Change rectangle clip to use the inside of the stroke, not the middle. (#2626)

crates/typst-library/src/layout/container.rs

@@ -155,7 +155,7 @@ impl Layout for BoxElem {
             let outset = self.outset(styles).relative_to(frame.size());
             let size = frame.size() + outset.sum_by_axis();
             let radius = self.radius(styles);
-            frame.clip(path_rect(size, radius, &stroke));
+            frame.clip(clip_rect(size, radius, &stroke));
         }
 
         // Add fill and/or stroke.
@@ -421,7 +421,7 @@ impl Layout for BlockElem {
                 let outset = self.outset(styles).relative_to(frame.size());
                 let size = frame.size() + outset.sum_by_axis();
                 let radius = self.radius(styles);
-                frame.clip(path_rect(size, radius, &stroke));
+                frame.clip(clip_rect(size, radius, &stroke));
             }
         }
 

crates/typst/src/geom/mod.rs

@@ -46,7 +46,7 @@ pub use self::paint::Paint;
 pub use self::path::{Path, PathItem};
 pub use self::point::Point;
 pub use self::ratio::Ratio;
-pub use self::rect::{path_rect, styled_rect};
+pub use self::rect::{clip_rect, styled_rect};
 pub use self::rel::Rel;
 pub use self::scalar::Scalar;
 pub use self::shape::{Geometry, Shape};

crates/typst/src/geom/rect.rs

@@ -43,16 +43,41 @@ impl PathExtension for Path {
 }
 
 /// Creates a new rectangle as a path.
-pub fn path_rect(
+pub fn clip_rect(
     size: Size,
     radius: Corners<Rel<Abs>>,
     stroke: &Sides<Option<FixedStroke>>,
 ) -> Path {
-    if stroke.is_uniform() && radius.iter().cloned().all(Rel::is_zero) {
-        Path::rect(size)
+    let stroke_widths = stroke
+        .as_ref()
+        .map(|s| s.as_ref().map_or(Abs::zero(), |s| s.thickness / 2.0));
+
+    let max_radius = (size.x.min(size.y)) / 2.0
+        + stroke_widths.iter().cloned().min().unwrap_or(Abs::zero());
+
+    let radius = radius.map(|side| side.relative_to(max_radius * 2.0).min(max_radius));
+
+    let corners = corners_control_points(size, radius, stroke, stroke_widths);
+
+    let mut path = Path::new();
+    if corners.top_left.arc_inner() {
+        path.arc_move(
+            corners.top_left.start_inner(),
+            corners.top_left.center_inner(),
+            corners.top_left.end_inner(),
+        );
     } else {
-        segmented_path_rect(size, radius, stroke)
+        path.move_to(corners.top_left.center_inner());
     }
+    for corner in [&corners.top_right, &corners.bottom_right, &corners.bottom_left] {
+        if corner.arc_inner() {
+            path.arc_line(corner.start_inner(), corner.center_inner(), corner.end_inner())
+        } else {
+            path.line_to(corner.center_inner());
+        }
+    }
+    path.close_path();
+    path
 }
 
 /// Create a styled rectangle with shapes.
@@ -110,46 +135,6 @@ fn corners_control_points(
     })
 }
 
-fn segmented_path_rect(
-    size: Size,
-    radius: Corners<Rel<Abs>>,
-    strokes: &Sides<Option<FixedStroke>>,
-) -> Path {
-    let stroke_widths = strokes
-        .as_ref()
-        .map(|s| s.as_ref().map_or(Abs::zero(), |s| s.thickness / 2.0));
-
-    let max_radius = (size.x.min(size.y)) / 2.0
-        + stroke_widths.iter().cloned().min().unwrap_or(Abs::zero());
-
-    let radius = radius.map(|side| side.relative_to(max_radius * 2.0).min(max_radius));
-
-    // insert stroked sides below filled sides
-    let mut path = Path::new();
-    let corners = corners_control_points(size, radius, strokes, stroke_widths);
-    let current = corners.iter().find(|c| !c.same).map(|c| c.corner);
-    if let Some(mut current) = current {
-        // multiple segments
-        // start at a corner with a change between sides and iterate clockwise all other corners
-        let mut last = current;
-        for _ in 0..4 {
-            current = current.next_cw();
-            if corners.get_ref(current).same {
-                continue;
-            }
-            // create segment
-            let start = last;
-            let end = current;
-            last = current;
-            path_segment(start, end, &corners, &mut path);
-        }
-    } else if strokes.top.is_some() {
-        // single segment
-        path_segment(Corner::TopLeft, Corner::TopLeft, &corners, &mut path);
-    }
-    path
-}
-
 /// Use stroke and fill for the rectangle
 fn segmented_rect(
     size: Size,

tests/typ/layout/clip.typ

@@ -54,3 +54,15 @@ First!
   clip: true,
   image("/files/rhino.png", width: 30pt)
 )
+---
+// Test clipping with `radius`, but without `stroke`.
+
+#set page(height: 60pt)
+
+#box(
+  radius: 5pt,
+  width: 20pt,
+  height: 20pt,
+  clip: true,
+  image("/files/rhino.png", width: 30pt)
+)