Problem with the installation of the Qwt (Qt6 installed from source)

LRDPRDX

Hi, Qt'ers

I have Qt6 (6.5) built from source and I am trying to install the Qwt library according to this guide: https://qwt.sourceforge.io/qwtinstall.html

/home/lparadox/Tools/qt/qt6-install/bin/qmake qwt.pro
make -j8

and I'm getting the error:

cd src/ && ( test -e Makefile || /home/lparadox/Tools/qt/qt6-install/bin/qmake -o Makefile /home/lparadox/Tools/qt/qwt-6.2.0/src/src.pro ) && make -f Makefile
make[1]: Entering directory '/home/lparadox/Tools/qt/qwt-6.2.0/src'
moc qwt_dyngrid_layout.h
compiling qwt_dyngrid_layout.cpp
compiling qwt_magnifier.cpp
compiling qwt_panner.cpp
compiling qwt_picker.cpp
compiling qwt_symbol.cpp
qwt_symbol.cpp:20:10: fatal error: qsvgrenderer.h: No such file or directory
   20 | #include <qsvgrenderer.h>
      |          ^~~~~~~~~~~~~~~~
compilation terminated.
make[1]: *** [Makefile:1453: obj/qwt_symbol.o] Error 1
make[1]: Leaving directory '/home/lparadox/Tools/qt/qwt-6.2.0/src'
make: *** [Makefile:53: sub-src-make_first-ordered] Error 2

I see the qsvgrenderer.h is present. Is this problem about the Qt version ?

JonB

@LRDPRDX
Where exactly is that file present? And is qwt_symbol.cpp in /home/lparadox/Tools/qt/qwt-6.2.0/src directory?

LRDPRDX

@JonB The Qt file is here:

/home/lparadox/Tools/qt/qt6-install/include/QtSvg

The qwt_symbol.cpp is present at the dir you pointed.

LRDPRDX

@JonB Should I modify the *.pri files somehow in order to the qwt build to find those includes ?

SGaist

@LRDPRDX Hi,

No, if not already present you should add QT += svg to the .pro file of Qwt.

LRDPRDX

@SGaist Hi

I added QT += svg in qwt.pro -- the same error BUT the message now is a bit different :

cd src/ && ( test -e Makefile || /home/lparadox/Tools/qt/qt6-install/bin/qmake -o Makefile /home/lparadox/Tools/qt/qwt-6.2.0/src/src.pro ) && make -f Makefile
make[1]: Entering directory '/home/lparadox/Tools/qt/qwt-6.2.0/src'
/usr/lib/qt5/bin/qmake -o Makefile src.pro
Project WARNING: QwtSvg is enabled in qwtconfig.pri, but Qt has not been built with svg support
compiling qwt_symbol.cpp
compiling qwt_text_label.cpp
compiling qwt_spline_curve_fitter.cpp
compiling qwt_weeding_curve_fitter.cpp
moc qwt_abstract_legend.h
moc qwt_legend.h
compiling qwt_legend_data.cpp
moc qwt_legend_label.h
qwt_symbol.cpp:20:10: fatal error: qsvgrenderer.h: No such file or directory
   20 | #include <qsvgrenderer.h>
      |          ^~~~~~~~~~~~~~~~
compilation terminated.
make[1]: *** [Makefile:1447: obj/qwt_symbol.o] Error 1
make[1]: *** Waiting for unfinished jobs....
make[1]: Leaving directory '/home/lparadox/Tools/qt/qwt-6.2.0/src'
make: *** [Makefile:53: sub-src-make_first-ordered] Error 2

I tried to disable QwtSvg in qwtconfig by commenting this line ( I will try to compile Qt with svg enabled later) :

QWT_CONFIG     += QwtSvg

Then make . The library seems to compile but the examples give errors :

