Sync Signals

SyncSignal<T> is a thread-safe version of Signal<T>. Use it when you need to read or write reactive state from outside the main UI thread.

Creating a sync signal

use vizia::prelude::*;

let progress = SyncSignal::new(0.0f32);

Sending updates from a background thread

SyncSignal implements Send + Sync, so it can be moved into threads and async tasks:

let progress = SyncSignal::new(0.0f32);

std::thread::spawn(move || {
    for i in 0..=100 {
        progress.set(i as f32 / 100.0);
        std::thread::sleep(std::time::Duration::from_millis(50));
    }
});

// Bind to the signal in the UI
Application::new(|cx| {
    ProgressBar::horizontal(cx, progress);
}).run();

Updates from the background thread are picked up on the next frame.

Read-only and write-only variants

Just like Signal, SyncSignal can be split:

let read = progress.read_only();   // SyncReadSignal<f32>
let write = progress.write_only(); // SyncWriteSignal<f32>

Share write with background threads and keep read in the UI.

When to use SyncSignal vs Signal

• Use Signal<T> for state that is only ever read and written from the UI thread.
• Use SyncSignal<T> when a background thread or async task needs to push updates.

See also

• Signals
• Writing Signals