Add QWheelEvent::inverted()

Some consumers of wheel events need to know if the
scrolling direction is inverted in order to provide
consistent behavior.

For example, the scrolling direction of a horizontal
slider should not change when the user toggles the
"natural scrolling" setting on OS X. In this case
the inverted bit will change state and the slider
can compensate.

This change adds a bit to QWheelEvent and sets it
on OS X.

Task-number: QTBUG-35972
Change-Id: I221435dea45d436d570b113bd0e24ee6f6832211
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>

4 files changed, 5 insertions, 3 deletions

diff --git a/src/widgets/itemviews/qlistview.cpp b/src/widgets/itemviews/qlistview.cpp
index 646ab58e3d..1f33649668 100644
--- a/src/widgets/itemviews/qlistview.cpp
+++ b/src/widgets/itemviews/qlistview.cpp
@@ -822,7 +822,7 @@ void QListView::wheelEvent(QWheelEvent *e)
             QPoint pixelDelta(e->pixelDelta().y(), e->pixelDelta().x());
             QPoint angleDelta(e->angleDelta().y(), e->angleDelta().x());
             QWheelEvent hwe(e->pos(), e->globalPos(), pixelDelta, angleDelta, e->delta(),
-                            Qt::Horizontal, e->buttons(), e->modifiers(), e->phase());
+                            Qt::Horizontal, e->buttons(), e->modifiers(), e->phase(), e->source(), e->inverted());
             if (e->spontaneous())
                 qt_sendSpontaneousEvent(d->hbar, &hwe);
             else
diff --git a/src/widgets/kernel/qapplication.cpp b/src/widgets/kernel/qapplication.cpp
index 2d23bb61a2..1d5bdc2db7 100644
--- a/src/widgets/kernel/qapplication.cpp
+++ b/src/widgets/kernel/qapplication.cpp
@@ -3331,7 +3331,7 @@ bool QApplication::notify(QObject *receiver, QEvent *e)
                     QApplicationPrivate::giveFocusAccordingToFocusPolicy(w, e, relpos);
 
                 QWheelEvent we(relpos, wheel->globalPos(), wheel->pixelDelta(), wheel->angleDelta(), wheel->delta(), wheel->orientation(), wheel->buttons(),
-                               wheel->modifiers(), phase, wheel->source());
+                               wheel->modifiers(), phase, wheel->source(), wheel->inverted());
                 bool eventAccepted;
                 while (w) {
                     we.spont = spontaneous && w == receiver;
diff --git a/src/widgets/kernel/qwidgetwindow.cpp b/src/widgets/kernel/qwidgetwindow.cpp
index 6a3785ea03..def371c36e 100644
--- a/src/widgets/kernel/qwidgetwindow.cpp
+++ b/src/widgets/kernel/qwidgetwindow.cpp
@@ -776,7 +776,7 @@ void QWidgetWindow::handleWheelEvent(QWheelEvent *event)
 
     QPoint mapped = widget->mapFrom(rootWidget, pos);
 
-    QWheelEvent translated(mapped, event->globalPos(), event->pixelDelta(), event->angleDelta(), event->delta(), event->orientation(), event->buttons(), event->modifiers(), event->phase(), event->source());
+    QWheelEvent translated(mapped, event->globalPos(), event->pixelDelta(), event->angleDelta(), event->delta(), event->orientation(), event->buttons(), event->modifiers(), event->phase(), event->source(), event->inverted());
     QGuiApplication::sendSpontaneousEvent(widget, &translated);
 }
 
diff --git a/src/widgets/widgets/qabstractslider.cpp b/src/widgets/widgets/qabstractslider.cpp
index d7d83c7821..13e7a6e5cf 100644
--- a/src/widgets/widgets/qabstractslider.cpp
+++ b/src/widgets/widgets/qabstractslider.cpp
@@ -758,6 +758,8 @@ void QAbstractSlider::wheelEvent(QWheelEvent * e)
     Q_D(QAbstractSlider);
     e->ignore();
     int delta = e->delta();
+    if (e->inverted())
+        delta = -delta;
     if (d->scrollByDelta(e->orientation(), e->modifiers(), delta))
         e->accept();
 }