...
linking ../bin/animation
compiling Plot.cpp
moc CpuPlot.h
/usr/bin/ld: obj/Plot.o: in function `Plot::updateCurves()':
Plot.cpp:(.text+0xf9): undefined reference to `QwtPlotCurve::setSamples(QList<QPointF> const&)'
/usr/bin/ld: obj/Plot.o: in function `Curve::updateSamples(double)':
Plot.cpp:(.text._ZN5Curve13updateSamplesEd[_ZN5Curve13updateSamplesEd]+0x4c): undefined reference to `QwtPlotCurve::setSamples(QList<QPointF> const&)'
collect2: error: ld returned 1 exit status
make[2]: *** [Makefile:364: ../bin/animation] Error 1
make[2]: Leaving directory '/home/lparadox/Tools/qt/qwt-6.2.0/examples/animation'
make[1]: *** [Makefile:72: sub-animation-make_first] Error 2
make[1]: *** Waiting for unfinished jobs....
compiling Plot.cpp
linking ../bin/barchart
linking ../bin/distrowatch
/usr/bin/ld: obj/BarChart.o: in function `BarChart::populate()':
BarChart.cpp:(.text+0x55e): undefined reference to `QwtPlotMultiBarChart::setSamples(QList<QList<double> > const&)'
collect2: error: ld returned 1 exit status
make[2]: *** [Makefile:364: ../bin/barchart] Error 1
make[2]: Leaving directory '/home/lparadox/Tools/qt/qwt-6.2.0/examples/barchart'
make[1]: *** [Makefile:97: sub-barchart-make_first] Error 2
linking ../bin/friedberg
/usr/bin/ld: obj/BarChart.o: in function `BarChart::BarChart(QWidget*)':
BarChart.cpp:(.text+0xfed): undefined reference to `QwtPlotBarChart::setSamples(QList<double> const&)'
collect2: error: ld returned 1 exit status
make[2]: *** [Makefile:364: ../bin/distrowatch] Error 1
make[2]: Leaving directory '/home/lparadox/Tools/qt/qwt-6.2.0/examples/distrowatch'
make[1]: *** [Makefile:172: sub-distrowatch-make_first] Error 2
compiling Editor.cpp
/usr/bin/ld: obj/Plot.o: in function `Plot::insertCurve(QString const&, QList<QPointF> const&, QColor const&)':
Plot.cpp:(.text+0x17b): undefined reference to `QwtPlotCurve::setSamples(QList<QPointF> const&)'
/usr/bin/ld: obj/Plot.o: in function `Plot::insertErrorBars(QString const&, QList<QwtIntervalSample> const&, QColor const&)':
Plot.cpp:(.text+0x28e): undefined reference to `QwtPlotIntervalCurve::setSamples(QList<QwtIntervalSample> const&)'
collect2: error: ld returned 1 exit status
make[2]: *** [Makefile:368: ../bin/friedberg] Error 1
make[2]: Leaving directory '/home/lparadox/Tools/qt/qwt-6.2.0/examples/friedberg'
make[1]: *** [Makefile:197: sub-friedberg-make_first] Error 2
linking ../bin/legends
/usr/bin/ld: obj/Plot.o: in function `Plot::insertCurve()':
Plot.cpp:(.text+0x7e4): undefined reference to `QwtPlotCurve::setSamples(QList<QPointF> const&)'
collect2: error: ld returned 1 exit status
make[2]: *** [Makefile:373: ../bin/legends] Error 1
make[2]: Leaving directory '/home/lparadox/Tools/qt/qwt-6.2.0/examples/legends'
make[1]: *** [Makefile:247: sub-legends-make_first] Error 2
linking ../bin/cpuplot
make[2]: Leaving directory '/home/lparadox/Tools/qt/qwt-6.2.0/examples/cpuplot'
linking ../bin/itemeditor
make[2]: Leaving directory '/home/lparadox/Tools/qt/qwt-6.2.0/examples/itemeditor'
make[1]: Leaving directory '/home/lparadox/Tools/qt/qwt-6.2.0/examples'
make: *** [Makefile:225: sub-examples-make_first-ordered] Error 2

JonB

@LRDPRDX
I do not understand what you are showing now. In the first paste there is an error during compilation on #include <qsvgrenderer.h>, in the second block it seems to have got past compilation and has undefined references during linking.

For the #include <qsvgrenderer.h> error, because it is inside < ... > the compiler will only seek this file in a directory passed on the command line via -I/home/lparadox/Tools/qt/qt6-install/include/QtSvg, it will not look in the current directory. That may be relevant to your situation.

SimonSchroeder

You should try a clean build (delete the build directory by hand and start over). Maybe the examples will compile then.

I am not sure how current the documentation is (https://qwt.sourceforge.io/index.html), but it states:

Qwt 6.2 might be usable in all environments where you find Qt. It is compatible with Qt 4.8 and all Qt5 versions.

and

Active development will happen in the develop branch supporting Qt >= 5.6 and relying on at least C++11. However all versions >= Qt 4.8 will actively be supported in the 6.x branches.

I am not sure if Qt 6 is supported by Qwt (but it might still work). Has anyone better information about this?

JonB

@SimonSchroeder said in Problem with the installation of the Qwt (Qt6 installed from source):

I am not sure if Qt 6 is supported by Qwt (but it might still work). Has anyone better information about this?

Don't know. Googling doesn't show much, a couple of references like

https://packages.fedoraproject.org/pkgs/qwt/qwt-qt6-devel/ --- so someone got it working under Fedora?
https://sourceforge.net/p/qwt/feature-requests/100/ --- managed it in 2022 with

Ok thats weird. I've just successfully compiled and linked Qwt with Qt6 by using a plain old "add_library" command instead of the "qt_add_library" version... Why this suddenly worked? I have no idea. Signals got generated in both versions...

?

Oh, see also https://forum.qt.io/topic/152458/qwt-widgets-not-showing-qt-designer

my qt version is 6.3.1 and qwt verison 6.1.6

That's Windows, but should indicate that has been made to work at least?

LRDPRDX

@JonB Ok. Let me explain. First I am saying that adding QT += svg gives the same error and showing the output with that error. But as I said the error message was a bit different. Because of the new message I removed the QWT_CONFIG += QwtSvg line from the qwtconfig.pri and that error disappeared. The compilation passed that erroneous point but the examples failed to link.

LRDPRDX

Thank you guys for your help.

I made it work. Actually I should have execute qmake6 not qmake. At least this worked.

So.

/home/lparadox/Tools/qt/qt6-install/bin/qmake6 qwt.pro
make -j8

After this I was able to make my project using Qwt.