move subtree with mouse

graphwidget.cpp

@@ -665,6 +665,22 @@ void GraphWidget::nodeSelected(Node *node)
     }
 }
 
+void GraphWidget::nodeMoved(QGraphicsSceneMouseEvent *event)
+{
+    QList <Node *> nodeList;
+    if (event->modifiers() == Qt::ShiftModifier)
+    {
+        nodeList = m_activeNode->subtree();
+    }
+    else
+    {
+        nodeList.push_back(m_activeNode);
+    }
+
+    foreach(Node *node, nodeList)
+        node->setPos(node->pos() + event->scenePos() - event->lastScenePos());
+}
+
 void GraphWidget::addEdge(Node *source, Node *destination)
 {
     if (destination == m_nodeList.first())

graphwidget.h

@@ -4,7 +4,7 @@
 #include <QGraphicsView>
 #include <QGraphicsScene>
 #include <QKeyEvent>
-#include <QMovie>
+#include <QGraphicsSceneMouseEvent>
 
 #include "node.h"
 
@@ -21,6 +21,7 @@ public:
     void insertNode();
     void setActiveNodeEditable();
     void nodeSelected(Node *node);
+    void nodeMoved(QGraphicsSceneMouseEvent *event);
     QList<Edge *> edges() const;
 
     void contentChanged(const bool &changed = true);

node.cpp

@@ -35,6 +35,11 @@ Node::~Node()
     foreach (EdgeElement element, m_edgeList) delete element.edge;
 }
 
+void Node::moveNode(QGraphicsSceneMouseEvent *event)
+{
+    QGraphicsItem::mouseMoveEvent(event);
+}
+
 void Node::addEdge(Edge *edge, bool startsFromThisNode)
 {
     m_edgeList.push_back(EdgeElement(edge, startsFromThisNode));
@@ -444,7 +449,7 @@ void Node::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
 
 void Node::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
 {
-    QGraphicsItem::mouseMoveEvent(event);
+    m_graph->nodeMoved(event);
 }
 
 QPainterPath Node::shape () const

node.h

@@ -16,6 +16,7 @@ public:
     Node(GraphWidget *graphWidget = 0);
     ~Node();
 
+    void moveNode(QGraphicsSceneMouseEvent *event);
     void addEdge(Edge *edge, bool startsFromThisNode);
     void deleteEdge(Node *otherEnd);
     void removeEdgeFromList(Edge *edge);