/////////////////////////////////////////////////////////////////////////////////
//
//  Copyright (C) 2017-     Statoil ASA
//
//  ResInsight is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  ResInsight is distributed in the hope that it will be useful, but WITHOUT ANY
//  WARRANTY; without even the implied warranty of MERCHANTABILITY or
//  FITNESS FOR A PARTICULAR PURPOSE.
//
//  See the GNU General Public License at <http://www.gnu.org/licenses/gpl.html>
//  for more details.
//
/////////////////////////////////////////////////////////////////////////////////

#include "RiuQwtPlotWheelZoomer.h"
#include "qwt_plot.h"
#include <QEvent>
#include <QWheelEvent>

#define RIU_SCROLLWHEEL_ZOOMFACTOR 1.1
#define RIU_SCROLLWHEEL_PANFACTOR 0.1

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
RiuQwtPlotWheelZoomer::RiuQwtPlotWheelZoomer( QwtPlot* plot )
    : QObject( plot )
    , m_plot( plot )
{
    plot->canvas()->installEventFilter( this );
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
void zoomOnAxis( QwtPlot* plot, QwtPlot::Axis axis, double zoomFactor, int eventPos )
{
    QwtScaleMap scaleMap   = plot->canvasMap( axis );
    double      zoomCenter = scaleMap.invTransform( eventPos );
    double      newMin     = zoomCenter - zoomFactor * ( zoomCenter - scaleMap.s1() );
    double      newMax     = zoomCenter + zoomFactor * ( -zoomCenter + scaleMap.s2() );
    plot->setAxisScale( axis, newMin, newMax );
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
bool RiuQwtPlotWheelZoomer::eventFilter( QObject* watched, QEvent* event )
{
    QWheelEvent* wheelEvent = dynamic_cast<QWheelEvent*>( event );
    if ( wheelEvent )
    {
        double zoomFactor = 1.0 / RIU_SCROLLWHEEL_ZOOMFACTOR;
        if ( wheelEvent->delta() > 0 )
        {
            zoomFactor = RIU_SCROLLWHEEL_ZOOMFACTOR;
        }

        zoomOnAxis( m_plot, QwtPlot::xBottom, zoomFactor, wheelEvent->pos().x() );
        zoomOnAxis( m_plot, QwtPlot::xTop, zoomFactor, wheelEvent->pos().x() );
        zoomOnAxis( m_plot, QwtPlot::yLeft, zoomFactor, wheelEvent->pos().y() );
        zoomOnAxis( m_plot, QwtPlot::yRight, zoomFactor, wheelEvent->pos().y() );

        m_plot->replot();
        emit zoomUpdated();
    }

    return false;
}