qwt_plot_renderer.cpp

Go to the documentation of this file.

/* -*- 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
 *****************************************************************************/

#include "qwt_plot_renderer.h"
#include "qwt_plot.h"
#include "qwt_painter.h"
#include "qwt_plot_layout.h"
#include "qwt_abstract_legend.h"
#include "qwt_scale_widget.h"
#include "qwt_scale_engine.h"
#include "qwt_text.h"
#include "qwt_text_label.h"
#include "qwt_math.h"
#include <qpainter.h>
#include <qpaintengine.h>
#include <qtransform.h>
#include <qprinter.h>
#include <qprintdialog.h>
#include <qfiledialog.h>
#include <qfileinfo.h>
#include <qstyle.h>
#include <qstyleoption.h>
#include <qimagewriter.h>

#ifndef QWT_NO_SVG
#ifdef QT_SVG_LIB
#if QT_VERSION >= 0x040500
#define QWT_FORMAT_SVG 1
#endif
#endif
#endif

#ifndef QT_NO_PRINTER
#define QWT_FORMAT_PDF 1
#endif

#ifndef QT_NO_PDF

// QPdfWriter::setResolution() has been introduced with
// Qt 5.3. Guess it is o.k. to stay with QPrinter for older
// versions.

#if QT_VERSION >= 0x050300

#ifndef QWT_FORMAT_PDF
#define QWT_FORMAT_PDF 1
#endif

#define QWT_PDF_WRITER 1

#endif
#endif

#ifndef QT_NO_PRINTER
// postscript support has been dropped in Qt5
#if QT_VERSION < 0x050000
#define QWT_FORMAT_POSTSCRIPT 1
#endif
#endif

#if QWT_FORMAT_SVG
#include <qsvggenerator.h>
#endif

#if QWT_PDF_WRITER
#include <qpdfwriter.h>
#endif

static QPainterPath qwtCanvasClip( 
    const QWidget* canvas, const QRectF &canvasRect )
{
    // The clip region is calculated in integers
    // To avoid too much rounding errors better
    // calculate it in target device resolution

    int x1 = qCeil( canvasRect.left() );
    int x2 = qFloor( canvasRect.right() );
    int y1 = qCeil( canvasRect.top() );
    int y2 = qFloor( canvasRect.bottom() );

    const QRect r( x1, y1, x2 - x1 - 1, y2 - y1 - 1 );

    QPainterPath clipPath;

    ( void ) QMetaObject::invokeMethod(
        const_cast< QWidget *>( canvas ), "borderPath",
        Qt::DirectConnection,
        Q_RETURN_ARG( QPainterPath, clipPath ), Q_ARG( QRect, r ) );

    return clipPath;
}

class QwtPlotRenderer::PrivateData
{
public:
    PrivateData():
        discardFlags( QwtPlotRenderer::DiscardNone ),
        layoutFlags( QwtPlotRenderer::DefaultLayout )
    {
    }

    QwtPlotRenderer::DiscardFlags discardFlags;
    QwtPlotRenderer::LayoutFlags layoutFlags;
};

QwtPlotRenderer::QwtPlotRenderer( QObject *parent ):
    QObject( parent )
{
    d_data = new PrivateData;
}

QwtPlotRenderer::~QwtPlotRenderer()
{
    delete d_data;
}

void QwtPlotRenderer::setDiscardFlag( DiscardFlag flag, bool on )
{
    if ( on )
        d_data->discardFlags |= flag;
    else
        d_data->discardFlags &= ~flag;
}

bool QwtPlotRenderer::testDiscardFlag( DiscardFlag flag ) const
{
    return d_data->discardFlags & flag;
}

void QwtPlotRenderer::setDiscardFlags( DiscardFlags flags )
{
    d_data->discardFlags = flags;
}

QwtPlotRenderer::DiscardFlags QwtPlotRenderer::discardFlags() const
{
    return d_data->discardFlags;
}

void QwtPlotRenderer::setLayoutFlag( LayoutFlag flag, bool on )
{
    if ( on )
        d_data->layoutFlags |= flag;
    else
        d_data->layoutFlags &= ~flag;
}

bool QwtPlotRenderer::testLayoutFlag( LayoutFlag flag ) const
{
    return d_data->layoutFlags & flag;
}

void QwtPlotRenderer::setLayoutFlags( LayoutFlags flags )
{
    d_data->layoutFlags = flags;
}

