qwt_plot_canvas.h

QWT5.01用于Qt开发的二维图形库程序

/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
 * 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
 *****************************************************************************/

// vim: expandtab

#ifndef QWT_PLOT_CANVAS_H
#define QWT_PLOT_CANVAS_H

#include <qframe.h>
#include <qpen.h>
#include "qwt_global.h"

class QwtPlot;
class QPixmap;

/*!
  \brief Canvas of a QwtPlot. 

  \sa  QwtPlot 
*/

class QWT_EXPORT QwtPlotCanvas : public QFrame
{
    Q_OBJECT
    friend class QwtPlot;

public:

    /*!
      \brief Paint attributes
 
      - PaintCached\n
        Paint double buffered and reuse the content of the pixmap buffer 
        for some spontaneous repaints that happen when a plot gets unhidden, 
        deiconified or changes the focus.
        Disabling the cache will improve the performance for
        incremental paints (using QwtPlotCurve::draw). 

      - PaintPacked\n
        Suppress system background repaints and paint it together with 
        the canvas contents.
        Painting packed might avoid flickering for expensive repaints,
        when there is a notable gap between painting the background
        and the plot contents.

      The default setting enables PaintCached and PaintPacked

      \sa setPaintAttribute(), testPaintAttribute(), paintCache()
     */
    enum PaintAttribute
    {
        PaintCached = 1,
        PaintPacked = 2
    };

    /*!
      \brief Focus indicator

      - NoFocusIndicator\n
        Don't paint a focus indicator

      - CanvasFocusIndicator\n
        The focus is related to the complete canvas.
        Paint the focus indicator using paintFocus()

      - ItemFocusIndicator\n
        The focus is related to an item (curve, point, ...) on
        the canvas. It is up to the application to display a
        focus indication using f.e. highlighting.

      \sa setFocusIndicator(), focusIndicator(), paintFocus()
    */

    enum FocusIndicator
    {
        NoFocusIndicator,
        CanvasFocusIndicator,
        ItemFocusIndicator
    };

    void setFocusIndicator(FocusIndicator);
    FocusIndicator focusIndicator() const;

    void setPaintAttribute(PaintAttribute, bool on = true);
    bool testPaintAttribute(PaintAttribute) const;

    QPixmap *paintCache();
    const QPixmap *paintCache() const;
    void invalidatePaintCache();

protected:
    explicit QwtPlotCanvas(QwtPlot *);
    virtual ~QwtPlotCanvas();

    virtual void hideEvent(QHideEvent *);

    virtual void paintEvent(QPaintEvent *);

    virtual void drawContents(QPainter *);
    virtual void drawFocusIndicator(QPainter *);

    void drawCanvas(QPainter *painter = NULL);

private:    
    void setSystemBackground(bool);

    class PrivateData;
    PrivateData *d_data;
};

#endif