Support inclusion of FlowView via Qt Designer (paceholder#107)

* Add constructor with parent argument

Support inclusion of FlowView via Qt Designer and generally through
.ui files (using promoted Widget feature).

* allow to set the scene after construction

* remove ill-posed default argument

* use delegating constructor

* improve initialization order

Author: ypnos

src/FlowView.cpp

@@ -27,10 +27,11 @@ using QtNodes::FlowView;
 using QtNodes::FlowScene;
 
 FlowView::
-FlowView(FlowScene *scene)
-  : QGraphicsView(scene)
-  , _clickPos(QPointF())
-  , _scene(scene)
+FlowView(QWidget *parent)
+  : QGraphicsView(parent)
+  , _clearSelectionAction(Q_NULLPTR)
+  , _deleteSelectionAction(Q_NULLPTR)
+  , _scene(Q_NULLPTR)
 {
   setDragMode(QGraphicsView::ScrollHandDrag);
   setRenderHint(QPainter::Antialiasing);
@@ -49,17 +50,14 @@ FlowView(FlowScene *scene)
   setCacheMode(QGraphicsView::CacheBackground);
 
   //setViewport(new QGLWidget(QGLFormat(QGL::SampleBuffers)));
+}
 
-  // setup actions
-  _clearSelectionAction = new QAction(QStringLiteral("Clear Selection"), this);
-  _clearSelectionAction->setShortcut(Qt::Key_Escape);
-  connect(_clearSelectionAction, &QAction::triggered, _scene, &QGraphicsScene::clearSelection);
-  addAction(_clearSelectionAction);
 
-  _deleteSelectionAction = new QAction(QStringLiteral("Delete Selection"), this);
-  _deleteSelectionAction->setShortcut(Qt::Key_Delete);
-  connect(_deleteSelectionAction, &QAction::triggered, this, &FlowView::deleteSelectedNodes);
-  addAction(_deleteSelectionAction);
+FlowView::
+FlowView(FlowScene *scene, QWidget *parent)
+  : FlowView(parent)
+{
+  setScene(scene);
 }
 
 
@@ -79,6 +77,27 @@ deleteSelectionAction() const
 }
 
 
+void
+FlowView::setScene(FlowScene *scene)
+{
+  _scene = scene;
+  QGraphicsView::setScene(_scene);
+
+  // setup actions
+  delete _clearSelectionAction;
+  _clearSelectionAction = new QAction(QStringLiteral("Clear Selection"), this);
+  _clearSelectionAction->setShortcut(Qt::Key_Escape);
+  connect(_clearSelectionAction, &QAction::triggered, _scene, &QGraphicsScene::clearSelection);
+  addAction(_clearSelectionAction);
+
+  delete _deleteSelectionAction;
+  _deleteSelectionAction = new QAction(QStringLiteral("Delete Selection"), this);
+  _deleteSelectionAction->setShortcut(Qt::Key_Delete);
+  connect(_deleteSelectionAction, &QAction::triggered, this, &FlowView::deleteSelectedNodes);
+  addAction(_deleteSelectionAction);
+}
+
+
 void
 FlowView::
 contextMenuEvent(QContextMenuEvent *event)

src/FlowView.hpp

@@ -14,7 +14,8 @@ class NODE_EDITOR_PUBLIC FlowView
 {
 public:
 
-  FlowView(FlowScene *scene);
+  FlowView(QWidget *parent = Q_NULLPTR);
+  FlowView(FlowScene *scene, QWidget *parent = Q_NULLPTR);
 
   FlowView(const FlowView&) = delete;
   FlowView operator=(const FlowView&) = delete;
@@ -23,6 +24,8 @@ class NODE_EDITOR_PUBLIC FlowView
 
   QAction* deleteSelectionAction() const;
 
+  void setScene(FlowScene *scene);
+
 public slots:
 
   void scaleUp();