slint Documentation

File: README.md Copy Chapter

Slint is an open-source declarative GUI toolkit for building native user interfaces for embedded systems, desktops, and mobile platforms.

Write your UI once in .slint, a simple markup language. Connect it to business logic written in Rust, C++, JavaScript, or Python.

Why Slint? Copy Chapter

The name Slint is derived from our design goals:

• Scalable: Slint should support responsive UI design, allow cross-platform
  usage across operating systems and processor architectures and support
  multiple programming languages.
• Lightweight: Slint should require minimal resources, in terms of memory
  and processing power, and yet deliver a smooth, smartphone-like user
  experience on any device.
• Intuitive: Designers and developers should feel productive while enjoying
  the GUI design and development process. The design creation tools should be
  intuitive to use for the designers. Similarly for the developers, the APIs
  should be consistent and easy to use, no matter which programming language
  they choose.
• Native: GUI built with Slint should match the end users' expectations of a
  native application irrespective of the platform - desktop, mobile, web or
  embedded system. The UI design should be compiled to machine code and provide
  flexibility that only a native application can offer: Access full operating
  system APIs, utilize all CPU and GPU cores, connect to any peripheral.

Beyond the design goals, here’s what makes Slint stand out:

• Independent UI Design: Use a declarative language to separate your UI from business logic. Designers can work in parallel with developers.
• Tooling: Iterate quickly with our Live Preview & editor integrations. Integrate from Figma with the Figma to Slint plugin.
• Stable APIs: Slint follows a stable 1.x API. We evolve carefully without breaking your code.

See what others have built: #MadeWithSlint

Examples Copy Chapter

Embedded Copy Section

Desktop Copy Section

Windows	macOS	Linux

Web using WebAssembly Copy Section

Printer Demo	Slide Puzzle	Energy Monitor	Widget Gallery	Weather demo

More examples and demos in the examples folder

Get Started Copy Chapter

Hello World Copy Section

The UI is defined in a Domain Specific Language that is declarative, easy to use,
intuitive, and provides a powerful way to describe graphical elements, their
placement, their hierarchy, property bindings, and the flow of data through the
different states.

Here's the obligatory "Hello World":

export component HelloWorld inherits Window {
    width: 400px;
    height: 400px;

    Text {
       y: parent.width / 2;
       x: parent.x + 200px;
       text: "Hello, world";
       color: blue;
    }
}

Documentation Copy Section

For more details, check out the Slint Documentation.

The examples folder contains examples and demos, showing how to
use the Slint markup language and how to interact with a Slint user interface
from supported programming languages.

The docs folder contains a lot more information, including
build instructions, and
internal developer docs.

Refer to the README of each language directory in the api folder:

• C++ (Documentation | Getting Started Template)
• Rust (Documentation | Tutorial Video | Getting Started Template)
• JavaScript/NodeJS (Beta) (Documentation | Getting Started Template)
• Python (Beta) (Documentation | Getting Started Template)

Architecture Copy Chapter

An application is composed of the business logic written in Rust, C++, Python, or
JavaScript and the .slint user interface design markup, which is compiled to
native code.

Compiler Copy Section

The .slint files are compiled ahead of time. The expressions in the .slint
are pure functions that the compiler can optimize. For example, the compiler
could choose to "inline" properties and remove those that are constant or
unchanged.

The compiler uses the typical compiler phases of lexing, parsing, optimization,
and finally code generation. It provides different back-ends for code generation
in the target language. The C++ code generator produces a C++ header file, the
Rust generator produces Rust code, and so on. An interpreter for dynamic
languages is also included.

Runtime Copy Section

The runtime library consists of an engine that supports properties declared in
the .slint language. Components with their elements, items, and properties are
laid out in a single memory region, to reduce memory allocations.

Rendering backends and styles are configurable at compile time:

• The femtovg renderer uses OpenGL ES 2.0 for rendering.
• The skia renderer uses Skia for rendering.
• The software renderer uses the CPU with no additional dependencies.

NOTE: When Qt is installed on the system, the qt style becomes available,
using Qt's QStyle to achieve native looking widgets.

Tooling Copy Section

We have a few tools to help with the development of .slint files:

• A LSP Server that adds features like auto-complete and live
  preview of the .slint files to many editors.
• It is bundled in a Visual Studio Code Extension
  available from the market place.
• A slint-viewer tool which displays the .slint files. The
  --auto-reload argument makes it easy to preview your UI while you are
  working on it (when using the LSP preview is not possible).
• SlintPad, an online editor to try out .slint syntax
  without installing anything (sources).
• A Figma to Slint plugin.

Please check our Editors README for tips on how to
configure your favorite editor to work well with Slint.

License Copy Chapter

See LICENSE.md for the licensing terms of the whole repository, including documentation and examples.

You can use Slint under any of the following licenses, at your choice:

1. Build proprietary desktop, mobile, or web applications for free with the Royalty-free License,
2. Build open source embedded, desktop, mobile, or web applications for free with the GNU GPLv3,
3. Build proprietary embedded, desktop, mobile, or web applications with the Commercial license.

