Draft multi-threaded image rendering in iced_wgpu

graphics/src/compositor.rs

@@ -2,7 +2,7 @@
 //! surfaces.
 use crate::core::Color;
 use crate::futures::{MaybeSend, MaybeSync};
-use crate::{Error, Settings, Viewport};
+use crate::{Error, Settings, Shell, Viewport};
 
 use raw_window_handle::{HasDisplayHandle, HasWindowHandle};
 use thiserror::Error;
@@ -21,8 +21,9 @@ pub trait Compositor: Sized {
     fn new<W: Window + Clone>(
         settings: Settings,
         compatible_window: W,
+        shell: Shell,
     ) -> impl Future<Output = Result<Self, Error>> {
-        Self::with_backend(settings, compatible_window, None)
+        Self::with_backend(settings, compatible_window, shell, None)
     }
 
     /// Creates a new [`Compositor`] with a backend preference.
@@ -32,6 +33,7 @@ pub trait Compositor: Sized {
     fn with_backend<W: Window + Clone>(
         _settings: Settings,
         _compatible_window: W,
+        _shell: Shell,
         _backend: Option<&str>,
     ) -> impl Future<Output = Result<Self, Error>>;
 
@@ -153,6 +155,7 @@ impl Compositor for () {
     async fn with_backend<W: Window + Clone>(
         _settings: Settings,
         _compatible_window: W,
+        _shell: Shell,
         _preferred_backend: Option<&str>,
     ) -> Result<Self, Error> {
         Ok(())

graphics/src/lib.rs

@@ -21,6 +21,7 @@ pub mod gradient;
 pub mod image;
 pub mod layer;
 pub mod mesh;
+pub mod shell;
 pub mod text;
 
 #[cfg(feature = "geometry")]
@@ -35,6 +36,7 @@ pub use image::Image;
 pub use layer::Layer;
 pub use mesh::Mesh;
 pub use settings::Settings;
+pub use shell::Shell;
 pub use text::Text;
 pub use viewport::Viewport;
 

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);
+}