Mac, Carbon: add support for device pixel scrolling (wheel event)

This patch makes use of the rather hidden API on Mac for
accessing the new mouse wheel event type. This will make
scrolling with Mighty Mouse or TrackPad look much more
slick.

Rev-By:prasanth

1 files changed, 62 insertions, 20 deletions

diff --git a/src/gui/kernel/qapplication_mac.mm b/src/gui/kernel/qapplication_mac.mm
index 7e8d96f..a656c7f 100644
--- a/src/gui/kernel/qapplication_mac.mm
+++ b/src/gui/kernel/qapplication_mac.mm
@@ -972,6 +972,7 @@ static EventTypeSpec app_events[] = {
     { kEventClassWindow, kEventWindowActivated },
     { kEventClassWindow, kEventWindowDeactivated },
 
+    { kEventClassMouse, kEventMouseScroll },
     { kEventClassMouse, kEventMouseWheelMoved },
     { kEventClassMouse, kEventMouseDown },
     { kEventClassMouse, kEventMouseUp },
@@ -1639,6 +1640,7 @@ QApplicationPrivate::globalEventProcessor(EventHandlerCallRef er, EventRef event
         case kEventMouseDown: edesc = "MouseButtonPress"; break;
         case kEventMouseUp: edesc = "MouseButtonRelease"; break;
         case kEventMouseDragged: case kEventMouseMoved: edesc = "MouseMove"; break;
+        case kEventMouseScroll: edesc = "MouseWheelScroll"; break;
         case kEventMouseWheelMoved: edesc = "MouseWheelMove"; break;
         }
         if(ekind == kEventMouseDown || ekind == kEventMouseUp)
@@ -1659,12 +1661,43 @@ QApplicationPrivate::globalEventProcessor(EventHandlerCallRef er, EventRef event
                               sizeof(mac_buttons), 0, &mac_buttons);
             buttons = qt_mac_get_buttons(mac_buttons);
         }
-        int wheel_delta=0;
-        if(ekind == kEventMouseWheelMoved) {
-            int mdelt = 0;
-            GetEventParameter(event, kEventParamMouseWheelDelta, typeSInt32, 0,
+
+        int wheel_deltaX = 0;
+        int wheel_deltaY = 0;
+        static EventRef compatibilityEvent = 0;
+
+        if (ekind == kEventMouseScroll) {
+            // kEventMouseScroll is the new way of dealing with mouse wheel
+            // events (kEventMouseWheelMoved was the old). kEventMouseScroll results
+            // in much smoother scrolling when using Mighty Mouse or TrackPad. For
+            // compatibility with older applications, carbon will also send us
+            // kEventMouseWheelMoved events if we dont eat this 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'. 
+            SInt32 mdelt = 0;
+            GetEventParameter(event, kEventParamMouseWheelSmoothHorizontalDelta, typeSInt32, 0,
+                              sizeof(mdelt), 0, &mdelt);
+            wheel_deltaX = mdelt;
+            GetEventParameter(event, kEventParamMouseWheelSmoothVerticalDelta, typeSInt32, 0,
                               sizeof(mdelt), 0, &mdelt);
-            wheel_delta = mdelt * 120;
+            wheel_deltaY = mdelt;
+            GetEventParameter(event, kEventParamEventRef, typeEventRef, 0,
+                              sizeof(compatibilityEvent), 0, &compatibilityEvent);
+        } else if (ekind == kEventMouseWheelMoved) {
+            if (event != compatibilityEvent) {
+                compatibilityEvent = 0;
+                int mdelt = 0;
+                GetEventParameter(event, kEventParamMouseWheelDelta, typeSInt32, 0,
+                        sizeof(mdelt), 0, &mdelt);
+                EventMouseWheelAxis axis;
+                GetEventParameter(event, kEventParamMouseWheelAxis, typeMouseWheelAxis, 0,
+                        sizeof(axis), 0, &axis);
+                if (axis == kEventMouseWheelAxisX)
+                    wheel_deltaX = mdelt * 120;
+                else
+                    wheel_deltaY = mdelt * 120;
+            }
         }
 
         Qt::MouseButton button = Qt::NoButton;
@@ -2054,20 +2087,29 @@ QApplicationPrivate::globalEventProcessor(EventHandlerCallRef er, EventRef event
                 qt_mac_dblclick.last_button = button;
                 qt_mac_dblclick.last_time = GetEventTime(event);
             }
-            if(wheel_delta) {
-                EventMouseWheelAxis axis;
-                GetEventParameter(event, kEventParamMouseWheelAxis, typeMouseWheelAxis, 0,
-                                  sizeof(axis), 0, &axis);
-                QWheelEvent qwe(plocal, p, wheel_delta, buttons, modifiers,
-                                axis == kEventMouseWheelAxisX ? Qt::Horizontal : Qt::Vertical);
-                QApplication::sendSpontaneousEvent(widget, &qwe);
-                if(!qwe.isAccepted() && QApplicationPrivate::focus_widget && QApplicationPrivate::focus_widget != widget) {
-                    QWheelEvent qwe2(QApplicationPrivate::focus_widget->mapFromGlobal(p), p,
-                                     wheel_delta, buttons, modifiers,
-                                     axis == kEventMouseWheelAxisX ? Qt::Horizontal : Qt::Vertical);
-                    QApplication::sendSpontaneousEvent(QApplicationPrivate::focus_widget, &qwe2);
-                    if(!qwe2.isAccepted())
-                        handled_event = false;
+
+            if (wheel_deltaX || wheel_deltaY) {
+                if (wheel_deltaX) {
+                    QWheelEvent qwe(plocal, p, wheel_deltaX, buttons, modifiers, Qt::Horizontal);
+                    QApplication::sendSpontaneousEvent(widget, &qwe);
+                    if (!qwe.isAccepted() && QApplicationPrivate::focus_widget && QApplicationPrivate::focus_widget != widget) {
+                        QWheelEvent qwe2(QApplicationPrivate::focus_widget->mapFromGlobal(p), p,
+                                wheel_deltaX, buttons, modifiers, Qt::Horizontal);
+                        QApplication::sendSpontaneousEvent(QApplicationPrivate::focus_widget, &qwe2);
+                        if (!qwe2.isAccepted())
+                            handled_event = false;
+                    }
+                }
+                if (wheel_deltaY) {
+                    QWheelEvent qwe(plocal, p, wheel_deltaY, buttons, modifiers, Qt::Vertical);
+                    QApplication::sendSpontaneousEvent(widget, &qwe);
+                    if (!qwe.isAccepted() && QApplicationPrivate::focus_widget && QApplicationPrivate::focus_widget != widget) {
+                        QWheelEvent qwe2(QApplicationPrivate::focus_widget->mapFromGlobal(p), p,
+                                wheel_deltaY, buttons, modifiers, Qt::Vertical);
+                        QApplication::sendSpontaneousEvent(QApplicationPrivate::focus_widget, &qwe2);
+                        if (!qwe2.isAccepted())
+                            handled_event = false;
+                    }
                 }
             } else {
 #ifdef QMAC_SPEAK_TO_ME
@@ -2130,7 +2172,7 @@ QApplicationPrivate::globalEventProcessor(EventHandlerCallRef er, EventRef event
                    plocal.x(), plocal.y(), event_desc, (QWidget*)widget,
                    widget ? widget->objectName().toLocal8Bit().constData() : "*Unknown*",
                    widget ? widget->metaObject()->className() : "*Unknown*",
-                   button, (int)buttons, (int)modifiers, wheel_delta);
+                   button, (int)buttons, (int)modifiers, wheel_deltaX);
 #endif
         } else {
             handled_event = false;