Refactored XML processing, improved copy&paste, new file format

17 files changed, 397 insertions, 145 deletions

diff --git a/src/databaserelationship.cpp b/src/databaserelationship.cpp
index 2858f60..02540c5 100644
--- a/src/databaserelationship.cpp
+++ b/src/databaserelationship.cpp
@@ -228,3 +228,17 @@ DatabaseRelationship::updateLayout()
 	m_arrowHead = matrix.map(m_arrowHead);
 	m_arrowHead.translate(lastSegment.p2());
 }
+
+#include "domutils.h"
+
+void
+DatabaseRelationship::loadFromXml(QDomElement element, DiagramDocument *document)
+{
+	DiagramConnection::loadFromXml(element, document);
+}
+
+void
+DatabaseRelationship::saveToXml(QDomDocument doc, QDomElement element)
+{
+	DiagramConnection::saveToXml(doc, element);
+}
diff --git a/src/databaserelationship.h b/src/databaserelationship.h
index f0edd68..e9e26d0 100644
--- a/src/databaserelationship.h
+++ b/src/databaserelationship.h
@@ -39,6 +39,12 @@ public:
 	enum { Type = DiagramItem::Relation };
 	virtual int type() const { return Type; }
 
+	static const char *staticTypeName() { return "database-relationship"; }
+	virtual const char *typeName() { return staticTypeName(); }
+
+	void loadFromXml(QDomElement element, DiagramDocument *document = 0);
+	void saveToXml(QDomDocument doc, QDomElement element);
+
 	void updatePositions();
 
 protected slots:
diff --git a/src/databasetable.cpp b/src/databasetable.cpp
index cfbeb5d..911457f 100644
--- a/src/databasetable.cpp
+++ b/src/databasetable.cpp
@@ -183,11 +183,46 @@ DatabaseTable::updateLayout()
 	update();
 }
 
-QMimeData *
-DatabaseTable::toMimeData()
+#include "domutils.h"
+
+void
+DatabaseTable::loadFromXml(QDomElement element, DiagramDocument *document)
 {
-	QMimeData *mimeData = new QMimeData();
-	QByteArray data = name().toUtf8();
-	mimeData->setData("application/dbmodel.object", data);
-	return mimeData;
+	DiagramItem::loadFromXml(element, document);
+	QDomElement tableElement = element.firstChildElement("table");
+	if (!tableElement.isNull()) {
+		setName(readStringElement(tableElement, "name"));
+		QDomElement columnListElement = tableElement.firstChildElement("column-list");
+		QDomElement columnElement = columnListElement.firstChildElement("column");
+		while (!columnElement.isNull()) {
+			Column *column = new Column();
+			column->setName(readStringElement(columnElement, "name"));
+			column->setDataType(readStringElement(columnElement, "data-type"));
+			column->setRequired(readStringElement(columnElement, "required") == "yes");
+			column->setPrimaryKey(readStringElement(columnElement, "primary-key") == "yes");
+			column->setNotes(readStringElement(columnElement, "notes"));
+			columnList()->appendColumn(column);
+			columnElement = columnElement.nextSiblingElement("column");
+		}
+	}
+}
+
+void
+DatabaseTable::saveToXml(QDomDocument doc, QDomElement element)
+{
+	DiagramItem::saveToXml(doc, element);
+	QDomElement tableElement = doc.createElement("table");
+	element.appendChild(tableElement);
+	appendStringElement(doc, tableElement, "name", name());
+	QDomElement columnListElement = doc.createElement("column-list");
+	tableElement.appendChild(columnListElement);
+	foreach (Column *column, columnList()->columns()) {
+		QDomElement columnElement = doc.createElement("column");
+		columnListElement.appendChild(columnElement);
+		appendStringElement(doc, columnElement, "name", column->name());
+		appendStringElement(doc, columnElement, "data-type", column->dataType());
+		appendStringElement(doc, columnElement, "required", column->isRequired() ? "yes" : QString());
+		appendStringElement(doc, columnElement, "primary-key", column->isPrimaryKey() ? "yes" : QString());
+		appendStringElement(doc, columnElement, "notes", column->notes());
+	}
 }
diff --git a/src/databasetable.h b/src/databasetable.h
index 9268b0d..8be1ee5 100644
--- a/src/databasetable.h
+++ b/src/databasetable.h
@@ -51,7 +51,13 @@ public:
 	enum { Type = DiagramItem::Table };
 	virtual int type() const { return Type; }
 
