Share retained stroke frame execution helpers

src/legacy_canvas_stroke_execution_services.h

@@ -293,6 +293,41 @@ std::size_t execute_legacy_canvas_stroke_frame_samples(
     return result;
 }
 
+template <typename ExecuteSample, typename BeginFace, typename PrepareDirtyRequest, typename FinishFace>
+[[nodiscard]] inline LegacyCanvasStrokeFaceDirtyResult execute_legacy_canvas_stroke_face_sample(
+    const LegacyCanvasStrokeFaceDirtyRequest& dirty_request,
+    ExecuteSample&& execute_sample,
+    BeginFace&& begin_face,
+    PrepareDirtyRequest&& prepare_dirty_request,
+    FinishFace&& finish_face,
+    glm::vec4* accumulated_dirty_box = nullptr,
+    glm::vec4* pass_dirty_box = nullptr,
+    bool* committed_dirty = nullptr,
+    bool* pass_dirty = nullptr) noexcept(noexcept(execute_sample()))
+{
+    LegacyCanvasStrokeFaceDirtyResult result;
+    begin_face();
+
+    auto request = dirty_request;
+    request.sample_dirty_box = execute_sample();
+    prepare_dirty_request(request);
+
+    finish_face(request.sample_dirty_box);
+
+    glm::vec4 accumulated = request.previous_accumulated_dirty_box;
+    result = apply_legacy_canvas_stroke_face_dirty_update(
+        request,
+        accumulated,
+        pass_dirty_box,
+        committed_dirty,
+        pass_dirty);
+    result.accumulated_dirty_box = accumulated;
+    if (accumulated_dirty_box) {
+        *accumulated_dirty_box = accumulated;
+    }
+    return result;
+}
+
 [[nodiscard]] inline LegacyCanvasStrokePadExecutionResult execute_legacy_canvas_stroke_pad_faces(
     const LegacyCanvasStrokePadExecutionRequest& request)
 {