C++ QwtPlotGrid::setMajPen方法代码示例

void MainWindow::setupPlot()
{
    plotTimer.setInterval(1000/settingsDialog->rate);
    connect(&plotTimer, SIGNAL(timeout()), this, SLOT(plotUpdate()));
    plotTimer.start();

    if (!ui->plot->legend()) {
        QwtLegend* legend = new QwtLegend;
        legend->setItemMode(QwtLegend::CheckableItem);
        ui->plot->insertLegend(legend, QwtPlot::RightLegend);
    }

    ui->plot->setAxisTitle(QwtPlot::xBottom, "seconds");
    ui->plot->setCanvasBackground(Qt::white);

    QColor gridColor;
    gridColor.setNamedColor("grey");
    QPen gridPen(gridColor);
    gridPen.setStyle(Qt::DotLine);
    QwtPlotGrid* grid = new QwtPlotGrid;
    grid->setMajPen(gridPen);
    grid->attach(ui->plot);

    connect(ui->plot, SIGNAL(legendChecked(QwtPlotItem*,bool)), this, SLOT(showCurve(QwtPlotItem*,bool)));
}

DataPlotFFT::DataPlotFFT(QWidget *parent):
    QwtPlot(parent),
    d_data(NULL),
    d_curve(NULL)
{
    setAutoReplot(false);

    setFrameStyle(QFrame::NoFrame);
    setLineWidth(0);
    setCanvasLineWidth(2);

    //plotLayout()->setAlignCanvasToScales(true);

    QwtPlotGrid *grid = new QwtPlotGrid;
    grid->setMajPen(QPen(Qt::gray, 0, Qt::DotLine));
    grid->attach(this);

    setCanvasBackground(Qt::white);
    //setCanvasBackground(QColor(29, 100, 141)); // nice blue

    //setAxisAutoScale(xBottom);
    //s/etAxisAutoScale(yLeft);

    setAxisScale(xBottom, 0.5, -0.5);
    setAxisScale(yLeft, -10.00, 10.00);
    setAxisAutoScale(yLeft);
    //setAxisAutoScale(xBottom);

    replot();
}

int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    QwtPlot plot;
    plot.setCanvasBackground(QColor(Qt::white));
    plot.setTitle("Bar Chart");

	QwtPlotGrid *grid = new QwtPlotGrid;
	grid->enableX(false);
	grid->enableYMin(true);
	grid->setMajPen(QPen(Qt::black, 0, Qt::DotLine));
	grid->setMinPen(QPen(Qt::gray, 0 , Qt::DotLine));
	grid->attach(&plot);

	BarChartItem *item = new BarChartItem();
	item->attach(&plot);
	QList< QPair<int, QString> > barHeights;
	barHeights.append(QPair<int, QString>(10, ""));
	barHeights.append(QPair<int, QString>(100, ""));
	barHeights.append(QPair<int, QString>(20, ""));
	item->setData(barHeights);

	plot.enableAxis(QwtPlot::xBottom, false);

	plot.resize(600, 400);
	plot.show();

	return app.exec();
}

RandomPlot::RandomPlot(QWidget *parent):
    IncrementalPlot(parent),
    d_timer(0),
    d_timerCount(0)
{
    setFrameStyle(QFrame::NoFrame);
    setLineWidth(0);
    setCanvasLineWidth(2);

    plotLayout()->setAlignCanvasToScales(true);

    QwtPlotGrid *grid = new QwtPlotGrid;
    grid->setMajPen(QPen(Qt::gray, 0, Qt::DotLine));
    grid->attach(this);

    setCanvasBackground(QColor(29, 100, 141)); // nice blue

    setAxisScale(xBottom, 0, c_rangeMax);
    setAxisScale(yLeft, 0, c_rangeMax);
    
    replot();

    // enable zooming

    (void) new Zoomer(canvas());
}

void HistPlot::populate()
{
	setTitle("Watching TV during a weekend");
	setAxisTitle(QwtPlot::yLeft, "Number of People");
	setAxisTitle(QwtPlot::xBottom, "Number of Hours");

	QwtPlotGrid *grid = new QwtPlotGrid;
	grid->enableX(false);
	grid->enableY(true);
	grid->enableXMin(false);
	grid->enableYMin(false);
	grid->setMajPen(QPen(Qt::black, 0, Qt::SolidLine));
	grid->attach(this);

	const double juneValues[] = { 7, 19, 24, 32, 10, 5, 3 };
	const double novemberValues[] = { 4, 15, 22, 34, 13, 8, 4 };

