeltaY] * 120;
-        deltaZ = (int)[theEvent deviceDeltaZ] * 120;
+        // The mouse device containts pixel scroll wheel support (Mighty Mouse, Trackpad).
+        // Since deviceDelta is delivered as pixels rather than degrees, we need to
+        // convert from pixels to degrees in a sensible manner.
+        // It looks like four degrees per pixel behaves most native.
+        // Qt expects the unit for delta to be 1/8 of a degree:
+        const int scrollFactor = 4 * 8;
+        deltaX = (int)[theEvent deviceDeltaX] * scrollFactor;
+        deltaY = (int)[theEvent deviceDeltaY] * scrollFactor;
+        deltaZ = (int)[theEvent deviceDeltaZ] * scrollFactor;
     } else { // carbonEventKind == kEventMouseWheelMoved
         // Mouse wheel deltas seem to tick in at increments of 0.1.
         // Qt widgets expect the delta to be a multiple of 120.
         const int scrollFactor = 10 * 120;
-        deltaX = [theEvent deltaX] * scrollFactor * qMax(0.6, 1.1 - qAbs([theEvent deltaX]));
-        deltaY = [theEvent deltaY] * scrollFactor * qMax(0.6, 1.1 - qAbs([theEvent deltaY]));
-        deltaZ = [theEvent deltaZ] * scrollFactor * qMax(0.6, 1.1 - qAbs([theEvent deltaZ]));
+        deltaX = [theEvent deltaX] * scrollFactor;
+        deltaY = [theEvent deltaY] * scrollFactor;
+        deltaZ = [theEvent deltaZ] * scrollFactor;
     }
 
     if (deltaX != 0) {