2 files changed, 88 insertions, 54 deletions

diff --git a/wgpu/src/window.rs b/wgpu/src/window.rs
index aac5fb9e..9545a14e 100644
--- a/wgpu/src/window.rs
+++ b/wgpu/src/window.rs
@@ -1,4 +1,5 @@
 //! Display rendering results on windows.
-mod compositor;
+pub mod compositor;
 
 pub use compositor::Compositor;
+pub use wgpu::Surface;
diff --git a/wgpu/src/window/compositor.rs b/wgpu/src/window/compositor.rs
index 365cb603..7406bfb8 100644
--- a/wgpu/src/window/compositor.rs
+++ b/wgpu/src/window/compositor.rs
@@ -1,8 +1,9 @@
-use crate::{Backend, Color, Error, Renderer, Settings, Viewport};
+//! Connect a window with a renderer.
+use crate::{Backend, Color, Error, Primitive, Renderer, Settings, Viewport};
 
 use futures::stream::{self, StreamExt};
 
-use iced_graphics::compositor;
+use iced_graphics::window::compositor;
 use iced_native::futures;
 use raw_window_handle::{HasRawDisplayHandle, HasRawWindowHandle};
 
@@ -112,6 +113,77 @@ impl<Theme> Compositor<Theme> {
     }
 }
 
+/// Creates a [`Compositor`] and its [`Backend`] for the given [`Settings`] and
+/// window.
+pub fn new<Theme, W: HasRawWindowHandle + HasRawDisplayHandle>(
+    settings: Settings,
+    compatible_window: Option<&W>,
+) -> Result<(Compositor<Theme>, Backend), Error> {
+    let compositor = futures::executor::block_on(Compositor::request(
+        settings,
+        compatible_window,
+    ))
+    .ok_or(Error::GraphicsAdapterNotFound)?;
+
+    let backend = compositor.create_backend();
+
+    Ok((compositor, backend))
+}
+
+/// Presents the given primitives with the given [`Compositor`] and [`Backend`].
+pub fn present<Theme, T: AsRef<str>>(
+    compositor: &mut Compositor<Theme>,
+    backend: &mut Backend,
+    surface: &mut wgpu::Surface,
+    primitives: &[Primitive],
+    viewport: &Viewport,
+    background_color: Color,
+    overlay: &[T],
+) -> Result<(), compositor::SurfaceError> {
+    match surface.get_current_texture() {
+        Ok(frame) => {
+            let mut encoder = compositor.device.create_command_encoder(
+                &wgpu::CommandEncoderDescriptor {
+                    label: Some("iced_wgpu encoder"),
+                },
+            );
+
+            let view = &frame
+                .texture
+                .create_view(&wgpu::TextureViewDescriptor::default());
+
+            backend.present(
+                &compositor.device,
+                &compositor.queue,
+                &mut encoder,
+                Some(background_color),
+                view,
+                primitives,
+                viewport,
+                overlay,
+            );
+
+            // Submit work
+            let _submission = compositor.queue.submit(Some(encoder.finish()));
+            frame.present();
+
+            Ok(())
+        }
+        Err(error) => match error {
+            wgpu::SurfaceError::Timeout => {
+                Err(compositor::SurfaceError::Timeout)
+            }
+            wgpu::SurfaceError::Outdated => {
+                Err(compositor::SurfaceError::Outdated)
+            }
+            wgpu::SurfaceError::Lost => Err(compositor::SurfaceError::Lost),
+            wgpu::SurfaceError::OutOfMemory => {
+                Err(compositor::SurfaceError::OutOfMemory)
+            }
+        },
+    }
+}
+
 impl<Theme> iced_graphics::window::Compositor for Compositor<Theme> {
     type Settings = Settings;
     type Renderer = Renderer<Theme>;
@@ -121,13 +193,7 @@ impl<Theme> iced_graphics::window::Compositor for Compositor<Theme> {
         settings: Self::Settings,
         compatible_window: Option<&W>,
     ) -> Result<(Self, Self::Renderer), Error> {
-        let compositor = futures::executor::block_on(Self::request(
-            settings,
-            compatible_window,
-        ))
-        .ok_or(Error::GraphicsAdapterNotFound)?;
-
-        let backend = compositor.create_backend();
+        let (compositor, backend) = new(settings, compatible_window)?;
 
         Ok((compositor, Renderer::new(backend)))
     }
@@ -178,49 +244,16 @@ impl<Theme> iced_graphics::window::Compositor for Compositor<Theme> {
         background_color: Color,
         overlay: &[T],
     ) -> Result<(), compositor::SurfaceError> {
-        match surface.get_current_texture() {
-            Ok(frame) => {
-                let mut encoder = self.device.create_command_encoder(
-                    &wgpu::CommandEncoderDescriptor {
-                        label: Some("iced_wgpu encoder"),
-                    },
-                );
-
-                let view = &frame
-                    .texture
-                    .create_view(&wgpu::TextureViewDescriptor::default());
-
-                renderer.with_primitives(|backend, primitives| {
-                    backend.present(
-                        &self.device,
-                        &self.queue,
-                        &mut encoder,
-                        Some(background_color),
-                        view,
-                        primitives,
-                        viewport,
-                        overlay,
-                    );
-                });
-
-                // Submit work
-                let _submission = self.queue.submit(Some(encoder.finish()));
-                frame.present();
-
-                Ok(())
-            }
-            Err(error) => match error {
-                wgpu::SurfaceError::Timeout => {
-                    Err(compositor::SurfaceError::Timeout)
-                }
-                wgpu::SurfaceError::Outdated => {
-                    Err(compositor::SurfaceError::Outdated)
-                }
-                wgpu::SurfaceError::Lost => Err(compositor::SurfaceError::Lost),
-                wgpu::SurfaceError::OutOfMemory => {
-                    Err(compositor::SurfaceError::OutOfMemory)
-                }
-            },
-        }
+        renderer.with_primitives(|backend, primitives| {
+            present(
+                self,
+                backend,
+                surface,
+                primitives,
+                viewport,
+                background_color,
+                overlay,
+            )
+        })
     }
 }