diagramscene.h Example File
graphicsview/diagramscene/diagramscene.h

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 #ifndef DIAGRAMSCENE_H
 #define DIAGRAMSCENE_H

 #include <QGraphicsScene>
 #include "diagramitem.h"
 #include "diagramtextitem.h"

 class QGraphicsSceneMouseEvent;
 class QMenu;
 class QPointF;
 class QGraphicsLineItem;
 class QFont;
 class QGraphicsTextItem;
 class QColor;

 class DiagramScene : public QGraphicsScene
 {
     Q_OBJECT

 public:
     enum Mode { InsertItem, InsertLine, InsertText, MoveItem };

     DiagramScene(QMenu *itemMenu, QObject *parent = 0);
     QFont font() const
         { return myFont; }
     QColor textColor() const
         { return myTextColor; }
     QColor itemColor() const
         { return myItemColor; }
     QColor lineColor() const
         { return myLineColor; }
     void setLineColor(const QColor &color);
     void setTextColor(const QColor &color);
     void setItemColor(const QColor &color);
     void setFont(const QFont &font);

 public slots:
     void setMode(Mode mode);
     void setItemType(DiagramItem::DiagramType type);
     void editorLostFocus(DiagramTextItem *item);

 signals:
     void itemInserted(DiagramItem *item);
     void textInserted(QGraphicsTextItem *item);
     void itemSelected(QGraphicsItem *item);

 protected:
     void mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent);
     void mouseMoveEvent(QGraphicsSceneMouseEvent *mouseEvent);
     void mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent);

 private:
     bool isItemChange(int type);

     DiagramItem::DiagramType myItemType;
     QMenu *myItemMenu;
     Mode myMode;
     bool leftButtonDown;
     QPointF startPoint;
     QGraphicsLineItem *line;
     QFont myFont;
     DiagramTextItem *textItem;
     QColor myTextColor;
     QColor myItemColor;
     QColor myLineColor;
 };

 #endif