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'''English''' | [[QtWayland SimplifiedChinese|简体中文]]
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=What is QtWayland?=
== What is QtWayland? ==


QtWayland is a Qt 5 module that wraps the functionality of Wayland. QtWayland is separated into a client and server side. The client side is the wayland platform plugin, and provides a way to run Qt applications as Wayland clients. The server side is the QtCompositor <span class="caps">API</span>, and allows users to write their own Wayland compositors.
QtWayland is a Qt 5 module that wraps the functionality of Wayland. QtWayland is separated into a client and server side. The client side is the wayland platform plugin, and provides a way to run Qt applications as Wayland clients. The server side is the Qt Wayland Compositor API, and allows users to write their own Wayland compositors.


==What is Wayland==
== What is Wayland ==


Wayland is a protocol for a compositor to talk to its clients as well as a C library implementation of that protocol. For more detailed information you should visit the [http://wayland.freedesktop.org/ Wayland project homepage] ''[wayland.freedesktop.org]''
Wayland is a protocol for a compositor to talk to its clients as well as a C library implementation of that protocol. For more detailed information you should visit the [http://wayland.freedesktop.org/ Wayland project homepage]


=Where can I find the code for QtWayland?=
== How can I get binaries for Qt Wayland? ==
Starting with Qt 5.11. the Qt installer should include binaries for Qt Wayland.


[http://qt.gitorious.org/qt/qtwayland Gitorious Repo] ''[qt.gitorious.org]''
If you are using Qt provided by your Linux distribution there is most likely a separate package for Qt Wayland, i.e. qt5-wayland (Arch Linux), or two separate packages, i.e. qtwaylandclient5 and qtwaylandcompositor5-dev (Ubuntu 17.10). Beware that distros may ship really old versions of Qt though, and the compositor API was first released as stable with Qt 5.8.


=How do I build QtWayland?=
You can however also build it from source yourself in case you want to use the development version or apply custom patches. See section below.


==Desktop build instructions==
== Where can I find the code for QtWayland? ==


===Setup build environment===
[http://code.qt.io/cgit/qt/qtwayland.git/tree/ Qt Wayland Repo]


The first step is to start with a reasonably modern Linux distribution. I use Ubuntu 12.04, so anything newer is just gravy.<br /> The following instructions are based off of the tips on: http://wayland.freedesktop.org/building.html
== How do I build QtWayland? ==


The first thing I do is start by creating an install directory for my Wayland dependencies and create an environment file to source:
==== Ubuntu 14.04 ====


So if I wanted to install my Wayland dependencies into the folder $HOME/Apps/Wayland I would create the folder, and then create the file:<br />''~/Apps/Wayland/wayland.sourceme''
Ubuntu 14.04 contains all necessary dependencies, so it is no longer necessary to build Wayland yourself.


So then source that file to set up your work environment:<br />''source ~/Apps/Wayland/wayland.sourceme''
The following packages are required (list may be incomplete)
* libwayland-dev
* libwayland-egl1-mesa
* libwayland-server0
* libgles2-mesa-dev
* libxkbcommon-dev


===Build dependencies===
==== Qt dependency ====


Most of the dependencies you need are released, but not yet available in the latest Linux distributions, so you will need to build them. Here are the instructions for each in the order that they need to be built:
You need Qt5.8 or newer for the compositor API. The modules you need at the very least are: <br>
qtbase <br>
qtdeclarative


====wayland====
==== Building the QtWayland module ====


====drm====
Once you have a working build of Qt 5, then pull down the latest QtWayland module code and configure with "qmake". Make sure that you use the version of qmake that you get with Qt 5 here.


====mesa====
<code>git clone git://code.qt.io/qt/qtwayland.git
cd qtwayland
git checkout v5.10.0 # replace with your qt version
qmake
make
make install</code>


====libxkbcommon====
== How do I use QtWayland? ==


====weston (optional)====
=== Run Qt applications as Wayland clients ===


===Qt dependency===
When you build the QtWayland module, you should get a new platform plugin for wayland. To use it you must first already have a Wayland compositor running. This could be either the Weston reference compositor provided by the Wayland project, or a Qt example compositor provided by QtWayland. Regardless the only thing you need to do as an application developer to run your GUI application as a wayland client is tell the application to use the right platform plugin:


Currently, you need to build the latest Qt (stable branch) (see http://lists.qt.io/pipermail/development/2013-December/014789.html ) <span class="caps">WITHOUT</span> using the wayland.sourceme environment. The modules you need at the very least are:<br /> qtbase<br /> qtjsbackend<br /> qtdeclarative
<code>./application -platform wayland</code>or:<code>export QT_QPA_PLATFORM=wayland
./application</code>


