From 3645d34d6a1ba1247238e830e9eefd52d9e5b986 Mon Sep 17 00:00:00 2001
From: Héctor Ramón Jiménez <hector@hecrj.dev>
Date: Thu, 21 Mar 2024 22:27:17 +0100
Subject: Implement composable, type-safe renderer fallback

---
 renderer/src/fallback.rs | 562 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 562 insertions(+)
 create mode 100644 renderer/src/fallback.rs

(limited to 'renderer/src/fallback.rs')

diff --git a/renderer/src/fallback.rs b/renderer/src/fallback.rs
new file mode 100644
index 00000000..a4c725c0
--- /dev/null
+++ b/renderer/src/fallback.rs
@@ -0,0 +1,562 @@
+use crate::core::image;
+use crate::core::renderer;
+use crate::core::svg;
+use crate::core::{
+    self, Background, Color, Point, Rectangle, Size, Transformation,
+};
+use crate::graphics;
+use crate::graphics::compositor;
+use crate::graphics::mesh;
+
+pub enum Renderer<L, R>
+where
+    L: core::Renderer,
+    R: core::Renderer,
+{
+    Left(L),
+    Right(R),
+}
+
+macro_rules! delegate {
+    ($renderer:expr, $name:ident, $body:expr) => {
+        match $renderer {
+            Self::Left($name) => $body,
+            Self::Right($name) => $body,
+        }
+    };
+}
+
+impl<L, R> Renderer<L, R>
+where
+    L: core::Renderer,
+    R: core::Renderer,
+{
+    #[cfg(feature = "geometry")]
+    pub fn draw_geometry<Geometry>(
+        &mut self,
+        layers: impl IntoIterator<Item = Geometry>,
+    ) where
+        L: graphics::geometry::Renderer,
+        R: graphics::geometry::Renderer,
+
+        Geometry: Into<geometry::Geometry<L::Geometry, R::Geometry>>,
+    {
+        use graphics::geometry::Renderer;
+
+        for layer in layers {
+            <Self as Renderer>::draw_geometry(self, layer.into());
+        }
+    }
+}
+
+impl<L, R> core::Renderer for Renderer<L, R>
+where
+    L: core::Renderer,
+    R: core::Renderer,
+{
+    fn fill_quad(
+        &mut self,
+        quad: renderer::Quad,
+        background: impl Into<Background>,
+    ) {
+        delegate!(self, renderer, renderer.fill_quad(quad, background.into()));
+    }
+
+    fn clear(&mut self) {
+        delegate!(self, renderer, renderer.clear());
+    }
+
+    fn start_layer(&mut self) {
+        delegate!(self, renderer, renderer.start_layer());
+    }
+
+    fn end_layer(&mut self, bounds: Rectangle) {
+        delegate!(self, renderer, renderer.end_layer(bounds));
+    }
+
+    fn start_transformation(&mut self) {
+        delegate!(self, renderer, renderer.start_transformation());
+    }
+
+    fn end_transformation(&mut self, transformation: Transformation) {
+        delegate!(self, renderer, renderer.end_transformation(transformation));
+    }
+}
+
+impl<L, R> core::text::Renderer for Renderer<L, R>
+where
+    L: core::text::Renderer,
+    R: core::text::Renderer<
+        Font = L::Font,
+        Paragraph = L::Paragraph,
+        Editor = L::Editor,
+    >,
+{
+    type Font = L::Font;
+    type Paragraph = L::Paragraph;
+    type Editor = L::Editor;
+
+    const ICON_FONT: Self::Font = L::ICON_FONT;
+    const CHECKMARK_ICON: char = L::CHECKMARK_ICON;
+    const ARROW_DOWN_ICON: char = L::ARROW_DOWN_ICON;
+
+    fn default_font(&self) -> Self::Font {
+        delegate!(self, renderer, renderer.default_font())
+    }
+
+    fn default_size(&self) -> core::Pixels {
+        delegate!(self, renderer, renderer.default_size())
+    }
+
+    fn load_font(&mut self, font: std::borrow::Cow<'static, [u8]>) {
+        delegate!(self, renderer, renderer.load_font(font));
+    }
+
+    fn fill_paragraph(
+        &mut self,
+        text: &Self::Paragraph,
+        position: Point,
+        color: Color,
+        clip_bounds: Rectangle,