	Histogram *histogramJune = new Histogram("Summer", Qt::red);
	histogramJune->setValues(
		sizeof(juneValues) / sizeof(double), juneValues);
	histogramJune->attach(this);

	Histogram *histogramNovember = new Histogram("Winter", Qt::blue);
	histogramNovember->setValues(
		sizeof(novemberValues) / sizeof(double), novemberValues);
	histogramNovember->attach(this);
}

EcgCh::EcgCh(QWidget *parent) :
    QwtPlot(parent)
{
     setMinimumHeight(10);
     setMinimumWidth(10);
     QwtPlotGrid *grid = new QwtPlotGrid;
     grid->enableXMin(true);
     grid->setMajPen(QPen(Qt::white, 0, Qt::DotLine));
     grid->setMinPen(QPen(Qt::gray, 0 , Qt::DotLine));
     grid->attach(this);
     setAxisTitle(QwtPlot::xBottom, "Czas [s]");
     setAxisTitle(QwtPlot::yLeft, "Amplituda [mv]");
//     picker = new QwtPlotPicker(QwtPlot::xBottom, QwtPlot::yLeft, QwtPlotPicker::CrossRubberBand, QwtPicker::AlwaysOn, canvas());
//     picker->setStateMachine(new QwtPickerDragPointMachine());
//     picker->setRubberBandPen(QColor(Qt::green));
//     picker->setRubberBand(QwtPicker::CrossRubberBand);
//     picker->setTrackerPen(QColor(Qt::white));
     curve = new QwtPlotCurve("signal");
     curve->setYAxis(QwtPlot::yLeft);
     curve->attach(this);
     peaksCurve = new QwtPlotCurve("signal");
     peaksCurve->setYAxis(QwtPlot::yLeft);
     peaksCurve->setStyle(QwtPlotCurve::CurveStyle::Dots);
     peaksCurve->setPen(QPen(Qt::red, 5));
     peaksCurve->attach(this);
     samples = new QVector<QPointF>;
     data = new QwtPointSeriesData;
     peaksSamples = new QVector<QPointF>;
     peaksData = new QwtPointSeriesData;
     replot();
}

SimDialog::SimDialog( QWidget * parent, Qt::WFlags f) 
	: QDialog(parent, f)
{
  setupUi(this);

  // setup the plot ...
  m_plot->setTitle("Comparing Similarity Measures");
  m_plot->insertLegend(new QwtLegend(), QwtPlot::BottomLegend);

  // set up the axes ...
  m_plot->setAxisTitle(QwtPlot::xBottom, "Variations");
  m_plot->setAxisScale(QwtPlot::xBottom, -10, 10);

  m_plot->setAxisTitle(QwtPlot::yLeft, "Similarity");
  m_plot->setAxisScale(QwtPlot::yLeft, -1.5, 1.5);

  // enable grid ...
  QwtPlotGrid *grid = new QwtPlotGrid;
  grid->enableXMin(true);
  grid->enableYMin(true);
  grid->setMajPen(QPen(Qt::black, 0, Qt::DotLine));
  grid->setMinPen(QPen(Qt::gray, 0 , Qt::DotLine));
  grid->attach(m_plot);

  //  Insert zero line at y = 0
  QwtPlotMarker *mY = new QwtPlotMarker();
  mY->setLabelAlignment(Qt::AlignRight|Qt::AlignTop);
  mY->setLineStyle(QwtPlotMarker::HLine);
  mY->setYValue(0.0);
  mY->attach(m_plot);

  //  Insert zero line at x = 0
  QwtPlotMarker *mX = new QwtPlotMarker();
  mX->setLabelAlignment(Qt::AlignRight|Qt::AlignTop);
  mX->setLineStyle(QwtPlotMarker::VLine);
  mX->setXValue(0.0);
  mX->attach(m_plot);

  // Insert new curves
  cReg = new QwtPlotCurve("Regular Similarity Measure");
  cReg->attach(m_plot);

  cOct = new QwtPlotCurve("Octree based Similarity Measure");
  cOct->attach(m_plot);

  // Set curve styles
  cReg->setPen(QPen(Qt::red, 2));
  cOct->setPen(QPen(Qt::blue, 2));

