qwt_plot_magnifier.cpp

/* -*- 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

#include <math.h>
#include <qevent.h>
#include "qwt_plot.h"
#include "qwt_plot_canvas.h"
#include "qwt_scale_div.h"
#include "qwt_plot_magnifier.h"

class QwtPlotMagnifier::PrivateData
{
public:
    PrivateData() {
        for ( int axis = 0; axis < QwtPlot::axisCnt; axis++ )
            isAxisEnabled[axis] = true;
    }

    bool isAxisEnabled[QwtPlot::axisCnt];
};

/*!
   Constructor
   \param canvas Plot canvas to be magnified
*/
QwtPlotMagnifier::QwtPlotMagnifier(QwtPlotCanvas *canvas):
    QwtMagnifier(canvas)
{
    d_data = new PrivateData();
}

//! Destructor
QwtPlotMagnifier::~QwtPlotMagnifier()
{
    delete d_data;
}

/*!
   \brief En/Disable an axis

   Axes that are enabled will be synchronized to the
   result of panning. All other axes will remain unchanged.

   \param axis Axis, see QwtPlot::Axis
   \param on On/Off

   \sa isAxisEnabled
*/
void QwtPlotMagnifier::setAxisEnabled(int axis, bool on)
{
    if ( axis >= 0 && axis < QwtPlot::axisCnt )
        d_data->isAxisEnabled[axis] = on;
}

/*!
   Test if an axis is enabled

   \param axis Axis, see QwtPlot::Axis
   \return True, if the axis is enabled

   \sa setAxisEnabled
*/
bool QwtPlotMagnifier::isAxisEnabled(int axis) const
{
    if ( axis >= 0 && axis < QwtPlot::axisCnt )
        return d_data->isAxisEnabled[axis];

    return true;
}

//! Return observed plot canvas
QwtPlotCanvas *QwtPlotMagnifier::canvas()
{
    QObject *w = parent();
    if ( w && w->inherits("QwtPlotCanvas") )
        return (QwtPlotCanvas *)w;

    return NULL;
}

//! Return Observed plot canvas
const QwtPlotCanvas *QwtPlotMagnifier::canvas() const
{
    return ((QwtPlotMagnifier *)this)->canvas();
}

//! Return plot widget, containing the observed plot canvas
QwtPlot *QwtPlotMagnifier::plot()
{
    QObject *w = canvas();
    if ( w ) {
        w = w->parent();
        if ( w && w->inherits("QwtPlot") )
            return (QwtPlot *)w;
    }

    return NULL;
}

//! Return plot widget, containing the observed plot canvas
const QwtPlot *QwtPlotMagnifier::plot() const
{
    return ((QwtPlotMagnifier *)this)->plot();
}

/*!
   Zoom in/out the axes scales
   \param factor A value < 1.0 zooms in, a value > 1.0 zooms out.
*/
void QwtPlotMagnifier::rescale(double factor)
{
    factor = qwtAbs(factor);
    if ( factor == 1.0 || factor == 0.0 )
        return;

    bool doReplot = false;
    QwtPlot* plt = plot();

    const bool autoReplot = plt->autoReplot();
    plt->setAutoReplot(false);

    for ( int axisId = 0; axisId < QwtPlot::axisCnt; axisId++ ) {
        const QwtScaleDiv *scaleDiv = plt->axisScaleDiv(axisId);
        if ( isAxisEnabled(axisId) && scaleDiv->isValid() ) {
            const double center =
                scaleDiv->lBound() + scaleDiv->range() / 2;
            const double width_2 = scaleDiv->range() / 2 * factor;

            plt->setAxisScale(axisId, center - width_2, center + width_2);
            doReplot = true;
        }
    }

    plt->setAutoReplot(autoReplot);

    if ( doReplot )
        plt->replot();
}