qwt_abstract_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_ABSTRACT_LEGEND_H
#define QWT_ABSTRACT_LEGEND_H
#include <QFrame>
#include <QVariant>
#include <QList>
#include "qwt_global.h"
#include "qwt_legend_data.h"
 
class QWT_EXPORT QwtAbstractLegend : public QFrame
{
    Q_OBJECT
 
public:
    // Constructor for QwtAbstractLegend
    explicit QwtAbstractLegend(QWidget* parent = nullptr);
 
    // Destructor for QwtAbstractLegend
    ~QwtAbstractLegend() override;
 
    // Render the legend into a given rectangle
    virtual void renderLegend(QPainter* painter, const QRectF& rect, bool fillBackground) const = 0;
 
    // Return true when no plot item is inserted
    virtual bool isEmpty() const = 0;
 
    // Return scroll extent
    virtual int scrollExtent(Qt::Orientation) const;
 
public Q_SLOTS:
 
    // Update the entries for a plot item
    virtual void updateLegend(const QVariant& itemInfo, const QList< QwtLegendData >& data) = 0;
};
 
#endif