QskScrollArea once more changed, this time again without having to copy

the viewport clip node

examples/thumbnails/main.cpp

@@ -15,6 +15,7 @@
 #include <QskBoxBorderMetrics.h>
 #include <QskBoxShapeMetrics.h>
 #include <QskAspect.h>
+#include <QskBoxBorderColors.h>
 #include <QskFocusIndicator.h>
 
 #include <QGuiApplication>
@@ -154,15 +155,27 @@ int main( int argc, char* argv[] )
         But here we only want to demonstrate how QskScrollArea works.
      */
 
-    auto scrollArea = new ScrollArea();
+    auto box = new QskLinearBox( Qt::Vertical );
+    box->setMargins( 20 );
+
+    auto buttonBox = new QskLinearBox( Qt::Horizontal, box );
+    buttonBox->setSizePolicy( Qt::Vertical, QskSizePolicy::Fixed );
+
+    new QskPushButton( "Push Me", buttonBox ); 
+    new QskPushButton( "Push Me", buttonBox ); 
+
+    auto scrollArea = new ScrollArea( box );
     scrollArea->setMargins( QMarginsF( 25, 25, 5, 5 ) );
     scrollArea->setScrolledItem( new IconGrid() );
 
+    auto focusIndicator = new QskFocusIndicator();
+    focusIndicator->setBoxBorderColorsHint( QskFocusIndicator::Panel, Qt::darkRed );
+
     QskWindow window;
     window.resize( 600, 600 );
     window.setColor( "SteelBlue" );
-    window.addItem( scrollArea );
+    window.addItem( box );
-    window.addItem( new QskFocusIndicator() );
+    window.addItem( focusIndicator );
 
     window.show();
 

src/controls/QskScrollArea.cpp

@@ -6,7 +6,6 @@
 #include "QskScrollArea.h"
 #include "QskScrollViewSkinlet.h"
 #include "QskLayoutConstraint.h"
-#include "QskBoxClipNode.h"
 #include "QskEvent.h"
 
 QSK_QT_PRIVATE_BEGIN
@@ -77,11 +76,9 @@ namespace
     {
     public:
         ViewportClipNode():
-            QQuickDefaultClipNode( QRectF() ),
+            QQuickDefaultClipNode( QRectF() )
-            m_otherGeometry( nullptr )
         {
             setGeometry( nullptr );
-            setFlag( QSGNode::OwnsGeometry, true );
 
             // clip nodes have no material, so this flag
             // is available to indicate our replaced clip node
@@ -89,17 +86,15 @@ namespace
             setFlag( QSGNode::OwnsMaterial, true );
         }
 
-        void copyFrom( const QSGClipNode* other, const QPointF& offset )
+        void copyFrom( const QSGClipNode* other )
         {
             if ( other == nullptr )
             {
-                if ( !( clipRect().isEmpty() && isRectangular() ) )
+                if ( !( isRectangular() && clipRect().isEmpty() ) )
                 {
-                    setClipRect( QRectF() );
                     setIsRectangular( true );
-
+                    setClipRect( QRectF() );
                     setGeometry( nullptr );
-                    m_otherGeometry = nullptr;
 
                     markDirty( QSGNode::DirtyGeometry );
                 }
@@ -109,11 +104,9 @@ namespace
 
             bool isDirty = false;
 
-            const auto newClipRect = other->clipRect().translated( offset );
+            if ( clipRect() != other->clipRect() )
-
-            if ( clipRect() != newClipRect )
             {
-                setClipRect( newClipRect );
+                setClipRect( other->clipRect() );
                 isDirty = true;
             }
 
@@ -122,9 +115,7 @@ namespace
                 if ( !isRectangular() )
                 {
                     setIsRectangular( true );
-
                     setGeometry( nullptr );
-                    m_otherGeometry = nullptr;
 
                     isDirty = true;
                 }
@@ -137,14 +128,10 @@ namespace
                     isDirty = true;
                 }
 
-                if ( ( geometry() == nullptr )
+                if ( geometry() != other->geometry() )
-                    || ( geometry()->vertexCount() != other->geometry()->vertexCount() )
-                    || ( other->geometry() != m_otherGeometry ) )
                 {
-                    setGeometry( QskBoxClipNode::translatedGeometry(
+                    // both nodes share the same geometry
-                        other->geometry(), offset ) );
+                    setGeometry( const_cast< QSGGeometry* >( other->geometry() ) );
-
-                    m_otherGeometry = other->geometry();
                     isDirty = true;
                 }
             }
@@ -162,8 +149,6 @@ namespace
                 into nops.
              */
         }
-
-        const QSGGeometry* m_otherGeometry;
     };
 }
 
@@ -184,6 +169,16 @@ public:
         return children.isEmpty() ? nullptr : children.first();
     }
 
+    virtual bool contains( const QPointF& pos ) const override final
+    {
+        return clipRect().contains( pos );
+    }
+
+    virtual QRectF clipRect() const override final
+    {
+        return scrollArea()->subControlRect( QskScrollView::Viewport );
+    }
+
 protected:
     virtual bool event( QEvent* event ) override final;
     virtual void windowChangeEvent( QskWindowChangeEvent* ) override final;
@@ -309,14 +304,9 @@ void QskScrollAreaClipItem::updateNode( QSGNode* )
         /*
             Update the clip node with the geometry of the clip node
             of the viewport of the scrollview.
-
-            Maybe it would be better to ask the skinlet for translated clip node
-            but we would have a dependency for QskScrollViewSkinlet then.
          */
         auto viewClipNode = static_cast< ViewportClipNode* >( clipNode );
-        viewClipNode->copyFrom( viewPortClipNode(), -position() );
+        viewClipNode->copyFrom( viewPortClipNode() );
-
-        Q_ASSERT( viewClipNode->isRectangular() || viewClipNode->geometry() );
     }
 }
 
@@ -442,34 +432,13 @@ public:
     somewhere below the paint node to have all items on the viewport being clipped.
     This is how it is done f.e. for the list boxes.
 
