The Environment

SCTK provides a system that handles the listing and instantiation of globals needed by your app: the Environment. This system is highly modular, but SCTK also provides a preset for it, that will automatically instantiate all the globals needed for a regular app. This preset comes in the form of two macros: default_environment! and new_default_environment!.

The first one is used to declare the environment struct for your app. We will use the desktop preset, and we need to also provide a name, this example will use MyApp, but you can use anything. The second macro needs to be called for initializing the environment, and we need to give it the desktop preset as well.

The new_default_environment! takes care of connecting to the Wayland socket, creating an event queue, and initializing the environment on it. On success it returns a tuple of 3 values:

• The environment, of type Environment<MyApp>
• The Display
• The EventQueue that the environment is associated with

The environment will then provide several methods mapping the functionality of the various underlying globals. SCTK generally provides an higher-level interface to the underlying functionality than what the Wayland protocol directly encodes via its globals.

The previous example of listing all globals can be reframed as such using the environment system:

use smithay_client_toolkit::{default_environment, new_default_environment};

default_environment!(MyApp, desktop);

fn main() {
    let (environment, display, event_queue) = new_default_environment!(MyApp, desktop)
        .expect("Failed to initialize the Wayland environment.");

    // environment.manager is the underlying GlobalManager
    println!("Available globals:");
    for (name, interface, version) in environment.manager.list() {
        println!("{}: {} (version {})", name, interface, version);
    }
}