Introduce `iced_renderer` subcrate featuring runtime renderer fallback

16 files changed, 371 insertions, 72 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 551e12ac..d999febe 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,9 +13,9 @@ categories = ["gui"]
 
 [features]
 # Enables the `Image` widget
-image = ["iced_wgpu/image", "image_rs"]
+image = ["iced_renderer/image", "image_rs"]
 # Enables the `Svg` widget
-svg = ["iced_wgpu/svg"]
+svg = ["iced_renderer/svg"]
 # Enables the `Canvas` widget
 canvas = ["iced_graphics/canvas"]
 # Enables the `QRCode` widget
@@ -35,7 +35,7 @@ system = ["iced_winit/system"]
 # Enables chrome traces
 chrome-trace = [
     "iced_winit/chrome-trace",
-    "iced_wgpu/tracing",
+    "iced_renderer/tracing",
 ]
 
 [badges]
@@ -48,6 +48,7 @@ members = [
     "graphics",
     "lazy",
     "native",
+    "renderer",
     "style",
     "wgpu",
     "winit",
@@ -59,6 +60,7 @@ iced_core = { version = "0.8", path = "core" }
 iced_futures = { version = "0.6", path = "futures" }
 iced_native = { version = "0.9", path = "native" }
 iced_graphics = { version = "0.7", path = "graphics" }
+iced_renderer = { version = "0.1", path = "renderer" }
 iced_winit = { version = "0.8", path = "winit", features = ["application"] }
 thiserror = "1.0"
 
@@ -67,12 +69,6 @@ version = "0.24"
 package = "image"
 optional = true
 
-[target.'cfg(not(target_arch = "wasm32"))'.dependencies]
-iced_wgpu = { version = "0.9", path = "wgpu" }
-
-[target.'cfg(target_arch = "wasm32")'.dependencies]
-iced_wgpu = { version = "0.9", path = "wgpu", features = ["webgl"] }
-
 [package.metadata.docs.rs]
 rustdoc-args = ["--cfg", "docsrs"]
 features = ["image", "svg", "canvas", "qr_code"]
diff --git a/graphics/src/lib.rs b/graphics/src/lib.rs
index 41bef2c3..bbbdfa0e 100644
--- a/graphics/src/lib.rs
+++ b/graphics/src/lib.rs
@@ -46,9 +46,9 @@ pub use primitive::Primitive;
 pub use renderer::Renderer;
 pub use transformation::Transformation;
 pub use viewport::Viewport;
-pub use window::compositor;
 
 pub use iced_native::alignment;
+pub use iced_native::text;
 pub use iced_native::{
     Alignment, Background, Color, Font, Point, Rectangle, Size, Vector,
 };
diff --git a/graphics/src/renderer.rs b/graphics/src/renderer.rs
index b052c094..859ebc04 100644
--- a/graphics/src/renderer.rs
+++ b/graphics/src/renderer.rs
@@ -43,8 +43,11 @@ impl<B: Backend, T> Renderer<B, T> {
 
     /// Runs the given closure with the [`Backend`] and the recorded primitives
     /// of the [`Renderer`].
-    pub fn with_primitives(&mut self, f: impl FnOnce(&mut B, &[Primitive])) {
-        f(&mut self.backend, &self.primitives);
+    pub fn with_primitives<O>(
+        &mut self,
+        f: impl FnOnce(&mut B, &[Primitive]) -> O,
+    ) -> O {
+        f(&mut self.backend, &self.primitives)
     }
 }
 
diff --git a/graphics/src/window/gl_compositor.rs b/graphics/src/window/gl_compositor.rs
index a45a7ca1..3e6dfd9e 100644
--- a/graphics/src/window/gl_compositor.rs
+++ b/graphics/src/window/gl_compositor.rs
@@ -1,6 +1,6 @@
 //! A compositor is responsible for initializing a renderer and managing window
 //! surfaces.
-use crate::compositor::Information;
+use crate::window::compositor::Information;
 use crate::{Color, Error, Size, Viewport};
 
