slint-ui

Slint-node (Beta)

npm

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

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

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

Prerequisites

To use Slint with Node.js, ensure the following programs are installed:

To use Slint with Deno, ensure the following programs are installed:

Building from Source

Slint-node comes with pre-built binaries for macOS, Linux, and Windows. If you'd like to use Slint-node on a system without pre-built binaries, you need to additional software:

Getting Started (Node.js)

  1. In a new directory, create a new Node.js project by calling npm init.
  2. Install Slint for your project using npm install slint-ui.
  3. Create a new file called main.slint with the following contents:
import { AboutSlint, Button, VerticalBox } from "std-widgets.slint";
export component Demo {
    in-out property <string> greeting <=> label.text;
    VerticalBox {
        alignment: start;
        label := Text {
            text: "Hello World!";
            font-size: 24px;
            horizontal-alignment: center;
        }
        AboutSlint {
            preferred-height: 150px;
        }
        HorizontalLayout { alignment: center; Button { text: "OK!"; } }
    }
}

This file declares the user interface.

  1. Create a new file called index.mjs with the following contents:
import * as slint from "slint-ui";
let ui = slint.loadFile("main.slint");
let demo = new ui.Demo();

await demo.run();

This is your main JavaScript entry point:

  • Import the Slint API as an ECMAScript module module. If you prefer you can also import it as CommonJS module.
  • Invoke loadFile() to compile and load the .slint file.
  • Instantiate the Demo component declared in main.slint.
  • Run it by showing it on the screen and reacting to user input.
  1. Run the example with node index.mjs

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

Getting Started (Deno)

  1. Create a new file called main.slint with the following contents:
import { AboutSlint, Button, VerticalBox } from "std-widgets.slint";
export component Demo {
    in-out property <string> greeting <=> label.text;
    VerticalBox {
        alignment: start;
        label := Text {
            text: "Hello World!";
            font-size: 24px;
            horizontal-alignment: center;
        }
        AboutSlint {
            preferred-height: 150px;
        }
        HorizontalLayout { alignment: center; Button { text: "OK!"; } }
    }
}

This file declares the user interface.

  1. Create a new file called deno.json (a Deno Import Map) with the following contents:
{
  "imports": {
    "slint-ui": "npm:slint-ui"
  }
}
  1. Create a new file called index.ts with the following contents:
import * as slint from "slint-ui";
let ui = slint.loadFile("main.slint");
let demo = new ui.Demo();

await demo.run();

This is your main JavaScript entry point:

  • Import the Slint API as an ECMAScript module module through Deno's NPM compatibility layer.
  • Invoke loadFile() to compile and load the .slint file.
  • Instantiate the Demo component declared in main.slint.
  • Run it by showing it on the screen and reacting to user input.
  1. Run the example with deno run --allow-read --allow-ffi --allow-sys index.ts

API Overview

Instantiating a Component

Use the loadFile function to load a .slint file. Instantiate the exported component with the new operator. Access exported callbacks and properties as JavaScript properties on the instantiated component. In addition, the returned object implements the ComponentHandle interface, to show/hide the instance or access the window.

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

ui/main.slint

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

    in property <int> counter;

    width: 400px;
    height: 200px;

    i-touch-area := TouchArea {}
}

The exported 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.

main.mjs

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("ui/main.slint");
let component = new ui.MainWindow({
    counter: 42,
    clicked: function() { console.log("hello"); }
});

Accessing a Properties

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

main.slint export component MainWindow { in-out property name; in-out property age: 42; }

let ui = slint.loadFile("main.slint");
let instance = new ui.MainWindow();
console.log(instance.age); // Prints 42
instance.name = "Joe";

Setting and Invoking Callbacks

Callbacks declared in .slint files are visible as JavaScript function properties on the component instance. Invoke them as function to invoke the callback, and assign JavaScript functions to set the callback handler.

ui/my-component.slint

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

    width: 400px;
    height: 200px;

    i-touch-area := TouchArea {}
}

main.mjs

import * as slint from "slint-ui";

let ui = slint.loadFile("ui/my-component.slint");
let component = new ui.MyComponent();

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

Type Mappings

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

.slint Type JavaScript Type Notes
int Number
bool Boolean
float Number
string String
color RgbaColor
brush Brush
image ImageData
length Number
physical_length Number
duration Number The number of milliseconds
angle Number The angle in degrees
relative-font-size Number Relative font size factor that is multiplied with the Window.default-font-size and can be converted to a length.
structure Object Structures are mapped to JavaScript objects where each structure field is a property.
array Model

Arrays and Models

Array properties can be set from JavaScript by passing either Array objects or implementations of the Model interface.

When passing a JavaScript Array object, the contents of the array are copied. Any changes to the JavaScript afterwards will not be visible on the Slint side.

Reading a Slint array property from JavaScript will always return a @{link Model}.

component.model = [1, 2, 3];
// component.model.push(4); // does not work, because assignment creates a copy.
// Use re-assignment instead.
component.model = component.model.concat(4);

Another option is to set an object that implements the Model interface.

Globals

You can declare globally available singletons in your .slint files. If exported, these singletons are accessible as properties on your main componen instance. Each global singleton is represented by an object with properties and callbacks, similar to API that's created for your .slint component.

For example the following .slint markup defines a global Logic singleton that's also exported:

export global Logic {
    callback to_uppercase(string) -> string;
}

Assuming this global is used together with the MyComponent from the previous section, you can access Logic like this:

import * as slint from "slint-ui";

let ui = slint.loadFile("ui/my-component.slint");
let component = new ui.MyComponent();

component.Logic.to_upper_case = (str) => {
    return str.toUpperCase();
};

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