QwtPlotRenderer::LayoutFlags QwtPlotRenderer::layoutFlags() const
{
    return d_data->layoutFlags;
}

void QwtPlotRenderer::renderDocument( QwtPlot *plot,
    const QString &fileName, const QSizeF &sizeMM, int resolution )
{
    renderDocument( plot, fileName,
        QFileInfo( fileName ).suffix(), sizeMM, resolution );
}

void QwtPlotRenderer::renderDocument( QwtPlot *plot,
    const QString &fileName, const QString &format,
    const QSizeF &sizeMM, int resolution )
{
    if ( plot == NULL || sizeMM.isEmpty() || resolution <= 0 )
        return;

    QString title = plot->title().text();
    if ( title.isEmpty() )
        title = "Plot Document";

    const double mmToInch = 1.0 / 25.4;
    const QSizeF size = sizeMM * mmToInch * resolution;

    const QRectF documentRect( 0.0, 0.0, size.width(), size.height() );

    const QString fmt = format.toLower();
    if ( fmt == QLatin1String( "pdf" ) )
    {
#if QWT_FORMAT_PDF

#if QWT_PDF_WRITER
        QPdfWriter pdfWriter( fileName );
        pdfWriter.setPageSizeMM( sizeMM );
        pdfWriter.setTitle( title );
        pdfWriter.setPageMargins( QMarginsF() );
        pdfWriter.setResolution( resolution ); 
        
        QPainter painter( &pdfWriter );
        render( plot, &painter, documentRect );
#else
        QPrinter printer;
        printer.setOutputFormat( QPrinter::PdfFormat );
        printer.setColorMode( QPrinter::Color );
        printer.setFullPage( true );
        printer.setPaperSize( sizeMM, QPrinter::Millimeter );
        printer.setDocName( title );
        printer.setOutputFileName( fileName );
        printer.setResolution( resolution );

        QPainter painter( &printer );
        render( plot, &painter, documentRect );
#endif
#endif
    }
    else if ( fmt == QLatin1String( "ps" ) )
    {
#if QWT_FORMAT_POSTSCRIPT
        QPrinter printer;
        printer.setOutputFormat( QPrinter::PostScriptFormat );
        printer.setColorMode( QPrinter::Color );
        printer.setFullPage( true );
        printer.setPaperSize( sizeMM, QPrinter::Millimeter );
        printer.setDocName( title );
        printer.setOutputFileName( fileName );
        printer.setResolution( resolution );

        QPainter painter( &printer );
        render( plot, &painter, documentRect );
#endif
    }
    else if ( fmt == QLatin1String( "svg" ) )
    {
#if QWT_FORMAT_SVG
        QSvgGenerator generator;
        generator.setTitle( title );
        generator.setFileName( fileName );
        generator.setResolution( resolution );
        generator.setViewBox( documentRect );

        QPainter painter( &generator );
        render( plot, &painter, documentRect );
#endif
    }
    else
    {
        if ( QImageWriter::supportedImageFormats().indexOf(
            format.toLatin1() ) >= 0 )
        {
            const QRect imageRect = documentRect.toRect();
            const int dotsPerMeter = qRound( resolution * mmToInch * 1000.0 );

            QImage image( imageRect.size(), QImage::Format_ARGB32 );
            image.setDotsPerMeterX( dotsPerMeter );
            image.setDotsPerMeterY( dotsPerMeter );
            image.fill( QColor( Qt::white ).rgb() );

            QPainter painter( &image );
            render( plot, &painter, imageRect );
            painter.end();

            image.save( fileName, format.toLatin1() );
        }
    }
}

void QwtPlotRenderer::renderTo(
    QwtPlot *plot, QPaintDevice &paintDevice ) const
{
    int w = paintDevice.width();
    int h = paintDevice.height();

    QPainter p( &paintDevice );
    render( plot, &p, QRectF( 0, 0, w, h ) );
}

#ifndef QT_NO_PRINTER

void QwtPlotRenderer::renderTo(
    QwtPlot *plot, QPrinter &printer ) const
{
    int w = printer.width();
    int h = printer.height();

    QRectF rect( 0, 0, w, h );
    double aspect = rect.width() / rect.height();
    if ( ( aspect < 1.0 ) )
        rect.setHeight( aspect * rect.width() );

