From e03a852fb2e25bbd591d622a2ce0b5769f0f496d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Elena=20Torr=C3=B3?= <elenatorro@gmail.com>
Date: Fri, 26 Jun 2026 15:39:46 +0200
Subject: [PATCH] :bug: Set evenodd when needed on stroke to path (#10446)

---
 .../data/workspace/path/shapes_to_path.cljs   | 22 ++++++++++---------
 frontend/src/app/render_wasm/api.cljs         | 18 +++++++++------
 render-wasm/src/mem.rs                        | 20 +++++++++++++++++
 render-wasm/src/wasm/paths.rs                 |  4 +++-
 4 files changed, 46 insertions(+), 18 deletions(-)

diff --git a/frontend/src/app/main/data/workspace/path/shapes_to_path.cljs b/frontend/src/app/main/data/workspace/path/shapes_to_path.cljs
index 61134948cd..6c55397514 100644
--- a/frontend/src/app/main/data/workspace/path/shapes_to_path.cljs
+++ b/frontend/src/app/main/data/workspace/path/shapes_to_path.cljs
@@ -104,17 +104,19 @@
   (into []
         (keep-indexed
          (fn [idx stroke]
-           (let [content (wasm.api/stroke-to-path (:id shape) idx)]
-             (when (some? content)
+           (let [result (wasm.api/stroke-to-path (:id shape) idx)]
+             (when (some? result)
                (cts/setup-shape
-                {:type      :path
-                 :id        (uuid/next)
-                 :name      (str (:name shape) " (stroke)")
-                 :parent-id parent-id
-                 :frame-id  frame-id
-                 :content   content
-                 :fills     [(stroke->fill stroke)]
-                 :strokes   []})))))
+                (cond-> {:type      :path
+                         :id        (uuid/next)
+                         :name      (str (:name shape) " (stroke)")
+                         :parent-id parent-id
+                         :frame-id  frame-id
+                         :content   (:content result)
+                         :fills     [(stroke->fill stroke)]
+                         :strokes   []}
+                  (:even-odd? result)
+                  (assoc :svg-attrs {:fillRule "evenodd"})))))))
         (:strokes shape)))
 
 (defn convert-selected-strokes-to-path
diff --git a/frontend/src/app/render_wasm/api.cljs b/frontend/src/app/render_wasm/api.cljs
index a1a0a2f6bf..d2e1be72bf 100644
--- a/frontend/src/app/render_wasm/api.cljs
+++ b/frontend/src/app/render_wasm/api.cljs
@@ -2272,21 +2272,25 @@
 
 (defn stroke-to-path
   "Converts a shape's stroke at the given index into a filled path.
-   Returns the stroke outline as PathData content."
+   Returns a map {:content <PathData> :even-odd? <boolean>}, or nil when the
+   stroke produces no geometry. The buffer carries two header words ahead of
+   the segments: [even-odd flag][length] (the flat segment list can't encode
+   the fill rule itself)."
   [id stroke-index]
   (use-shape id)
   (try
-    (let [offset (-> (h/call wasm/internal-module "_convert_stroke_to_path" stroke-index)
-                     (mem/->offset-32))
-          heap   (mem/get-heap-u32)
-          length (aget heap offset)]
+    (let [offset    (-> (h/call wasm/internal-module "_convert_stroke_to_path" stroke-index)
+                        (mem/->offset-32))
+          heap      (mem/get-heap-u32)
+          even-odd? (not (zero? (aget heap offset)))
+          length    (aget heap (inc offset))]
       (if (pos? length)
         (let [data    (mem/slice heap
-                                 (+ offset 1)
+                                 (+ offset 2)
                                  (* length path.impl/SEGMENT-U32-SIZE))
               content (path/from-bytes data)]
           (mem/free)
-          content)
+          {:content content :even-odd? even-odd?})
         (do (mem/free)
             nil)))
     (catch :default cause
diff --git a/render-wasm/src/mem.rs b/render-wasm/src/mem.rs
index 1c8531e7e9..a786f8eb55 100644
--- a/render-wasm/src/mem.rs
+++ b/render-wasm/src/mem.rs
@@ -95,3 +95,23 @@ pub fn write_vec<T: SerializableResult>(result: Vec<T>) -> *mut u8 {
 
     write_bytes(result_bytes)
 }
+
+/*
+  Like `write_vec`, but prepends an extra u32 header word before the
+  length. Layout: [header u32][length u32][items...]
+*/
+pub fn write_vec_with_header<T: SerializableResult>(header: u32, result: Vec<T>) -> *mut u8 {
+    let elem_size = size_of::<T::BytesType>();
+    let bytes_len = 8 + result.len() * elem_size;
+    let mut result_bytes = vec![0; bytes_len];
+
+    result_bytes[0..4].clone_from_slice(&header.to_le_bytes());
+    result_bytes[4..8].clone_from_slice(&result.len().to_le_bytes());
+
+    for (i, item) in result.iter().enumerate() {
+        let base = 8 + i * elem_size;
+        item.clone_to_slice(&mut result_bytes[base..base + elem_size]);
+    }
+
+    write_bytes(result_bytes)
+}
diff --git a/render-wasm/src/wasm/paths.rs b/render-wasm/src/wasm/paths.rs
index 2350edb393..b035ee4f81 100644
--- a/render-wasm/src/wasm/paths.rs
+++ b/render-wasm/src/wasm/paths.rs
@@ -243,6 +243,7 @@ pub extern "C" fn current_to_path() -> *mut u8 {
 #[no_mangle]
 pub extern "C" fn convert_stroke_to_path(stroke_index: i32) -> *mut u8 {
     let mut result = Vec::<RawSegmentData>::default();
+    let mut even_odd = false;
     with_current_shape!(state, |shape: &Shape| {
         let idx = stroke_index as usize;
         if let Some(stroke) = shape.strokes.get(idx) {
@@ -257,6 +258,7 @@ pub extern "C" fn convert_stroke_to_path(stroke_index: i32) -> *mut u8 {
                 shape.svg_attrs.as_ref(),
                 false,
             ) {
+                even_odd = path.is_even_odd();
                 result = path
                     .segments()
                     .iter()
@@ -267,7 +269,7 @@ pub extern "C" fn convert_stroke_to_path(stroke_index: i32) -> *mut u8 {
         }
     });
 
-    mem::write_vec(result)
+    mem::write_vec_with_header(even_odd as u32, result)
 }
 
 #[cfg(test)]