How do I install QtCompositor module?

Aras

I want to give wayland a try and reading through some online documentation I understand I need to install QtCompositor module which does not automatically get installed with installation of Qt.

I found this documentation but it seems out dated.

I am using Ubuntu Linux 17.20 and Qt5.9.2. Can anyone point me to up to date instructions on how to install QTCompositor or detail instructions on how to get started with QtWayland? I am assuming that is what I should use to access wayland API from Qt. Any help is much appreciated!

SGaist

Hi,

QtWayland is now part of the Qt distribution, you can start from here.

Aras

@SGaist thank you for the reply but although I have a recent installation of Qt distribution (5.9.2 binary) I still get the following error:

QQmlApplicationEngine failed to load component
qrc:///main.qml:4 module "QtWayland.Compositor" is not installed

Thanks for the link. I tried running the minimal example mentioned on that link, but I still get the above error.

Any ideas why, or how I could install QtWayland.Compositor module?

SGaist

When you say binary, do you mean from the online/offline installer ?

Aras

Yes I download qt-opensource-linux-x64-5.9.2.run offline installer a few weeks ago and installed it.

More info about my system just in case:

Linux 4.13.0-17-generic #20-Ubuntu SMP Mon Nov 6 10:04:08 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
~$ qmake -v
QMake version 3.1
Using Qt version 5.9.2 in /home/aras/Qt5.9.2/5.9.2/gcc_64/lib

Thanks!

Aras

Looks like there is an open bug for this issue: https://bugreports.qt.io/browse/QTBUG-63011
I also found another thread on this forum that does not have an answer:.
If it is a bug I'd love to know if there is a workaround. There must be a way right?

SGaist

Well, I think that QTBUG-60601 is even more relevant to your case. Short version: build the module from source.

Download the source from the installer and then the classic /path/to/Qt/5.9.X/gcc_64/bin/qmake && make && make install

Aras

@SGaist do you mean I should build qt itself from source? Are you sure? It does look like QtWayland is installed along with Qt. I have a folder called ~/Qt5.9.2/5.9.2/Src/qtwayland which I think is the wayland module. Is it possible it is installed but just not available for some reason?

I also found this other open bug that suggest wayland module needs a qmldir file. Do you know what file it is talking about? What should I put in that file and were do I place it to fix it.

I kind of like developing against the binary version of Qt. It is a lot of work to build it from source (sorry I know I am lazy). Thanks!

SGaist

That bug is for a static compilation which is not what you are going to do.

Build only the QtWayland module, not the whole of Qt.

Aras

@SGaist ok I'll give it a go. Can you specify where I should download the source for this module from?

Aras

@SGaist is it good to clone from https://code.qt.io/cgit/qt/qtwayland.git/ and build it? The path does not look like what you suggested but I think it is the same module. yes?

Aras

Well that wayland module cloned from the link I posted does not build on my system. It gave this error:

In file included from ../../include/QtWaylandClient/5.10.0/QtWaylandClient/private/qwaylandwindow_p.h:1:0,
                 from qwaylandshmwindow_p.h:54,
                 from qwaylandintegration.cpp:43:
../../include/QtWaylandClient/5.10.0/QtWaylandClient/private/../../../../../src/client/qwaylandwindow_p.h:150:10: error: ‘void QtWaylandClient::QWaylandWindow::setWindowState(Qt::WindowStates)’ marked ‘override’, but does not override
     void setWindowState(Qt::WindowStates state) override;
          ^~~~~~~~~~~~~~
qwaylandintegration.cpp: In constructor ‘QtWaylandClient::QWaylandIntegration::QWaylandIntegration()’:
qwaylandintegration.cpp:141:49: error: invalid new-expression of abstract class type ‘QtWaylandClient::QWaylandDrag’
     mDrag.reset(new QWaylandDrag(mDisplay.data()));
                                                 ^
In file included from qwaylandintegration.cpp:51:0:
qwaylanddnd_p.h:68:31: note:   because the following virtual functions are pure within ‘QtWaylandClient::QWaylandDrag’:
 class Q_WAYLAND_CLIENT_EXPORT QWaylandDrag : public QBasicDrag
                               ^~~~~~~~~~~~
In file included from qwaylanddnd_p.h:54:0,
                 from qwaylandintegration.cpp:51:
/home/aras/Qt5.9.2/5.9.2/gcc_64/include/QtGui/5.9.2/QtGui/qpa/qplatformdrag.h:98:24: note: 	virtual QMimeData* QPlatformDrag::platformDropData()
     virtual QMimeData *platformDropData() = 0;
                        ^~~~~~~~~~~~~~~~
Makefile:2911: recipe for target '.obj/qwaylandintegration.o' failed
make[2]: *** [.obj/qwaylandintegration.o] Error 1
make[2]: Leaving directory '/home/aras/Projects/qtwayland/src/client'
Makefile:73: recipe for target 'sub-client-make_first' failed
make[1]: *** [sub-client-make_first] Error 2
make[1]: Leaving directory '/home/aras/Projects/qtwayland/src'
Makefile:46: recipe for target 'sub-src-make_first' failed
make: *** [sub-src-make_first] Error 2
aras@aras-GL752VW:~/Projects/qtwayland$ git status 
On branch 5.10
Your branch is up-to-date with 'origin/5.10'.

SGaist

You should rather build the module that you have in the Src folder or at least checkout the matching branch from your clone.

Aras

@SGaist said in How do I install QtCompositor module?:

or at least checkout the matching branch from your clone.

Duh! Yes that was it. I just checked out 5.9.3 and build and installed. That worked like a charm. Thank you!

for the record, this is what I did:

git clone git://code.qt.io/qt/qtwayland.git
cd qtwayland
Projects/qtwayland$ git checkout origin/5.9.3
qmake
make 
make install

And this time there was no error and I successfully ran, for the first time, a simple Wayland sample application. :)