If you face linker errors related to libGL and undefined references, it may be necessary to compile Qt5 and link it with the self compiled mesa. Maybe due to the way that mesa was compiled and installed, the configure script will require to explicitly define the version of OpenGL to be used with: ./configure -opengl es2
=== Create and Run your own Wayland Compositor with Qt5 ===
 
===Building the QtWayland module===
 
Once you have a working build of Qt 5, then pull down the latest QtWayland module code and configure with “qmake” this time using the wayland.sourceme environment. Make sure that you use the version of qmake that you get with Qt 5 here. This will make sure that the Wayland platform plugin and QtCompositor <span class="caps">API</span> are build using your special versions of OpenGL and Wayland.
 
==Raspberry Pi build instructions==
 
Coming soon…
 
=How do I use QtWayland?=


==Run Qt applications as Wayland clients==
==== Running example compositors ====


When you build the QtWayland module, you should get a new platform plugin for wayland. To use it you must first already have a Wayland compositor running. This could be either the Weston reference compositor provided by the Wayland project, or a Qt example compositor provided by QtWayland. Regardless the only thing you need to do as an application developer to run your <span class="caps">GUI</span> application as a wayland client is:
The QtWayland module provides a couple of example compositors that demonstrate how the Qt Wayland Compositor API works. These are built in the examples folder of the QtWayland module. You may need to explicitly build them (depending on how you configured Qt):
<code>cd qtwayland
make sub-examples</code>


==Create and Run your own Wayland Compositor with Qt5==
These examples represent the server side of Wayland, so they do not use the wayland platform plugin, but rather whatever platform you need to run on. Generally this is going to be either ''eglfs'', ''kms'', or if you want to run in X11 ''xcb''. You can also run a nested compositor if you run the compositor on the ''wayland'' platform plugin.


===Running example compositors===
If you wanted to run the pure-qml compositor in X11 you would run the following:


The QtWayland module provides a couple of example compositors that demonstrate how the QtCompositor <span class="caps">API</span> works. These are built in the examples folder of the QtWayland module if you add “wayland-compositor” to the <span class="caps">CONFIG</span> variable when starting qmake, as in :<br />
<code>cd qtwayland/examples/wayland/pure-qml
 
./pure-qml -platform xcb</code>
These examples represent the server side of Wayland, so they do not use the wayland platform plugin, but rather whatever platform you need to run on. Generally this is going to be either ''eglfs'', ''kms'', or if you want to run in X11 ''xcb''.
 
If you wanted to run the qml-compositor in X11 you would run the following:


And now that you have a Wayland compositor running, you can connect and display Wayland clients.
And now that you have a Wayland compositor running, you can connect and display Wayland clients.


===Creating your own compositor===
==== Creating your own compositor ====


The <span class="caps">API</span> to create a Wayland compositor and control associated events (e.g. a new client connected) is exposed through the QtWayland class WaylandCompositor. Its constructor expects as the primary parameter a pointer to a QWindow object, which allows some flexibility when implementing your compositor.
Compositors can be implemented using QML, or you can use the C++ API if you need more low-level control.


Thanks to this, there are 3 different approaches while implementing a compositor:
* QML-based: See minimal-qml and pure-qml. [https://www.youtube.com/watch?v=9vWMUTvFgdU Tutorial], [https://www.youtube.com/watch?v=mIg1P3i2ZfI talk]
* C++-based: See the minimal-cpp and qwindow-compositor examples.


* QWindow based: the instance will be used to setup the WaylandCompositor object.
The project file will need to use the compositor module (i.e. add in the .pro file '''QT += waylandcompositor''').


* QWidget based: in this case, the base widget window handle will be used.
== Troubleshooting ==


* <span class="caps">QML</span> based: your C++ application will use a QQuickView object to setup the WaylandCompositor. At the time of writing, there is no way to create a compositor using only <span class="caps">QML</span>.
=== libGL linker issues ===
 
If you face linker errors related to libGL and undefined references, it may be necessary to compile Qt5 and link it with the self compiled mesa. Maybe due to the way that mesa was compiled and installed, the configure script will require to explicitly define the version of OpenGL to be used with: ./configure -opengl es2
WaylandCompositor is a pure abstract virtual class, which means that it is not possible to create instances of it. A common pattern while implementing a compositor is inherit from WaylandCompositor and implement the function method '''void surfaceCreated(WaylandSurface *surface)'''.
 
This method will be executed every time a new client connects (i.e. an application was started and requests the services of the compositor), being represented as a WaylandSurface object. There are some signals that this object can generate and must be treated by the compositor, namely:
 
* mapped(): emitted when the client has connected to the compositor.
 
