diagramscene.h Example File

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  #ifndef DIAGRAMSCENE_H
  #define DIAGRAMSCENE_H

  #include "diagramitem.h"
  #include "diagramtextitem.h"

  #include <QGraphicsScene>

  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 };

      explicit 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) Q_DECL_OVERRIDE;
      void mouseMoveEvent(QGraphicsSceneMouseEvent *mouseEvent) Q_DECL_OVERRIDE;
      void mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent) Q_DECL_OVERRIDE;

  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 // DIAGRAMSCENE_H