1 files changed, 121 insertions, 0 deletions
diff --git a/graphics/src/renderer.rs b/graphics/src/renderer.rs
new file mode 100644
index 00000000..fa63991b
--- /dev/null
+++ b/graphics/src/renderer.rs
@@ -0,0 +1,121 @@
+use crate::{Backend, Defaults, Primitive};
+use iced_native::layout::{self, Layout};
+use iced_native::mouse;
+use iced_native::{
+    Background, Color, Element, Point, Rectangle, Vector, Widget,
+};
+
+/// A backend-agnostic renderer that supports all the built-in widgets.
+#[derive(Debug)]
+pub struct Renderer<B: Backend> {
+    backend: B,
+}
+
+impl<B: Backend> Renderer<B> {
+    /// Creates a new [`Renderer`] from the given [`Backend`].
+    pub fn new(backend: B) -> Self {
+        Self { backend }
+    }
+
+    /// Returns a reference to the [`Backend`] of the [`Renderer`].
+    pub fn backend(&self) -> &B {
+        &self.backend
+    }
+
+    /// Returns a mutable reference to the [`Backend`] of the [`Renderer`].
+    pub fn backend_mut(&mut self) -> &mut B {
+        &mut self.backend
+    }
+}
+
+impl<B> iced_native::Renderer for Renderer<B>
+where
+    B: Backend,
+{
+    type Output = (Primitive, mouse::Interaction);
+    type Defaults = Defaults;
+
+    fn layout<'a, Message>(
+        &mut self,
+        element: &Element<'a, Message, Self>,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        let layout = element.layout(self, limits);
+
+        self.backend.trim_measurements();
+
+        layout
+    }
+
+    fn overlay(
+        &mut self,
+        (base_primitive, base_cursor): (Primitive, mouse::Interaction),
+        (overlay_primitives, overlay_cursor): (Primitive, mouse::Interaction),
+        overlay_bounds: Rectangle,
+    ) -> (Primitive, mouse::Interaction) {
+        (
+            Primitive::Group {
+                primitives: vec![
+                    base_primitive,
+                    Primitive::Clip {
+                        bounds: Rectangle {
+                            width: overlay_bounds.width + 0.5,
+                            height: overlay_bounds.height + 0.5,
+                            ..overlay_bounds
+                        },
+                        offset: Vector::new(0, 0),
+                        content: Box::new(overlay_primitives),
+                    },
+                ],
+            },
+            if base_cursor > overlay_cursor {
+                base_cursor
+            } else {
+                overlay_cursor
+            },
+        )
+    }
+}
+
+impl<B> layout::Debugger for Renderer<B>
+where
+    B: Backend,
+{
+    fn explain<Message>(
+        &mut self,
+        defaults: &Defaults,
+        widget: &dyn Widget<Message, Self>,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+        color: Color,
+    ) -> Self::Output {
+        let (primitive, cursor) =
+            widget.draw(self, defaults, layout, cursor_position, viewport);
+
+        let mut primitives = Vec::new();
+
+        explain_layout(layout, color, &mut primitives);
+        primitives.push(primitive);
+
+        (Primitive::Group { primitives }, cursor)
+    }
+}
+
+fn explain_layout(
+    layout: Layout<'_>,
+    color: Color,
+    primitives: &mut Vec<Primitive>,
+) {
+    primitives.push(Primitive::Quad {
+        bounds: layout.bounds(),
+        background: Background::Color(Color::TRANSPARENT),
+        border_radius: 0.0,
+        border_width: 1.0,
+        border_color: [0.6, 0.6, 0.6, 0.5].into(),
+    });
+
+    for child in layout.children() {
+        explain_layout(child, color, primitives);
+    }
+}