+    ) {
+        delegate!(
+            self,
+            renderer,
+            renderer.fill_paragraph(text, position, color, clip_bounds)
+        );
+    }
+
+    fn fill_editor(
+        &mut self,
+        editor: &Self::Editor,
+        position: Point,
+        color: Color,
+        clip_bounds: Rectangle,
+    ) {
+        delegate!(
+            self,
+            renderer,
+            renderer.fill_editor(editor, position, color, clip_bounds)
+        );
+    }
+
+    fn fill_text(
+        &mut self,
+        text: core::Text<'_, Self::Font>,
+        position: Point,
+        color: Color,
+        clip_bounds: Rectangle,
+    ) {
+        delegate!(
+            self,
+            renderer,
+            renderer.fill_text(text, position, color, clip_bounds)
+        );
+    }
+}
+
+impl<L, R> image::Renderer for Renderer<L, R>
+where
+    L: image::Renderer,
+    R: image::Renderer<Handle = L::Handle>,
+{
+    type Handle = L::Handle;
+
+    fn measure_image(&self, handle: &Self::Handle) -> Size<u32> {
+        delegate!(self, renderer, renderer.measure_image(handle))
+    }
+
+    fn draw_image(
+        &mut self,
+        handle: Self::Handle,
+        filter_method: image::FilterMethod,
+        bounds: Rectangle,
+    ) {
+        delegate!(
+            self,
+            renderer,
+            renderer.draw_image(handle, filter_method, bounds)
+        );
+    }
+}
+
+impl<L, R> svg::Renderer for Renderer<L, R>
+where
+    L: svg::Renderer,
+    R: svg::Renderer,
+{
+    fn measure_svg(&self, handle: &svg::Handle) -> Size<u32> {
+        delegate!(self, renderer, renderer.measure_svg(handle))
+    }
+
+    fn draw_svg(
+        &mut self,
+        handle: svg::Handle,
+        color: Option<Color>,
+        bounds: Rectangle,
+    ) {
+        delegate!(self, renderer, renderer.draw_svg(handle, color, bounds));
+    }
+}
+
+impl<L, R> mesh::Renderer for Renderer<L, R>
+where
+    L: mesh::Renderer,
+    R: mesh::Renderer,
+{
+    fn draw_mesh(&mut self, mesh: graphics::Mesh) {
+        delegate!(self, renderer, renderer.draw_mesh(mesh));
+    }
+}
+
+pub enum Compositor<L, R>
+where
+    L: graphics::Compositor,
+    R: graphics::Compositor,
+{
+    Left(L),
+    Right(R),
+}
+
+pub enum Surface<L, R> {
+    Left(L),
+    Right(R),
+}
+
+impl<L, R> graphics::Compositor for Compositor<L, R>
+where
+    L: graphics::Compositor,
+    R: graphics::Compositor,
+    L::Settings: From<crate::Settings>,
+    R::Settings: From<crate::Settings>,
+{
+    type Settings = crate::Settings;
+    type Renderer = Renderer<L::Renderer, R::Renderer>;
+    type Surface = Surface<L::Surface, R::Surface>;
+
+    async fn new<W: compositor::Window + Clone>(
+        settings: Self::Settings,
+        compatible_window: W,
+    ) -> Result<Self, graphics::Error> {
+        if let Ok(left) = L::new(settings.into(), compatible_window.clone())
+            .await
+            .map(Self::Left)
+        {
+            return Ok(left);
+        }
+
+        R::new(settings.into(), compatible_window)
+            .await
+            .map(Self::Right)
+    }
+
+    fn create_renderer(&self) -> Self::Renderer {
+        match self {
+            Self::Left(compositor) => {
+                Renderer::Left(compositor.create_renderer())
+            }
+            Self::Right(compositor) => {
+                Renderer::Right(compositor.create_renderer())
+            }
+        }
+    }
+
+    fn create_surface<W: compositor::Window + Clone>(
+        &mut self,
+        window: W,
+        width: u32,
+        height: u32,
+    ) -> Self::Surface {
+        match self {