  // Populate the volume combos ...
  MainWindow* _win  = (MainWindow *)this->parent();
  viewer3d *  _view = (viewer3d *) _win->getViewer();
  QList<Volume*> _vols = _view->getVolumes();

  // append Volume names to combo boxes ...
  // Need to modify Volume class so that it stored patient name ...
  // More importantly modify PatientBrowser so that the data can be directly
  // loaded.
}

StPlot::StPlot(QWidget* parent): 
  QwtPlot(parent),
  viewFactor(-1.0)
{
  setMinimumHeight(10);
  setMinimumWidth(10);
  QwtPlotGrid *grid = new QwtPlotGrid;
  grid->enableXMin(true);
  grid->setMajPen(QPen(Qt::white, 0, Qt::DotLine));
  grid->setMinPen(QPen(Qt::gray, 0 , Qt::DotLine));
  grid->attach(this);
  setAxisTitle(QwtPlot::xBottom, "Czas [s]");
  setAxisTitle(QwtPlot::yLeft, "Amplituda [mv]");
  
  curve = new QwtPlotCurve("Filtered signal");
  curve->setYAxis(QwtPlot::yLeft);
  curve->attach(this);

  ISOPoints = new QwtPlotCurve("ISO");
  ISOPoints->setStyle(QwtPlotCurve::NoCurve);
  ISOPoints->setSymbol(new QwtSymbol(QwtSymbol::Ellipse,QColor(Qt::green), QColor(Qt::green), QSize(5, 5)));
  ISOPoints->setYAxis(QwtPlot::yLeft);
  ISOPoints->attach(this);
  
  JPoints = new QwtPlotCurve("J");
  JPoints->setStyle(QwtPlotCurve::NoCurve);
  JPoints->setSymbol(new QwtSymbol(QwtSymbol::Ellipse,QColor(Qt::blue), QColor(Qt::blue), QSize(5, 5)));
  JPoints->setYAxis(QwtPlot::yLeft);
  JPoints->attach(this);
  
  STPoints = new QwtPlotCurve("ST");
  STPoints->setStyle(QwtPlotCurve::NoCurve);
  STPoints->setSymbol(new QwtSymbol(QwtSymbol::Ellipse,QColor(Qt::red), QColor(Qt::red), QSize(5, 5)));
  STPoints->setYAxis(QwtPlot::yLeft);
  STPoints->attach(this);

  RPoints = new QwtPlotCurve("R");
  RPoints->setStyle(QwtPlotCurve::NoCurve);
  RPoints->setSymbol(new QwtSymbol(QwtSymbol::Ellipse,QColor(Qt::yellow), QColor(Qt::yellow), QSize(5, 5)));
  RPoints->setYAxis(QwtPlot::yLeft);
  //RPoints->attach(this);

  legend = new QwtLegend();
  legend->setItemMode(QwtLegend::ReadOnlyItem);
  legend->setWhatsThis("Click on an item to show/hide the plot");
  this->insertLegend(legend, QwtPlot::RightLegend);
  
  samples = new QVector<QPointF>;
  data = new QwtPointSeriesData;
  replot();
  
  zoomer = new QwtPlotZoomer(QwtPlot::xBottom, QwtPlot::yLeft, canvas());
  zoomer->setMousePattern(QwtEventPattern::MouseSelect1, Qt::NoButton);
  zoomer->setMousePattern(QwtEventPattern::MouseSelect2, Qt::NoButton);
  zoomer->setMousePattern(QwtEventPattern::MouseSelect3, Qt::NoButton);
  zoomer->setMousePattern(QwtEventPattern::MouseSelect4, Qt::NoButton);
  zoomer->setMousePattern(QwtEventPattern::MouseSelect5, Qt::NoButton);
  zoomer->setMousePattern(QwtEventPattern::MouseSelect6, Qt::NoButton);
}

// Init X axis.
void DataPlot::setGridPlot()
{
    QwtPlotGrid *grid = new QwtPlotGrid;
    grid->enableXMin(true);
    grid->enableYMin(true);
    grid->setMajPen(QPen(Qt::black, 0, Qt::DotLine));
    grid->setMinPen(QPen(Qt::gray, 0 , Qt::DotLine));
    grid->attach(this);
}

QmitkHistogramWidget::QmitkHistogramWidget(QWidget * parent, bool showreport)
  : QDialog(parent)
{
  QBoxLayout *layout = new QVBoxLayout(this);

