qwt_text_engine.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_TEXT_ENGINE_H
#define QWT_TEXT_ENGINE_H
 
#include "qwt_global.h"
#include <qsize.h>
 
class QFont;
class QRectF;
class QString;
class QPainter;
 
class QWT_EXPORT QwtTextEngine
{
public:
    // Virtual destructor
    virtual ~QwtTextEngine();
 
    // Find the height for a given width
    virtual double heightForWidth(const QFont& font, int flags, const QString& text, double width) const = 0;
 
    // Return the size needed to render text
    virtual QSizeF textSize(const QFont& font, int flags, const QString& text) const = 0;
 
    // Test if a string can be rendered by this text engine
    virtual bool mightRender(const QString& text) const = 0;
 
    // Return margins around the texts
    virtual void
    textMargins(const QFont& font, const QString& text, double& left, double& right, double& top, double& bottom) const = 0;
 
    // Draw the text in a clipping rectangle
    virtual void draw(QPainter* painter, const QRectF& rect, int flags, const QString& text) const = 0;
 
protected:
    QwtTextEngine();
 
private:
    QwtTextEngine(const QwtTextEngine&)            = delete;
    QwtTextEngine& operator=(const QwtTextEngine&) = delete;
};
 
class QWT_EXPORT QwtPlainTextEngine : public QwtTextEngine
{
public:
    // Constructor
    QwtPlainTextEngine();
    // Destructor
    ~QwtPlainTextEngine() override;
 
    // Calculate height for a given width
    virtual double heightForWidth(const QFont& font, int flags, const QString& text, double width) const override;
 
    // Return the size needed to render text
    virtual QSizeF textSize(const QFont& font, int flags, const QString& text) const override;
 
    // Draw the text
    virtual void draw(QPainter*, const QRectF& rect, int flags, const QString& text) const override;
 
    // Test if a string can be rendered
    virtual bool mightRender(const QString&) const override;
 
    // Return text margins
    virtual void
    textMargins(const QFont&, const QString&, double& left, double& right, double& top, double& bottom) const override;
 
private:
    QWT_DECLARE_PRIVATE(QwtPlainTextEngine)
};
 
#ifndef QT_NO_RICHTEXT
 
class QWT_EXPORT QwtRichTextEngine : public QwtTextEngine
{
public:
    // Constructor
    QwtRichTextEngine();
 
    // Calculate height for a given width
    virtual double heightForWidth(const QFont& font, int flags, const QString& text, double width) const override;
 
    // Return the size needed to render text
    virtual QSizeF textSize(const QFont& font, int flags, const QString& text) const override;
 
    // Draw the text
    virtual void draw(QPainter*, const QRectF& rect, int flags, const QString& text) const override;
 
    // Test if a string can be rendered
    virtual bool mightRender(const QString&) const override;
 
    // Return text margins
    virtual void
    textMargins(const QFont&, const QString&, double& left, double& right, double& top, double& bottom) const override;
 
private:
    QString taggedText(const QString&, int flags) const;
};
 
#endif  // !QT_NO_RICHTEXT
 
#endif