Tooltip in qwt

Hello. I have to do the following: when I point to the value (big dot - qwtSymbol) a coordinate of this value will be appeared . I found on the internet the method realization and I change it a little:

Code:

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void Monitoring::showToolTip(QMouseEvent* ev){
 
    if(ev == QEvent::MouseMove) {
 
    double distance = 1e99;
    int point_index = first_c->closestPoint(QPoint(ev->x(), ev->y()), &distance); // for my one of my curves
 
    QwtPlotMarker* tooltip = new QwtPlotMarker();
    tooltip->setLabel(QString("hello")); //for debugging
    tooltip->attach(funPlot);
    funPlot->replot();
}

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But I don't understand how to call this function. I thought I could call it through the signal-slot construction, but I can't pick up appropriate signal.

I would advice against using this code as it results in heavy replots, while moving the mouse.

Something like tooltips can be done in a much better way using QwtPlotPicker. Have a look the bode or spectrogram example - moving the mouse over the plot canvas and you will see.
To display a specific informationfor a position you would have to overload QwtPlotPicker::trackerText or QwtPlotPicker::trackerTextF. At positions, where you don't want display any information simply return QString::null.

Uwe

Thanks for you answer. But how can I find the coordinates qwtSymbols on my plot?

Usually symbols are related to some points in plot coordinates. You can translate between plot and widget coordinates using the canvas maps ( see QwtPlot::canvasMap() ).
Maybe the code the code from curvetracker example helps.

Uwe