Difference between revisions of "Building Qt 5 from Git"
(must add ninja as well)
(No qt5-default thing from Ubuntu 21.04.)
|Line 44:||Line 44:|
RPM-based distros with yum offer a similar tool called yum-builddep.
RPM-based distros with yum offer a similar tool called yum-builddep.
'''Note:''' if you see the following error message while running the commands above on Ubuntu:
'''Note:''' if you see the following error message while running the commands above on Ubuntu:
Latest revision as of 08:34, 3 November 2021
This article provides hints for checking out and building the Qt 5 repositories. This is primarily for developers who want to contribute to the Qt library itself, or who want to try the latest unreleased code.
If you simply want to build a specific release of Qt from source to use the libraries in your own project, you can download the source code from the Official Releases page or the Archive. Alternatively, commercial customers can download the Source Packages via the Qt Account portal.
To compile Qt 6, see Building Qt 6 from Git.
To compile Qt Creator, see Building Qt Creator from Git.
- 1 System Requirements
- 2 Getting the source code
- 3 Configuring and Building
- 4 Installing (Linux / OS X)
- 5 Cleaning
- 6 Getting updates
- 7 Using latest branches in the submodules
- 8 Issues
- 9 Questions and comments
All desktop platforms
- Git (>= 1.6.x)
- Perl (>=5.14)
- Python (>=2.6.x)
- A working C++ compiler
For more detailed information, see Building Qt Sources
- Clang (>=6.x)
For Windows, bison, flex and gperf are provided with the source code at c:\pathToQt\gnuwin32\bin. Get Ruby from http://rubyinstaller.org/. You can download the precompiled ICU packages from download.qt.io, or see Compiling-ICU to compile your own.
Ubuntu/Debian based systems have a convenient way of installing build-depends for any package:
sudo apt-get build-dep qt5-default sudo apt-get install libxcb-xinerama0-dev
RPM-based distros with yum offer a similar tool called yum-builddep.
Note: if you see the following error message while running the commands above on Ubuntu:
E: You must put some 'source' URIs in your sources.list
Then you will need to enable the "Source code" option in Software and Updates > Ubuntu Software under the "Downloadable from the Internet" section. This setting can also be found by running software-properties-gtk.
Convenience packages (Ubuntu 11.10 -- 12.10 only)
For Ubuntu/Debian, Gabor Loki has provided a custom PPA with the sedkit-env-webkit meta package that installs all required dependencies for building Qt/Qt WebKit. You can add the PPA by calling:
sudo apt-add-repository ppa:u-szeged/sedkit &&\ sudo apt-get update &&\ sudo apt-get install sedkit-env-qtwebkit
For other distros, get the separate components below.
|Ubuntu and/or Debian:|
Libxcb is now the default window-system backend for platforms based on X11/Xorg, and you should therefore install libxcb and its accompanying packages. Qt5 should build with whatever libxcb version is available in your distro's packages (but you may optionally wish to use v1.8 or higher to have threaded rendering support). The README lists the required packages.
|Chakra Linux:||Install the ArchLinux packages, plus xcb-util-keysyms. It's available from CCR.|
|Centos 5/6||Install missing Qt build dependencies:
yum install libxcb libxcb-devel xcb-util xcb-util-devel
Install Red Hat DevTools 1.1 for CentOS-5/6 x86_64, they are required due to outdated GCC shipped with default CentOS:
wget http://people.centos.org/tru/devtools-1.1/devtools-1.1.repo -O /etc/yum.repos.d/devtools-1.1.repo yum install devtoolset-1.1
Initialise your newly installed dev tools:
scl enable devtoolset-1.1 bash # Test - Expect to see gcc version 4.7.2 (not gcc version 4.4.7) gcc -v
For more info on preparing the environment on CentOS, see this thread.
|Centos 7||Update to gcc 7:
yum install centos-release-scl yum install devtoolset-7-gcc* scl enable devtoolset-7 bash
Install missing Qt build dependencies (Qt 5.13):
yum install libxcb libxcb-devel xcb-util xcb-util-devel mesa-libGL-devel libxkbcommon-devel
For Qt Quick 2, a graphics driver with native OpenGL 2.0 support is highly recommended.
It is recommended to build with accessibility enabled, install libatspi 2 and libdbus-1 development packages.
