🐛 Fix dot/dahs/mixed strokes

render-wasm/src/render/strokes.rs

@@ -26,7 +26,7 @@ fn draw_stroke_on_rect(
     // Draw the different kind of strokes for a rect is straightforward, we just need apply a stroke to:
     // - The same rect if it's a center stroke
     // - A bigger rect if it's an outer stroke
-    // - A smaller rect if it's an outer stroke
+    // - A smaller rect if it's an inner stroke
     let stroke_rect = stroke.aligned_rect(rect, scale);
     let mut paint = stroke.to_paint(selrect, svg_attrs, antialias);
 
@@ -34,7 +34,9 @@ fn draw_stroke_on_rect(
     let filter = compose_filters(blur, shadow);
     paint.set_image_filter(filter);
 
-    match corners {
+    // By default just draw the rect. Only dotted inner/outer strokes need
+    // clipping to prevent the dotted pattern from appearing in wrong areas.
+    let draw_stroke = || match corners {
         Some(radii) => {
             let radii = stroke.outer_corners(radii);
             let rrect = RRect::new_rect_radii(stroke_rect, &radii);
@@ -43,6 +45,24 @@ fn draw_stroke_on_rect(
         None => {
             canvas.draw_rect(stroke_rect, &paint);
         }
+    };
+
+    if let Some(clip_op) = stroke.clip_op() {
+        let layer_rec = skia::canvas::SaveLayerRec::default().paint(&paint);
+        canvas.save_layer(&layer_rec);
+        match corners {
+            Some(radii) => {
+                let rrect = RRect::new_rect_radii(*rect, radii);
+                canvas.clip_rrect(rrect, clip_op, antialias);
+            }
+            None => {
+                canvas.clip_rect(*rect, clip_op, antialias);
+            }
+        }
+        draw_stroke();
+        canvas.restore();
+    } else {
+        draw_stroke();
     }
 }
 
@@ -62,7 +82,7 @@ fn draw_stroke_on_circle(
     // Draw the different kind of strokes for an oval is straightforward, we just need apply a stroke to:
     // - The same oval if it's a center stroke
     // - A bigger oval if it's an outer stroke
-    // - A smaller oval if it's an outer stroke
+    // - A smaller oval if it's an inner stroke
     let stroke_rect = stroke.aligned_rect(rect, scale);
     let mut paint = stroke.to_paint(selrect, svg_attrs, antialias);
 
@@ -70,7 +90,19 @@ fn draw_stroke_on_circle(
     let filter = compose_filters(blur, shadow);
     paint.set_image_filter(filter);
 
-    canvas.draw_oval(stroke_rect, &paint);
+    // By default just draw the circle. Only dotted inner/outer strokes need
+    // clipping to prevent the dotted pattern from appearing in wrong areas.
+    if let Some(clip_op) = stroke.clip_op() {
+        let layer_rec = skia::canvas::SaveLayerRec::default().paint(&paint);
+        canvas.save_layer(&layer_rec);
+        let mut clip_path = skia::Path::new();
+        clip_path.add_oval(rect, None);
+        canvas.clip_path(&clip_path, clip_op, antialias);
+        canvas.draw_oval(stroke_rect, &paint);
+        canvas.restore();
+    } else {
+        canvas.draw_oval(stroke_rect, &paint);
+    }
 }
 
 fn draw_outer_stroke_path(

render-wasm/src/shapes/strokes.rs

@@ -119,6 +119,19 @@ impl Stroke {
         self.width *= value;
     }
 
+    /// Returns the clip operation for dotted inner/outer strokes.
+    /// Returns `None` when no clipping is needed (center or non-dotted).
+    pub fn clip_op(&self) -> Option<skia::ClipOp> {
+        if self.style != StrokeStyle::Dotted || self.kind == StrokeKind::Center {
+            return None;
+        }
+        match self.kind {
+            StrokeKind::Inner => Some(skia::ClipOp::Intersect),
+            StrokeKind::Outer => Some(skia::ClipOp::Difference),
+            StrokeKind::Center => None,
+        }
+    }
+
     pub fn delta(&self) -> f32 {
         match self.kind {
             StrokeKind::Inner => 0.,
@@ -128,20 +141,28 @@ impl Stroke {
     }
 
     pub fn outer_rect(&self, rect: &Rect) -> Rect {
-        match self.kind {
-            StrokeKind::Inner => Rect::from_xywh(
-                rect.left + (self.width / 2.),
-                rect.top + (self.width / 2.),
-                rect.width() - self.width,
-                rect.height() - self.width,
-            ),
-            StrokeKind::Center => Rect::from_xywh(rect.left, rect.top, rect.width(), rect.height()),
-            StrokeKind::Outer => Rect::from_xywh(
-                rect.left - (self.width / 2.),
-                rect.top - (self.width / 2.),
-                rect.width() + self.width,
-                rect.height() + self.width,
-            ),
+        match (self.kind, self.style) {
+            (StrokeKind::Inner, StrokeStyle::Dotted) | (StrokeKind::Outer, StrokeStyle::Dotted) => {
+                // Boundary so circles center on it and semicircles match after clipping
+                *rect
+            }
+            _ => match self.kind {
+                StrokeKind::Inner => Rect::from_xywh(
+                    rect.left + (self.width / 2.),
+                    rect.top + (self.width / 2.),
+                    rect.width() - self.width,
+                    rect.height() - self.width,
+                ),
+                StrokeKind::Center => {
+                    Rect::from_xywh(rect.left, rect.top, rect.width(), rect.height())
+                }
+                StrokeKind::Outer => Rect::from_xywh(
+                    rect.left - (self.width / 2.),
+                    rect.top - (self.width / 2.),
+                    rect.width() + self.width,
+                    rect.height() + self.width,
+                ),
+            },
         }
     }
 
@@ -155,6 +176,11 @@ impl Stroke {
     }
 
     pub fn outer_corners(&self, corners: &Corners) -> Corners {
+        if matches!(self.style, StrokeStyle::Dotted | StrokeStyle::Dashed) {
+            // Path at boundary so no corner offset
+            return *corners;
+        }
+
         let offset = match self.kind {
             StrokeKind::Center => 0.0,
             StrokeKind::Inner => -self.width / 2.0,