Crate gtk4

Expand description

Rust GTK 4 bindings

The project website is here.

Rust bindings of GTK 4, part of gtk4-rs.

This library contains safe Rust bindings for GTK 4, a multi-platform GUI toolkit. It is a part of gtk-rs.

Most of this documentation is generated from the C API. Until all parts of the documentation have been reviewed there will be incongruities with the actual Rust API.

For a gentle introduction to gtk-rs we recommend the online book GUI development with Rust and GTK 4.

Minimum supported Rust version

Currently, the minimum supported Rust version is 1.56.0.

“Hello, World!” example program

GTK needs to be initialized before use by calling init. Creating an Application will call init for you.

The gtk4 crate is usually renamed to gtk. You can find an example in the features section for how to do this globally in your Cargo.toml.

use gtk4 as gtk;
use gtk::prelude::*;
use gtk::{Application, ApplicationWindow};

fn main() {
    let app = Application::builder()
        .application_id("org.example.HelloWorld")
        .build();

    app.connect_activate(|app| {
        // We create the main window.
        let window = ApplicationWindow::builder()
            .application(app)
            .default_width(320)
            .default_height(200)
            .title("Hello, World!")
            .build();

        // Show the window.
        window.show();
    });

    app.run();
}

The main loop

In a typical GTK application you set up the UI, assign signal handlers and run the main event loop.

use gtk4 as gtk;
use gtk::prelude::*;
use gtk::{Application, ApplicationWindow, Button};

fn main() {
    let application = Application::builder()
        .application_id("com.example.FirstGtkApp")
        .build();

    application.connect_activate(|app| {
        let window = ApplicationWindow::builder()
            .application(app)
            .title("First GTK Program")
            .default_width(350)
            .default_height(70)
            .build();

        let button = Button::with_label("Click me!");
        button.connect_clicked(|_| {
            eprintln!("Clicked!");
        });
        window.set_child(Some(&button));

        window.show();
    });

    application.run();
}

Threads

GTK is not thread-safe. Accordingly, none of this crate’s structs implement Send or Sync.

The thread where init was called is considered the main thread. OS X has its own notion of the main thread and init must be called on that thread. After successful initialization, calling any gtk or gdk functions (including init) from other threads will panic.

Any thread can schedule a closure to be run by the main loop on the main thread via glib::idle_add or glib::timeout_add. While working with GTK you might need the glib::idle_add_local or glib::timeout_add_local version without the Send bound. Those may only be called from the main thread.

Panics

The gtk and gdk crates have some run-time safety and contract checks.

Any constructor or free function will panic if called before init or on a non-main thread.
Any &str or &Path parameter with an interior null (\0) character will cause a panic.
Some functions will panic if supplied out-of-range integer parameters. All such cases will be documented individually but they are not yet.
A panic in a closure that handles signals or in any other closure passed to a gtk function will abort the process.

Features

Library versions

By default this crate provides only GTK 4.0 APIs. You can access additional functionality by selecting one of the v4_2, v4_4, etc. features.

Cargo.toml example:

[dependencies.gtk]
package = "gtk4"
version = "0.x.y"
features = ["v4_2"]

Take care when choosing the version to target: some of your users might not have easy access to the latest ones. The higher the version, the fewer users will have it installed.

Feature	Description
`v4_6`	Enable the new APIs part of GTK 4.6
`v4_4`	Enable the new APIs part of GTK 4.4
`v4_2`	Enable the new APIs part of GTK 4.2