  //***histogram***

  QGroupBox *hgroupbox = new QGroupBox("", this);

  hgroupbox->setMinimumSize(900, 400);

  m_Plot = new QwtPlot(hgroupbox);
  m_Plot->setCanvasBackground(QColor(Qt::white));
  m_Plot->setTitle("Histogram");
  QwtText text = m_Plot->titleLabel()->text();
  text.setFont(QFont("Helvetica", 12, QFont::Normal));

  QwtPlotGrid *grid = new QwtPlotGrid;
  grid->enableXMin(true);
  grid->enableYMin(true);
  grid->setMajPen(QPen(Qt::black, 0, Qt::DotLine));
  grid->setMinPen(QPen(Qt::gray, 0 , Qt::DotLine));
  grid->attach(m_Plot);

  layout->addWidget(hgroupbox);

  layout->setSpacing(20);

  if (showreport == true)
  {
    //***report***
    QGroupBox *rgroupbox = new QGroupBox("", this);

    rgroupbox->setMinimumSize(900, 400);

    QLabel *label = new QLabel("Gray  Value  Analysis", rgroupbox);
    label->setAlignment(Qt::AlignHCenter);
    label->setFont(QFont("Helvetica", 14, QFont::Bold));

    m_Textedit = new QTextEdit(rgroupbox);
    m_Textedit->setFont(QFont("Helvetica", 12, QFont::Normal));
    m_Textedit->setReadOnly(true);

    layout->addWidget(rgroupbox);
  }

  m_Picker = new QwtPlotPicker(QwtPlot::xBottom, QwtPlot::yLeft,
    QwtPicker::PointSelection, 
    QwtPlotPicker::NoRubberBand, QwtPicker::AlwaysOn, 
    m_Plot->canvas());

  connect(m_Picker, SIGNAL(selected(const QwtDoublePoint &)),
    SLOT(OnSelect(const QwtDoublePoint &)));
}

void GenericHistogramView::populate()
{
  QwtPlotGrid* grid = new QwtPlotGrid();
  grid->enableX(false);
  grid->enableY(true);
  grid->enableXMin(false);
  grid->enableYMin(false);
  grid->setMajPen(QPen(Qt::black, 0, Qt::DotLine));
  grid->attach(_qwtPlot);

	for(unsigned int i = 0; i < _image->getNbChannels(); ++i)
	{
		imagein::Array<unsigned int>* histogram;
		if(_projection)
			histogram = new imagein::ProjectionHistogram(*_image, _value, _horizontal, *_rectangle, i);
		else
			histogram = new imagein::Histogram(*_image, i, *_rectangle);
		
		int values[histogram->getWidth()];

		for(unsigned int j = 0; j < histogram->getWidth(); ++j)
			values[j] = (*histogram)[j];
		
		GraphicalHistogram* graphicalHisto;
		switch(i)
		{
			case 0:
				if(_image->getNbChannels() == 1 || _image->getNbChannels() == 2)
					graphicalHisto = new GraphicalHistogram("Black", Qt::black);
				else
					graphicalHisto = new GraphicalHistogram("Red", Qt::red);
			break;
			case 1:
				if(_image->getNbChannels() == 1 || _image->getNbChannels() == 2)
					graphicalHisto = new GraphicalHistogram("Alpha", Qt::white);
				else
					graphicalHisto = new GraphicalHistogram("Green", Qt::green);
			break;
			case 2:
				graphicalHisto = new GraphicalHistogram("Blue", Qt::blue);
			break;
			case 3:
				graphicalHisto = new GraphicalHistogram("Alpha", Qt::black);
			break;
			default:
				graphicalHisto = new GraphicalHistogram("Default", Qt::black);
		}
		graphicalHisto->setValues(sizeof(values) / sizeof(int), values);
		if(_horizontal)
			graphicalHisto->setOrientation(Qt::Horizontal);
		graphicalHisto->attach(_qwtPlot);
    _graphicalHistos.push_back(graphicalHisto);
	}
}

RTVTPlotWindow::RTVTPlotWindow(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::RTVTPlotWindow)
{
    ui->setupUi(this);

    connect(ui->plotChannelListView, SIGNAL(clicked(QModelIndex)), this, SLOT(curveSelected(QModelIndex)));
    // Setup curves
    numberOfCurves = 10;
    startColorIndex = 0;
    channelListStringModel = new QStringListModel();
    channelListStringModel->setStringList(channelStringList);
    ui->plotChannelListView->setModel(channelListStringModel);

