Share retained preview pass sequence helper

src/legacy_node_stroke_preview_execution_services.h

@@ -130,4 +130,45 @@ struct LegacyNodeStrokePreviewMixPassRequest {
     return plan;
 }
 
+struct LegacyNodeStrokePreviewPassSequenceRequest {
+    bool dual_pass_enabled = false;
+    std::function<void()> prepare_dual_pass;
+    std::function<void()> execute_dual_pass;
+    std::function<void()> capture_background;
+    std::function<void()> prepare_main_pass;
+    std::function<void()> execute_main_pass;
+    std::function<void()> finish_main_pass;
+    std::function<void()> execute_final_composite;
+    std::function<void()> copy_preview_result;
+};
+
+[[nodiscard]] inline bool execute_legacy_node_stroke_preview_pass_sequence(
+    const LegacyNodeStrokePreviewPassSequenceRequest& request)
+{
+    if (!request.capture_background ||
+        !request.prepare_main_pass ||
+        !request.execute_main_pass ||
+        !request.finish_main_pass ||
+        !request.execute_final_composite ||
+        !request.copy_preview_result) {
+        return false;
+    }
+
+    if (request.dual_pass_enabled) {
+        if (!request.prepare_dual_pass || !request.execute_dual_pass) {
+            return false;
+        }
+        request.prepare_dual_pass();
+        request.execute_dual_pass();
+    }
+
+    request.capture_background();
+    request.prepare_main_pass();
+    request.execute_main_pass();
+    request.finish_main_pass();
+    request.execute_final_composite();
+    request.copy_preview_result();
+    return true;
+}
+
 } // namespace pp::panopainter