Module slint::docs::cargo_features

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§Feature flags and backend selection.

Use the following feature flags in your Cargo.toml to enable additional features.

  • compat-1-2 (enabled by default) — Mandatory feature: This feature is required to keep the compatibility with Slint 1.2 Newer patch version may put current functionality behind a new feature that would be enabled by default only if this feature was added. More info in this blog post

  • std (enabled by default) — Enable use of the Rust standard library.

  • gettext — Enable the translations using gettext

    the @tr(...) code from .slint files will be transformed into call to dgettext with the crate name as domain name

    translations must be enabled with the init_translations! macro

  • libm — This feature enables floating point arithmetic emulation using the libm crate. Use this in MCU environments where the processor does not support floating point arithmetic.

  • log — If enabled, calls of debug() in .slint files use to the log::debug!() macro of the log crate instead of just println!().

  • serde — Implement the serde::Serialize and serde::Deserialize for some of the base types such as SharedString and SharedVector.

  • software-renderer-systemfonts — This feature enables the software renderer to pick up fonts from the operating system for text rendering.

  • unsafe-single-threaded — Slint uses internally some thread_local state.

    When the std feature is enabled, Slint can use std::thread_local!, but when in a #![no_std] environment, we need a replacement. Using this feature, Slint will just use static variable disregarding Rust’s Send and Sync safety

    Safety : You must ensure that there is only one single thread that call into the Slint API

  • accessibility (enabled by default) — Enable integration with operating system provided accessibility APIs

    Enabling this feature will try to expose the tree of UI elements to OS provided accessibility APIs to support screen readers and other assistive technologies.

  • raw-window-handle-06 — Enable integration with raw-window-handle version 0.6. This provides a Window::window_handle() function that returns a struct that implements HasWindowHandle and HasDisplayHandle implementation.

§Backends

Slint needs a backend that will act as liaison between Slint and the OS. By default, Slint will use the Qt backend, if Qt is installed, otherwise, it will use Winit with FemtoVG. Both backends are compiled in. If you want to not compile one of these you need to disable the default feature and re-enable one backend. It is also possible to use Slint without backend if you provide the platform abstraction yourself with platform::set_platform().

If you enable the Winit backend, you need to also include a renderer. renderer-femtovg is the only stable renderer, the other ones are experimental

It is also possible to select the backend and renderer at runtime when several are enabled, using the SLINT_BACKEND environment variable.

  • SLINT_BACKEND=Qt selects the Qt backend
  • SLINT_BACKEND=winit selects the winit backend
  • SLINT_BACKEND=winit-femtovg selects the winit backend with the FemtoVG renderer
  • SLINT_BACKEND=winit-skia selects the winit backend with the skia renderer
  • SLINT_BACKEND=winit-software selects the winit backend with the software renderer

If the selected backend is not available, the default will be used.

Here are the cargo features controlling the backend:

  • backend-qt — The Qt backend feature uses Qt for the windowing system integration and rendering. This backend also provides the native style. It requires Qt 5.15 or later to be installed. If Qt is not installed, the backend will not be operational
  • backend-winit — The winit crate is used for the event loop and windowing system integration. It supports Windows, macOS, web browsers, X11 and Wayland. X11 and wayland are only available when compiling for Linux or other Unix-like operating systems. With this feature, both X11 and Wayland are supported. For a smaller build, omit this feature and select one of the other specific backend-winit-XX features.
  • backend-winit-x11 — Simliar to backend-winit this enables the winit based event loop but only with support for the X Window System on Unix.
  • backend-winit-wayland — Simliar to backend-winit this enables the winit based event loop but only with support for the Wayland window system on Unix.
  • backend-default (enabled by default) — Alias to a backend and renderer that depends on the platform. Will select the Qt backend on linux if present, and the winit otherwise
  • renderer-femtovg (enabled by default) — Render using the FemtoVG crate.
  • renderer-skia — Render using Skia.
  • renderer-skia-opengl — Same as renderer-skia, but Skia will always use OpenGL.
  • renderer-skia-vulkan — Same as renderer-skia, but Skia will always use Vulkan.
  • renderer-software (enabled by default) — Render using the software renderer.
  • backend-linuxkms — KMS with Vulkan or EGL and libinput on Linux are used to render the application in full screen mode, without any windowing system. Requires libseat. If you don’t have libseat, select backend-linuxkms-noseat instead. (Experimental)
  • backend-linuxkms-noseat — KMS with Vulkan or EGL and libinput on Linux are used to render the application in full screen mode, without any windowing system. (Experimental)
  • backend-android-activity-05 — Use the backend based on the android-activity crate. (Using it’s native activity feature)

More information about the backend and renderers is available in the Slint Documentation