Cocoa: support QWheelEvent::Phase

The started & ended phases are required for implementing correctly
behaving transient scrollbars (ie. they become and stay visible when
touching the pad with two fingers).

Change-Id: I718d991ba6fd7e949cf9790f3bae285000fce576
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>

1 files changed, 17 insertions, 1 deletions

diff --git a/src/plugins/platforms/cocoa/qnsview.mm b/src/plugins/platforms/cocoa/qnsview.mm
index 288d4b4742..285e4aeb9f 100644
--- a/src/plugins/platforms/cocoa/qnsview.mm
+++ b/src/plugins/platforms/cocoa/qnsview.mm
@@ -876,7 +876,23 @@ static QTouchDevice *touchDevice = 0;
             currentWheelModifiers = [QNSView convertKeyModifiers:[theEvent modifierFlags]];
         }
 
-        QWindowSystemInterface::handleWheelEvent(m_window, qt_timestamp, qt_windowPoint, qt_screenPoint, pixelDelta, angleDelta, currentWheelModifiers);
+        QWheelEvent::Phase ph = QWheelEvent::Changed;
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_8
+        if (QSysInfo::QSysInfo::MacintoshVersion >= QSysInfo::MV_10_8) {
+            // On 10.8 and above, MayBegin is likely to happen.  We treat it the same as an actual begin.
+            if (phase == NSEventPhaseMayBegin)
+                ph = QWheelEvent::Started;
+        } else
+#endif
+        if (phase == NSEventPhaseBegan) {
+            // On 10.7, MayBegin will not happen, so Began is the actual beginning.
+            ph = QWheelEvent::Started;
+        }
+        if (phase == NSEventPhaseEnded || phase == NSEventPhaseCancelled) {
+            ph = QWheelEvent::Ended;
+        }
+
+        QWindowSystemInterface::handleWheelEvent(m_window, qt_timestamp, qt_windowPoint, qt_screenPoint, pixelDelta, angleDelta, currentWheelModifiers, ph);
 
         if (phase == NSEventPhaseEnded || phase == NSEventPhaseCancelled) {
             currentWheelModifiers = Qt::NoModifier;