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Thread: QwtPlotPicker/ Curvetracker - change Rubberband position

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    Lightbulb QwtPlotPicker/ Curvetracker - change Rubberband position

    Hi all,

    I am experiencing a problem when using the Curvetracker-Example to display data of my curve. While modifying the trackertext Function works perfectly for my purposes I do not seem to be able to modify the drawrubberband function properly.
    I simply want to move the V-Line-Rubberband to a position, where the Curve actually has a sample, while the trackerlabel keeps aligned to my Cursor.

    To accomplish that, I modified drawRubberband the following way:
    void CurveTracker::drawRubberBand( QPainter *painter ) const

    const QRect pRect = pickArea().boundingRect().toRect();

    QwtScaleMap xmap= plot()->canvasMap(QwtPlot::xBottom);

    float pos_x = xmap.transform(QwtDate::toDouble( QDateTime( Dates[dates_index], QTime( 0, 0 ), Qt::UTC)));

    QLineF line;
    line.setLine( pos_x,, pos_x, pRect.bottom() );

    QwtPainter::drawLine( painter,line);

    While pos_x definitely calculates the right x-Coordinate, the Rubberband is only visible when moving the Cursor exactly at the point, where the Rubberband should be drawn.

    I have already looked into QwtPicker.cpp, but cannot figure out, what I am missing.
    I am using Qwt 6.1rc3 an Qt 4.7.3.

    Help would be highly appreciated .

    Edit: Looked into it for days, and when posting here, I got it. Of course one has to reimplement QwtPicker::rubberBandMask() as well. Hope it helps someone at least.
    Last edited by bisasatan; 13th May 2013 at 14:19. Reason: Solved

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