Centralize retained menu popup attachment

src/legacy_ui_overlay_services.cpp

@@ -3,6 +3,7 @@
 
 #include "app.h"
 #include "node.h"
+#include "node_popup_menu.h"
 
 namespace pp::panopainter {
 
@@ -31,4 +32,45 @@ pp::foundation::Status attach_legacy_overlay_node(
     return pp::foundation::Status::success();
 }
 
+pp::foundation::Result<std::shared_ptr<NodePopupMenu>> add_legacy_popup_menu(
+    App& app,
+    const char* template_id,
+    float x,
+    float y,
+    float rtl_anchor_width) noexcept
+{
+    if (!template_id) {
+        return pp::foundation::Result<std::shared_ptr<NodePopupMenu>>::failure(
+            pp::foundation::Status::invalid_argument("legacy popup template id is null"));
+    }
+
+    auto* template_root = app.layout[const_hash(template_id)];
+    if (!template_root || template_root->m_children.empty()) {
+        return pp::foundation::Result<std::shared_ptr<NodePopupMenu>>::failure(
+            pp::foundation::Status::invalid_argument("legacy popup template is missing"));
+    }
+
+    auto popup = template_root->m_children[0]->clone<NodePopupMenu>();
+    if (!popup) {
+        return pp::foundation::Result<std::shared_ptr<NodePopupMenu>>::failure(
+            pp::foundation::Status::invalid_argument("legacy popup clone failed"));
+    }
+
+    popup->update();
+    if (auto* root = app.layout[app.main_id]) {
+        if (YGNodeStyleGetDirection(root->y_node) == YGDirectionRTL) {
+            x = x - popup->m_size.x + rtl_anchor_width;
+        }
+    }
+    popup->SetPositioning(YGPositionTypeAbsolute);
+    popup->SetPosition(x, y);
+
+    const auto status = attach_legacy_overlay_node(app, popup);
+    if (!status.ok()) {
+        return pp::foundation::Result<std::shared_ptr<NodePopupMenu>>::failure(status);
+    }
+
+    return pp::foundation::Result<std::shared_ptr<NodePopupMenu>>::success(popup);
+}
+
 } // namespace pp::panopainter