Import dxf is managed by undo command

sources/editor/UndoCommand/openelmtcommand.cpp

@@ -0,0 +1,62 @@
+/*
+	Copyright 2006-2022 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "openelmtcommand.h"
+#include "../elementscene.h"
+
+#include <QDomDocument>
+#include <QObject>
+
+OpenElmtCommand::OpenElmtCommand(const QDomDocument &document,
+								 QPointer<ElementScene> scene,
+								 QUndoCommand *parent) :
+	QUndoCommand{parent},
+	m_document{document.cloneNode().toDocument()},
+	m_scene{scene}
+{
+	setText(QObject::tr("Ouvrir un element"));
+}
+
+void OpenElmtCommand::undo()
+{
+	for (const auto &item : qAsConst(m_graphics_item)) {
+		m_scene->removeItem(item);
+	}
+}
+
+void OpenElmtCommand::redo()
+{
+	if (!m_scene) {
+		return;
+	}
+
+	if (m_first_redo)
+	{
+		m_scene->fromXml(m_document, QPointF(), true, &m_graphics_item);
+		m_first_redo = false;
+
+			//m_document is now useless,
+			//we clear it to use less memory
+		m_document.clear();
+	}
+	else {
+		for (const auto &item : qAsConst(m_graphics_item)) {
+			m_scene->addItem(item);
+		}
+	}
+	m_scene->slot_select(m_graphics_item);
+}