Draft multi-threaded image rendering in iced_wgpu

graphics/src/shell.rs

@@ -0,0 +1,45 @@
+//! Control the windowing runtime from a renderer.
+use std::sync::Arc;
+
+/// A windowing shell.
+#[derive(Clone)]
+pub struct Shell(Arc<dyn Notifier>);
+
+impl Shell {
+    /// Creates a new [`Shell`].
+    pub fn new(notifier: impl Notifier) -> Self {
+        Self(Arc::new(notifier))
+    }
+
+    /// Creates a headless [`Shell`].
+    pub fn headless() -> Self {
+        struct Headless;
+
+        impl Notifier for Headless {
+            fn request_redraw(&self) {}
+
+            fn invalidate_layout(&self) {}
+        }
+
+        Self::new(Headless)
+    }
+
+    /// Requests for all windows of the [`Shell`] to be redrawn.
+    pub fn request_redraw(&self) {
+        self.0.request_redraw();
+    }
+
+    /// Requests for all layouts of the [`Shell`] to be recomputed.
+    pub fn invalidate_layout(&self) {
+        self.0.invalidate_layout();
+    }
+}
+
+/// A type that can notify a shell of certain events.
+pub trait Notifier: Send + Sync + 'static {
+    /// Requests for all windows of the [`Shell`] to be redrawn.
+    fn request_redraw(&self);
+
+    /// Requests for all layouts of the [`Shell`] to be recomputed.
+    fn invalidate_layout(&self);
+}