You'll need at least alsa-lib (>= 1.0.15) and gstreamer (>=0.10.24) with the base-plugins package.
dnf install pulseaudio-libs-devel alsa-lib-devel gstreamer1-devel gstreamer1-plugins-base-devel wayland-devel
QDoc Documentation Generator Tool
su -c 'dnf install llvm-devel'
Install the latest Xcode from the App Store. Verify that your Xcode install is properly set up for command line use:
xcodebuild -version && xcodebuild -showsdks
This should give you eg:
Xcode 6.2 Build version 6C131e
OS X SDKs: OS X 10.9 -sdk macosx10.9 OS X 10.10 -sdk macosx10.10
iOS SDKs: iOS 8.2 -sdk iphoneos8.2
iOS Simulator SDKs: Simulator - iOS 8.2 -sdk iphonesimulator8.2
You can verify that the right Xcode is being used by running:
If this points to /Developer you're probably using an older Xcode version. Switch to the latest one by running:
sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer
If you have not installed CMake and Ninja, you need to do that
- Launch "MaintenanceTool", and choose "Add or remove components" (click next)
- under "Qt -> Developer and Design Tools", check "CMake" and "Ninja" (click next, and complete that)
- in Terminal, ensure you add the folder containing cmake to your $PATH, eg: export PATH=$PATH:/path_to/Qt/Tools/CMake/CMake.app/Contents/bin
Windows Graphics Drivers
The full feature set of Qt Quick 2 requires OpenGL 2.1 or higher or OpenGL ES 2.0 to work. Several options are available:
- Using the native OpenGL driver for your graphics card (Note: The stock Windows driver only supports OpenGL 1.1, which is insufficient).
- Using the ANGLE-library to translate OpenGL calls into DirectX. A copy of ANGLE is bundled in Qt 5.
- Using a software rasterizer shipped in the Qt SDK. See MesaLlvmpipe for instructions on how that is built.
Starting with Qt 5.8, many Qt Quick applications can also be run with the built-in software backend (previously known as the Qt Quick 2D Renderer). This is not the same as running through a full OpenGL software rasterizer, and is a lot more lightweight. See the documentation on how to request a specific backend.
Qt can be built to dynamically choose the OpenGL implementation (see Dynamically Loading Graphics Drivers) by passing the option -opengl dynamic to configure. To build Qt to always use the native OpenGL driver, pass -opengl desktop. To build Qt to always use ANGLE, pass -opengl es2.
- Qt < 5.12: Building ANGLE with Windows SDKs prior to Windows Kit 8 requires the DirectX SDK to be installed, and the path to the d3d_compiler<xx>.dll to be added to the PATH variable.
- Qt >= 5.12: Qt needs at least a Windows 10 SDK in order to build ANGLE. No additional manual setup is needed
- Building ANGLE with Windows SDKs prior to Windows Kit 8 requires the DirectX SDK to be installed, and the path to the d3d_compiler<xx>.dll to be added to the PATH variable.
Any project that uses run-time shader compilation must have D3DCOMPILER_xx.DLL copied to the local executable path for the project. This DLL is available in this sub-directory of the Windows SDK installation under %ProgramFiles(x86)%\Windows Kits\<version>\Redist\D3D\<arch> where <arch> is x86 and x64 (see ).
Supported Compilers on Windows
- Visual Studio 2019
- Visual Studio 2017 (might need a recent service pack, especially for QtWebEngine)
- MinGW-w64 based compiler with g++ version 7.3 or higher (e.g. MinGW-builds, see also MinGW-64-bit).
- Add the compiler to the PATH environment variable. Visual Studio usually ships .bat files named vcvarsall.bat or similar that can be called with a command line parameter for choosing the toolchain (/x86, /x64, etc) to set up the environment.
- Windows SDK v6.0A/v7.0A contains the same compiler as Visual Studio 2008/2010.
- Windows SDK 8.0 and later do not include a compiler.
- As of 16.3.2012, if you wish to install both Visual Studio 2010 and the standalone SDK, you need to follow this order (see readme.html provided with the service pack):
- Install Visual Studio 2010
- Install Windows SDK 7.1. See also the Cannot Install Windows SDK page.
- Install Visual Studio 2010 SP1
- Install Visual C++ 2010 SP1 Compiler Update for the Windows SDK 7.1
Windows Build environment
We recommend creating a command prompt that provides the build environment (see the Qt Creator README ). In this environment, Python (e.g. Active Python 2.7 later) and Perl (e.g. StrawberryPerl 5.12 or later) should be in the PATH. Ruby is required for WebKit.
