How to use qwt?

[ssaguiar]

Hi:

I wish to know how can I use the qwt in my app because I just don't get it. My app is working ok, but I need to plot a 2D grph in a QLabel container (or anything that is more apropriate to use with qwt).
I tried but can't find where to insert the code. The qwt is very poor in tutorials.
I wish to have in my app something like the QwtSpectrogram example.
Attached is my code.

Thanks for any help.

[ssaguiar]

I have found how to make the 2D graphics.
At the end of my mainwindow.cpp, i have this code:

void MainWindow::View_tank_Details(QString local)
{
    QwtPlot *myPlot         = new QwtPlot;
    QwtPlotCurve *m_curve   = new QwtPlotCurve;
 
    for (refIndx=0; refIndx<16; refIndx++)
    {
        if (cardinalP[refIndx].contains(local))
        {
            //ui->Tanque1Level->display((fuelvalues[refIndx]*FUELTANKCAP)/1023);
            TankIndex = refIndx;
            ui->Tanque1Level->display(rand() % 30000);
            ui->GraphTitle->setText(local);
        }
    }
 
    myPlot = new QwtPlot(ui->GraphPlot );
    myPlot->setGeometry( 5, 70, 590, 325 );
    myPlot->setStyleSheet("background-color:black; color:rgb(255,255,255);border: 0px;");
    //myPlot->setTitle(title);
    myPlot->setAxisTitle(QwtPlot::xBottom, "Horas");
    myPlot->setAxisTitle(QwtPlot::yLeft, "Litros");
    myPlot->setAxisScale(QwtPlot::xBottom, 0, 96);//48);
    myPlot->setAxisMaxMajor(QwtPlot::xBottom, 12);//24);
    myPlot->setAxisMaxMinor(QwtPlot::xBottom, 0);
    myPlot->setAxisScale(QwtPlot::yLeft, 0, 30000);
 
    // grid
    QwtPlotGrid *grid = new QwtPlotGrid;
    grid->enableXMin(true);
    grid->setMajPen(QPen(Qt::white, 0, Qt::DotLine));
    grid->setMinPen(QPen(Qt::white, 0 , Qt::DotLine));
    grid->attach(myPlot);
 
    for (int i = 0; i < 97; i++)//49; i++)
    {
        xplot[i] = i;
        //yplot[i] = (rand() % 30000);//i * (rand() % 30000) * cos(i / M_PI);
        yplot[i] = (i * (rand() % 300) * cos(i / M_PI));
        //yplot[i] = testcnt;
    }
 
    m_curve= new QwtPlotCurve();
    m_curve->setSymbol(new QwtSymbol(QwtSymbol::Cross, Qt::NoBrush, QPen(Qt::white), QSize(5, 5) ) );
    //m_curve->setPen(QColor(Qt::yellow));
    m_curve->setCurveAttribute(QwtPlotCurve::Fitted);
    m_curve->setLegendAttribute(QwtPlotCurve::LegendShowLine);
    m_curve->setPen(QPen(QColor::fromRgb(0, 0, 255), 1));
    m_curve->setRawSamples(xplot, yplot, 97);//49);
    m_curve->setTitle("Curva do nivel de combustivel");
    m_curve->attach(myPlot);
 
    QwtPlotPicker *d_picker = new QwtPlotPicker(QwtPlot::xBottom, QwtPlot::yLeft,
                                     QwtPlotPicker::CrossRubberBand, QwtPicker::AlwaysOn,
                                     myPlot->canvas());
 
    d_picker->setRubberBandPen(QColor(Qt::green));
    d_picker->setRubberBand(QwtPicker::CrossRubberBand);
    d_picker->setTrackerPen(QColor(Qt::yellow));
 
 
    myPlot->show();
}

void MainWindow::View_tank_Details(QString local)
{
    QwtPlot *myPlot         = new QwtPlot;
    QwtPlotCurve *m_curve   = new QwtPlotCurve;

    for (refIndx=0; refIndx<16; refIndx++)
    {
        if (cardinalP[refIndx].contains(local))
        {
            //ui->Tanque1Level->display((fuelvalues[refIndx]*FUELTANKCAP)/1023);
            TankIndex = refIndx;
            ui->Tanque1Level->display(rand() % 30000);
            ui->GraphTitle->setText(local);
        }
    }

    myPlot = new QwtPlot(ui->GraphPlot );
    myPlot->setGeometry( 5, 70, 590, 325 );
    myPlot->setStyleSheet("background-color:black; color:rgb(255,255,255);border: 0px;");
    //myPlot->setTitle(title);
    myPlot->setAxisTitle(QwtPlot::xBottom, "Horas");
    myPlot->setAxisTitle(QwtPlot::yLeft, "Litros");
    myPlot->setAxisScale(QwtPlot::xBottom, 0, 96);//48);
    myPlot->setAxisMaxMajor(QwtPlot::xBottom, 12);//24);
    myPlot->setAxisMaxMinor(QwtPlot::xBottom, 0);
    myPlot->setAxisScale(QwtPlot::yLeft, 0, 30000);

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

    for (int i = 0; i < 97; i++)//49; i++)
    {
        xplot[i] = i;
        //yplot[i] = (rand() % 30000);//i * (rand() % 30000) * cos(i / M_PI);
        yplot[i] = (i * (rand() % 300) * cos(i / M_PI));
        //yplot[i] = testcnt;
    }

    m_curve= new QwtPlotCurve();
    m_curve->setSymbol(new QwtSymbol(QwtSymbol::Cross, Qt::NoBrush, QPen(Qt::white), QSize(5, 5) ) );
    //m_curve->setPen(QColor(Qt::yellow));
    m_curve->setCurveAttribute(QwtPlotCurve::Fitted);
    m_curve->setLegendAttribute(QwtPlotCurve::LegendShowLine);
    m_curve->setPen(QPen(QColor::fromRgb(0, 0, 255), 1));
    m_curve->setRawSamples(xplot, yplot, 97);//49);
    m_curve->setTitle("Curva do nivel de combustivel");
    m_curve->attach(myPlot);

    QwtPlotPicker *d_picker = new QwtPlotPicker(QwtPlot::xBottom, QwtPlot::yLeft,
                                     QwtPlotPicker::CrossRubberBand, QwtPicker::AlwaysOn,
                                     myPlot->canvas());

    d_picker->setRubberBandPen(QColor(Qt::green));
    d_picker->setRubberBand(QwtPicker::CrossRubberBand);
    d_picker->setTrackerPen(QColor(Qt::yellow));


    myPlot->show();
}

To copy to clipboard, switch view to plain text mode 

It created the plot area, adds the grid, plot the curve and adds the QwtPlotPicker.

Now, i just need to:

1 - make the QwtPlotPicker show just the data of the marked points (the ones that were ploted from the tables), not all the points of the plot;
2 - make the QwtPlotPicker text without the decimal values (just the left values);
3 - make the QwtPlotPicker show only the values of the Y (liters) and not the X (hours);
4 - make the QwtPlotPicker semi-transparent (now the background is transparent);

Sergio