wheel scrolling improved

src/controls/QskListView.cpp

@@ -6,6 +6,14 @@
 #include "QskListView.h"
 #include "QskAspect.h"
 #include "QskColorFilter.h"
+#include "QskEvent.h"
+
+#if QT_VERSION >= QT_VERSION_CHECK( 5, 9, 0 )
+#include <qguiapplication.h>
+#include <qstylehints.h>
+#endif
+
+#include <qmath.h>
 
 QSK_SUBCONTROL( QskListView, Cell )
 QSK_SUBCONTROL( QskListView, Text )
@@ -263,6 +271,58 @@ void QskListView::mouseReleaseEvent( QMouseEvent* event )
     Inherited::mouseReleaseEvent( event );
 }
 
+#ifndef QT_NO_WHEELEVENT
+
+QPointF QskListView::scrollOffset( const QWheelEvent* event ) const
+{
+    QPointF offset;
+
+    const auto pos = qskWheelPosition( event );
+
+    if ( subControlRect( VerticalScrollBar ).contains( pos ) )
+    {
+        const auto steps = qskWheelSteps( event );
+        offset.setY( steps );
+    }
+    else if ( subControlRect( HorizontalScrollBar ).contains( pos ) )
+    {
+        const auto steps = qskWheelSteps( event );
+        offset.setX( steps );
+    }
+    else if ( viewContentsRect().contains( pos ) )
+    {
+        offset = event->angleDelta() / QWheelEvent::DefaultDeltasPerStep;
+    }
+
+    if ( offset.x() != 0.0 )
+    {
+        offset.rx() *= viewContentsRect().width(); // pagewise
+    }
+    else if ( offset.y() != 0.0 )
+    {
+        const auto viewHeight = viewContentsRect().height();
+        const qreal rowHeight = this->rowHeight();
+
+        int numLines = 3;
+#if QT_VERSION >= QT_VERSION_CHECK( 5, 9, 0 )
+        numLines = QGuiApplication::styleHints()->wheelScrollLines();
+#endif
+
+        qreal dy = numLines * rowHeight;
+        if ( event->modifiers() & ( Qt::ControlModifier | Qt::ShiftModifier ) )
+            dy = qMax( dy, viewHeight );
+
+        // we should align to row boundaries. TODO ...
+        offset.setY( offset.y() * dy );
+    }
+
+    // using the animated scrollTo instead ?
+
+    return offset;
+}
+
+#endif
+
 void QskListView::updateScrollableSize()
 {
     const double h = rowCount() * rowHeight();

src/controls/QskListView.h

@@ -89,6 +89,10 @@ class QSK_EXPORT QskListView : public QskScrollView
     void mousePressEvent( QMouseEvent* ) override;
     void mouseReleaseEvent( QMouseEvent* ) override;
 
+#ifndef QT_NO_WHEELEVENT
+    virtual QPointF scrollOffset( const QWheelEvent* ) const override;
+#endif
+
     void updateScrollableSize();
 
     void componentComplete() override;

src/controls/QskScrollBox.cpp

@@ -405,15 +405,16 @@ QPointF QskScrollBox::scrollOffset( const QWheelEvent* event ) const
     QPointF offset;
 
     const auto pos = qskWheelPosition( event );
-    if ( viewContentsRect().contains( pos ) )
+    const auto viewRect = viewContentsRect();
+
+    if ( viewRect.contains( pos ) )
     {
         offset = event->pixelDelta();
-
         if ( offset.isNull() )
-        {
             offset = event->angleDelta() / QWheelEvent::DefaultDeltasPerStep;
-            offset *= 20.0; // how to find such a value ???
-        }
+
+        offset.rx() *= viewRect.width();
+        offset.ry() *= viewRect.height();
     }
 
     return offset;

src/controls/QskScrollView.cpp

@@ -8,9 +8,6 @@
 #include "QskBoxBorderMetrics.h"
 #include "QskEvent.h"
 
-#include <qguiapplication.h>
-#include <qstylehints.h>
-
 QSK_SUBCONTROL( QskScrollView, Panel )
 QSK_SUBCONTROL( QskScrollView, Viewport )
 QSK_SUBCONTROL( QskScrollView, HorizontalScrollBar )
@@ -21,15 +18,6 @@ QSK_SUBCONTROL( QskScrollView, VerticalScrollHandle )
 QSK_SYSTEM_STATE( QskScrollView, VerticalHandlePressed, QskAspect::FirstSystemState << 1 )
 QSK_SYSTEM_STATE( QskScrollView, HorizontalHandlePressed, QskAspect::FirstSystemState << 2 )
 
-static int qskScrollLines()
-{
-#if QT_VERSION >= QT_VERSION_CHECK( 5, 9, 0 )
-    return QGuiApplication::styleHints()->wheelScrollLines();
-#else
-    return 3;
-#endif
-}
-
 class QskScrollView::PrivateData
 {
   public:
@@ -226,20 +214,31 @@ QPointF QskScrollView::scrollOffset( const QWheelEvent* event ) const
     QPointF offset;
 
     const auto pos = qskWheelPosition( event );
+    const auto viewRect = viewContentsRect();
 
     if ( subControlRect( VerticalScrollBar ).contains( pos ) )
     {
         const auto steps = qskWheelSteps( event );
-        offset.setY( steps * qskScrollLines() );
+        offset.setY( steps );
     }
     else if ( subControlRect( HorizontalScrollBar ).contains( pos ) )
     {
         const auto steps = qskWheelSteps( event );
-        offset.setX( steps * qskScrollLines() );
+        offset.setX( steps );
     }
-    else
+    else if ( viewRect.contains( pos ) )
     {
-        offset = Inherited::scrollOffset( event );
+        offset = event->pixelDelta();
+        if ( offset.isNull() )
+            offset = event->angleDelta() / QWheelEvent::DefaultDeltasPerStep;
+    }
+
+    if ( !offset.isNull() )
+    {
+        const auto vs = viewRect.size() / 3.0;
+
+        offset.rx() *= vs.width();
+        offset.ry() *= vs.height();
     }
 
     return offset;