Set Up Development Environment#

Prerequisites#

  • A C++ compiler that supports C++20 (e.g., MSVC 2019 16.6 on Windows)

  • cmake (3.21 or newer)

    • Slint comes with a CMake integration that automates the compilation step of the .slint markup language files and offers a CMake target for convenient linkage.

    • Note: We recommend using the Ninja generator of CMake for the most efficient build and .slint dependency tracking. Install Ninja and select the CMake Ninja backend by passing -GNinja or set the CMAKE_GENERATOR environment variable to Ninja.

Install Slint#

To install Slint, either download the binary packages or build from sources.

Note: Binary packages are available for only Linux and Windows on x86-64 architecture. The recommended and most flexible way to use the C++ API is to build Slint from sources.

Install Binary Packages#

The Slint binary packages work without any Rust development environment.

Steps:

  1. Open https://github.com/slint-ui/slint/releases

  2. Click on the latest release

  3. From “Assets” (“XXX” refers to the version of the latest release),

    • for Linux x86-64 architecture - download slint-cpp-XXX-Linux-x86_64.tar.gz

    • for Windows x86-64 architecture - download slint-cpp-XXX-win64.exe

  4. Unpack the downloaded archive (Linux) or run the installer executable (Windows).

  5. Set environment variables

    • set CMAKE_PREFIX_PATH to the installation directory of Slint. Alternatively you can pass -DCMAKE_PREFIX_PATH=/path/to/installed/slint argument when invoking cmake. This helps find_package(Slint) to find Slint from within a CMakeLists.txt file.

    • add the lib sub-directory in the installation directory of Slint to LD_LIBRARY_PATH (Linux) or to the PATH environment variable (Windows). This is necessary to find the Slint libraries when running a Slint program.

In the next section you will learn how to use the installed library in your application and how to work with .slint UI files.

Build From Sources#

First you need to install the prerequisites:

  • Install Rust by following the Rust Getting Started Guide. If you already have Rust installed, make sure that it’s at least version 1.60 or newer. You can check which version you have installed by running rustc --version. Once this is done, you should have the rustc compiler and the cargo build system installed in your path.

You can either choose to compile Slint from source along with your application or include Slint as an external CMake package.

  • To compile Slint along with your application, include Slint into your CMake project using CMake’s FetchContent feature. Insert the following snippet into your CMakeLists.txt to make CMake download the latest released 1.x version, compile it, and make the CMake integration available:

include(FetchContent)
FetchContent_Declare(
    Slint
    GIT_REPOSITORY https://github.com/slint-ui/slint.git
    # `release/1` will auto-upgrade to the latest Slint >= 1.0.0 and < 2.0.0
    # `release/1.0` will auto-upgrade to the latest Slint >= 1.0.0 and < 1.1.0
    GIT_TAG release/1
    SOURCE_SUBDIR api/cpp
)
FetchContent_MakeAvailable(Slint)

  • To include Slint as an external CMake package, build Slint from source like a regular CMake project, install it into a prefix directory of your choice and use find_package(Slint) in your CMakeLists.txt.

Resource Embedding#

By default, images or fonts that your Slint files reference are loaded from disk at run-time. This minimises build times, but requires that the directory structure with the files remains stable. If you want to build a program that runs anywhere, then you can configure the Slint compiler to embed such sources into the binary.

Set the SLINT_EMBED_RESOURCES target property on your CMake target to one of the following values:

  • embed-files: The raw files are embedded in the application binary.

  • embed-for-software-renderer: The files will be loaded by the Slint compiler, optimized for use with the software renderer and embedded in the application binary.

  • as-absolute-path: The paths of files are made absolute and will be used at run-time to load the resources from the file system. This is the default.

This target property is initialised from the global DEFAULT_SLINT_EMBED_RESOURCES cache variable. Set it to configure the default for all CMake targets.