* damaged(): <span class="caps">TODO</span>
 
* destroyed(): emitted when the client quits (i.e. the application has exited)
 
* unmapped(): <span class="caps">TODO</span>
 
* extendedSurfaceReady(): <span class="caps">TODO</span>
 
The project file will need to use the compositor module (i.e. add in the .pro file '''QT += compositor'''). It is interesting to comment that at time of writing, there are some <span class="caps">QML</span> related <span class="caps">API</span>s only available by adding a define in the project file (i.e. '''<span class="caps">DEFINES</span> += QT_COMPOSITOR_QUICK''').
 
===Starting the compositor standalone===
 
<span class="caps">TODO</span>

Latest revision as of 13:14, 28 March 2019

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What is QtWayland?

QtWayland is a Qt 5 module that wraps the functionality of Wayland. QtWayland is separated into a client and server side. The client side is the wayland platform plugin, and provides a way to run Qt applications as Wayland clients. The server side is the Qt Wayland Compositor API, and allows users to write their own Wayland compositors.

What is Wayland

Wayland is a protocol for a compositor to talk to its clients as well as a C library implementation of that protocol. For more detailed information you should visit the Wayland project homepage

How can I get binaries for Qt Wayland?

Starting with Qt 5.11. the Qt installer should include binaries for Qt Wayland.

If you are using Qt provided by your Linux distribution there is most likely a separate package for Qt Wayland, i.e. qt5-wayland (Arch Linux), or two separate packages, i.e. qtwaylandclient5 and qtwaylandcompositor5-dev (Ubuntu 17.10). Beware that distros may ship really old versions of Qt though, and the compositor API was first released as stable with Qt 5.8.

You can however also build it from source yourself in case you want to use the development version or apply custom patches. See section below.

Where can I find the code for QtWayland?

Qt Wayland Repo

How do I build QtWayland?

Ubuntu 14.04

Ubuntu 14.04 contains all necessary dependencies, so it is no longer necessary to build Wayland yourself.

The following packages are required (list may be incomplete)

  • libwayland-dev
  • libwayland-egl1-mesa
  • libwayland-server0
  • libgles2-mesa-dev
  • libxkbcommon-dev

Qt dependency

You need Qt5.8 or newer for the compositor API. The modules you need at the very least are:
qtbase
qtdeclarative

Building the QtWayland module

Once you have a working build of Qt 5, then pull down the latest QtWayland module code and configure with "qmake". Make sure that you use the version of qmake that you get with Qt 5 here. 

git clone git://code.qt.io/qt/qtwayland.git
cd qtwayland
git checkout v5.10.0 # replace with your qt version
qmake
make
make install

How do I use QtWayland?

Run Qt applications as Wayland clients

When you build the QtWayland module, you should get a new platform plugin for wayland. To use it you must first already have a Wayland compositor running. This could be either the Weston reference compositor provided by the Wayland project, or a Qt example compositor provided by QtWayland. Regardless the only thing you need to do as an application developer to run your GUI application as a wayland client is tell the application to use the right platform plugin: 

./application -platform wayland

or:

export QT_QPA_PLATFORM=wayland
./application

Create and Run your own Wayland Compositor with Qt5

Running example compositors

The QtWayland module provides a couple of example compositors that demonstrate how the Qt Wayland Compositor API works. These are built in the examples folder of the QtWayland module. You may need to explicitly build them (depending on how you configured Qt): 

cd qtwayland
make sub-examples

These examples represent the server side of Wayland, so they do not use the wayland platform plugin, but rather whatever platform you need to run on. Generally this is going to be either eglfs, kms, or if you want to run in X11 xcb. You can also run a nested compositor if you run the compositor on the wayland platform plugin.

If you wanted to run the pure-qml compositor in X11 you would run the following: 

cd qtwayland/examples/wayland/pure-qml
./pure-qml -platform xcb

And now that you have a Wayland compositor running, you can connect and display Wayland clients.

Creating your own compositor

Compositors can be implemented using QML, or you can use the C++ API if you need more low-level control.

  • QML-based: See minimal-qml and pure-qml. Tutorial, talk
  • C++-based: See the minimal-cpp and qwindow-compositor examples.

The project file will need to use the compositor module (i.e. add in the .pro file QT += waylandcompositor).

Troubleshooting

libGL linker issues

If you face linker errors related to libGL and undefined references, it may be necessary to compile Qt5 and link it with the self compiled mesa. Maybe due to the way that mesa was compiled and installed, the configure script will require to explicitly define the version of OpenGL to be used with: ./configure -opengl es2

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