Implement `Frame::fill` and `Frame::stroke`

3 files changed, 100 insertions, 2 deletions

diff --git a/wgpu/src/widget/canvas.rs b/wgpu/src/widget/canvas.rs
index 7b84f36c..6bfeed9a 100644
--- a/wgpu/src/widget/canvas.rs
+++ b/wgpu/src/widget/canvas.rs
@@ -133,6 +133,16 @@ impl Default for LineCap {
     }
 }
 
+impl From<LineCap> for lyon::tessellation::LineCap {
+    fn from(line_cap: LineCap) -> lyon::tessellation::LineCap {
+        match line_cap {
+            LineCap::Butt => lyon::tessellation::LineCap::Butt,
+            LineCap::Square => lyon::tessellation::LineCap::Square,
+            LineCap::Round => lyon::tessellation::LineCap::Round,
+        }
+    }
+}
+
 #[derive(Debug, Clone, Copy)]
 pub enum LineJoin {
     Miter,
@@ -146,6 +156,16 @@ impl Default for LineJoin {
     }
 }
 
+impl From<LineJoin> for lyon::tessellation::LineJoin {
+    fn from(line_join: LineJoin) -> lyon::tessellation::LineJoin {
+        match line_join {
+            LineJoin::Miter => lyon::tessellation::LineJoin::Miter,
+            LineJoin::Round => lyon::tessellation::LineJoin::Round,
+            LineJoin::Bevel => lyon::tessellation::LineJoin::Bevel,
+        }
+    }
+}
+
 #[derive(Debug, Clone, Copy)]
 pub enum Fill {
     Color(Color),
diff --git a/wgpu/src/widget/canvas/frame.rs b/wgpu/src/widget/canvas/frame.rs
index e5daeedb..82ff526b 100644
--- a/wgpu/src/widget/canvas/frame.rs
+++ b/wgpu/src/widget/canvas/frame.rs
@@ -33,7 +33,79 @@ impl Frame {
         Point::new(self.width as f32 / 2.0, self.height as f32 / 2.0)
     }
 
-    pub fn fill(&mut self, path: &Path, fill: Fill) {}
+    pub fn fill(&mut self, path: &Path, fill: Fill) {
+        use lyon::tessellation::{
+            BuffersBuilder, FillOptions, FillTessellator,
+        };
 
-    pub fn stroke(&mut self, path: &Path, stroke: Stroke) {}
+        let mut buffers = BuffersBuilder::new(
+            &mut self.buffers,
+            FillVertex(match fill {
+                Fill::Color(color) => color.into_linear(),
+            }),
+        );
+
+        let mut tessellator = FillTessellator::new();
+
+        let _ = tessellator
+            .tessellate_path(path.raw(), &FillOptions::default(), &mut buffers)
+            .expect("Tessellate path");
+    }
+
+    pub fn stroke(&mut self, path: &Path, stroke: Stroke) {
+        use lyon::tessellation::{
+            BuffersBuilder, StrokeOptions, StrokeTessellator,
+        };
+
+        let mut buffers = BuffersBuilder::new(
+            &mut self.buffers,
+            StrokeVertex(stroke.color.into_linear()),
+        );
+
+        let mut tessellator = StrokeTessellator::new();
+
+        let mut options = StrokeOptions::default();
+        options.line_width = stroke.width;
+        options.start_cap = stroke.line_cap.into();
+        options.end_cap = stroke.line_cap.into();
+        options.line_join = stroke.line_join.into();
+
+        let _ = tessellator
+            .tessellate_path(path.raw(), &options, &mut buffers)
+            .expect("Stroke path");
+    }
+}
+
+struct FillVertex([f32; 4]);
+
+impl lyon::tessellation::FillVertexConstructor<triangle::Vertex2D>
+    for FillVertex
+{
+    fn new_vertex(
+        &mut self,
+        position: lyon::math::Point,
+        _attributes: lyon::tessellation::FillAttributes<'_>,
+    ) -> triangle::Vertex2D {
+        triangle::Vertex2D {
+            position: [position.x, position.y],
+            color: self.0,
+        }
+    }
+}
+
+struct StrokeVertex([f32; 4]);
+
+impl lyon::tessellation::StrokeVertexConstructor<triangle::Vertex2D>
+    for StrokeVertex
+{
+    fn new_vertex(
+        &mut self,
+        position: lyon::math::Point,
+        _attributes: lyon::tessellation::StrokeAttributes<'_, '_>,
+    ) -> triangle::Vertex2D {
+        triangle::Vertex2D {
+            position: [position.x, position.y],
+            color: self.0,
+        }
+    }
 }
diff --git a/wgpu/src/widget/canvas/path.rs b/wgpu/src/widget/canvas/path.rs
index 86326e8e..96206256 100644
--- a/wgpu/src/widget/canvas/path.rs
+++ b/wgpu/src/widget/canvas/path.rs
@@ -9,10 +9,16 @@ impl Path {
     pub fn new(f: impl FnOnce(&mut Builder)) -> Self {
         let mut builder = Builder::new();
 
+        // TODO: Make it pure instead of side-effect-based (?)
         f(&mut builder);
 
         builder.build()
     }
+
+    #[inline]
+    pub(crate) fn raw(&self) -> &lyon::path::Path {
+        &self.raw
+    }
 }
 
 #[allow(missing_debug_implementations)]