    QPainter p( &printer );
    render( plot, &p, rect );
}

#endif

#if QWT_FORMAT_SVG

void QwtPlotRenderer::renderTo(
    QwtPlot *plot, QSvgGenerator &generator ) const
{
    QRectF rect = generator.viewBoxF();
    if ( rect.isEmpty() )
        rect.setRect( 0, 0, generator.width(), generator.height() );

    if ( rect.isEmpty() )
        rect.setRect( 0, 0, 800, 600 ); // something

    QPainter p( &generator );
    render( plot, &p, rect );
}

#endif

void QwtPlotRenderer::render( QwtPlot *plot,
    QPainter *painter, const QRectF &plotRect ) const
{
    if ( painter == 0 || !painter->isActive() ||
            !plotRect.isValid() || plot->size().isNull() )
    {
        return;
    }

    if ( !( d_data->discardFlags & DiscardBackground ) )
        QwtPainter::drawBackgound( painter, plotRect, plot );

    /*
      The layout engine uses the same methods as they are used
      by the Qt layout system. Therefore we need to calculate the
      layout in screen coordinates and paint with a scaled painter.
     */
    QTransform transform;
    transform.scale(
        double( painter->device()->logicalDpiX() ) / plot->logicalDpiX(),
        double( painter->device()->logicalDpiY() ) / plot->logicalDpiY() );

    QRectF layoutRect = transform.inverted().mapRect( plotRect );

    if ( !( d_data->discardFlags & DiscardBackground ) )
    {
        // subtract the contents margins

        int left, top, right, bottom;
        plot->getContentsMargins( &left, &top, &right, &bottom );
        layoutRect.adjust( left, top, -right, -bottom );
    }

    QwtPlotLayout *layout = plot->plotLayout();

    int baseLineDists[QwtPlot::axisCnt];
    int canvasMargins[QwtPlot::axisCnt];

    for ( int axisId = 0; axisId < QwtPlot::axisCnt; axisId++ )
    {
        canvasMargins[ axisId ] = layout->canvasMargin( axisId );

        if ( d_data->layoutFlags & FrameWithScales )
        {
            QwtScaleWidget *scaleWidget = plot->axisWidget( axisId );
            if ( scaleWidget )
            {
                baseLineDists[axisId] = scaleWidget->margin();
                scaleWidget->setMargin( 0 );
            }

            if ( !plot->axisEnabled( axisId ) )
            {
                int left = 0;
                int right = 0;
                int top = 0;
                int bottom = 0;

                // When we have a scale the frame is painted on
                // the position of the backbone - otherwise we
                // need to introduce a margin around the canvas

                switch( axisId )
                {
                    case QwtPlot::yLeft:
                        layoutRect.adjust( 1, 0, 0, 0 );
                        break;
                    case QwtPlot::yRight:
                        layoutRect.adjust( 0, 0, -1, 0 );
                        break;
                    case QwtPlot::xTop:
                        layoutRect.adjust( 0, 1, 0, 0 );
                        break;
                    case QwtPlot::xBottom:
                        layoutRect.adjust( 0, 0, 0, -1 );
                        break;
                    default:
                        break;
                }
                layoutRect.adjust( left, top, right, bottom );
            }
        }
    }

    // Calculate the layout for the document.

    QwtPlotLayout::Options layoutOptions = QwtPlotLayout::IgnoreScrollbars;

    if ( ( d_data->layoutFlags & FrameWithScales ) ||
        ( d_data->discardFlags & DiscardCanvasFrame ) )
    {
        layoutOptions |= QwtPlotLayout::IgnoreFrames;
    } 


    if ( d_data->discardFlags & DiscardLegend )
        layoutOptions |= QwtPlotLayout::IgnoreLegend;

    if ( d_data->discardFlags & DiscardTitle )
        layoutOptions |= QwtPlotLayout::IgnoreTitle;

    if ( d_data->discardFlags & DiscardFooter )
        layoutOptions |= QwtPlotLayout::IgnoreFooter;

    layout->activate( plot, layoutRect, layoutOptions );

    // canvas

    QwtScaleMap maps[QwtPlot::axisCnt];
    buildCanvasMaps( plot, layout->canvasRect(), maps );
    if ( updateCanvasMargins( plot, layout->canvasRect(), maps ) )
    {
        // recalculate maps and layout, when the margins
        // have been changed

        layout->activate( plot, layoutRect, layoutOptions );
        buildCanvasMaps( plot, layout->canvasRect(), maps );
    }

