Link nodes and remove and delete the link too when deleting one of the nodes.

code/studio/src/plugins/gui_editor/expression_editor.cpp

@@ -81,7 +81,24 @@ void ExpressionEditor::onDeleteSelection()
 	QList< QGraphicsItem* > l = m_scene->selectedItems();
 	QListIterator< QGraphicsItem* > itr( l );
 	while( itr.hasNext() )
-		m_scene->removeItem( itr.next() );
+	{
+		QGraphicsItem *item = itr.next();
+
+		ExpressionNode *node = dynamic_cast< ExpressionNode* >( item );
+		if( node != NULL )		
+		{
+			ExpressionLink *link = node->link();
+			if( link != NULL )
+			{
+				link->unlink();
+				m_scene->removeItem( link );
+				delete link;
+			}
+		}
+
+		m_scene->removeItem( item );
+		delete item;
+	}
 }
 
 void ExpressionEditor::onSelectionChanged()
@@ -93,11 +110,12 @@ void ExpressionEditor::onSelectionChanged()
 void ExpressionEditor::onLinkItems()
 {
 	QList< QGraphicsItem* > l = m_scene->selectedItems();
-	QGraphicsItem *from = l[ 0 ];
-	QGraphicsItem *to = l[ 1 ];
+	ExpressionNode *from = static_cast< ExpressionNode* >( l[ 0 ] );
+	ExpressionNode *to = static_cast< ExpressionNode* >( l[ 1 ] );
 
 	ExpressionLink *link = new ExpressionLink();
 	link->link( from, to );
+
 	m_scene->addItem( link );
 }
 

code/studio/src/plugins/gui_editor/expression_link.cpp

@@ -17,6 +17,7 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include "expression_link.h"
+#include "expression_node.h"
 #include <QGraphicsItem>
 #include <QPen>
 
@@ -25,17 +26,38 @@ QGraphicsLineItem( parent )
 {
 	m_from = NULL;
 	m_to = NULL;
+
+	setFlags( QGraphicsItem::ItemIsSelectable );
 }
 
 ExpressionLink::~ExpressionLink()
 {
+	unlink();
+}
+
+void ExpressionLink::link( ExpressionNode *from, ExpressionNode *to )
+{
+	m_from = from;
+	m_to = to;
+	m_from->setLink( this );
+	m_to->setLink( this );
+
+	nodeMoved();
+}
+
+void ExpressionLink::unlink()
+{
+	m_from->setLink( NULL );
+	m_to->setLink( NULL );
+}
+
+void ExpressionLink::nodeMoved()
+{
+	setLine( QLineF( m_from->pos(), m_to->pos() ) );
 }
 
 void ExpressionLink::paint( QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget )
 {
-	if( m_from != NULL )
-		setLine( QLineF( m_from->pos(), m_to->pos() ) );
-
 	setPen( QPen( Qt::darkRed ) );
 
 	QGraphicsLineItem::paint( painter, option, widget );

code/studio/src/plugins/gui_editor/expression_link.h

@@ -21,22 +21,24 @@
 
 #include <QGraphicsItem>
 
+class ExpressionNode;
+
 class ExpressionLink : public QGraphicsLineItem
 {
 public:
 	ExpressionLink( QGraphicsItem *parent = NULL );
 	~ExpressionLink();
 
-	void link( QGraphicsItem *from, QGraphicsItem *to ){ 
-		m_from = from;
-		m_to = to;
-	}
+	void link( ExpressionNode *from, ExpressionNode *to );
+	void unlink();
+
+	void nodeMoved();
 
 	void paint( QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget );
 
 private:
-	QGraphicsItem *m_from;
-	QGraphicsItem *m_to;
+	ExpressionNode *m_from;
+	ExpressionNode *m_to;
 
 };
 

code/studio/src/plugins/gui_editor/expression_node.cpp

@@ -18,12 +18,14 @@
 
 
 #include "expression_node.h"
+#include "expression_link.h"
 #include <QPainter>
 #include <QStyleOption>
 
 ExpressionNode::ExpressionNode( QGraphicsItem *parent ) :
 QGraphicsItem( parent )
 {
+	m_link = NULL;
 }
 
 ExpressionNode::~ExpressionNode()
@@ -48,3 +50,13 @@ void ExpressionNode::paint( QPainter *painter, const QStyleOptionGraphicsItem *o
 	painter->drawRect( boundingRect() );
 }
 
+
+void ExpressionNode::mouseMoveEvent( QGraphicsSceneMouseEvent *e )
+{
+	if( m_link != NULL )
+		m_link->nodeMoved();
+
+	QGraphicsItem::mouseMoveEvent( e );
+}
+
+

code/studio/src/plugins/gui_editor/expression_node.h

@@ -22,6 +22,8 @@
 
 #include <QGraphicsItem>
 
+class ExpressionLink;
+
 class ExpressionNode : public QGraphicsItem
 {
 public:
@@ -31,6 +33,15 @@ public:
 	QRectF boundingRect() const;
 	void paint( QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget );
 
+	void setLink( ExpressionLink *link ){ m_link = link; }
+	ExpressionLink* link() const{ return m_link; }
+
+protected:
+	void mouseMoveEvent( QGraphicsSceneMouseEvent *e );
+
+private:
+	ExpressionLink *m_link;
+
 };
 
 #endif