-	QMimeData *toMimeData();
+	static const char *staticTypeName() { return "database-table"; }
+	virtual const char *typeName() { return staticTypeName(); }
+
+	void loadFromXml(QDomElement element, DiagramDocument *document = 0);
+	void saveToXml(QDomDocument doc, QDomElement element);
+
+// 	QMimeData *toMimeData();
 
 signals:
 	void propertyChanged(const QString &name, const QVariant &value);
diff --git a/src/diagramconnection.cpp b/src/diagramconnection.cpp
index 1b1865a..545f9bf 100644
--- a/src/diagramconnection.cpp
+++ b/src/diagramconnection.cpp
@@ -15,6 +15,8 @@
 // 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
 #include "diagramconnection.h"
+#include "diagramdocument.h"
+#include "diagramobject.h"
 
 DiagramConnection::DiagramConnection(DiagramItem *parent)
 	: DiagramItem(parent)
@@ -42,3 +44,32 @@ void
 DiagramConnection::updatePositions()
 {
 }
+
+#include "domutils.h"
+
+void
+DiagramConnection::loadFromXml(QDomElement element, DiagramDocument *document)
+{
+	DiagramItem::loadFromXml(element, document);
+	QDomElement connectionElement = element.firstChildElement("connection");
+	if (!connectionElement.isNull()) {
+		QString sourceId = readStringElement(connectionElement, "source");
+		QString targetId = readStringElement(connectionElement, "target");
+		if (document) {
+			setSource(qobject_cast<DiagramObject *>(document->itemById(sourceId)));
+			setTarget(qobject_cast<DiagramObject *>(document->itemById(targetId)));
+		}
+	}
+}
+
+void
+DiagramConnection::saveToXml(QDomDocument doc, QDomElement element)
+{
+	DiagramItem::saveToXml(doc, element);
+	QDomElement connectionElement = doc.createElement("connection");
+	element.appendChild(connectionElement);
+	if (m_objects[0] != NULL)
+		appendStringElement(doc, connectionElement, "source", m_objects[0]->id());
+	if (m_objects[1] != NULL)
+		appendStringElement(doc, connectionElement, "target", m_objects[1]->id());
+}
diff --git a/src/diagramconnection.h b/src/diagramconnection.h
index 1ad52e5..9ea97d5 100644
--- a/src/diagramconnection.h
+++ b/src/diagramconnection.h
@@ -35,6 +35,9 @@ public:
 
 	virtual void updatePositions();
 
+	virtual void loadFromXml(QDomElement element, DiagramDocument *document = 0);
+	void saveToXml(QDomDocument doc, QDomElement element);
+
 signals:
 	void endPointChanged();
 
diff --git a/src/diagramdocument.cpp b/src/diagramdocument.cpp
index b8ad744..d1ae22e 100644
--- a/src/diagramdocument.cpp
+++ b/src/diagramdocument.cpp
@@ -91,6 +91,7 @@ DiagramDocument::mousePressEvent(QGraphicsSceneMouseEvent *event)
 	m_trackingMoves = true;
 	if (m_mode == AddTable && event->button() == Qt::LeftButton) {
 		DatabaseTable *table = new DatabaseTable();
+		table->createId();
 		table->setPos(event->scenePos());
 		undoStack()->push(new AddItemCommand(this, table));
 		clearSelection();
@@ -135,6 +136,7 @@ DiagramDocument::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
 		DatabaseTable *target = qgraphicsitem_cast<DatabaseTable *>(itemAt(m_line->line().p2()));
 		if (source && target && source != target) {
 			DatabaseRelationship *relation = new DatabaseRelationship();
+			relation->createId();
 			relation->setSource(source);
 			relation->setTarget(target);
 			undoStack()->push(new AddItemCommand(this, relation));
@@ -185,73 +187,33 @@ DiagramDocument::findConnections(DiagramObject *object)
 	return result;
 }
 
