Globals

A global is a singleton declared at the top level of a .slint file with the global keyword. It holds properties, callbacks, and functions that are shared across the whole project rather than belonging to an element:

global Name {
    // property, callback, and function declarations
}

slint

A global is declared once and referred to by name. It is never instantiated as an element; writing Name { } in an element tree is an error.

Contents

The body of a global may contain:

• Property declarations — in, out, in-out, or private, each with an optional binding (see Properties).
• Callback declarations — optionally pure (see Callbacks).
• Function declarations — optionally pure, and private, protected, or public (see Functions).

Nothing else is allowed. A global cannot contain elements or child components, @children, an animate block, states, transitions, or an init callback; each is a compile error.

A global exists independently of any window, so it has no scale factor and no default font size. Expressions inside a global therefore cannot convert between logical (px) and physical (phx) lengths, nor between rem and logical lengths.

Accessing members

Reach a global’s members through its name, from any binding, callback, or function in the project, and from other globals:

Name.property
Name.callback(arguments)
Name.function(arguments)

slint

As with all identifiers, - and _ are interchangeable.

A global is a singleton: one instance is shared by every component in a component tree. Separate windows — and a window and a SystemTrayIcon exported alongside it — each hold their own instance, so their globals are initialized independently.

global Palette {
    in-out property<color> primary: blue;
    in-out property<color> secondary: green;
}

export component Example inherits Rectangle {
    background: Palette.primary;
    border-color: Palette.secondary;
    border-width: 2px;
}

slint

Exporting

An exported global can be imported into other files. A global re-exported from the file that also exports the application’s root component is additionally exposed to the native API, where the business logic reads and writes its properties and sets its callbacks. The Globals guide shows this for each language.

A global’s property or callback can be the target of a two-way binding, which re-exposes it on a component.