+            Self::Left(compositor) => {
+                Surface::Left(compositor.create_surface(window, width, height))
+            }
+            Self::Right(compositor) => {
+                Surface::Right(compositor.create_surface(window, width, height))
+            }
+        }
+    }
+
+    fn configure_surface(
+        &mut self,
+        surface: &mut Self::Surface,
+        width: u32,
+        height: u32,
+    ) {
+        match (self, surface) {
+            (Self::Left(compositor), Surface::Left(surface)) => {
+                compositor.configure_surface(surface, width, height);
+            }
+            (Self::Right(compositor), Surface::Right(surface)) => {
+                compositor.configure_surface(surface, width, height);
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    fn fetch_information(&self) -> compositor::Information {
+        delegate!(self, compositor, compositor.fetch_information())
+    }
+
+    fn present<T: AsRef<str>>(
+        &mut self,
+        renderer: &mut Self::Renderer,
+        surface: &mut Self::Surface,
+        viewport: &graphics::Viewport,
+        background_color: Color,
+        overlay: &[T],
+    ) -> Result<(), compositor::SurfaceError> {
+        match (self, renderer, surface) {
+            (
+                Self::Left(compositor),
+                Renderer::Left(renderer),
+                Surface::Left(surface),
+            ) => compositor.present(
+                renderer,
+                surface,
+                viewport,
+                background_color,
+                overlay,
+            ),
+            (
+                Self::Right(compositor),
+                Renderer::Right(renderer),
+                Surface::Right(surface),
+            ) => compositor.present(
+                renderer,
+                surface,
+                viewport,
+                background_color,
+                overlay,
+            ),
+            _ => unreachable!(),
+        }
+    }
+
+    fn screenshot<T: AsRef<str>>(
+        &mut self,
+        renderer: &mut Self::Renderer,
+        surface: &mut Self::Surface,
+        viewport: &graphics::Viewport,
+        background_color: Color,
+        overlay: &[T],
+    ) -> Vec<u8> {
+        match (self, renderer, surface) {
+            (
+                Self::Left(compositor),
+                Renderer::Left(renderer),
+                Surface::Left(surface),
+            ) => compositor.screenshot(
+                renderer,
+                surface,
+                viewport,
+                background_color,
+                overlay,
+            ),
+            (
+                Self::Right(compositor),
+                Renderer::Right(renderer),
+                Surface::Right(surface),
+            ) => compositor.screenshot(
+                renderer,
+                surface,
+                viewport,
+                background_color,
+                overlay,
+            ),
+            _ => unreachable!(),
+        }
+    }
+}
+
+#[cfg(feature = "wgpu")]
+impl<L, R> iced_wgpu::primitive::pipeline::Renderer for Renderer<L, R>
+where
+    L: iced_wgpu::primitive::pipeline::Renderer,
+    R: core::Renderer,
+{
+    fn draw_pipeline_primitive(
+        &mut self,
+        bounds: Rectangle,
+        primitive: impl iced_wgpu::primitive::pipeline::Primitive,
+    ) {
+        match self {
+            Self::Left(renderer) => {
+                renderer.draw_pipeline_primitive(bounds, primitive);
+            }
+            Self::Right(_) => {
+                log::warn!(
+                    "Custom shader primitive is not supported with this renderer."
