document.h Example File

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 #ifndef DOCUMENT_H
 #define DOCUMENT_H

 #include <QWidget>

 QT_FORWARD_DECLARE_CLASS(QUndoStack)
 QT_FORWARD_DECLARE_CLASS(QTextStream)

 class Shape
 {
 public:
     enum Type { Rectangle, Circle, Triangle };

     Shape(Type type = Rectangle, const QColor &color = Qt::red, const QRect &rect = QRect());

     Type type() const;
     QString name() const;
     QRect rect() const;
     QRect resizeHandle() const;
     QColor color() const;

     static QString typeToString(Type type);
     static Type stringToType(const QString &s, bool *ok = 0);

     static const QSize minSize;

 private:
     Type m_type;
     QRect m_rect;
     QColor m_color;
     QString m_name;

     friend class Document;
 };

 class Document : public QWidget
 {
     Q_OBJECT

 public:
     Document(QWidget *parent = 0);

     QString addShape(const Shape &shape);
     void deleteShape(const QString &shapeName);
     Shape shape(const QString &shapeName) const;
     QString currentShapeName() const;

     void setShapeRect(const QString &shapeName, const QRect &rect);
     void setShapeColor(const QString &shapeName, const QColor &color);

     bool load(QTextStream &stream);
     void save(QTextStream &stream);

     QString fileName() const;
     void setFileName(const QString &fileName);

     QUndoStack *undoStack() const;

 signals:
     void currentShapeChanged(const QString &shapeName);

 protected:
     void paintEvent(QPaintEvent *event);
     void mousePressEvent(QMouseEvent *event);
     void mouseReleaseEvent(QMouseEvent *event);
     void mouseMoveEvent(QMouseEvent *event);

 private:
     void setCurrentShape(int index);
     int indexOf(const QString &shapeName) const;
     int indexAt(const QPoint &pos) const;
     QString uniqueName(const QString &name) const;

     QList<Shape> m_shapeList;
     int m_currentIndex;
     int m_mousePressIndex;
     QPoint m_mousePressOffset;
     bool m_resizeHandlePressed;
     QString m_fileName;

     QUndoStack *m_undoStack;
 };

 #endif // DOCUMENT_H