-void
-appendStringElement(QDomDocument &doc, QDomElement &parent, const QString &name, const QString &value)
-{
-	if (!value.isEmpty()) {
-		QDomElement element = doc.createElement(name);
-		element.appendChild(doc.createTextNode(value));
-		parent.appendChild(element);
-	}
-}
-
-QString
-readStringElement(QDomElement &parent, const QString &name, const QString &defaultValue = QString())
-{
-	QDomElement element = parent.firstChildElement(name);
-	if (!element.isNull()) {
-		return element.text();
-	}
-	return defaultValue;
-}
+#include "domutils.h"
 
 void
 DiagramDocument::save(const QString &fileName)
 {
 	QDomDocument doc;
 
-	QDomElement root = doc.createElement("database-model");
-	doc.appendChild(root);
-
-	QDomElement tableListElement = doc.createElement("table-list");
-	root.appendChild(tableListElement);
-
-	QList<DatabaseTable *> tables = itemsByType<DatabaseTable>();
-	foreach (DatabaseTable *table, tables) {
-		QDomElement tableElement = doc.createElement("table");
-		tableListElement.appendChild(tableElement);
-		
-		QDomElement positionElement = doc.createElement("position");
-		positionElement.setAttribute("x", table->pos().x());
-		positionElement.setAttribute("y", table->pos().y());
-		tableElement.appendChild(positionElement);
+	QDomProcessingInstruction xml = doc.createProcessingInstruction("xml", "version=\"1.0\" encoding=\"UTF-8\"");
+	doc.appendChild(xml);
 
-		QDomElement nameElement = doc.createElement("name");
-		nameElement.appendChild(doc.createTextNode(table->name()));
-		tableElement.appendChild(nameElement);
+	QDomElement root = doc.createElement("diagram");
+	root.setAttribute("xmlns", "http://oxygene.sk/ns/diagram/1/");
+	doc.appendChild(root);
 
-		QDomElement columnListElement = doc.createElement("column-list");
-		tableElement.appendChild(columnListElement);
+	QDomElement itemList = doc.createElement("item-list");
+	root.appendChild(itemList);
 
-		foreach (Column *column, table->columnList()->columns()) {
-			QDomElement columnElement = doc.createElement("column");
-			columnListElement.appendChild(columnElement);
-			appendStringElement(doc, columnElement, "name", column->name());
-			appendStringElement(doc, columnElement, "data-type", column->dataType());
-			appendStringElement(doc, columnElement, "required", column->isRequired() ? "yes" : QString());
-			appendStringElement(doc, columnElement, "primary-key", column->isPrimaryKey() ? "yes" : QString());
-			appendStringElement(doc, columnElement, "notes", column->notes());
-		}
+	foreach (DiagramObject *item, itemsByType<DiagramObject>()) {
+		QDomElement element = doc.createElement("item");
+		itemList.appendChild(element);
+		item->saveToXml(doc, element);
 	}
-	
-	QDomElement relationListElement = doc.createElement("relation-list");
-	root.appendChild(relationListElement);
 
-	foreach (DatabaseRelationship *relation, itemsByType<DatabaseRelationship>()) {
-		QDomElement relationElement = doc.createElement("relation");
-		relationElement.setAttribute("from", QString::number(tables.indexOf(relation->sourceTable())));
-		relationElement.setAttribute("to", QString::number(tables.indexOf(relation->targetTable())));
-		relationListElement.appendChild(relationElement);
+	foreach (DiagramConnection *item, itemsByType<DiagramConnection>()) {
+		QDomElement element = doc.createElement("item");
+		itemList.appendChild(element);
+		item->saveToXml(doc, element);
 	}
 
 	QFile file(fileName);
@@ -264,6 +226,8 @@ DiagramDocument::save(const QString &fileName)
 	setFileName(fileName);
 }
 