    // Setup the plot view
    ui->plotQwtView->setCanvasBackground(QColor(Qt::darkBlue));
    ui->plotQwtView->setTitle("Frequency Response of Amplifier");
    ui->plotQwtView->setTitle("Amplitude");
    ui->plotQwtView->setAxisTitle(QwtPlot::yLeft,"dBm");
    ui->plotQwtView->setAxisTitle(QwtPlot::xBottom,"Frequency (Hz)");

    // grid
    QwtPlotGrid *grid = new QwtPlotGrid;
    grid->enableXMin(true);
    grid->setMajPen(QPen(Qt::white, 0, Qt::DotLine));
    grid->setMinPen(QPen(Qt::gray, 0 , Qt::DotLine));
    grid->attach(ui->plotQwtView);

    ui->plotQwtView->setAxisMaxMajor(QwtPlot::xBottom, 6);
    ui->plotQwtView->setAxisMaxMinor(QwtPlot::xBottom, 10);
    ui->plotQwtView->setAxisScaleEngine(QwtPlot::xBottom, new QwtLog10ScaleEngine);

    //QwtPlotGrid *gridy = new QwtPlotGrid();
    //gridy->attach(ui->plotQwtView);


    /*QwtLog10ScaleEngine * log10SE = new QwtLog10ScaleEngine();
    double x1=0.0, x2=4.3, stepSize=0.1;

    log10SE->autoScale(100, x1, x2, stepSize);

    QwtLinearScaleEngine * yAxisEngine = new  QwtLinearScaleEngine();
    double y1=-100.0, y2 = 10.0, yStep = 10.0;

    yAxisEngine->autoScale(10, y1, y2, yStep);*/

    //ui->plotQwtView->setAxisScaleEngine(QwtPlot::xBottom,log10SE);
    //ui->plotQwtView->setAxisScaleEngine(QwtPlot::yLeft,yAxisEngine);

    //ui->plotQwtView->setAxis

    ui->plotQwtView->replot();

}

MavPlot::MavPlot(QWidget *parent) : QwtPlot(parent), _havePrintColors(false) {
    setAutoReplot(false);
    setTitle("MAV System Data Plot");
    setCanvasBackground(QColor(Qt::darkGray));

    // legend
    QwtLegend *legend = new QwtLegend;
    insertLegend(legend, QwtPlot::BottomLegend);
    #if (QWT_VERSION < QWT_VERSION_CHECK(6,1,0))
        legend->setItemMode(QwtLegend::ClickableItem);
        connect(this, SIGNAL(legendClicked(QwtPlotItem*)), SLOT(legendClicked(QwtPlotItem*)));
    #else
        legend->setDefaultItemMode(QwtLegendData::Clickable);        
        connect(legend, SIGNAL(clicked(const QVariant&, int)), SLOT(legendClickedNew(const QVariant&, int)));
    #endif    

    // grid
    QwtPlotGrid *grid = new QwtPlotGrid;
    grid->enableXMin(true);
    #if (QWT_VERSION < QWT_VERSION_CHECK(6,1,0))
        grid->setMajPen(QPen(Qt::gray, 0, Qt::DotLine));
        grid->setMinPen(QPen(QColor(0x8, 0x8, 0x8), 0 , Qt::DotLine));
    #else
        grid->setMajorPen(QPen(Qt::gray, 0, Qt::DotLine));
        grid->setMinorPen(QPen(QColor(0x8, 0x8, 0x8), 0 , Qt::DotLine));
    #endif
    grid->attach(this);

    // axes
    //enableAxis(QwtPlot::yRight);
    setAxisTitle(QwtPlot::xBottom, "time");
    setAxisScaleDraw(QwtPlot::xBottom, new HumanReadableTime()); // no need to de-alloc or store, plot does it

    // A-B markers
    for (int i=0; i<2; i++) {
        _user_markers[i].setLineStyle(QwtPlotMarker::VLine);
        _user_markers[i].setLabelAlignment(Qt::AlignRight | Qt::AlignBottom);
        _user_markers[i].setLinePen(QPen(QColor(255, 140, 0), 0, Qt::SolidLine));
        _user_markers_visible[i] = false;
    }
    _user_markers[0].setLabel(QwtText("A"));
    _user_markers[1].setLabel(QwtText("B"));

