1 files changed, 77 insertions, 0 deletions
diff --git a/src/xml/helper-observer.cpp b/src/xml/helper-observer.cpp
new file mode 100644
index 0000000..05161e9
--- /dev/null
+++ b/src/xml/helper-observer.cpp
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include "helper-observer.h"
+
+#include "object/sp-object.h"
+
+namespace Inkscape {
+namespace XML {
+
+// Very simple observer that just emits a signal if anything happens to a node
+SignalObserver::SignalObserver()
+    : _oldsel(nullptr)
+{}
+
+SignalObserver::~SignalObserver()
+{
+    set(nullptr); // if _oldsel!=nullptr, remove observer and decrease refcount
+}
+
+// Add this observer to the SPObject and remove it from any previous object
+void SignalObserver::set(SPObject* o)
+{
+  // XML Tree being used directly in this function in the following code
+  //   while it shouldn't be
+  // Pointer to object is stored, so refcounting should be increased/decreased
+    if(_oldsel) {
+        if (_oldsel->getRepr()) {
+            _oldsel->getRepr()->removeObserver(*this);
+        }
+        sp_object_unref(_oldsel);
+        _oldsel = nullptr;
+    }
+    if(o) {
+        if (o->getRepr()) {
+            o->getRepr()->addObserver(*this);
+            sp_object_ref(o);
+            _oldsel = o;
+        }
+    }
+}
+
+void SignalObserver::notifyChildAdded(XML::Node&, XML::Node&, XML::Node*)
+{ signal_changed()(); }
+
+void SignalObserver::notifyChildRemoved(XML::Node&, XML::Node&, XML::Node*)
+{ signal_changed()(); }
+
+void SignalObserver::notifyChildOrderChanged(XML::Node&, XML::Node&, XML::Node*, XML::Node*)
+{ signal_changed()(); }
+
+void SignalObserver::notifyContentChanged(XML::Node&, Util::ptr_shared, Util::ptr_shared)
+{}
+
+void SignalObserver::notifyAttributeChanged(XML::Node&, GQuark, Util::ptr_shared, Util::ptr_shared)
+{ signal_changed()(); }
+
+void SignalObserver::notifyElementNameChanged(Node&, GQuark, GQuark)
+{
+    signal_changed()();
+}
+
+sigc::signal<void>& SignalObserver::signal_changed()
+{
+    return _signal_changed;
+}
+
+} //namespace XML
+} //namespace Inkscape
+