Hint: If you installed git with the non-recommended setting to add git's entire Unix environment to PATH, make sure that Perl is added to the path in front of git, since that ships an incompatible build of perl, which would cause the scripts to fail. Also, MinGW builds of Qt become Msys builds due to the presence of sh.exe; and those who've tried have had more success configuring and building for MinGW in MS's cmd.exe Command Prompt than in the Git Bash shell.
Multicore building: To speed up building when using nmake, the compiler can be instructed to use all available CPU cores in one of the following ways:
- Pass the option -mp to Qt's configure
- Set the environment variable CL (specifying Visual Studio compiler options) to /MP (On the command line: set CL=/MP)
- Use the tool jom instead of nmake. (Using jom instead of nmake reduces compile time quite a bit)
Configuring Visual Studio 2013 on Windows 8, 8.1 & 10
Setting the environment variables to properly build Qt can be done by following the steps below:
- Create a file called qt5vars.bat, paste the following inside it and save it
Hint: Remember to change <arch> to your desired platform and double-check that the paths are correct for Qt and Visual Studio
@echo off REM Set up \Microsoft Visual Studio 2015, where <arch> is \c amd64, \c x86, etc. CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" <arch> REM Edit this location to point to the source code of Qt SET _ROOT=C:\qt5 SET PATH=%_ROOT%\qtbase\bin;%_ROOT%\gnuwin32\bin;%PATH% REM Uncomment the below line when using a git checkout of the source repository SET PATH=%_ROOT%\qtrepotools\bin;%PATH% REM Uncomment the below line when building with OpenSSL enabled. If so, make sure the directory points REM to the correct location (binaries for OpenSSL). REM SET PATH=C:\OpenSSL-Win32\bin;%PATH% REM When compiling with ICU, uncomment the lines below and change <icupath> appropriately: REM SET INCLUDE=<icupath>\include;%INCLUDE% REM SET LIB=<icupath>\lib;%LIB% REM SET PATH=<icupath>\lib;%PATH% REM Contrary to earlier recommendations, do NOT set QMAKESPEC. SET _ROOT= REM Keeps the command line open when this script is run. cmd /k
Complete the steps below after you have cloned Qt5 from Git
- After having cloned Qt5 from Git (assuming it's at C:\Qt5), move qt5vars.bat to the Qt5 folder
- Double-click on the script to run it. Once it runs the script, the command prompt will stay open to enter additional commands.
- Navigate to C:\Qt5 in the command prompt
The working directory should be c:\Qt5.
All the required environment variables are now correctly set up and building Qt5 with nmake should work now. You have to run qt5vars.bat and use the command prompt every time you build Qt5 with nmake.
The above steps also work for setting up nmake to build jom.
Configuring MinGW on Windows 8, 8.1 & 10
The configuration process is similar to above except for a few minor changes in the qt5vars.bat script:
@echo off REM Edit this location to point to the source code of Qt SET _ROOT=C:\qt5 SET PATH=%_ROOT%\qtbase\bin;%_ROOT%\gnuwin32\bin;%PATH% REM Uncomment the below line when using a git checkout of the source repository SET PATH=%_ROOT%\qtrepotools\bin;%PATH% REM Uncomment the below line when building with OpenSSL enabled. If so, make sure the directory points REM to the correct location (binaries for OpenSSL). REM SET PATH=C:\OpenSSL-Win32\bin;%PATH% REM When compiling with ICU, uncomment the lines below and change <icupath> appropriately: REM Note that -I <icupath>\include and -L <icupath>\lib need to be passed to REM configure separately (that works for MSVC as well). REM SET PATH=<icupath>\lib;%PATH% REM Contrary to earlier recommendations, do NOT set QMAKESPEC. SET _ROOT= REM Keeps the command line open when this script is run. cmd /k
ICU on Windows
Qt 5 can make use of the ICU library for UNICODE and Localization support. This is required for building Qt WebKit. You can use pre-compiled versions of ICU with a Visual Studio 2010 dependency from the website, get pre-compiled versions for different compilers from download.qt.io, or compile ICU on your own.
The absolute paths of include and lib folders of the ICU installation must be passed with -I and -L option to Qt's configure. In addition, uic.exe needs to find the ICU DLLs during compilation, for which the lib folder of the ICU installation must be added to the PATH environment variable.