 use core::ffi::c_void;
diff --git a/renderer/Cargo.toml b/renderer/Cargo.toml
new file mode 100644
index 00000000..2a179f3a
--- /dev/null
+++ b/renderer/Cargo.toml
@@ -0,0 +1,26 @@
+[package]
+name = "iced_renderer"
+version = "0.1.0"
+edition = "2021"
+
+[features]
+image = ["iced_wgpu/image"]
+svg = ["iced_wgpu/svg"]
+tracing = ["iced_wgpu/tracing"]
+
+[dependencies]
+raw-window-handle = "0.5"
+
+[dependencies.iced_native]
+version = "0.9"
+path = "../native"
+
+[dependencies.iced_graphics]
+version = "0.7"
+path = "../graphics"
+
+[target.'cfg(not(target_arch = "wasm32"))'.dependencies]
+iced_wgpu = { version = "0.9", path = "../wgpu" }
+
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+iced_wgpu = { version = "0.9", path = "../wgpu", features = ["webgl"] }
diff --git a/renderer/src/backend.rs b/renderer/src/backend.rs
new file mode 100644
index 00000000..a9a09593
--- /dev/null
+++ b/renderer/src/backend.rs
@@ -0,0 +1,94 @@
+use crate::{Font, Point, Size};
+
+use iced_graphics::backend;
+use iced_graphics::text;
+
+use std::borrow::Cow;
+
+pub enum Backend {
+    Wgpu(iced_wgpu::Backend),
+}
+
+impl iced_graphics::Backend for Backend {}
+
+impl backend::Text for Backend {
+    const ICON_FONT: Font = Font::Name("Iced-Icons");
+    const CHECKMARK_ICON: char = '\u{f00c}';
+    const ARROW_DOWN_ICON: char = '\u{e800}';
+
+    fn default_font(&self) -> Font {
+        match self {
+            Self::Wgpu(backend) => backend.default_font(),
+        }
+    }
+
+    fn default_size(&self) -> f32 {
+        match self {
+            Self::Wgpu(backend) => backend.default_size(),
+        }
+    }
+
+    fn measure(
+        &self,
+        contents: &str,
+        size: f32,
+        font: Font,
+        bounds: Size,
+    ) -> (f32, f32) {
+        match self {
+            Self::Wgpu(backend) => {
+                backend.measure(contents, size, font, bounds)
+            }
+        }
+    }
+
+    fn hit_test(
+        &self,
+        contents: &str,
+        size: f32,
+        font: Font,
+        bounds: Size,
+        position: Point,
+        nearest_only: bool,
+    ) -> Option<text::Hit> {
+        match self {
+            Self::Wgpu(backend) => backend.hit_test(
+                contents,
+                size,
+                font,
+                bounds,
+                position,
+                nearest_only,
+            ),
+        }
+    }
+
+    fn load_font(&mut self, font: Cow<'static, [u8]>) {
+        match self {
+            Self::Wgpu(backend) => {
+                backend.load_font(font);
+            }
+        }
+    }
+}
+
+#[cfg(feature = "image")]
+impl backend::Image for Backend {
+    fn dimensions(&self, handle: &iced_native::image::Handle) -> Size<u32> {
+        match self {
+            Self::Wgpu(backend) => backend.dimensions(handle),
+        }
+    }
+}
+
+#[cfg(feature = "svg")]
+impl backend::Svg for Backend {
+    fn viewport_dimensions(
+        &self,
+        handle: &iced_native::svg::Handle,
+    ) -> Size<u32> {
+        match self {
+            Self::Wgpu(backend) => backend.viewport_dimensions(handle),
+        }
+    }
+}
diff --git a/renderer/src/lib.rs b/renderer/src/lib.rs
new file mode 100644
index 00000000..d0ba6793
--- /dev/null
+++ b/renderer/src/lib.rs
@@ -0,0 +1,17 @@
+pub mod window;
+
+mod backend;
+mod settings;
+
+pub use backend::Backend;
+pub use settings::Settings;
+
+pub use iced_graphics::{
+    Antialiasing, Color, Error, Font, Point, Size, Viewport,
+};
+
+/// The default graphics renderer for [`iced`].
+///
+/// [`iced`]: https://github.com/iced-rs/iced
+pub type Renderer<Theme = iced_native::Theme> =
+    iced_graphics::Renderer<Backend, Theme>;
diff --git a/renderer/src/settings.rs b/renderer/src/settings.rs
new file mode 100644
index 00000000..c4dc248b
--- /dev/null
+++ b/renderer/src/settings.rs
@@ -0,0 +1,30 @@
+use crate::{Antialiasing, Font};
+
+/// The settings of a [`Backend`].
+///
+/// [`Backend`]: crate::Backend
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct Settings {
+    /// The default [`Font`] to use.
+    pub default_font: Font,
+
+    /// The default size of text.
+    ///
+    /// By default, it will be set to `16.0`.
+    pub default_text_size: f32,
+
+    /// The antialiasing strategy that will be used for triangle primitives.
+    ///
+    /// By default, it is `None`.
+    pub antialiasing: Option<Antialiasing>,
+}
+
+impl Default for Settings {
+    fn default() -> Settings {
+        Settings {
+            default_font: Font::SansSerif,
+            default_text_size: 16.0,
+            antialiasing: None,
+        }
+    }
+}
diff --git a/renderer/src/window.rs b/renderer/src/window.rs
new file mode 100644
index 00000000..a7c8911b
--- /dev/null
+++ b/renderer/src/window.rs
@@ -0,0 +1,3 @@
+mod compositor;
+
+pub use compositor::Compositor;
diff --git a/renderer/src/window/compositor.rs b/renderer/src/window/compositor.rs
new file mode 100644
index 00000000..ad78d8bf
--- /dev/null
+++ b/renderer/src/window/compositor.rs
@@ -0,0 +1,96 @@
+use crate::{Backend, Color, Error, Renderer, Settings, Viewport};
+
+use raw_window_handle::{HasRawDisplayHandle, HasRawWindowHandle};
+
+pub use iced_graphics::window::compositor::{Information, SurfaceError};
+
+pub enum Compositor<Theme> {
+    Wgpu(iced_wgpu::window::Compositor<Theme>),
+}
+
+pub enum Surface {
+    Wgpu(iced_wgpu::window::Surface),
+}
+
+impl<Theme> iced_graphics::window::Compositor for Compositor<Theme> {
+    type Settings = Settings;
+    type Renderer = Renderer<Theme>;
+    type Surface = Surface;
+
+    fn new<W: HasRawWindowHandle + HasRawDisplayHandle>(
+        settings: Self::Settings,
+        compatible_window: Option<&W>,
+    ) -> Result<(Self, Self::Renderer), Error> {
+        let (compositor, backend) = iced_wgpu::window::compositor::new(
+            iced_wgpu::Settings {
+                default_font: settings.default_font,
+                default_text_size: settings.default_text_size,
+                antialiasing: settings.antialiasing,
+                ..iced_wgpu::Settings::from_env()
+            },
+            compatible_window,
+        )?;
+
+        Ok((
+            Self::Wgpu(compositor),
+            Renderer::new(Backend::Wgpu(backend)),
+        ))
+    }
+
+    fn create_surface<W: HasRawWindowHandle + HasRawDisplayHandle>(
+        &mut self,
+        window: &W,
+    ) -> Surface {
+        match self {
+            Self::Wgpu(compositor) => {
+                Surface::Wgpu(compositor.create_surface(window))
+            }
+        }
+    }
+
+    fn configure_surface(
+        &mut self,
+        surface: &mut Surface,
+        width: u32,
+        height: u32,
+    ) {
+        match (self, surface) {
+            (Self::Wgpu(compositor), Surface::Wgpu(surface)) => {
+                compositor.configure_surface(surface, width, height);
+            }
+        }
+    }
+
+    fn fetch_information(&self) -> Information {
+        match self {
+            Self::Wgpu(compositor) => compositor.fetch_information(),
+        }
+    }
+
+    fn present<T: AsRef<str>>(
+        &mut self,
+        renderer: &mut Self::Renderer,
+        surface: &mut Self::Surface,
+        viewport: &Viewport,
+        background_color: Color,
+        overlay: &[T],
+    ) -> Result<(), SurfaceError> {
+        renderer.with_primitives(|backend, primitives| {
+            match (self, backend, surface) {
+                (
+                    Self::Wgpu(compositor),
+                    Backend::Wgpu(backend),
+                    Surface::Wgpu(surface),
+                ) => iced_wgpu::window::compositor::present(
+                    compositor,
+                    backend,
+                    surface,
+                    primitives,
+                    viewport,
+                    background_color,
+                    overlay,
+                ),
+            }
+        })
+    }
+}
diff --git a/src/application.rs b/src/application.rs
index 9a1c1855..b9871556 100644
--- a/src/application.rs
+++ b/src/application.rs
@@ -198,11 +198,11 @@ pub trait Application: Sized {
             default_font: settings.default_font,
             default_text_size: settings.default_text_size,
             antialiasing: if settings.antialiasing {
-                Some(crate::renderer::settings::Antialiasing::MSAAx4)
+                Some(crate::renderer::Antialiasing::MSAAx4)
             } else {
                 None
             },
-            ..crate::renderer::Settings::from_env()
+            ..crate::renderer::Settings::default()
         };
 