See the Slint licensing options on the website and the Licensing FAQ.

Contributions Copy Chapter

We welcome your contributions: in the form of code, bug reports or feedback.
For contribution guidelines see CONTRIBUTING.md.

Frequently Asked Questions Copy Chapter

Please see our separate FAQ.

About us (SixtyFPS GmbH) Copy Chapter

We are passionate about software - API design, cross-platform software
development and user interface components. Our aim is to make developing user
interfaces fun for everyone: from Python, JavaScript, C++, or Rust developers all the
way to UI/UX designers. We believe that software grows organically and keeping
it open source is the best way to sustain that growth. Our team members are
located remotely in Germany, Finland, and US.

Stay up to date Copy Section

• Follow @slint_ui on X/Twitter.
• Follow @[email protected] on Mastodon.
• Follow @slint-ui on LinkedIn.
• Follow @slint.dev on Bluesky
• Subscribe to our YouTube channel

Contact us Copy Section

Feel free to join Github discussions
for general chat or questions. Use Github issues
to report public suggestions or bugs.

We chat in our Mattermost instance where you are
welcome to listen in or ask your questions.

You can of course also contact us privately via email to [email protected].

File: api/rs/slint/README.md Copy Chapter

Slint

A Rust UI toolkit

Slint is a Rust based UI toolkit to build native user interfaces on desktop platforms and for embedded devices.
This crate provides the Rust APIs to interact with the user interface implemented in Slint.

The complete Rust documentation for Slint can be viewed online at https://slint.rs/docs/rust/slint/.

Getting Started Copy Chapter

The crate documentation shows how to use this crate.

Hello World Copy Section

The most basic "Hello world" application can be achieved with a few lines of code:

In your Cargo.toml add:

[dependencies]
slint = "1.16.0"

And in your main.rs:

slint::slint!{
    export component HelloWorld {
        Text {
            text: "hello world";
            color: green;
        }
    }
}
fn main() {
    HelloWorld::new().unwrap().run().unwrap();
}

The slint crate documentation
contains more advanced examples and alternative ways to use this crate.

To quickly get started, use the Template Repository with
the code of a minimal application using Slint as a starting point for your program.

1. Download and extract the ZIP archive of the Rust Template.
2. Rename the extracted directory and change into it:

mv slint-rust-template-main my-project
cd my-project

More examples Copy Chapter

You can quickly try out the examples by cloning this repo and running them with cargo run

# Runs the "printerdemo" example
cargo run --release --bin printerdemo

File: api/rs/macros/README.md Copy Chapter

NOTE: This library is an internal crate for the Slint project.
This crate should not be used directly by applications using Slint.
You should use the slint crate instead.

WARNING: This crate does not follow the semver convention for versioning and can
only be used with version = "=x.y.z" in Cargo.toml.

File: api/node/README.md Copy Chapter

Slint-node (Beta)

Slint is a UI toolkit that supports different programming languages.
Slint-node is the integration with Node.js.

To get started you use the walk-through tutorial.
We also have a Getting Started Template repository with
the code of a minimal application using Slint that can be used as a starting point to your program.

Warning: Beta
Slint-node is still in the early stages of development: APIs will change and important features are still being developed.

Slint Language Manual Copy Chapter

The Slint Language Documentation covers the Slint UI description language
in detail.

API documentation (local build) Copy Chapter

Published API docs for this binding live under slint.dev …/docs/node/. See docs/building.md and docs/nodejs/README.md.

Installing Slint Copy Chapter

Slint is available via NPM, so you can install by running the following command:

npm install slint-ui

This requires Node.js (v20 or newer). Pre-built binaries are
included for Linux (x86-64 and ARM64, glibc), macOS (ARM64), and Windows (x86-64 and ARM64).

Building from Source Copy Section

On platforms without pre-built binaries, build Slint-node from a checkout of this repository by running
pnpm install && pnpm build in api/node. You need to install the following components:

• pnpm
• Rust compiler

You will also need a few more dependencies, see https://github.com/slint-ui/slint/blob/master/docs/building.md#prerequisites

Using Slint Copy Chapter

First, import the API from the slint-ui module. In the following examples we're using ECMAScript module syntax, but if you prefer you can also import the API using CommonJS syntax.

To initialize the API, you first need to import the slint-ui module in our code:

import * as slint from "slint-ui";

Next, load a slint file with the loadFile function:

let ui = slint.loadFile("ui/main.slint");

Combining these two steps leads us to the obligatory "Hello World" example:

import * as slint from "slint-ui";
let ui = slint.loadFile(new URL(".ui/main.slint", import.meta.url));
let main = new ui.Main();
main.run();

For a full example, see /examples/todo/node.