At run-time, the ICU DLLs need to be found. This can be achieved by copying the DLLs to the application folder or adding the lib folder of the ICU installation to the PATH environment variable.
Getting the source code
First, cd into the directory where you want the "qt5" directory to live. Then, clone the top-level Qt 5 git repository:
$ git clone git://code.qt.io/qt/qt5.git
or (if you're behind a firewall and want to use the https protocol):
$ git clone https://code.qt.io/qt/qt5.git
This creates a local branch that tracks "origin/dev". If you plan to submit changes to Qt, stay on this branch. Otherwise, check out the target branch (see Branch Guidelines):
$ cd qt5 $ git checkout 5.12
Getting the Qt 5.15 LTS Commercial source code
The Qt 5.15 LTS Commercial source codes are available in the tqtc shadow repositories and their lts branches. The lts branches have a common prefix, "tqtc/lts-". For example, "tqtc/lts-5.15".
You can get sources for all Qt submodules or just one specific Qt submodule. The clone commands are visible in the Gerrit as follows:
- sign in to Gerrit with your Qt account (that has a valid commercial license): https://codereview.qt-project.org
- In Browse > Repositories, type "tqtc-qt5" to Filter field to open the top-level Qt 5 shadow repository. If you like to open some submodule shadow repository, type "tqtc-qt<submodule>". For example, "tqtc-qtbase".
- Under the Download topic, you can see the clone commands for different protocols (anonymous HTTP, HTTP, SSH).
- remember to check that you have either uploaded your SSH key or set the HTTP password. See steps 5 and 6 in .
Cloning all the Qt submodules
First clone the top-level Qt 5 git repository (the anonymous HTTP clone command is used in the following example):
$ git clone "https://codereview.qt-project.org/qt/tqtc-qt5"
Then check out the target branch. Currently only the tqtc/lts-5.15 branch is available:
$ cd tqtc-qt5 $ git checkout tqtc/lts-5.15
Get the submodule source code (options are described in the next section):
$ perl init-repository
Cloning specific Qt submodule
Ypu can clone some specific Qt submodule, for example Qt Base (the anonymous HTTP clone command is used in the following example). The lts branch is the default branch that is cloned:
$ git clone "https://codereview.qt-project.org/qt/tqtc-qtbase"
Getting the submodule source code
As described in the README.git, initialize the repository using the init-repository script, which clones the various sub-modules of Qt 5.
Relevant options for init-repository:
- --module-subset=default,-qtwebengine : Consider skipping the web module (Qt WebEngine) by passing this option. It is quite big and takes a long time to compile (and is often a source of compile errors), so it is recommended to only download it if you intend to use it. You can always re-run init-repository later on to add it.
- --branch : Check out the branch tips instead of the SHA1s of the latest successful integration build.
- --codereview-username <Jira/Gerrit username> : If you plan to contribute to Qt, you may specify your codereview username (pay attention to capitalization!) so that the git remotes are properly set up. Note that it is recommended to adjust your ssh configuration instead.
$ cd qt5 $ perl init-repository
In order to build a specific release of Qt, you can checkout the desired tag:
$ cd qt5 $ git checkout 5.12.0 $ perl init-repository
Note: init-repository is currently unable to initialize tags that are too old. An alternative way to build a specific release or branch of Qt5 (although without linking of the gerrit account for code reviewing) is to use git submodule update --init in place of the init-repository script. That translates to:
$ git clone https://code.qt.io/qt/qt5.git # cloning the repo $ cd qt5 $ git checkout v5.8.0 # checking out the specific release or branch $ git submodule update --init --recursive # updating each submodule to match the supermodule
More information can be found in Get The Source.
Configuring and Building
The Qt5 build system should be fairly resilient against any "outside distractions" - it shouldn't matter whether you have other Qt versions in PATH, and QTDIR is entirely ignored. However, make sure that you have no qmake-specific environment variables like QMAKEPATH or QMAKEFEATURES set, and the qmake -query output does not refer to any other Qt versions ($HOME/.config/Qt/QMake.conf should be empty).
For more configure options, see Qt Configure Options.