         Ok(crate::runtime::application::run::<
diff --git a/src/lib.rs b/src/lib.rs
index 31ec4f48..bb162f2d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -182,7 +182,7 @@ pub mod touch;
 pub mod widget;
 pub mod window;
 
-use iced_wgpu as renderer;
+use iced_renderer as renderer;
 use iced_winit as runtime;
 
 pub use iced_native::theme;
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,
+            )
+        })
     }
 }
diff --git a/winit/src/application.rs b/winit/src/application.rs
index 889becad..1bfce3a1 100644
--- a/winit/src/application.rs
+++ b/winit/src/application.rs
@@ -17,8 +17,8 @@ use crate::{
 
 use iced_futures::futures;
 use iced_futures::futures::channel::mpsc;
-use iced_graphics::compositor;
 use iced_graphics::window;
+use iced_graphics::window::compositor;
 use iced_native::program::Program;
 use iced_native::time::Instant;
 use iced_native::user_interface::{self, UserInterface};
diff --git a/winit/src/system.rs b/winit/src/system.rs
index 619086b8..8a7b2a11 100644
--- a/winit/src/system.rs
+++ b/winit/src/system.rs
@@ -2,7 +2,7 @@
 use crate::command::{self, Command};
 pub use iced_native::system::*;
 
-use iced_graphics::compositor;
+use iced_graphics::window::compositor;
 
 /// Query for available system information.
 pub fn fetch_information<Message>(