Introduction to QtWebEngine
QtWebEngine integrates
chromium's web capabilities into
Qt. It ships with its own copy of ninja which it uses for the build
if it cannot find a system copy, and various copies of libraries
from ffmpeg, icu, libvpx, and zlib (including libminizip) which
have been forked by the chromium
developers.
This package and browsers using it may be useful if you need to use
a website designed for google chrome, or chromium, browsers.
![[Important]](../images/important.png)
Important
Qt-5.15 reached End Of Life on 26 May 2023. Extended lifetime
Qt5.15 LTS has been extended until 26th May 2025 for those with
subscription licenses. Because qtwebengine uses chromium code
under the LGPL, it appears that any new backported CVE fixes for
QtWebEngine will be available after Qt makes public releases of
its current versions.
![[Warning]](../images/warning.png)
Warning
QtWebEngine uses a forked copy of chromium, and is therefore
vulnerable to many issues found there. The Qt developers have
always preferred to make releases at the same time as the rest of
Qt (rather than adding emergency fixes), but with stable versions
getting released after the current development version. Now that
they are keen to move to Qt6, the 5.15.3 and later Qt-5.15
releases are initially only available to paying customers.
QtWebEngine is something of an exception because of its LGPL
licence, but getting the git sources (with the forked chromium
submodule) to a position where they will successfully build on a
current BLFS system can take a lot of effort and therefore
updates to the book may be delayed.
It seems likely that future 5.15-series versions will also be
released long after the chromium vulnerabilities are known, but
fixes for QtWebEngine can be found in git and the editors take
the view that known vulnerabilities in browsers should be fixed.
The tarball linked to below was created from the 5.15 git branch
and the 87-branch of the chromium submodule (which is forked from
chromium). See the GIT-VERSIONS file in the tarball for details
of the latest commits.
This package is known to build and work properly using an LFS 12.1
platform.
Warning
By default, ninja will use all online CPUs +2 (if at least 4
exist), even if they are not available to the current task
because the build terminal has been restricted with 'taskset'. In
BLFS, this package takes more time to build than any other. In
one example, the build of this package crashed at about the 90
percent point due to an out of memory problem on a system with 24
cores and 32 GB of memory.
To work around this, see the Command Explanations below.
![[Note]](../images/note.png)
Note
If you are upgrading and have installed a newer version of
ICU-74.2 since you last installed Qt-5.15.12, you will need
to reinstall Qt5 before upgrading, otherwise the final link of
this package will fail with a warning that the version of icu
libraries needed by libQt5Core.so may conflict with the version
used for this package.
Unusually, the shipped GN build system (used to create the Ninja
files) requires a static libstdc++.a although the installed libraries
correctly use the shared version. If that static library is not
present, the build will fail quite quickly. Please note that if
you try to build webengine as part of Qt and the static library is not available,
that build will either complete without installing webengine, or
else fail during the install (both variants were observed in
5.12.0).
Package Information
Additional Downloads
qtwebengine Dependencies
Required
nodejs-20.11.1, nss-3.98, pciutils-3.10.0, Python-3.11.1, and (Qt-5.15.12 or qt-components-5.15.12 with qtlocation
and qtwebchannel)
Recommended
Note
If these packages are not installed, the build process will
compile and install its own (perhaps older) version, with the
side effect of increasing build and installed disk space and
build time.
either alsa-lib-1.2.11 or PulseAudio-17.0 (or both), FFmpeg-6.1.1, ICU-74.2, libwebp-1.3.2, libxslt-1.1.39, and Opus-1.4
Optional
libevent-2.1.12, MIT
Kerberos V5-1.21.2, pipewire-1.0.3, Poppler-24.02.0, jsoncpp,
libsrtp, snappy
Installation of qtwebengine
Apply a patch to fix several issues that can prevent the build from
completing, and to force it to use python3:
patch -Np1 -i ../qtwebengine-5.15.17-build_fixes-2.patch
If building with system FFmpeg-6.1.1
as the editors recommend, apply a patch that resolves problems when
building with ffmpeg-5 and later:
patch -Np1 -i ../qtwebengine-5.15.17-ffmpeg5_fixes-1.patch
Although the build_fixes patch has ensured that git is not invoked
during the build, the build system has labyrinthine rules of
byzantine complexity, and in particular trying to build without two
.git directories will lead to it
eventually falling into unexpected and unbuildable code which
references a private header that has not been created. Avoid this
by creating the required directories:
mkdir -pv .git src/3rdparty/chromium/.git
Because this version of qtwebengine is aimed at a later release
than the current public releases, change it to build for qt-5.15.12
using a sed:
sed -e '/^MODULE_VERSION/s/5.*/5.15.12/' -i .qmake.conf
Now, ensure that the local headers are available when not building
as part of the complete Qt-5.15.12:
find -type f -name "*.pr[io]" |
xargs sed -i -e 's|INCLUDEPATH += |&$$QTWEBENGINE_ROOT/include |'
Next, allow the pulseaudio library to be linked at build time,
instead of run time. This also prevents an issue with newer
pulseaudio:
sed -e '/link_pulseaudio/s/false/true/' \
-i src/3rdparty/chromium/media/media_options.gni
Next, fix a build failure that occurs when libxml2-2.12.0 or later
is installed:
sed -e 's/xmlError/const xmlError/' \
-i src/3rdparty/chromium/third_party/blink/renderer/core/xml/xslt_processor.h \
-i src/3rdparty/chromium/third_party/blink/renderer/core/xml/xslt_processor_libxslt.cc
Install qtwebengine by running the
following commands:
mkdir build &&
cd build &&
PATH=/opt/python3.11/bin:$PATH qmake .. -- \
-system-ffmpeg \
-proprietary-codecs \
-webengine-icu &&
make
This package does not come with a test suite.