-    But when having QQuickItems on the viewport we run into 2 fundamental
+    But when having QQuickItems on the viewport we run into a fundamental limitation
-    limitations of the Qt/Quick design.
+    of the Qt/Quick design: node subtrees for the children have to be in parallel to
+    the paint node.
 
-    a) The node subtrees for the children are in parallel to the paint node.
+    We work around this problem, by inserting an extra item between the scroll area
-    b) The default clipNode() is always rectangular and only for the
+    and the scrollable item. This item replaces its default clip node by its own node,
-       complete boundingRect() of the item.
+    that references the geometry of the viewport clip node.
-
-    Both limitations are hardcoded in QQuickWindow without offering ways
-    to customize the operations. Even worse: obviously the code was once started
-    with having more flexible APIs in mind, but for some reasons it was never
-    finalized and not even the existing APIs are internally used properly.
-
-    ( F.e there would be a virtual method QQuickItem::clipRect(), but QQuickWindow
-      uses erroneously QQuickItem::contains() to filter events - grmpf. )
-
-    --
-
-    This class works around those limitations, by inserting a clip item
-    that replaces its default clip node by copying out the geometry of clip node
-    for view port.
-
-    This clip item needs to have exactly the same position + size as the
-    viewport, so that clipping of the mouse/touch/hover/wheel in QQuickWindow
-    works properly.  Unfortunately we then have to copy + translate the geometry of
-    the view port instead of simply sharing it between the 2 clip nodes.
-
-    But even then, filtering of events does not yet work perfect for non rectangular
-    clip regions. Maybe it could be done by adding a childMouseEventFilter(). TODO ...
  */
 
 QskScrollArea::QskScrollArea( QQuickItem* parentItem ):
@@ -501,7 +470,8 @@ void QskScrollArea::updateLayout()
 {
     Inherited::updateLayout();
 
-    m_data->clipItem->setGeometry( viewContentsRect() );
+    // the clipItem always has the same geometry as the scroll area
+    m_data->clipItem->setSize( size() );
     adjustItem();
 }
 
@@ -605,9 +575,12 @@ QQuickItem* QskScrollArea::scrolledItem() const
 
 void QskScrollArea::translateItem()
 {
-    auto item = scrolledItem();
+    auto item = m_data->clipItem->scrolledItem();
     if ( item )
-        item->setPosition( -scrollPos() );
+    {
+        const QPointF pos = viewContentsRect().topLeft() - scrollPos();
+        item->setPosition( pos );
+    }
 }
 
 #include "moc_QskScrollArea.cpp"

src/nodes/QskBoxClipNode.cpp

@@ -60,54 +60,3 @@ void QskBoxClipNode::setBox( const QRectF& rect,
 
     markDirty( QSGNode::DirtyGeometry );
 }
-
-template< class Point >
-static inline void qskCopyPoints( const Point* from, Point* to,
-    int numPoints, const QPointF& offset )
-{
-    if ( offset.isNull() )
-    {
-        memcpy( to, from, numPoints * sizeof( Point ) );
-    }
-    else
-    {
-        const float dx = offset.x();
-        const float dy = offset.y();
-
-        for ( int i = 0; i < numPoints; i++ )
-        {
-            to[i].x = from[i].x + dx;
-            to[i].y = from[i].y + dy;
-        }
-    }
-}
-
-QSGGeometry* QskBoxClipNode::translatedGeometry(
-    const QSGGeometry* geometry, const QPointF& offset )
-{
-    if ( geometry == nullptr || geometry->vertexCount() == 0 )
-        return nullptr;
-
-    QSGGeometry* g = nullptr;
-
-    if ( geometry->sizeOfVertex() == sizeof( QSGGeometry::Point2D ) )
-    {
-        g = new QSGGeometry(
-            QSGGeometry::defaultAttributes_Point2D(), geometry->vertexCount(),
-            geometry->indexCount(), geometry->indexType() );
-
-        qskCopyPoints( geometry->vertexDataAsPoint2D(),
-            g->vertexDataAsPoint2D(), g->vertexCount(), offset );
-    }
-    else if ( geometry->sizeOfVertex() == sizeof( QSGGeometry::ColoredPoint2D ) )
-    {
-        g = new QSGGeometry(
-            QSGGeometry::defaultAttributes_ColoredPoint2D(), geometry->vertexCount(),
-            geometry->indexCount(), geometry->indexType() );
-            
-        qskCopyPoints( geometry->vertexDataAsColoredPoint2D(),
-            g->vertexDataAsColoredPoint2D(), g->vertexCount(), offset );
-    }
-
-    return g;
-}

src/nodes/QskBoxClipNode.h

@@ -21,8 +21,6 @@ public:
     void setBox( const QRectF&,
         const QskBoxShapeMetrics&, const QskBoxBorderMetrics& );
 
-    static QSGGeometry* translatedGeometry( const QSGGeometry*, const QPointF& );
-
 private:
     uint m_hash;
     QRectF m_rect;