+                );
+            }
+        }
+    }
+}
+
+#[cfg(feature = "geometry")]
+mod geometry {
+    use super::Renderer;
+    use crate::core::{Point, Radians, Size, Vector};
+    use crate::graphics::geometry::{self, Fill, Path, Stroke, Text};
+
+    impl<L, R> geometry::Renderer for Renderer<L, R>
+    where
+        L: geometry::Renderer,
+        R: geometry::Renderer,
+    {
+        type Geometry = Geometry<L::Geometry, R::Geometry>;
+        type Frame = Frame<L::Frame, R::Frame>;
+
+        fn new_frame(&self, size: iced_graphics::core::Size) -> Self::Frame {
+            match self {
+                Self::Left(renderer) => Frame::Left(renderer.new_frame(size)),
+                Self::Right(renderer) => Frame::Right(renderer.new_frame(size)),
+            }
+        }
+
+        fn draw_geometry(&mut self, geometry: Self::Geometry) {
+            match (self, geometry) {
+                (Self::Left(renderer), Geometry::Left(geometry)) => {
+                    renderer.draw_geometry(geometry);
+                }
+                (Self::Right(renderer), Geometry::Right(geometry)) => {
+                    renderer.draw_geometry(geometry);
+                }
+                _ => unreachable!(),
+            }
+        }
+    }
+
+    pub enum Geometry<L, R> {
+        Left(L),
+        Right(R),
+    }
+
+    impl<L, R> geometry::Geometry for Geometry<L, R>
+    where
+        L: geometry::Geometry,
+        R: geometry::Geometry,
+    {
+        type Cache = Geometry<L::Cache, R::Cache>;
+
+        fn load(cache: &Self::Cache) -> Self {
+            match cache {
+                Geometry::Left(cache) => Self::Left(L::load(cache)),
+                Geometry::Right(cache) => Self::Right(R::load(cache)),
+            }
+        }
+
+        fn cache(self) -> Self::Cache {
+            match self {
+                Self::Left(geometry) => Geometry::Left(geometry.cache()),
+                Self::Right(geometry) => Geometry::Right(geometry.cache()),
+            }
+        }
+    }
+
+    pub enum Frame<L, R> {
+        Left(L),
+        Right(R),
+    }
+
+    impl<L, R> geometry::Frame for Frame<L, R>
+    where
+        L: geometry::Frame,
+        R: geometry::Frame,
+    {
+        type Geometry = Geometry<L::Geometry, R::Geometry>;
+
+        fn width(&self) -> f32 {
+            delegate!(self, frame, frame.width())
+        }
+
+        fn height(&self) -> f32 {
+            delegate!(self, frame, frame.height())
+        }
+
+        fn size(&self) -> Size {
+            delegate!(self, frame, frame.size())
+        }
+
+        fn center(&self) -> Point {
+            delegate!(self, frame, frame.center())
+        }
+
+        fn fill(&mut self, path: &Path, fill: impl Into<Fill>) {
+            delegate!(self, frame, frame.fill(path, fill));
+        }
+
+        fn fill_rectangle(
+            &mut self,
+            top_left: Point,
+            size: Size,
+            fill: impl Into<Fill>,
+        ) {
+            delegate!(self, frame, frame.fill_rectangle(top_left, size, fill));
+        }
+
+        fn stroke<'a>(&mut self, path: &Path, stroke: impl Into<Stroke<'a>>) {
+            delegate!(self, frame, frame.stroke(path, stroke));
+        }
+
+        fn fill_text(&mut self, text: impl Into<Text>) {
+            delegate!(self, frame, frame.fill_text(text));
+        }
+
+        fn push_transform(&mut self) {
+            delegate!(self, frame, frame.push_transform());
+        }
+
+        fn pop_transform(&mut self) {
+            delegate!(self, frame, frame.pop_transform());
+        }
+
+        fn draft(&mut self, size: Size) -> Self {
+            match self {
+                Self::Left(frame) => Self::Left(frame.draft(size)),
+                Self::Right(frame) => Self::Right(frame.draft(size)),
+            }
+        }
+
+        fn paste(&mut self, frame: Self, at: Point) {
+            match (self, frame) {
+                (Self::Left(target), Self::Left(source)) => {
+                    target.paste(source, at);
+                }
+                (Self::Right(target), Self::Right(source)) => {
+                    target.paste(source, at);
+                }
+                _ => unreachable!(),
+            }
+        }
+
+        fn translate(&mut self, translation: Vector) {
+            delegate!(self, frame, frame.translate(translation));
+        }
+
+        fn rotate(&mut self, angle: impl Into<Radians>) {
+            delegate!(self, frame, frame.rotate(angle));
+        }
+
+        fn scale(&mut self, scale: impl Into<f32>) {
+            delegate!(self, frame, frame.scale(scale));
+        }
+
+        fn scale_nonuniform(&mut self, scale: impl Into<Vector>) {
+            delegate!(self, frame, frame.scale_nonuniform(scale));
+        }
+    }
+
+    impl<L, R> From<Frame<L, R>> for Geometry<L::Geometry, R::Geometry>
+    where
+        L: geometry::Frame,
+        R: geometry::Frame,
+    {
+        fn from(frame: Frame<L, R>) -> Self {
+            match frame {
+                Frame::Left(frame) => Self::Left(frame.into()),
+                Frame::Right(frame) => Self::Right(frame.into()),
+            }
+        }
+    }
+}
-- 
cgit