+#include "diagramitemregistry.h"
+
 void
 DiagramDocument::load(const QString &fileName)
 {
@@ -273,61 +237,29 @@ DiagramDocument::load(const QString &fileName)
 		doc.setContent(&file);
 		file.close();
 	}
-
 	setFileName(fileName);
-
-	QDomElement root = doc.firstChildElement("database-model");
-
-	QList<DatabaseTable *> tables;
-
-	QDomElement tableListElement = root.firstChildElement("table-list");
-	QDomElement tableElement = tableListElement.firstChildElement("table");
-	while (!tableElement.isNull()) {
-		DatabaseTable *table = new DatabaseTable;
-
-		QDomElement positionElement = tableElement.firstChildElement("position");
-		if (!positionElement.isNull()) {
-			QPoint pos;
-			pos.setX(positionElement.attribute("x", "0").toInt());
-			pos.setY(positionElement.attribute("y", "0").toInt());
-			table->setPos(pos);
+	QDomElement root = doc.firstChildElement("diagram");
+	QDomElement itemListElement = root.firstChildElement("item-list");
+	QDomElement itemElement = itemListElement.firstChildElement("item");
+	while (!itemElement.isNull()) {
+		QString itemTypeName = itemElement.attribute("type");
+		DiagramItem *item = DiagramItemRegistry::createItem(itemTypeName);
+		if (item == NULL) {
+			qWarning() << "Unknown item type:" << itemTypeName;
 		}
-
-		table->setName(readStringElement(tableElement, "name"));
-
-		QDomElement columnListElement = tableElement.firstChildElement("column-list");
-		QDomElement columnElement = columnListElement.firstChildElement("column");
-		while (!columnElement.isNull()) {
-			Column *column = new Column();
-			column->setName(readStringElement(columnElement, "name"));
-			column->setDataType(readStringElement(columnElement, "data-type"));
-			column->setRequired(readStringElement(columnElement, "required") == "yes");
-			column->setPrimaryKey(readStringElement(columnElement, "primary-key") == "yes");
-			column->setNotes(readStringElement(columnElement, "notes"));
-			table->columnList()->appendColumn(column);
-			columnElement = columnElement.nextSiblingElement("column");
+		else {
+			item->loadFromXml(itemElement, this);
+			addItem(item);
 		}
-
-		addItem(table);
-		tables.append(table);
-
-		tableElement = tableElement.nextSiblingElement("table");
+		itemElement = itemElement.nextSiblingElement("item");
 	}
+}
 
-	QDomElement relationListElement = root.firstChildElement("relation-list");
-	QDomElement relationElement = relationListElement.firstChildElement("relation");
-	while (!relationElement.isNull()) {
-		relationElement = relationElement.nextSiblingElement("relation");
-		bool ok;
-		int index0 = relationElement.attribute("from").toInt(&ok);
-		if (ok) {
-			int index1 = relationElement.attribute("to").toInt(&ok);
-			if (ok) {
-				DatabaseRelationship *relation = new DatabaseRelationship();
-				relation->setSource(tables[index0]);
-				relation->setTarget(tables[index1]);
-				addItem(relation);
-			}
-		}
-	}
+DiagramItem *
+DiagramDocument::itemById(const QUuid &id)
+{
+	foreach (DiagramItem *item, itemsByType<DiagramItem>())
+		if (item->id() == id)
+			return item;
+	return 0;
 }
diff --git a/src/diagramdocument.h b/src/diagramdocument.h
index 79d38d9..747508b 100644
--- a/src/diagramdocument.h
+++ b/src/diagramdocument.h
@@ -23,6 +23,7 @@
 #include <QDomDocument>
 #include <QGraphicsLineItem>
 #include <QSet>
+#include <QUuid>
 
 class DatabaseTable;
 class DatabaseRelationship;
@@ -55,6 +56,8 @@ public:
 	QString fileName() { return m_fileName; }
 	void setFileName(const QString &fileName) { m_fileName = fileName; }
 
+	DiagramItem *itemById(const QUuid &id);
+
 	QUndoStack *undoStack() const { return m_undoStack; }
 
 	void itemMoved(DiagramItem *table);
diff --git a/src/diagramitem.cpp b/src/diagramitem.cpp
index ddb6269..bcb5e24 100644
--- a/src/diagramitem.cpp
+++ b/src/diagramitem.cpp
@@ -14,9 +14,98 @@
 // with this program; if not, write to the Free Software Foundation, Inc.,
 // 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
+#include <QMimeData>
+#include <QDomProcessingInstruction>
+#include <QDebug>
+#include "diagramdocument.h"
 #include "diagramitem.h"
+#include "diagramitemregistry.h"
 