    // now start painting

    painter->save();
    painter->setWorldTransform( transform, true );

    renderCanvas( plot, painter, layout->canvasRect(), maps );

    if ( !( d_data->discardFlags & DiscardTitle )
        && ( !plot->titleLabel()->text().isEmpty() ) )
    {
        renderTitle( plot, painter, layout->titleRect() );
    }

    if ( !( d_data->discardFlags & DiscardFooter )
        && ( !plot->footerLabel()->text().isEmpty() ) )
    {
        renderFooter( plot, painter, layout->footerRect() );
    }

    if ( !( d_data->discardFlags & DiscardLegend )
        && plot->legend() && !plot->legend()->isEmpty() )
    {
        renderLegend( plot, painter, layout->legendRect() );
    }

    for ( int axisId = 0; axisId < QwtPlot::axisCnt; axisId++ )
    {
        QwtScaleWidget *scaleWidget = plot->axisWidget( axisId );
        if ( scaleWidget )
        {
            int baseDist = scaleWidget->margin();

            int startDist, endDist;
            scaleWidget->getBorderDistHint( startDist, endDist );

            renderScale( plot, painter, axisId, startDist, endDist,
                baseDist, layout->scaleRect( axisId ) );
        }
    }

    painter->restore();

    // restore all setting to their original attributes.
    for ( int axisId = 0; axisId < QwtPlot::axisCnt; axisId++ )
    {
        if ( d_data->layoutFlags & FrameWithScales )
        {
            QwtScaleWidget *scaleWidget = plot->axisWidget( axisId );
            if ( scaleWidget  )
                scaleWidget->setMargin( baseLineDists[axisId] );
        }

        layout->setCanvasMargin( canvasMargins[axisId] );
    }

    layout->invalidate();

}

void QwtPlotRenderer::renderTitle( const QwtPlot *plot,
    QPainter *painter, const QRectF &rect ) const
{
    painter->setFont( plot->titleLabel()->font() );

    const QColor color = plot->titleLabel()->palette().color(
            QPalette::Active, QPalette::Text );

    painter->setPen( color );
    plot->titleLabel()->text().draw( painter, rect );
}

void QwtPlotRenderer::renderFooter( const QwtPlot *plot,
    QPainter *painter, const QRectF &rect ) const
{
    painter->setFont( plot->footerLabel()->font() );

    const QColor color = plot->footerLabel()->palette().color(
            QPalette::Active, QPalette::Text );

    painter->setPen( color );
    plot->footerLabel()->text().draw( painter, rect );
}


void QwtPlotRenderer::renderLegend( const QwtPlot *plot,
    QPainter *painter, const QRectF &rect ) const
{
    if ( plot->legend() )
    {
        bool fillBackground = !( d_data->discardFlags & DiscardBackground );
        plot->legend()->renderLegend( painter, rect, fillBackground );
    }
}

void QwtPlotRenderer::renderScale( const QwtPlot *plot,
    QPainter *painter,
    int axisId, int startDist, int endDist, int baseDist,
    const QRectF &rect ) const
{
    if ( !plot->axisEnabled( axisId ) )
        return;

    const QwtScaleWidget *scaleWidget = plot->axisWidget( axisId );
    if ( scaleWidget->isColorBarEnabled()
        && scaleWidget->colorBarWidth() > 0 )
    {
        scaleWidget->drawColorBar( painter, scaleWidget->colorBarRect( rect ) );
        baseDist += scaleWidget->colorBarWidth() + scaleWidget->spacing();
    }

    painter->save();

    QwtScaleDraw::Alignment align;
    double x, y, w;

    switch ( axisId )
    {
        case QwtPlot::yLeft:
        {
            x = rect.right() - 1.0 - baseDist;
            y = rect.y() + startDist;
            w = rect.height() - startDist - endDist;
            align = QwtScaleDraw::LeftScale;
            break;
        }
        case QwtPlot::yRight:
        {
            x = rect.left() + baseDist;
            y = rect.y() + startDist;
            w = rect.height() - startDist - endDist;
            align = QwtScaleDraw::RightScale;
            break;
        }
        case QwtPlot::xTop:
        {
            x = rect.left() + startDist;
            y = rect.bottom() - 1.0 - baseDist;
            w = rect.width() - startDist - endDist;
            align = QwtScaleDraw::TopScale;
            break;
        }
        case QwtPlot::xBottom:
        {
            x = rect.left() + startDist;
            y = rect.top() + baseDist;
            w = rect.width() - startDist - endDist;
            align = QwtScaleDraw::BottomScale;
            break;
        }
        default:
            return;
    }

    scaleWidget->drawTitle( painter, align, rect );

    painter->setFont( scaleWidget->font() );