Now, as the root user:
make install
Remove references to the build directory from installed library
dependency (prl) files by running the following commands as the
root user:
find $QT5DIR/ -name \*.prl \
-exec sed -i -e '/^QMAKE_PRL_BUILD_DIR/d' {} \;
Command Explanations
PATH=/opt/python3.11/bin:$PATH:
This switch forces this package to use the version of Python 3.11
that is installed in /opt. This is done to reduce the chances for
problems that may occur during the build, and to simplify the
instructions since this package is incompatible with Python 3.12
without additional modifications.
qmake: This will
build the included copy of ninja
if it is not already installed and use it to configure the build.
-- -system-ffmpeg -proprietary-codecs
-webengine-icu: If any options are passed to qmake
they must come after '--' which must follow '..' that points to the
main directory. The options here cause it to use system ffmpeg and
system icu. The '-proprietary-codecs' option allows ffmpeg to
decode H264 and H265 codecs. If built as part of full Qt5, the
system icu is automatically used (only) by Qt5Core if it is
available, but unless this option is used webengine will always use
its shipped copy of icu, adding time and space to the build. Remove
the -system-ffmpeg switch
if you don't have FFmpeg-6.1.1 installed and want to build
this package with an internal copy of ffmpeg.
-webengine-jumbo-build 0: If this is
added to the qmake command it will cause the 'Jumbo Build Merge
Limit' to be reported as 'no' instead of 8. That turns off the
jumbo build. Some distros do that to get a smaller build on some
architectures such as MIPS. On x86_64 it might save a little space
in the build, but the build time will increase by a very large
amount.
-webengine-kerberos: Add this if you
have installed MIT Kerberos V5-1.21.2 and wish to
connect from a browser using QtWebEngine to a webserver which
requires you to connect via kerberos.
NINJAJOBS=4 make: If you patched system
ninja in LFS to recognize the NINJAJOBS environment variable, this
command will run system ninja with the specified number of jobs
(i.e. 4). There are several reasons why you might want to use
options like this this:
-
Building on a subset of CPUs allows measuring the build time
for a smaller number of processors, and/or running other
CPU-intensive tasks at the same time. For an editor on a
machine with a lot of CPUs, trying to measure the build time
for a 4-CPU machine, NINJAJOBS=4
make will give a reasonable approximation (there is a
short period where N+2 python and node jobs run).
-
On a machine with only 4 CPUs online, the default of
scheduling N+2 jobs for qtwebengine is slower by between 3%
and 7%, probably because of the size of the C++ files and
their many includes and templates. Therefore, if in doubt set
NINJAJOBS to the number of CPUs.
-
Reducing the number of cores being used on long running, CPU
intensive packages may alleviate heat problems.
-
Reducing the number of cores will prevent potential
out-of-memory problems on systems that do not have enough
memory (or swap) when all cores are active. A suggested
approach is to limit the number of cores to about one core
for each 1.5 GB of combined RAM and swap space.
Configuring QtWebEngine
Configuration Information
If you are upgrading from an older minor version of this
application, for some webpages to load you may need to clear the
browser caches, e.g. for
falkon they will be found in
~/.cache/falkon/. You will need to
do this if the browser starts to render the page and then changes
to a blank tab with a message that something went wrong, and a
button to Retry. Even after removing the old caches, you may need
to retry a few times for each affected tab.
If a browser using this package fails to run and when run from a
term it reports 'Trace/breakpoint trap' that is probably a kernel
configuration issue - there is no need to rebuild QtWebEngine,
see the next section, recompile the kernel and reboot to the new
kernel.
Kernel
Configuration
This package does not require any of the optional kernel namespace
items, but if User namespace is enabled PID namespace must also be
enabled. In that case enable the following options in the kernel
configuration and recompile the kernel if necessary:
General setup --->
-*- Namespaces support ---> [NAMESPACES]
# Enable or disable *both* of them:
[ /*] User namespace [USER_NS]
[ /*] PID Namespaces [PID_NS]
Contents
Installed Programs:
qtwebengine_convert_dict and
QtWebEngineProcess (in $QT5DIR/libexec)
Installed Libraries:
libQt5Pdf.so, libQt5PdfWidgets.so,
libQt5WebEngineCore.so, libQt5WebEngine.so, and
libQt5WebEngineWidgets.so
Installed Directories:
$QT5DIR/include/QtPdf,
$QT5DIR/include/QtPdfWidgets, $QT5DIR/include/QtWebEngine,
$QT5DIR/include/QtWebEngineCore,
$QT5DIR/include/QtWebEngineWidgets, $QT5DIR/qml/QtWebEngine,
and $QT5DIR/translations/qtwebengine_locales
Short Descriptions
|
qtwebengine_convert_dict
|
converts hunspell dictionaries (.dic) to chromium format (.bdic)
|
|
QtWebEngineProcess
|
is a libexec program which runs a zygote process (one
that listens for spawn requests from a master process and
will fork itself in response)
|
|
libQtWebEngine.so
|
provides QML types for rendering web content within a QML
application
|
|
libQtWebEngineCore.so
|
provides public API shared by both QtWebEngine and
QtWebEngineWidgets
|
|
libQtWebEngineWidgets.so
|
provides a web browser engine as well as C++ classes to
render and interact with web content
|