Qt for UWP

Qt for UWP allows you to run Qt applications on devices supporting the Universal Windows Platform (UWP). Microsoft Windows 10 introduced UWP, which provides a common application platform on every device that runs Windows 10, as a successor to Windows Runtime (WinRT) introduced by Windows 8. The UWP core APIs are the same on all Windows devices, and therefore applications that only use the core APIs will run on any Windows 10 device, such as a desktop PC, or Xbox One.

The Qt port was originally written for WinRT and updated to support UWP. The port uses the C++ capabilities. While UWP supports the component extensions internally, they are not used inside Qt and you do not need to use them. UWP applications run in a sandboxed environment for security reasons and support different architectures, such as ARM and x86.

Supported Configurations

The following configurations are supported.

Universal Windows Platforms include Windows 10, Windows 10 IoT devices, Xbox One, and HoloLens.

Requirements

Development for UWP requires a Microsoft Windows development host. The minimum version supported is Windows 10.

Qt supports UWP apps running on any variant of Windows 10 or later on the desktop PC, IoT, Xbox One, and so on.

If you are targeting a remote device, follow the instructions by Visual Studio to set it up correctly.

Getting Started

Notes to Desktop Users

As UWP applications run in a sandboxed environment, some restrictions should be taken into account when considering porting or writing cross-platform applications:

• The class QProcess is not implemented (indicated by the macro QT_NO_PROCESS being defined) as no subprocesses can be launched.
• Some paths returned by QStandardPaths::writableLocation() may be empty.
• A UWP application may not do socket-based communication with another application running on the same host (as this would violate the sandboxing).
• Applications run in fullscreen mode only (see QStyleHints). On desktop, the screen size varies as the application is resized.
• There are no environment variables. Qt emulates the functionality by maintaining the values locally, so that qputenv() and related functions continue to work. All known variables influencing Qt can be set in source code.
• UWP applications are UI applications by nature. This implies that console type applications will have a window created internally, which is always visible.
• Applications should not exit programmatically. In particular, calling exit() before the UI is shown causes a crash.
• The UWP clipboard is local to the application; it cannot be retrieved by a desktop application.

Building Applications

You can develop applications for UWP just as any other Qt applications. Use your favorite editor or IDE (such as Qt Creator) and create your application or load a Qt example. Then run qmake and nmake/jom to build your application.

Building Applications with Visual Studio

To launch your project with Visual Studio a corresponding project needs to be created. qmake supports converting a .pro project into Visual Studio format by passing the parameters -tp vc.

 qmake -tp vc <your project>.pro

Be aware of using the correct match of qmake and Visual Studio. As the Visual Studio format is generic, it does not return an immediate error if for instance you open a Windows Phone project inside Visual Studio for Windows.

This creates a project which supports building applications and running them with Visual Studio. It does not embed Qt libraries into the package and requires you to add them manually. For this purpose, the command line tool windeployqt has been included in the installed package. To enable automatic parsing of dependencies and adding the libraries and dependencies into the application package, create the project with the following options:

 qmake -tp vc <your project>.pro "CONFIG+=windeployqt"

Building Applications with Qt Creator

You will not need to do any conversion to open your project in Qt Creator. Please follow the generic instructions on how to open and build a project.

Qt Creator deploys your application on the UWP device, if the device is detected by the PC.

Building from Source

We assume that you have cloned the Qt 5 repositories (or obtained the Qt sources elsewhere) and followed the platform-independent requirements for building Qt. The process of building Qt is found in the Building Qt Sources page.

Qt for UWP is always built as a cross-build, because tools, such as qmake, are built as desktop applications. For compiling those, a desktop development environment is required. If you have installed Visual Studio for Windows, this will only create binaries for UWP. You will need Visual Studio for Windows Desktop as well to create those desktop tools.