    QwtScaleDraw *sd = const_cast<QwtScaleDraw *>( scaleWidget->scaleDraw() );
    const QPointF sdPos = sd->pos();
    const double sdLength = sd->length();

    sd->move( x, y );
    sd->setLength( w );

    QPalette palette = scaleWidget->palette();
    palette.setCurrentColorGroup( QPalette::Active );
    sd->draw( painter, palette );

    // reset previous values
    sd->move( sdPos );
    sd->setLength( sdLength );

    painter->restore();
}

void QwtPlotRenderer::renderCanvas( const QwtPlot *plot,
    QPainter *painter, const QRectF &canvasRect, 
    const QwtScaleMap *map ) const
{
    const QWidget *canvas = plot->canvas();

    QRectF r = canvasRect.adjusted( 0.0, 0.0, -1.0, -1.0 );

    if ( d_data->layoutFlags & FrameWithScales )
    {
        painter->save();

        r.adjust( -1.0, -1.0, 1.0, 1.0 );
        painter->setPen( QPen( Qt::black ) );

        if ( !( d_data->discardFlags & DiscardCanvasBackground ) )
        {
            const QBrush bgBrush =
                canvas->palette().brush( plot->backgroundRole() );
            painter->setBrush( bgBrush );
        }

        QwtPainter::drawRect( painter, r );

        painter->restore();
        painter->save();

        painter->setClipRect( canvasRect );
        plot->drawItems( painter, canvasRect, map );

        painter->restore();
    }
    else if ( canvas->testAttribute( Qt::WA_StyledBackground ) )
    {
        QPainterPath clipPath;

        painter->save();

        if ( !( d_data->discardFlags & DiscardCanvasBackground ) )
        {
            QwtPainter::drawBackgound( painter, r, canvas );
            clipPath = qwtCanvasClip( canvas, canvasRect );
        }

        painter->restore();
        painter->save();

        if ( clipPath.isEmpty() )
            painter->setClipRect( canvasRect );
        else
            painter->setClipPath( clipPath );

        plot->drawItems( painter, canvasRect, map );

        painter->restore();
    }
    else
    {
        QPainterPath clipPath;

        int frameWidth = 0;

        if ( !( d_data->discardFlags & DiscardCanvasFrame ) )
        {
            const QVariant fw = canvas->property( "frameWidth" );
            if ( fw.type() == QVariant::Int )
                frameWidth = fw.toInt();

            clipPath = qwtCanvasClip( canvas, canvasRect );
        }

        QRectF innerRect = canvasRect.adjusted( 
            frameWidth, frameWidth, -frameWidth, -frameWidth );

        painter->save();

        if ( clipPath.isEmpty() )
        {
            painter->setClipRect( innerRect );
        }
        else
        {
            painter->setClipPath( clipPath );
        }

        if ( !( d_data->discardFlags & DiscardCanvasBackground ) )
        {
            QwtPainter::drawBackgound( painter, innerRect, canvas );
        }

        plot->drawItems( painter, innerRect, map );

        painter->restore();

        if ( frameWidth > 0 )
        {
            painter->save();

            const int frameStyle =
                canvas->property( "frameShadow" ).toInt() |
                canvas->property( "frameShape" ).toInt();

            const int frameWidth = canvas->property( "frameWidth" ).toInt();


            const QVariant borderRadius = canvas->property( "borderRadius" );
            if ( borderRadius.type() == QVariant::Double 
                && borderRadius.toDouble() > 0.0 )
            {
                const double r = borderRadius.toDouble();

                QwtPainter::drawRoundedFrame( painter, canvasRect,
                    r, r, canvas->palette(), frameWidth, frameStyle );
            }
            else
            {
                const int midLineWidth = canvas->property( "midLineWidth" ).toInt();