API Overview Copy Chapter

Instantiating a Component Copy Section

The following example shows how to instantiate a Slint component from JavaScript.

ui/main.slint

export component MainWindow inherits Window {
    callback clicked <=> i-touch-area.clicked;

    in property  counter;

    width: 400px;
    height: 200px;

    i-touch-area := TouchArea {}
}

Each exported Window component is exposed as a type constructor. The type constructor takes as parameter
an object which allow to initialize the value of public properties or callbacks. A name declared with a
dash in .slint can be given either as declared ("my-property") or with underscores (my_property),
which is how it is exposed on the instance.

main.js

import * as slint from "slint-ui";
// In this example, the main.slint file exports a module which
// has a counter property and a clicked callback
let ui = slint.loadFile(new URL("ui/main.slint", import.meta.url));
let component = new ui.MainWindow({
    counter: 42,
    clicked: function() { console.log("hello"); }
});

Accessing a property Copy Section

Properties declared as out or in-out in .slint files are visible as JavaScript on the component instance.

component.counter = 42;
console.log(component.counter);

Callbacks Copy Section

Callbacks in Slint can be defined using the callback keyword and can be connected to a callback of an other component
using the <=> syntax.

ui/my-component.slint

export component MyComponent inherits Window {
    callback clicked <=> i-touch-area.clicked;

    width: 400px;
    height: 200px;

    i-touch-area := TouchArea {}
}

The callbacks in Slint are exposed as properties in JavaScript and that can be called as a function.

main.js

import * as slint from "slint-ui";

let ui = slint.loadFile(new URL("ui/my-component.slint", import.meta.url));
let component = new ui.MyComponent();

// connect to a callback
component.clicked = function() { console.log("hello"); };
// emit a callback
component.clicked();

Functions Copy Section

Functions in Slint can be defined using the function keyword.

ui/my-component.slint

export component MyComponent inherits Window {
    width: 400px;
    height: 200px;

    public function my-function() -> int {
        return 42;
    }
}

If the function is marked public, it can also be called from JavaScript.

main.js

import * as slint from "slint-ui";

let ui = slint.loadFile(new URL("ui/my-component.slint", import.meta.url));
let component = new ui.MyComponent();

// call a public function
let result = component.my_function();

Type Mappings Copy Section

The types used for properties in .slint design markup each translate to specific types in JavaScript. The follow table summarizes the entire mapping:

Arrays and Models Copy Section

For property of array type, they can either be set using an array.
In that case, getting the property also return an array.
If the array was set within the .slint file, the array can be obtained

component.model = [1, 2, 3];
// component.model.push(4); // does not work, because it operate on a copy
// but re-assigning works
component.model = component.model.concat(4);

Another option is to set a model object. A model object has the following function:

• rowCount(): returns the number of element in the model.
• rowData(index): return the row at the given index
• setRowData(index, data): called when the model need to be changed. this.notify.rowDataChanged must be called if successful.

As an example, here is the implementation of the ArrayModel (which is available as slint.ArrayModel)

import * as slint from "slint-ui";

let array = [1, 2, 3];

export class ArrayModel<T> extends slint.Model<T> {
    private a: Array<T>

   constructor(arr: Array<T>) {
        super();
        this.a = arr;
    }

    rowCount() {
        return this.a.length;
    }

    rowData(row: number) {
       return this.a[row];
    }

    setRowData(row: number, data: T) {
        this.a[row] = data;
        this.notify.rowDataChanged(row);
    }

    push(...values: T[]) {
        let size = this.a.length;
        Array.prototype.push.apply(this.a, values);
        this.notify.rowAdded(size, arguments.length);
    }

    remove(index: number, size: number) {
        let r = this.a.splice(index, size);
        this.notify.rowRemoved(index, size);
    }

    get length(): number {
        return this.a.length;
    }

    values(): IterableIterator<T> {
        return this.a.values();
    }

    entries(): IterableIterator<[number, T]> {
        return this.a.entries()
    }
}

let model = new ArrayModel(array);

component.model = model;
model.push(4); // this works
// does NOT work, getting the model does not return the right object
// component.model.push(5);

structs Copy Section

An exported struct can be created either by defining an object literal or by using the new keyword.

my-component.slint

export struct Person {
    name: string,
    age: int
}

export component MyComponent inherits Window {
    in-out property  person;
}

main.js

import * as slint from "slint-ui";

let ui = slint.loadFile(new URL("my-component.slint", import.meta.url));
let component = new ui.MyComponent();

// object literal
component.person = { name: "Peter", age: 22 };

// new keyword (sets property values to default e.g. '' for string)
component.person = new ui.Person();

// new keyword with parameters
component.person = new ui.Person({ name: "Tim", age: 30 });

enums Copy Section

A value of an exported enum can be set as string or by using the value from the exported enum.

my-component.slint

export enum Position {
    top,
    bottom
}

export component MyComponent inherits Window {
    in-out property  position;
}

main.js

import * as slint from "slint-ui";

let ui = slint.loadFile(new URL("my-component.slint", import.meta.url));
let component = new ui.MyComponent();

// set enum value as string
component.position = "top";

// use the value of the enum
component.position = ui.Position.bottom;