Note: To build qdoc and Qt documentation in future you should set LLVM_INSTALL_DIR environment variable pointing to directory where LLVM is installed (it should be top level directory, the configuration scripts use relative path tracing from this directory). For example, in Linux with LLVM installed in isolated directory (/usr/llvm), at a bash prompt:
$ export LLVM_INSTALL_DIR=/usr/llvm
A build script called configure (or configure.bat for Windows) will be in the directory that you git cloned the source code into (~/qt5 if you followed the directions above). You will want to call that script from a different, parallel-level directory, because (unless you are using a Qt Autotest Environment) you do not want to build Qt in the directory that holds the source code. Instead, you should use a "shadow build," meaning you should not build into the source directory.
For Linux / macOS, to install in ~/qt5-build (an arbitrary name), assuming you are in ~:
$ mkdir qt5-build $ cd qt5-build $ ../qt5/configure -developer-build -opensource -nomake examples -nomake tests
For Windows, again assuming you are in ~:
$ mkdir qt5-build $ cd qt5-build $ ..\\qt5\configure -developer-build -opensource -nomake examples -nomake tests
The -developer-build option causes more symbols to be exported in order to allow more classes and functions to be unit tested than in a regular Qt build. It also defaults to a 'debug' build, and installs the binaries in the current directory, avoiding the need for 'make install'. '-opensource' sets the license to be GPL/LGPL. The -nomake examples and -nomake tests parameters make sure examples and tests aren't compiled by default. You can always decide to compile them later by hand.
- You can add -confirm-license to get rid of the question whether you agree to the license.
- On Windows, you might not be able to build if sh.exe is in your PATH (for example due to a git or msys installation). Such an error is indicated by qt5-src\qtbase\bin\qmake.exe: command not found and alike. In this case, make sure that sh.exe is not in your path. You will have to re-configure if your installation is already configured.
- If you are planning to make contributions with git, it is advised to configure and build the source in a separate directory so the binaries are not seen by git. This can be done by navigating to the desired build directory and calling configure/make in that directory. (But shadow builds are discouraged in Qt Autotest Environment.)
- Note: If you do a shadow build, follow the instructions above for creating a build directory that is parallel to the source directory. Do NOT make the build directory a subdirectory of the source tree. The build will probably fail in weird ways if the build directory is not exactly parallel to the source directory.
Now trigger the build from within the build directory by running:
$ make -j$(nproc)
For Windows (MSVC), choose one of the following, depending on your setup/environment:
Or only build a specific module, e.g. declarative, and modules it depends on:
$ make module-qtdeclarative
Building Qt WebKit
The tools bison, flex and gperf which are required for building are provided for convenience in the folder gnuwin32\bin. If you are using shadow builds, you must add this directory to your PATH, else no special actions need to be done manually in order to use them.
Installing (Linux / OS X)
- Note: Installation is only needed if you haven't used the configure options -developer-build or -prefix "%PWD%/qtbase". Otherwise, you can just use Qt from the build directory.
To install, run
$ make install
To get a really clean tree use:
$ git submodule foreach --recursive "git clean -dfx" && git clean -dfx
since make confclean no longer works from the top-level of the repo.
To update both the qt5.git repo as well as the submodules to the list of revisions that are known to work, run
$ git pull $ perl init-repository -f
In addition, you should pass the same parameters to init-repository as you did in Getting the source code.
Unlike a "normal" git submodule update, this ensures that any changes to the module structure are automatically pulled as well.
If you are planning to do nightly builds, consider using the script qt5_tool that lives in qtrepotools/bin. It provides options for updating the repository, cleaning and building. For example, qt5_tool -u -c -b can be used to clean, update and build. qt5_tool -p -c -b would be used to pull all modules to the head of their master branches.
Depending upon what changed in the source since it was last updated you might have to run configure again. The safe thing to do is to always run config.status -recheck-all in the build directory after updating.
- Hint1: The submodule update does a checkout in submodules, potentially hiding any local commits you've done. If the latter happened to you (and you haven't been working with branches anyhow), git reflog is your friend.
- Hint2: When creating scripts for updates on Windows, note that git clean often fails if some process locks a file or folder.
Using latest branches in the submodules
By default, the checkout will not contain the latest stable/dev branches of each individual submodule repository, but a combination of versions that are known to work together. If you want to get the absolute latest stuff you can do so on a per-module basis, e.g.
