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
    ~QwtLegend() override;
 
    // 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();
 
    QWT_DECLARE_PRIVATE(QwtLegend)
};
 
#endif