 DiagramItem::DiagramItem(DiagramItem *parent)
 	: QGraphicsItem(parent)
 {
 }
+
+void
+DiagramItem::setId(QUuid id)
+{
+	m_id = id;
+}
+
+void
+DiagramItem::createId()
+{
+	m_id = QUuid::createUuid();
+}
+
+DiagramDocument *
+DiagramItem::document() const
+{
+	return qobject_cast<DiagramDocument *>(scene());
+}
+
+void
+DiagramItem::loadFromXml(QDomElement element, DiagramDocument *)
+{
+	setId(element.attribute("id", QUuid()));
+	QDomElement positionElement = element.firstChildElement("position");
+	if (!positionElement.isNull()) {
+		QPoint pos;
+		pos.setX(positionElement.attribute("x", "0").toInt());
+		pos.setY(positionElement.attribute("y", "0").toInt());
+		setPos(pos);
+	}
+}
+
+void
+DiagramItem::saveToXml(QDomDocument doc, QDomElement element)
+{
+	element.setAttribute("type", typeName());
+	element.setAttribute("id", id());
+	QDomElement positionElement = doc.createElement("position");
+	positionElement.setAttribute("x", pos().x());
+	positionElement.setAttribute("y", pos().y());
+	element.appendChild(positionElement);
+}
+
+QMimeData *
+DiagramItem::toMimeData()
+{
+	QDomDocument doc;
+	QDomProcessingInstruction xml = doc.createProcessingInstruction("xml", "version=\"1.0\" encoding=\"UTF-8\"");
+	doc.appendChild(xml);
+	QDomElement element = doc.createElement("item");
+	doc.appendChild(element);
+	saveToXml(doc, element);
+
+	QByteArray data;
+	QTextStream stream(&data);
+	doc.save(stream, 0);
+
+	QMimeData *mimeData = new QMimeData();
+	mimeData->setData("application/dbmodel.item", data);
+	return mimeData;
+}
+
+DiagramItem *
+DiagramItem::fromMimeData(const QMimeData *mimeData)
+{
+	QByteArray data = mimeData->data("application/dbmodel.item");
+	if (data.isNull())
+		return 0;
+
+	QDomDocument doc;
+	doc.setContent(data);
+
+	QDomElement element = doc.firstChildElement("item");
+	if (element.isNull())
+		return 0;
+
+	DiagramItem *item = DiagramItemRegistry::createItem(element.attribute("type"));
+	if (item == NULL)
+		return 0;
+
+	item->loadFromXml(element);
+	item->createId();
+	return item;
+}
diff --git a/src/diagramitem.h b/src/diagramitem.h
index f66a48c..3444f8d 100644
--- a/src/diagramitem.h
+++ b/src/diagramitem.h
@@ -18,16 +18,41 @@
 #define DATABASEMODELITEM_H
 
 #include <QGraphicsItem>
+#include <QDomDocument>
+#include <QDomElement>
+#include <QUuid>
+class QMimeData;
+class DiagramDocument;
 
 class DiagramItem : public QObject, public QGraphicsItem
 {
+	Q_OBJECT
+
 public:
 	enum {
 		Table = UserType + 1,
 		Relation
 	};
 
+	DiagramDocument *document() const;
+
+	QUuid id() const { return m_id; }
+	void setId(QUuid id);
+	void createId();
+
 	DiagramItem(DiagramItem *parent = 0);
+
+	static const char *staticTypeName() { return ""; }
+	virtual const char *typeName() = 0;
+
+	virtual void loadFromXml(QDomElement element, DiagramDocument *document = 0);
+	virtual void saveToXml(QDomDocument doc, QDomElement element);
+
+	virtual QMimeData *toMimeData();
+	static DiagramItem *fromMimeData(const QMimeData *mimeData);
+
+public:
+	QUuid m_id;
 };
 