Please make sure to use an x86 command prompt (either use the VS x86 Native Tools Command Prompt or call vcvarsall.bat without any parameter or with x86) for every UWP build. While the toolchain which is used for the target is set automatically, the command prompt decides what will be used for the host tools like qmake or moc. Building these tools might fail if another command prompt is used.

The UWP mkspec format is <platform>-<architecture>-<toolchain> where architecture can be arm, x86, or x64. The following is an example of building qtbase for UWP:

 > ./configure -xplatform winrt-x64-msvc2017 -release
 > nmake/jom

Running Applications from Command Line

UWP applications must be packaged (including all dependencies) and installed or registered with the application service in order to be launched. The WinRT Runner Tool can be used to launch these applications from the command line.

Package Content

Package content consists of the application executable and its dependencies, as for every Windows application. The dependencies are the needed (Qt) libraries and plugins. Note that Qt plugins have to be put into a folder named after their category (platforms, imageformats, and so on) without using a plugins folder as root. For more information, see Qt for Windows - Deployment.

As UWP applications are run in a sandboxed environment, setting the path variable to point to the files required will not work.

The windeployqt convenience tool looks up the application's dependencies and copies Qt libraries and plugins to the appropriate directories, as necessary.

Because all resources are placed to one directory, you can register the directory using an XML file (AppxManifest.xml) and Windows Powershell. The reference for these manifest files can be found here. The target processor architecture must be specified (as opposed to the default, 'neutral'). As soon as these requirements are met, change into your packaged directory in PowerShell and call:

 > Add-AppxPackage -Register AppxManifest.xml

If that worked, you should be able to find your application in Windows' start screen. To remove your application, use Windows' built-in way to uninstall applications (right-click or tap and hold the application and choose Uninstall).

WinRT Runner Tool

The WinRT Runner Tool can be found in QTDIR/bin/winrtrunner. It is intended to aid in the deployment, launching, and debugging of Qt for WinRT applications. It can be used from the command line, or invoked by the IDE.

 Usage: winrtrunner [options] package [arguments]
 winrtrunner installs, runs, and collects test results for packages made with Qt.

 Options:
   --test                            Install, start, collect output, stop (if
                                     needed), and uninstall the package. This is
                                     the default action of winrtrunner.
   --start                           Start the package. The package is installed
                                     if it is not already installed. Pass
                                     --install to force reinstallation.
   --debug <debugger>                Start the package with the debugger
                                     attached. The package is installed if it is
                                     not already installed. Pass --install to
                                     force reinstallation.
   --debugger-arguments <arguments>  Arguments that are passed to the debugger
                                     when --debug is used. If no debugger was
                                     provided this option is ignored.
   --suspend                         Suspend a running package. When combined
                                     with --stop or --test, the app will be
                                     suspended before being terminated.
   --stop                            Terminate a running package. Can be be
                                     combined with --start and --suspend.
   --wait <seconds>                  If the package is running, waits the given
                                     number of seconds before continuing to the
                                     next task. Passing 0 causes the runner to
                                     wait indefinitely.
   --install                         (Re)installs the package.
   --remove                          Uninstalls the package.
   --device <name|index>             Specifies the device to target as a device
                                     name or index. Use --list-devices to find
                                     available devices. The default device is the
                                     first device found for the active run
                                     profile.
   --profile <name>                  Force a particular run profile.
   --list-devices                    List the available devices (for use with
                                     --device).
   --verbose <level>                 The verbosity level of the message output
                                     (0 - silent, 1 - info, 2 - debug). Defaults
                                     to 1.
   --ignore-errors                   Always exit with code 0, regardless of the
                                     error state.
   --loopbackexempt <mode>           Enables localhost communication for
                                     clients,servers or both. Adding this
                                     possibility for servers needs elevated
                                     rights and might ask for these in a
                                     dialog.Possible values: client, server,
                                     clientserver
   -?, -h, --help                    Displays this help.

 Arguments:
   package [arguments]               The executable or package manifest to act
                                     upon. Arguments after the package name will
                                     be passed to the application when it starts.