Tool tip in point of curve

Hello!
I have curve built by 100 points, how can i add tool tip with x and y to this points
I try to use qwt symbol for this goal, but there is not method setToolTip
In advance many thanks for your help!

You can use QwtPlotPicker with QwtPicker::AlwaysOn to display text as you traverse the graph. See examples too.

i need to see coordinates not all the time, i need to see it if mouse moved near some point
I know, that i can redefine mouse move event in qwt symbolm but there no more easy way?

Quote:

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Originally Posted by ruzik

i need to see coordinates not all the time, i need to see it if mouse moved near some point
I know, that i can redefine mouse move event in qwt symbolm but there no more easy way?

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No you can't - QwtSymbol is no QWidget.

Instead you can follow the hint of pkj using a customized picker:

Code:

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class YourPlotPicker:: public QwtPlotPicker
{
    ....
 
    virtual QwtText trackerTextF( const QPointF &pos ) const
    {
        QwtPlotCurve *curve = NULL;
        double dist = 10e10;
        int index = -1;
 
        const QwtPlotItemList& itmList = plot()->itemList();
        for ( QwtPlotItemIterator it = itmList.begin();
            it != itmList.end(); ++it )
        {
            if ( ( *it )->rtti() == QwtPlotItem::Rtti_PlotCurve )
           {
                QwtPlotCurve *c = static_cast<QwtPlotCurve *>( *it );
 
                double d;
                int idx = c->closestPoint( pos, &d );
                if ( d < dist )
                {
                    curve = c;
                    index = idx;
                    dist = d;
                }
            }
        }
 
        QString text;
 
        const int maxPixels = 10;
        if ( dist < maxPixels )
        {
            const QPointF pos = curve->sample( index );
            text.sprintf( "%.4f, %.4f", pos.x(), pos.y() );
        }
 
        return QwtText( text );
    }
};

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QwtPlotCurve::closestPoint() iterates over all points what might be too slow for many points. If can implement something faster using the characteristics of your samples ( f.e when they have increasing x values ) better implement it. In the worst case you need to introduce some spatial organized index like a quadtree.

Uwe

Thank you for your help!

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Added after 50 minutes:

Oh, function clossestPoint() dont work right!
//http://hostingkartinok.com/image/01201110/54dfa7b8bb51489265f5c2141a17a7df.jpg
For example look at this
http://hostingkartinok.com/image/012...947e6bc613.jpg
I checked: in the higher point distance is bigger, even if the cursor directly on the chart