 #endif
diff --git a/src/diagramitemregistry.cpp b/src/diagramitemregistry.cpp
new file mode 100644
index 0000000..ebc4f10
--- /dev/null
+++ b/src/diagramitemregistry.cpp
@@ -0,0 +1,46 @@
+// Copyright (C) 2008  Lukas Lalinsky
+//
+// This program 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.
+//
+// This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+#include <QDebug>
+#include "diagramitem.h"
+#include "diagramitemregistry.h"
+
+DiagramItemRegistry *DiagramItemRegistry::m_registry = 0;
+
+template <class T> DiagramItem *__createItem() { return new T(); }
+#define ADD_TYPE(x) m_map[x::staticTypeName()] = &(__createItem<x>);
+
+DiagramItem *
+DiagramItemRegistry::createItem(const QString &typeName)
+{
+	if (!DiagramItemRegistry::m_registry)
+		DiagramItemRegistry::m_registry = new DiagramItemRegistry();
+	if (!DiagramItemRegistry::m_registry->m_map.contains(typeName))
+		return 0;
+	return DiagramItemRegistry::m_registry->m_map[typeName]();
+}
+
+// =========================================================================
+// =========================================================================
+
+#include "databasetable.h"
+#include "databaserelationship.h"
+
+DiagramItemRegistry::DiagramItemRegistry()
+{
+	ADD_TYPE(DatabaseTable);
+	ADD_TYPE(DatabaseRelationship);
+}
diff --git a/src/diagramitemregistry.h b/src/diagramitemregistry.h
new file mode 100644
index 0000000..7806574
--- /dev/null
+++ b/src/diagramitemregistry.h
@@ -0,0 +1,36 @@
+// Copyright (C) 2008  Lukas Lalinsky
+//
+// This program 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.
+//
+// This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+#ifndef DIAGRAMITEMREGISTRY_H
+#define DIAGRAMITEMREGISTRY_H
+
+#include <QString>
+class DiagramItem;
+
+typedef DiagramItem *(*createItemFunc)();
+
+class DiagramItemRegistry
+{
+public:
+	static DiagramItem *createItem(const QString &typeName);
+
+private:
+	DiagramItemRegistry();
+	static DiagramItemRegistry *m_registry;
+	QMap<QString, createItemFunc> m_map;
+};
+
+#endif
diff --git a/src/diagramobject.cpp b/src/diagramobject.cpp
index 1bc6300..e0d6c17 100644
--- a/src/diagramobject.cpp
+++ b/src/diagramobject.cpp
@@ -14,29 +14,10 @@
 // with this program; if not, write to the Free Software Foundation, Inc.,
 // 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
-#include <QMimeData>
 #include "diagramobject.h"
-#include "databasetable.h"
 
 DiagramObject::DiagramObject(DiagramItem *parent)
 	: DiagramItem(parent)
 {
 	setZValue(100.0);
 }
-
-QMimeData *
-DiagramObject::toMimeData()
-{
-	return 0;
-}
-
-DiagramObject *
-DiagramObject::fromMimeData(const QMimeData *mimeData)
-{
-	QByteArray data = mimeData->data("application/dbmodel.object");
-	if (data.isNull())
-		return 0;
-	DatabaseTable *table = new DatabaseTable();
-	table->setName(data);
-	return table;
-}
diff --git a/src/diagramobject.h b/src/diagramobject.h
index c7b4dd3..6650968 100644
--- a/src/diagramobject.h
+++ b/src/diagramobject.h
@@ -18,15 +18,13 @@
 #define DIAGRAMOBJECT_H
 
 #include "diagramitem.h"
-class QMimeData;
 
 class DiagramObject : public DiagramItem
 {
+	Q_OBJECT
+
 public:
 	DiagramObject(DiagramItem *parent = 0);
-
-	virtual QMimeData *toMimeData();
-	static DiagramObject *fromMimeData(const QMimeData *mimeData);
 };
 
