pieview.h Example File

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  #ifndef PIEVIEW_H
  #define PIEVIEW_H

  #include <QAbstractItemView>

  class PieView : public QAbstractItemView
  {
      Q_OBJECT

  public:
      PieView(QWidget *parent = 0);

      QRect visualRect(const QModelIndex &index) const Q_DECL_OVERRIDE;
      void scrollTo(const QModelIndex &index, ScrollHint hint = EnsureVisible) Q_DECL_OVERRIDE;
      QModelIndex indexAt(const QPoint &point) const Q_DECL_OVERRIDE;

  protected slots:
      void dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight,
                       const QVector<int> &roles = QVector<int>()) Q_DECL_OVERRIDE;
      void rowsInserted(const QModelIndex &parent, int start, int end) Q_DECL_OVERRIDE;
      void rowsAboutToBeRemoved(const QModelIndex &parent, int start, int end) Q_DECL_OVERRIDE;

  protected:
      bool edit(const QModelIndex &index, EditTrigger trigger, QEvent *event) Q_DECL_OVERRIDE;
      QModelIndex moveCursor(QAbstractItemView::CursorAction cursorAction,
                             Qt::KeyboardModifiers modifiers) Q_DECL_OVERRIDE;

      int horizontalOffset() const Q_DECL_OVERRIDE;
      int verticalOffset() const Q_DECL_OVERRIDE;

      bool isIndexHidden(const QModelIndex &index) const Q_DECL_OVERRIDE;

      void setSelection(const QRect&, QItemSelectionModel::SelectionFlags command) Q_DECL_OVERRIDE;

      void mousePressEvent(QMouseEvent *event) Q_DECL_OVERRIDE;

      void mouseMoveEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
      void mouseReleaseEvent(QMouseEvent *event) Q_DECL_OVERRIDE;

      void paintEvent(QPaintEvent *event) Q_DECL_OVERRIDE;
      void resizeEvent(QResizeEvent *event) Q_DECL_OVERRIDE;
      void scrollContentsBy(int dx, int dy) Q_DECL_OVERRIDE;

      QRegion visualRegionForSelection(const QItemSelection &selection) const Q_DECL_OVERRIDE;

  private:
      QRect itemRect(const QModelIndex &item) const;
      QRegion itemRegion(const QModelIndex &index) const;
      int rows(const QModelIndex &index = QModelIndex()) const;
      void updateGeometries() Q_DECL_OVERRIDE;

      int margin;
      int totalSize;
      int pieSize;
      int validItems;
      double totalValue;
      QPoint origin;
      QRubberBand *rubberBand;
  };

  #endif // PIEVIEW_H