qwt_legend.h

/******************************************************************************
 * Qwt Widget Library
 * Copyright (C) 1997   Josef Wilgen
 * Copyright (C) 2002   Uwe Rathmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the Qwt License, Version 1.0
 *
 * Modified by ChenZongYan in 2024 <czy.t@163.com>
 *   Summary of major modifications (see ChangeLog.md for full history):
 *   1. CMake build system & C++11 throughout.
 *   2. Core panner/ zoomer refactored:
 *        - QwtPanner → QwtCachePanner (pixmap-cache version)
 *        - New real-time QwtPlotPanner derived from QwtPicker.
 *   3. Zoomer supports multi-axis.
 *   4. Parasite-plot framework:
 *        - QwtFigure, QwtPlotParasiteLayout, QwtPlotTransparentCanvas,
 *        - QwtPlotScaleEventDispatcher, built-in pan/zoom on axis.
 *   5. New picker: QwtPlotSeriesDataPicker (works with date axis).
 *   6. Raster & color-map extensions:
 *        - QwtGridRasterData (2-D table + interpolation)
 *        - QwtLinearColorMap::stopColors(), stopPos() API rename.
 *   7. Bar-chart: expose pen/brush control.
 *   8. Amalgamated build: single QwtPlot.h / QwtPlot.cpp pair in src-amalgamate.
 *****************************************************************************/
 
#ifndef QWT_LEGEND_H
#define QWT_LEGEND_H
 
#include "qwt_global.h"
#include "qwt_abstract_legend.h"
#include "qwt_legend_data.h"
 
#include <qvariant.h>
 
class QScrollBar;
 
class QWT_EXPORT QwtLegend : public QwtAbstractLegend
{
    Q_OBJECT
 
  public:
    // Constructor for QwtLegend
    explicit QwtLegend( QWidget* parent = nullptr );
    // Destructor
    virtual ~QwtLegend();
 
    // Set the maximum number of columns
    void setMaxColumns( uint numColums );
    // Return the maximum number of columns
    uint maxColumns() const;
 
    // Set the default mode for legend items
    void setDefaultItemMode( QwtLegendData::Mode );
    // Return the default mode for legend items
    QwtLegendData::Mode defaultItemMode() const;
 
    // Return the contents widget
    QWidget* contentsWidget();
    // Return the contents widget (const version)
    const QWidget* contentsWidget() const;
 
    // Return the legend widget for a specific item
    QWidget* legendWidget( const QVariant&  ) const;
    // Return all legend widgets for a specific item
    QList< QWidget* > legendWidgets( const QVariant& ) const;
 
    // Return the item info for a specific widget
    QVariant itemInfo( const QWidget* ) const;
 
    // Event filter for event handling
    virtual bool eventFilter( QObject*, QEvent* ) override;
 
    // Return the size hint
    virtual QSize sizeHint() const override;
    // Return the height for a given width
    virtual int heightForWidth( int w ) const override;
 
    // Return the horizontal scroll bar
    QScrollBar* horizontalScrollBar() const;
    // Return the vertical scroll bar
    QScrollBar* verticalScrollBar() const;
 
    // Render the legend to a painter
    virtual void renderLegend( QPainter*,
        const QRectF&, bool fillBackground ) const override;
 
    // Render a single legend item
    virtual void renderItem( QPainter*,
        const QWidget*, const QRectF&, bool fillBackground ) const;
 
    // Check if the legend is empty
    virtual bool isEmpty() const override;
    // Return the scroll extent for a specific orientation
    virtual int scrollExtent( Qt::Orientation ) const override;
 
  Q_SIGNALS:
    void clicked( const QVariant& itemInfo, int index );
 
    void checked( const QVariant& itemInfo, bool on, int index );
 
  public Q_SLOTS:
    virtual void updateLegend( const QVariant&,
        const QList< QwtLegendData >& ) override;
 
  protected Q_SLOTS:
    void itemClicked();
    void itemChecked( bool );
 
  protected:
    virtual QWidget* createWidget( const QwtLegendData& ) const;
    virtual void updateWidget( QWidget*, const QwtLegendData& );
 
  private:
    void updateTabOrder();
 
    class PrivateData;
    PrivateData* m_data;
};
 
#endif