Building Qt6 WebEngine from Source

Please check platform notes for required dependencies https://doc.qt.io/qt-6/qtwebengine-platform-notes.html.

Note: Starting from 6.12 QtWebEngine is no longer a submodule of qt5 repository, meaning that if you clone qt5 main repository (git://code.qt.io/qt/qt5.git) the QtWebEngine module will be not there and it has to be cloned in separate step.

Overview

As a first step we clone minimum subset of Qt6 modules required for QtWebEngine build and compile them. Secondly we clone QtWebEngine repository and use compiled Qt6 modules to build QtWebEngine.

Open the build shell

All the build commands we execute in a build shell / terminal.

On Windows platform Developer Command Prompt is required, therefore for example for Visual Studio Build Tools 2022 the correct setup requires:

call "C:\Program File (x86)\Microsoft Visial Studio\2022\BuildTools\VC\Auxilary\Build\vcvarsall.bat" amd64

Note: The location of the script may vary please refer to the Microsoft documentation.

Obtain the Qt6 source code

Select the location for the source code and checkout the qt6 source:

git clone git://code.qt.io/qt/qt5.git qt6

Select branch

Let's assume we want to compile latest Qt 6.12.

cd qt6
git checkout origin/6.12

Initialize all required modules

Starting with Qt 6.8 you can simply after cloning qt5 repository and selecting branch call 'init-repository' cmake script. This will also setup all the required submodules.

./init-repository --module-subset=qtbase,qtshadertools,qtdeclarative --no-resolve-deps

Note: On Windows platform you should use 'init-repository.bat' instead of 'init-repository' command.

Shadow build

It is a common practice to compile the project in separate build directory instead of doing in-source build, therefore we create build directory:

Note: On Windows platform you should use 'md' instead of 'mkdir' command

mkdir build
cd build

Configure top level build and build required qt6 submodules

From our 'build' directory we call the configure from qt6 'source' directory to make prefix build, which means that we will compile and than install to the specific installation directory defined with 'prefix' argument.

On Linux the configure command line for the release builds might look like:

../configure -release -nomake tests -nomake examples -no-pch -linker mold -prefix /opt/qt/6.12

Note: To speed up linking time for WebEngine we decided to use mold linker.

On Windows the configure command line for the release build might look like:

..\configure.bat -release -nomake tests -nomake examples -no-pch -prefix C:\opt\qt\6.12

On Mac the configure command line for the release framework builds might look like:

../configure -release -framework -release -nomake tests -nomake examples -no-pch -prefix /opt/qt/6.12

or Mac universal build :

../configure -release -framework -nomake tests -nomake examples -no-pch -prefix /opt/qt/6.12 -- -DCMAKE_OSX_ARCHITECTURES="x86_64;arm64"

Note: For other configure options please refer to the configure guide https://doc.qt.io/qt-6/configure-options.html

To build and install modules you just need to call cmake:

cmake --build . --parallel
cmake --install .

Note: On Windows in case of debug and release build please use "ninja install" instead of "cmake --install ." due to cmake issue

Obtain the Qt6 WebEngine source code

Now let's focus on QtWebEngine build, first clone the repository with required sub repository.

git clone git://code.qt.io/qt/qtwebengine.git qtwebengine
cd qtwebengine
git submodule init
git submodule update

Configure and build QtWebEngine module

To configure and build QtWebEngine module we use the qt-configure-module wrapper script from the installed in previous step Qt.

Note: On Windows you might want to call 'C:\opt\qt\6.12\bin\qt-cofigure-module.bat' instead of 'qt-cofigure-module'

mkdir qtwebengine-build
cd qtwebengine-build
/opt/qt/6.12/bin/qt-configure-module ../../qtwebengine
cmake --build . --parallel
cmake --install .
cd ..