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Thread: Interfacing to :qwt_plot_curve.h: void setSamples( const QVector< QPointF >& );

  1. #1
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    Question Interfacing to :qwt_plot_curve.h: void setSamples( const QVector< QPointF >& );

    Hi,

    I have a QPolygonF of points which I would like to pass to: qwt_plot_curve.h: void setSamples( const QVector< QPointF >& ) however I cannot seem to get the correct syntax:

    essential code snippet:

    QwtPlotCurve curve;
    .
    .
    QPolygonF points;
    .
    .
    points+=QPointF(xData, yData); // in loop
    .
    .
    curve.setSamples(points);

    My problem is that at link time I get the following error:

    undefined reference to `QwtPlotCurve::setSamples(QVector<QPointF> const&)'

    This is the only linker error all the other Qwt symbols are resolved.

    nm shows that the available symbols are:

    libqwt.so.6.3.0:000000000010df40 T QwtPlotCurve::setSamples(QList<QPointF> const&)
    libqwt.so.6.3.0:000000000010def0 T QwtPlotCurve::setSamples(QwtSeriesData<QPointF>*)
    libqwt.so.6.3.0:000000000010e588 T QwtPlotCurve::setSamples(QList<double> const&, QList<double> const&)
    libqwt.so.6.3.0:000000000010e850 T QwtPlotCurve::setSamples(QList<double> const&)
    libqwt.so.6.3.0:000000000010e990 T QwtPlotCurve::setSamples(float const*, float const*, int)
    libqwt.so.6.3.0:000000000010e718 T QwtPlotCurve::setSamples(double const*, int)
    libqwt.so.6.3.0:000000000010e8f0 T QwtPlotCurve::setSamples(QList<float> const&)
    libqwt.so.6.3.0:000000000010e650 T QwtPlotCurve::setSamples(QList<float> const&, QList<float> const&)
    libqwt.so.6.3.0:000000000010ecd8 T QwtPlotCurve::setSamples(float const*, int)
    libqwt.so.6.3.0:000000000010e230 T QwtPlotCurve::setSamples(double const*, double const*, int)

    Could anyone suggest a way forward, the Qt is version 6.5.2 Qwt is latest from git.

    Thanks

  2. #2
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    Default Re: Interfacing to :qwt_plot_curve.h: void setSamples( const QVector< QPointF >& )

    QList and QVector are the same in Qt6.
    See qcontainerfwd.h:
    Qt Code:
    1. template<typename T> using QVector = QList<T>;
    To copy to clipboard, switch view to plain text mode 

    HTH,
    Uwe
    Last edited by Uwe; 13th March 2024 at 08:54.

  3. #3
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    Default Re: Interfacing to :qwt_plot_curve.h: void setSamples( const QVector< QPointF >& )

    Quote Originally Posted by Uwe View Post
    QList and QVector are the same in Qt6.
    See qcontainerfwd.h:
    Qt Code:
    1. template<typename T> using QVector = QList<T>;
    To copy to clipboard, switch view to plain text mode 

    HTH,
    Uwe
    Thanks I replaced the QPolygonF with QVector<QPointF> but I get the same linker error:

    My application is exporting the right unresolved symbol:

    myPlotApp.o: U QwtPlotCurve::setSamples(QVector<QPointF> const&)

    But the nearest sysmbol in libqwt.so.6.3.0 is:

    libqwt.so.6.3.0:000000000010df40 T QwtPlotCurve::setSamples(QList<QPointF> const&)

    I wonder if this is a compiler problem not a syntax issue ?

    the .o file in the Qwt build directory only refers to QList<QPointF> :

    src/obj/qwt_plot_curve.o:0000000000001840 T QwtPlotCurve::setSamples(QList<QPointF> const&)

  4. #4
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    Default Re: Interfacing to :qwt_plot_curve.h: void setSamples( const QVector< QPointF >& )

    I Think I solved the problem I rebuilt Qt6 and Qwt and my application (in that order) and the issue has gone.
    Thanks for the help.

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