kitemviews: handle macOS pixel wheel scrolling immediately

2 files changed, 32 insertions, 1 deletions

diff --git a/src/kitemviews/kitemlistcontainer.cpp b/src/kitemviews/kitemlistcontainer.cpp
index 3ec56e5f1..b221ca5ff 100644
--- a/src/kitemviews/kitemlistcontainer.cpp
+++ b/src/kitemviews/kitemlistcontainer.cpp
@@ -187,7 +187,12 @@ void KItemListContainer::wheelEvent(QWheelEvent *event)
         return;
     }
 
-    const bool scrollHorizontally = (qAbs(event->angleDelta().y()) < qAbs(event->angleDelta().x())) || (!verticalScrollBar()->isVisible());
+#ifdef Q_OS_MACOS
+    const QPoint scrollDelta = event->hasPixelDelta() ? event->pixelDelta() : event->angleDelta();
+#else
+    const QPoint scrollDelta = event->angleDelta();
+#endif
+    const bool scrollHorizontally = (qAbs(scrollDelta.y()) < qAbs(scrollDelta.x())) || (!verticalScrollBar()->isVisible());
     KItemListSmoothScroller *smoothScroller = scrollHorizontally ? m_horizontalSmoothScroller : m_verticalSmoothScroller;
 
     smoothScroller->handleWheelEvent(event);
diff --git a/src/kitemviews/private/kitemlistsmoothscroller.cpp b/src/kitemviews/private/kitemlistsmoothscroller.cpp
index 915b6b3d5..7cedf9d94 100644
--- a/src/kitemviews/private/kitemlistsmoothscroller.cpp
+++ b/src/kitemviews/private/kitemlistsmoothscroller.cpp
@@ -209,6 +209,32 @@ void KItemListSmoothScroller::handleWheelEvent(QWheelEvent *event)
 {
     const bool previous = m_smoothScrolling;
 
+#ifdef Q_OS_MACOS
+    if (event->hasPixelDelta()) {
+        const QPoint pixelDelta = event->pixelDelta();
+        const int scrollDelta = qAbs(pixelDelta.x()) > qAbs(pixelDelta.y()) ? pixelDelta.x() : pixelDelta.y();
+        const int oldValue = m_scrollBar->value();
+        const int newValue = qBound(m_scrollBar->minimum(), oldValue - scrollDelta, m_scrollBar->maximum());
+        if (newValue == oldValue) {
+            event->ignore();
+            return;
+        }
+
+        m_smoothScrolling = false;
+        if (m_animation->state() == QAbstractAnimation::Running) {
+            m_animation->stop();
+        }
+        if (QObject *target = targetObject()) {
+            target->setProperty(propertyName(), newValue);
+        }
+        m_scrollBar->setValue(newValue);
+        event->accept();
+
+        m_smoothScrolling = previous;
+        return;
+    }
+#endif
+
     m_smoothScrolling = true;
 
     QWheelEvent *copy = event->clone();