 #endif
diff --git a/src/domutils.h b/src/domutils.h
new file mode 100644
index 0000000..045f0bb
--- /dev/null
+++ b/src/domutils.h
@@ -0,0 +1,43 @@
+// Copyright (C) 2008  Lukas Lalinsky
+//
+// This program 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.
+//
+// This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+#ifndef DOMUTILS_H
+#define DOMUTILS_H
+
+#include <QDomDocument>
+#include <QDomElement>
+
+inline void
+appendStringElement(QDomDocument &doc, QDomElement &parent, const QString &name, const QString &value)
+{
+	if (!value.isEmpty()) {
+		QDomElement element = doc.createElement(name);
+		element.appendChild(doc.createTextNode(value));
+		parent.appendChild(element);
+	}
+}
+
+inline QString
+readStringElement(QDomElement &parent, const QString &name, const QString &defaultValue = QString())
+{
+	QDomElement element = parent.firstChildElement(name);
+	if (!element.isNull()) {
+		return element.text();
+	}
+	return defaultValue;
+}
+
+#endif
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
index 8cd8cab..81d23e9 100644
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -157,17 +157,17 @@ MainWindow::setupActions()
 	m_actionSave->setText(tr("&Save"));
 	m_actionSave->setIcon(QIcon(":/icons/16x16/document-save.png"));
 	m_actionSave->setShortcut(QKeySequence(tr("Ctrl+S")));
-	m_actionSave->setDisabled(true);
+	//m_actionSave->setDisabled(true);
 	connect(m_actionSave, SIGNAL(triggered(bool)), SLOT(save()));
 
 	m_actionSaveAs = new QAction(this);
 	m_actionSaveAs->setText(tr("Save &As..."));
 	m_actionSaveAs->setIcon(QIcon(":/icons/16x16/document-save-as.png"));
-	m_actionSaveAs->setDisabled(true);
+	//m_actionSaveAs->setDisabled(true);
 	connect(m_actionSaveAs, SIGNAL(triggered(bool)), SLOT(saveAs()));
 
-	connect(m_undoGroup, SIGNAL(cleanChanged(bool)), m_actionSave, SLOT(setDisabled(bool)));
-	connect(m_undoGroup, SIGNAL(cleanChanged(bool)), m_actionSaveAs, SLOT(setDisabled(bool)));
+	//connect(m_undoGroup, SIGNAL(cleanChanged(bool)), m_actionSave, SLOT(setDisabled(bool)));
+	//connect(m_undoGroup, SIGNAL(cleanChanged(bool)), m_actionSaveAs, SLOT(setDisabled(bool)));
 
 	m_actionExportPNG = new QAction(this);
 	m_actionExportPNG->setText(tr("Export..."));
@@ -547,8 +547,10 @@ MainWindow::paste()
 {
 	const QMimeData *mimeData = QApplication::clipboard()->mimeData(QClipboard::Clipboard);
 	if (mimeData) {
-		DiagramObject *object = DiagramObject::fromMimeData(mimeData);
-		m_model->undoStack()->push(new AddItemCommand(m_model, object));
+		DiagramItem *item = DiagramItem::fromMimeData(mimeData);
+		if (item) {
+			m_model->undoStack()->push(new AddItemCommand(m_model, item));
+		}
 	}
 }
 
@@ -558,7 +560,7 @@ MainWindow::updateClipboard(QClipboard::Mode mode)
 	if (mode != QClipboard::Clipboard)
 		return;
 	const QMimeData *mimeData = QApplication::clipboard()->mimeData(QClipboard::Clipboard);
-	if (mimeData && mimeData->formats().contains("application/dbmodel.object"))
+	if (mimeData && mimeData->formats().contains("application/dbmodel.item"))
 		m_actionPaste->setEnabled(true);
 	else
 		m_actionPaste->setEnabled(false);
diff --git a/src/src.pro b/src/src.pro
index 6a6fa5a..bb398dd 100644
--- a/src/src.pro
+++ b/src/src.pro
@@ -15,6 +15,7 @@ SOURCES = \
 	databaserelationship.cpp \
 	diagramconnection.cpp \
 	diagramitem.cpp \
+	diagramitemregistry.cpp \
 	diagramobject.cpp \
 	tableproperties.cpp \
 	commands.cpp
@@ -30,6 +31,7 @@ HEADERS = \
 	databaserelationship.h \
 	diagramconnection.h \
 	diagramitem.h \
+	diagramitemregistry.h \
 	diagramobject.h \
 	tableproperties.h \
 	range.h \