                QwtPainter::drawFrame( painter, canvasRect,
                    canvas->palette(), canvas->foregroundRole(),
                    frameWidth, midLineWidth, frameStyle );
            }
            painter->restore();
        }
    }
}

void QwtPlotRenderer::buildCanvasMaps( const QwtPlot *plot,
    const QRectF &canvasRect, QwtScaleMap maps[] ) const
{
    for ( int axisId = 0; axisId < QwtPlot::axisCnt; axisId++ )
    {
        maps[axisId].setTransformation(
            plot->axisScaleEngine( axisId )->transformation() );

        const QwtScaleDiv &scaleDiv = plot->axisScaleDiv( axisId );
        maps[axisId].setScaleInterval(
            scaleDiv.lowerBound(), scaleDiv.upperBound() );

        double from, to;
        if ( plot->axisEnabled( axisId ) )
        {
            const int sDist = plot->axisWidget( axisId )->startBorderDist();
            const int eDist = plot->axisWidget( axisId )->endBorderDist();
            const QRectF scaleRect = plot->plotLayout()->scaleRect( axisId );

            if ( axisId == QwtPlot::xTop || axisId == QwtPlot::xBottom )
            {
                from = scaleRect.left() + sDist;
                to = scaleRect.right() - eDist;
            }
            else
            {
                from = scaleRect.bottom() - eDist;
                to = scaleRect.top() + sDist;
            }
        }
        else
        {
            int margin = 0;
            if ( !plot->plotLayout()->alignCanvasToScale( axisId ) )
                margin = plot->plotLayout()->canvasMargin( axisId );

            if ( axisId == QwtPlot::yLeft || axisId == QwtPlot::yRight )
            {
                from = canvasRect.bottom() - margin;
                to = canvasRect.top() + margin;
            }
            else
            {
                from = canvasRect.left() + margin;
                to = canvasRect.right() - margin;
            }
        }
        maps[axisId].setPaintInterval( from, to );
    }
}

bool QwtPlotRenderer::updateCanvasMargins( QwtPlot *plot,
    const QRectF &canvasRect, const QwtScaleMap maps[] ) const
{
    double margins[QwtPlot::axisCnt];
    plot->getCanvasMarginsHint( maps, canvasRect,
        margins[QwtPlot::yLeft], margins[QwtPlot::xTop], 
        margins[QwtPlot::yRight], margins[QwtPlot::xBottom] );

    bool marginsChanged = false;
    for ( int axisId = 0; axisId < QwtPlot::axisCnt; axisId++ )
    {
        if ( margins[axisId] >= 0.0 )
        {
            const int m = qCeil( margins[axisId] );
            plot->plotLayout()->setCanvasMargin( m, axisId);
            marginsChanged = true;
        }
    }

    return marginsChanged;
}

bool QwtPlotRenderer::exportTo( QwtPlot *plot, const QString &documentName,
     const QSizeF &sizeMM, int resolution )
{       
    if ( plot == NULL )
        return false;
    
    QString fileName = documentName;

    // What about translation 

#ifndef QT_NO_FILEDIALOG
    const QList<QByteArray> imageFormats =
        QImageWriter::supportedImageFormats();
        
    QStringList filter;
#if QWT_FORMAT_PDF
    filter += QString( "PDF " ) + tr( "Documents" ) + " (*.pdf)";
#endif
#if QWT_FORMAT_SVG
    filter += QString( "SVG " ) + tr( "Documents" ) + " (*.svg)";
#endif
#if QWT_FORMAT_POSTSCRIPT
    filter += QString( "Postscript " ) + tr( "Documents" ) + " (*.ps)";
#endif
    
    if ( imageFormats.size() > 0 )
    {
        QString imageFilter( tr( "Images" ) );
        imageFilter += " (";
        for ( int i = 0; i < imageFormats.size(); i++ )
        {
            if ( i > 0 )
                imageFilter += " ";
            imageFilter += "*."; 
            imageFilter += imageFormats[i];
        }   
        imageFilter += ")";
        
        filter += imageFilter;
    }   
    
    fileName = QFileDialog::getSaveFileName(
        NULL, tr( "Export File Name" ), fileName,
        filter.join( ";;" ), NULL, QFileDialog::DontConfirmOverwrite );
#endif  
    if ( fileName.isEmpty() )
        return false;

    renderDocument( plot, fileName, sizeMM, resolution );

    return true;
}