$ cd qtdeclarative $ git fetch $ git checkout -b 5.9 origin/5.9
or tell init-repository to check out branches in all repositories:
$ perl init-repository -f --branch
Some Unix shell tricks for developing Qt can be useful when you are making or reviewing changes in multiple modules.
configure fails with "No QPA platform plugin enabled!" (Linux)
You should install the libxcb and it's accompanying packages, see 'System Requirements'.
configure fails with errors like "cannot stat file ..."
Your perl version is too old, Qt 5 beta1 needs at least 5.14.
configure fails to enable qdoc on Debian
Debian allows parallel installs of libclang-<version>-dev in /usr/lib/llvm-<version> so LLVM_INSTALL_DIR should be /usr/lib/llvm-<version> to build qdoc. Not /usr/llvm.
qmlscene segfaults "Cannot create platform GL context, none of GLX, EGL, DRI2 is enabled" (Linux)
Try installing the libx11-xcb-dev package:
$ sudo apt-get install libx11-xcb-dev
afterwards you have to re-run configure and force qtbase/src/plugins/platforms/xcb to recompile.
WebKit doesn't compile, missing ICU
Currently there is no configure time check for ICU, so install it through the package manager through
$ sudo apt-get install libicu-dev
$ su - -c "yum install libicu-devel"
- You can also compile Qt without Qt WebKit by deleting / renaming the qtwebkit, qtwebkit-examples-and-demos directories.
- The --no-webkit option of configure added, see QTBUG-20577 issue.
Qt D-Bus fails to build due to "inconsistent user-defined literal suffixes"
This occurs when you attempt to build Qt 5 with GCC 4.7 while D-Bus < 1.4.20 is present on your system. (For example, the default Fedora 17 installation is prone to this error.) The error message is this:
qdbusinternalfilters.cpp:124:36: error: inconsistent user-defined literal suffixes ‘DBUS_INTROSPECT_1_0_XML_PUBLIC_IDENTIFIER’ and ‘DBUS_INTROSPECT_1_0_XML_SYSTEM_IDENTIFIER’ in string literal
Note: The error is in the header files of D-Bus itself, and it has been fixed upstream, see https://bugs.freedesktop.org/show_bug.cgi?id=46147.
Solution: either upgrade to a newer version of D-Bus or edit that one line of the header file manually.
...::isNull is not defined (from qvariant_p.h)
C++11 support is detected while your GCC doesn't properly support it. Fixed by passing -no-c11 to the configure options.
Currently unresolved bug with the build of assembly files, see discussion at http://comments.gmane.org/gmane.comp.lib.qt.devel/5933
Fixed by passing -no-pch to the configure options.
Bug with GCC versions < 4.4.x, see bug report at https://bugzilla.redhat.com/show_bug.cgi?id=493929. Fixed by adding QMAKE_CXXFLAGS_RELEASE *= -fno-inline in qtdeclarative/src/qml/qml.pro.
Touchscreen (or Wacom tablet) doesn't work
Qt depends on having libxi (including development headers), supporting XInput protocol 2.2 or higher, available at build time in order to have multi-touch support. Otherwise configure will fall back to XInput 2.0 which does not support touchscreens. To prove that is the problem, try this:
$ export QT_XCB_DEBUG_XINPUT_DEVICES=1
and try your Qt application again. At startup, Qt will enumerate the input devices available, like this
XInput version 2.2 is available and Qt supports 2.2 or greater input device … (keyboard, mouse etc.) … input device Advanced Silicon S.A CoolTouch™ System has valuator "Abs MT Position X" recognized? true has valuator "Abs MT Position Y" recognized? true has touch class with mode 1 it's a touchscreen with type 0 capabilities 0x21 max touch points 10
If it does not say Qt supports 2.2 or greater, it means the headers weren't available when Qt was built, so the support for touch was not included. If you do have 2.2 or greater but it doesn't say it's a touchscreen at the end, there may be some other problem such that the touchscreen is not recognized, and you may want to write up a bug, after verifying that touch works in other X11 applications.
Note that if you're shadow-building Qt, the source directory and build directory must be on the same drive, nested equally deeply. Also, make sure there are no old build artifacts in the source directory.
Debugging OpenGL issues (Windows)
Set the environment variable QT_QPA_VERBOSE=gl:1 and run the application with DebugView installed. The log will show the requested vs obtained OpenGL version. If the log tells you that it only has OpenGL 1.1, Qt Quick 2 will not work. Note that qmlscene will not report errors about unsupported OpenGL versions.
Questions and comments
Please raise questions & comments about this article in this forum thread.