Features#

The Slint library supports a set of features, not all of them enabled by default. You might want to adapt the set of enabled features to optimize your binary size. For example you might want to support only the wayland stack on Linux. Enable the backend-winit-wayland feature while turning off the backend-winit-x11 feature to do so.

Slint’s CMake configuration uses CMake options prefixed with SLINT_FEATURE_ to expose Slint’s feature flags at compile time. To have a wayland-only stack with the CMake setup you would for example use:

cmake -DSLINT_FEATURE_BACKEND_WINIT=OFF -DSLINT_FEATURE_BACKEND_WINIT_WAYLAND=ON ...

Alternatively, you can use cmake-gui or ccmake for a more interactive way to discover and toggle features.

This works when compiling Slint as a package, using cmake --build and cmake --install, or when including Slint using FetchContent.

Rust Flags#

Slint uses Corrosion to build Slint, which is developed in Rust. You can utilize Corrosion’s global CMake variables to control certain aspects of the Rust build process.

Furthermore, you can set the SLINT_LIBRARY_CARGO_FLAGS cache variable to specify additional flags for the Slint runtime during the build.

Platform Backends#

In Slint, a backend is the module that encapsulates the interaction with the operating system, in particular the windowing sub-system. Multiple backends can be compiled into Slint and one backend is selected for use at run-time on application start-up. You can configure Slint without any built-in backends, and instead develop your own backend by implementing Slint’s platform abstraction and window adapter interfaces.

For more information about the available backends, their system requirements, and configuration options, see the Backend & Renderers Documentation.

Compile Time Backend Selection#

By default Slint will include both the Qt and winit back-ends – if both are detected at compile time. You can enable or disable back-ends using the SLINT_FEATURE_BACKEND_ features. For example, to exclude the winit back-end, you would disable the SLINT_FEATURE_BACKEND_WINIT option in your CMake project configuration.

The winit back-end needs a renderer. SLINT_FEATURE_RENDERER_FEMTOVG and SLINT_FEATURE_RENDERER_SKIA are the only stable renderers, the other ones are experimental.

Run Time Backend Selection#

It’s also possible to select any of the compiled in backends and renderer at runtime, using the SLINT_BACKEND environment variable.

  • SLINT_BACKEND=Qt selects the Qt back-end

  • SLINT_BACKEND=winit selects the winit back-end

  • SLINT_BACKEND=winit-femtovg selects the winit back-end with the femtovg renderer

  • SLINT_BACKEND=winit-skia selects the winit back-end with the skia renderer

  • SLINT_BACKEND=winit-software selects the winit back-end with the software renderer

If the selected back-end or renderer isn’t available, the default will be used instead.

Cross-compiling#

It’s possible to cross-compile Slint to a different target architecture when building with CMake. You need to make sure your CMake setup is ready for cross-compilation, as documented in the upstream CMake documentation.

If you are building against a Yocto SDK, it is sufficient to source the SDK’s environment setup file.

Since Slint is implemented using the Rust programming language, you need to determine which Rust target matches the target architecture that you’re compiling for. Please consult the upstream Rust documentation to find the correct target name. Now you need to install the Rust toolchain:

rustup target add <target-name>

Then you’re ready to iconfigure your CMake project you need to add -DRust_CARGO_TARGET=<target name> to the CMake command line. This ensures that the Slint library is built for the correct architecture.

For example if you are building against an embedded Linux Yocto SDK targeting an ARM64 board, the following commands show how to compile:

Install the Rust targe toolchain once:

rustup target add aarch64-unknown-linux-gnu

Set up the environment and build:

. /path/to/yocto/sdk/environment-setup-cortexa53-crypto-poky-linux
cd <PROJECT_ROOT>
mkdir build
cd build
cmake -DRust_CARGO_TARGET=aarch64-unknown-linux-gnu -DCMAKE_INSTALL_PREFIX=/slint/install/path ...
cmake --build .
cmake --install .