    // data marker
    _data_marker.setLineStyle(QwtPlotMarker::VLine);
    _data_marker.setLinePen(QPen(QColor(255, 160, 47), 2, Qt::SolidLine));
    _data_marker.setLabel(QwtText("data"));
    _data_marker.setLabelAlignment(Qt::AlignTop | Qt::AlignRight);
    _data_marker_visible = false;
    _data_marker.setZ(9999); // higher value -> paint on top of everything else

    setAutoReplot(true);
}

int qfit::setupGui()
{
//   if(QApplication::arguments().size() > 1)
//     filePath->setText(QApplication::arguments().at(1));
    if(QApplication::argc() == 2) {
        filePath->setText(QApplication::argv()[1]);
    }
    selectFit->addItem(tr("Fit Linear"));/*TODO add once are available in FitTools
  selectFit->addItem(tr("Fit Slope"));
  selectFit->addItem(tr("Fit Horizontal"));
  selectFit->addItem(tr("Fit Exponential"));
  selectFit->addItem(tr("Fit Logarithmic"));*/

#ifdef Qwt6_FOUND
    // plot stuff
    // panning with the middle mouse button
    QwtPlotPanner *panner = new QwtPlotPanner(qwtPlot->canvas());
    panner->setMouseButton(Qt::MidButton);
    // zoom in/out with the wheel
    (void) new QwtPlotMagnifier(qwtPlot->canvas());
    // zoom an area with left button
    QwtPlotZoomer *zoomer = new QwtPlotZoomer(qwtPlot->canvas());
    zoomer->setRubberBandPen(QColor(Qt::black));
    zoomer->setTrackerPen(QColor(Qt::black));
    zoomer->setMousePattern(QwtEventPattern::MouseSelect2, Qt::RightButton, Qt::ControlModifier);
    zoomer->setMousePattern(QwtEventPattern::MouseSelect3, Qt::RightButton);

    // canvas
    qwtPlot->canvas()->setLineWidth(1);
    qwtPlot->canvas()->setFrameStyle(QFrame::Box | QFrame::Plain);
    qwtPlot->canvas()->setBorderRadius(10);
    qwtPlot->canvas()->setPalette(Qt::darkGray);
    //grid
    QwtPlotGrid *grid = new QwtPlotGrid();
    grid->setMajPen(QPen(Qt::white, 0, Qt::DotLine));
//   grid->setMinPen(QPen(Qt::gray, 0, Qt::DotLine));
    grid->attach(qwtPlot);
#endif

    // tooltips
    infoButton->setToolTip(trUtf8("About"));
    openFileButton->setToolTip(trUtf8("Open file"));
    selectFit->setToolTip(trUtf8("Fit typology"));
    startFit->setToolTip(trUtf8("GO!"));
    cleanLogButton->setToolTip(trUtf8("Clear log"));

#ifdef Qwt6_FOUND
    savePlotButton->setToolTip(trUtf8("Save plot"));
#endif

    return(0);
}

int main(int argc, char **argv)
{
    QApplication a(argc, argv);

    QwtPlot plot;
    plot.setCanvasBackground(QColor(Qt::white));
    plot.setTitle("Histogram");

    QwtPlotGrid *grid = new QwtPlotGrid;
    grid->enableXMin(true);
    grid->enableYMin(true);
    grid->setMajPen(QPen(Qt::black, 0, Qt::DotLine));
    grid->setMinPen(QPen(Qt::gray, 0 , Qt::DotLine));
    grid->attach(&plot);

    HistogramItem *histogram = new HistogramItem();
    histogram->setColor(Qt::darkCyan);

    const int numValues = 20;

    QwtArray<QwtDoubleInterval> intervals(numValues);
    QwtArray<double> values(numValues);

    double pos = 0.0;
    for ( int i = 0; i < (int)intervals.size(); i++ )
    {
        const int width = 5 + rand() % 15;
        const int value = rand() % 100;

        intervals[i] = QwtDoubleInterval(pos, pos + double(width));
        values[i] = value; 

        pos += width;
    }

    histogram->setData(QwtIntervalData(intervals, values));
    histogram->attach(&plot);

    plot.setAxisScale(QwtPlot::yLeft, 0.0, 100.0);
    plot.setAxisScale(QwtPlot::xBottom, 0.0, pos);
    plot.replot();

#if QT_VERSION < 0x040000
    a.setMainWidget(&plot);
#endif

    plot.resize(600,400);
    plot.show();

    return a.exec(); 
}