Merge remote-tracking branch 'origin/master' into feat/multi-window-support

# Conflicts:
#	Cargo.toml
#	core/src/window/icon.rs
#	core/src/window/id.rs
#	core/src/window/position.rs
#	core/src/window/settings.rs
#	examples/integration/src/main.rs
#	examples/integration_opengl/src/main.rs
#	glutin/src/application.rs
#	native/src/subscription.rs
#	native/src/window.rs
#	runtime/src/window/action.rs
#	src/lib.rs
#	src/window.rs
#	winit/Cargo.toml
#	winit/src/application.rs
#	winit/src/icon.rs
#	winit/src/settings.rs
#	winit/src/window.rs

1 files changed, 105 insertions, 0 deletions

diff --git a/graphics/src/compositor.rs b/graphics/src/compositor.rs
new file mode 100644
index 00000000..f7b86045
--- /dev/null
+++ b/graphics/src/compositor.rs
@@ -0,0 +1,105 @@
+//! A compositor is responsible for initializing a renderer and managing window
+//! surfaces.
+use crate::{Error, Viewport};
+
+use iced_core::Color;
+
+use raw_window_handle::{HasRawDisplayHandle, HasRawWindowHandle};
+use thiserror::Error;
+
+/// A graphics compositor that can draw to windows.
+pub trait Compositor: Sized {
+    /// The settings of the backend.
+    type Settings: Default;
+
+    /// The iced renderer of the backend.
+    type Renderer: iced_core::Renderer;
+
+    /// The surface of the backend.
+    type Surface;
+
+    /// Creates a new [`Compositor`].
+    fn new<W: HasRawWindowHandle + HasRawDisplayHandle>(
+        settings: Self::Settings,
+        compatible_window: Option<&W>,
+    ) -> Result<(Self, Self::Renderer), Error>;
+
+    /// Crates a new [`Surface`] for the given window.
+    ///
+    /// [`Surface`]: Self::Surface
+    fn create_surface<W: HasRawWindowHandle + HasRawDisplayHandle>(
+        &mut self,
+        window: &W,
+        width: u32,
+        height: u32,
+    ) -> Self::Surface;
+
+    /// Configures a new [`Surface`] with the given dimensions.
+    ///
+    /// [`Surface`]: Self::Surface
+    fn configure_surface(
+        &mut self,
+        surface: &mut Self::Surface,
+        width: u32,
+        height: u32,
+    );
+
+    /// Returns [`Information`] used by this [`Compositor`].
+    fn fetch_information(&self) -> Information;
+
+    /// Presents the [`Renderer`] primitives to the next frame of the given [`Surface`].
+    ///
+    /// [`Renderer`]: Self::Renderer
+    /// [`Surface`]: Self::Surface
+    fn present<T: AsRef<str>>(
+        &mut self,
+        renderer: &mut Self::Renderer,
+        surface: &mut Self::Surface,
+        viewport: &Viewport,
+        background_color: Color,
+        overlay: &[T],
+    ) -> Result<(), SurfaceError>;
+
+    /// Screenshots the current [`Renderer`] primitives to an offscreen texture, and returns the bytes of
+    /// the texture ordered as `RGBA` in the sRGB color space.
+    ///
+    /// [`Renderer`]: Self::Renderer;
+    fn screenshot<T: AsRef<str>>(
+        &mut self,
+        renderer: &mut Self::Renderer,
+        surface: &mut Self::Surface,
+        viewport: &Viewport,
+        background_color: Color,
+        overlay: &[T],
+    ) -> Vec<u8>;
+}
+
+/// Result of an unsuccessful call to [`Compositor::present`].
+#[derive(Clone, PartialEq, Eq, Debug, Error)]
+pub enum SurfaceError {
+    /// A timeout was encountered while trying to acquire the next frame.
+    #[error(
+        "A timeout was encountered while trying to acquire the next frame"
+    )]
+    Timeout,
+    /// The underlying surface has changed, and therefore the surface must be updated.
+    #[error(
+        "The underlying surface has changed, and therefore the surface must be updated."
+    )]
+    Outdated,
+    /// The swap chain has been lost and needs to be recreated.
+    #[error("The surface has been lost and needs to be recreated")]
+    Lost,
+    /// There is no more memory left to allocate a new frame.
+    #[error("There is no more memory left to allocate a new frame")]
+    OutOfMemory,
+}
+
+/// Contains information about the graphics (e.g. graphics adapter, graphics backend).
+#[derive(Debug)]
+pub struct Information {
+    /// Contains the graphics adapter.
+    pub adapter: String,
+    /// Contains the graphics backend.
+    pub backend: String,
+}