Custom Wayland extensions/protocols in Qt clients

[ehopperdietzel]

Hello, I would like to know if its possible to implement custom Wayland extensions in a Qt client? Or at least a way to get access to the wl_display handle? I've searched with no luck, and I think it would be very useful.

[JKSH]

Hi, and welcome!

@ehopperdietzel said in Custom Wayland extensions/protocols in Qt clients:

I would like to know if its possible to implement custom Wayland extensions in a Qt client?

Are these what you're looking for?

• https://doc.qt.io/qt-6/qwaylandcompositorextension.html
• https://doc.qt.io/qt-6/qtwaylandcompositor-custom-shell-example.html

[ehopperdietzel]

Hi @JKSH ! Thanks for the reply ! Sadly thats not what I am looking for, the links you provided are for implementing custom Wayland extensions in Qt compositors, or custom client shells. What I need is to implement custom extensions but in a client application (not shells). And that would be possible if I could get access to the wl_display used by the client. I think maybe QGuiApplication::QNativeInterface() could return a handle to wl_display when using the wayland or wayland-egl platform plugin, but not sure since the documentation doesn't say that. I'll check it out.

[JKSH]

@ehopperdietzel said in Custom Wayland extensions/protocols in Qt clients:

I think maybe QGuiApplication::QNativeInterface() could return a handle to wl_display when using the wayland or wayland-egl platform plugin, but not sure since the documentation doesn't say that. I'll check it out.

You're definitely on the right track! I believe you want to call QGuiApplication::platformNativeInterface()->nativeResourceForIntegration("wl_display"); on the Wayland platform.

You can examine the source code here:

• https://code.woboq.org/qt6/qtbase/src/gui/kernel/qguiapplication.cpp.html#_ZN15QGuiApplication23platformNativeInterfaceEv
• https://code.woboq.org/qt6/qtwayland/src/client/qwaylandnativeinterface.cpp.html#_ZN15QtWaylandClient23QWaylandNativeInterface28nativeResourceForIntegrationERK10QByteArray
• https://code.woboq.org/qt6/qtwayland/src/client/qwaylanddisplay_p.h.html#QtWaylandClient::wl_display

[ehopperdietzel]

OMG ! I tested it and it works !! Thank you so so much !! ❤️ @JKSH

The QPlatformNativeInterface class is defined here if someone wondered:

#include <QtGui/6.2.4/QtGui/qpa/qplatformnativeinterface.h>

Of course you should replace 6.2.4 with the version you're using.

[JKSH]

That's great news, @ehopperdietzel !

Just note that this is all private API, so there is a small risk that it might break in a future version of Qt.

[JKSH]

@ehopperdietzel said in Custom Wayland extensions/protocols in Qt clients:

#include <QtGui/6.2.4/QtGui/qpa/qplatformnativeinterface.h>

Of course you should replace 6.2.4 with the version you're using.

A somewhat more portable way is:

1. Add the "gui-private" module to your project (e.g. QT += gui-private in your .pro file)
2. Write #include <qpa/qplatformnativeinterface.h>

[ehopperdietzel]

@JKSH Thank you ! I didn't know that, it's way more convenient