TabBar: allow wheel events to change currentIndex

Setting wheelEnabled to true allows wheel events to increment or
decrement the currentIndex. We keep track of the total amount of
angleDelta so that touchpads and high resolution mouse wheels don't
change the currentIndex too rapidly.

Fixes: QTBUG-99619
Change-Id: I9bda828338ee5136efcdd6abeca8e5be15da0822
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
(cherry picked from commit 2ead10bf55733defe58616de7fe2c28452d00c93)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 26 insertions, 0 deletions

diff --git a/src/quicktemplates2/qquicktabbar.cpp b/src/quicktemplates2/qquicktabbar.cpp
index 512b917d58..f7010722b6 100644
--- a/src/quicktemplates2/qquicktabbar.cpp
+++ b/src/quicktemplates2/qquicktabbar.cpp
@@ -118,6 +118,9 @@ public:
 
     bool updatingLayout = false;
     QQuickTabBar::Position position = QQuickTabBar::Header;
+#if QT_CONFIG(wheelevent)
+    QPoint accumulatedAngleDelta;
+#endif
 };
 
 class QQuickTabBarAttachedPrivate : public QObjectPrivate
@@ -386,6 +389,26 @@ void QQuickTabBar::itemRemoved(int index, QQuickItem *item)
         polish();
 }
 
+#if QT_CONFIG(wheelevent)
+void QQuickTabBar::wheelEvent(QWheelEvent *event)
+{
+    Q_D(QQuickTabBar);
+    QQuickContainer::wheelEvent(event);
+    if (d->wheelEnabled) {
+        d->accumulatedAngleDelta += event->angleDelta();
+        int xSteps = d->accumulatedAngleDelta.x() / QWheelEvent::DefaultDeltasPerStep;
+        int ySteps = d->accumulatedAngleDelta.y() / QWheelEvent::DefaultDeltasPerStep;
+        if (xSteps > 0 || ySteps > 0) {
+            decrementCurrentIndex();
+            d->accumulatedAngleDelta = QPoint();
+        } else if (xSteps < 0 || ySteps < 0) {
+            incrementCurrentIndex();
+            d->accumulatedAngleDelta = QPoint();
+        }
+    }
+}
+#endif
+
 QFont QQuickTabBar::defaultFont() const
 {
     return QQuickTheme::font(QQuickTheme::TabBar);
diff --git a/src/quicktemplates2/qquicktabbar_p.h b/src/quicktemplates2/qquicktabbar_p.h
index 9734d9b7db..a99fb444a5 100644
--- a/src/quicktemplates2/qquicktabbar_p.h
+++ b/src/quicktemplates2/qquicktabbar_p.h
@@ -92,6 +92,9 @@ protected:
     void itemAdded(int index, QQuickItem *item) override;
     void itemMoved(int index, QQuickItem *item) override;
     void itemRemoved(int index, QQuickItem *item) override;
+#if QT_CONFIG(wheelevent)
+    void wheelEvent(QWheelEvent *event) override;
+#endif
 
     QFont defaultFont() const override;