Added base UI

.gitignore

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+# Created by .ignore support plugin (hsz.mobi)
+### JetBrains template
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio, WebStorm and Rider
+# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
+
+# User-specific stuff
+.idea/**/workspace.xml
+.idea/**/tasks.xml
+.idea/**/usage.statistics.xml
+.idea/**/dictionaries
+.idea/**/shelf
+
+# Generated files
+.idea/**/contentModel.xml
+
+# Sensitive or high-churn files
+.idea/**/dataSources/
+.idea/**/dataSources.ids
+.idea/**/dataSources.local.xml
+.idea/**/sqlDataSources.xml
+.idea/**/dynamic.xml
+.idea/**/uiDesigner.xml
+.idea/**/dbnavigator.xml
+
+# Gradle
+.idea/**/gradle.xml
+.idea/**/libraries
+
+# Gradle and Maven with auto-import
+# When using Gradle or Maven with auto-import, you should exclude module files,
+# since they will be recreated, and may cause churn.  Uncomment if using
+# auto-import.
+# .idea/artifacts
+# .idea/compiler.xml
+# .idea/jarRepositories.xml
+# .idea/modules.xml
+# .idea/*.iml
+# .idea/modules
+# *.iml
+# *.ipr
+
+# CMake
+cmake-build-*/
+
+# Mongo Explorer plugin
+.idea/**/mongoSettings.xml
+
+# File-based project format
+*.iws
+
+# IntelliJ
+out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Cursive Clojure plugin
+.idea/replstate.xml
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+fabric.properties
+
+# Editor-based Rest Client
+.idea/httpRequests
+
+# Android studio 3.1+ serialized cache file
+.idea/caches/build_file_checksums.ser
+
+### Maven template
+target/
+pom.xml.tag
+pom.xml.releaseBackup
+pom.xml.versionsBackup
+pom.xml.next
+release.properties
+dependency-reduced-pom.xml
+buildNumber.properties
+.mvn/timing.properties
+# https://github.com/takari/maven-wrapper#usage-without-binary-jar
+.mvn/wrapper/maven-wrapper.jar
+
+### Java template
+# Compiled class file
+*.class
+
+# Log file
+*.log
+
+# BlueJ files
+*.ctxt
+
+# Mobile Tools for Java (J2ME)
+.mtj.tmp/
+
+# Package Files #
+*.jar
+*.war
+*.nar
+*.ear
+*.zip
+*.tar.gz
+*.rar
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*
+
+.idea/
+*.iml
+

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>nl.andrewlalis</groupId>
+    <artifactId>EntityRelationMappingEditor</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>8</source>
+                    <target>8</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.formdev</groupId>
+            <artifactId>flatlaf</artifactId>
+            <version>1.0-rc3</version>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.18.16</version>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+</project>

src/main/java/nl/andrewlalis/erme/EntityRelationMappingEditor.java

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+package nl.andrewlalis.erme;
+
+import com.formdev.flatlaf.FlatLightLaf;
+import nl.andrewlalis.erme.view.EditorFrame;
+
+public class EntityRelationMappingEditor {
+
+	public static void main(String[] args) {
+		if (!FlatLightLaf.install()) {
+			System.err.println("Could not install FlatLight Look and Feel.");
+		}
+		final EditorFrame frame = new EditorFrame();
+		frame.setVisible(true);
+	}
+}

src/main/java/nl/andrewlalis/erme/control/actions/ExitAction.java

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+package nl.andrewlalis.erme.control.actions;
+
+import javax.swing.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.InputEvent;
+import java.awt.event.KeyEvent;
+
+public class ExitAction extends AbstractAction {
+	private static ExitAction instance;
+
+	public static ExitAction getInstance() {
+		if (instance == null) {
+			instance = new ExitAction();
+		}
+		return instance;
+	}
+
+	public ExitAction() {
+		super("Exit");
+		this.putValue(Action.SHORT_DESCRIPTION, "Exit the program.");
+		this.putValue(Action.ACCELERATOR_KEY, KeyStroke.getKeyStroke(KeyEvent.VK_Q, InputEvent.SHIFT_DOWN_MASK | InputEvent.CTRL_DOWN_MASK));
+	}
+
+	@Override
+	public void actionPerformed(ActionEvent e) {
+		System.exit(0);
+	}
+}

src/main/java/nl/andrewlalis/erme/control/actions/ExportToImageAction.java

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+package nl.andrewlalis.erme.control.actions;
+
+import javax.swing.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.InputEvent;
+import java.awt.event.KeyEvent;
+
+public class ExportToImageAction extends AbstractAction {
+	private static ExportToImageAction instance;
+
+	public static ExportToImageAction getInstance() {
+		if (instance == null) {
+			instance = new ExportToImageAction();
+		}
+		return instance;
+	}
+
+	public ExportToImageAction() {
+		super("Export to Image");
+		this.putValue(Action.SHORT_DESCRIPTION, "Export the current diagram to an image.");
+		this.putValue(Action.ACCELERATOR_KEY, KeyStroke.getKeyStroke(KeyEvent.VK_E, InputEvent.CTRL_DOWN_MASK));
+	}
+
+	@Override
+	public void actionPerformed(ActionEvent e) {
+		System.out.println("Export to image.");
+	}
+}

src/main/java/nl/andrewlalis/erme/control/actions/RedoAction.java

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+package nl.andrewlalis.erme.control.actions;
+
+import javax.swing.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.InputEvent;
+import java.awt.event.KeyEvent;
+
+public class RedoAction extends AbstractAction {
+	private static RedoAction instance;
+
+	public static RedoAction getInstance() {
+		if (instance == null) {
+			instance = new RedoAction();
+		}
+		return instance;
+	}
+
+	public RedoAction() {
+		super("Redo");
+		this.putValue(Action.SHORT_DESCRIPTION, "Redoes a previously undone action.");
+		this.putValue(Action.ACCELERATOR_KEY, KeyStroke.getKeyStroke(KeyEvent.VK_Z, InputEvent.CTRL_DOWN_MASK | InputEvent.SHIFT_DOWN_MASK));
+	}
+
+	@Override
+	public void actionPerformed(ActionEvent e) {
+		System.out.println("Redo");
+	}
+}

src/main/java/nl/andrewlalis/erme/control/actions/UndoAction.java

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+package nl.andrewlalis.erme.control.actions;
+
+import javax.swing.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.InputEvent;
+import java.awt.event.KeyEvent;
+
+public class UndoAction extends AbstractAction {
+	private static UndoAction instance;
+
+	public static UndoAction getInstance() {
+		if (instance == null) {
+			instance = new UndoAction();
+		}
+		return instance;
+	}
+
+	public UndoAction() {
+		super("Undo");
+		this.putValue(Action.SHORT_DESCRIPTION, "Undo the last action.");
+		this.putValue(Action.ACCELERATOR_KEY, KeyStroke.getKeyStroke(KeyEvent.VK_Z, InputEvent.CTRL_DOWN_MASK));
+	}
+
+	@Override
+	public void actionPerformed(ActionEvent e) {
+		System.out.println("Undo");
+	}
+}

src/main/java/nl/andrewlalis/erme/control/diagram/DiagramMouseListener.java

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+package nl.andrewlalis.erme.control.diagram;
+
+import nl.andrewlalis.erme.model.MappingModel;
+import nl.andrewlalis.erme.model.Relation;
+import nl.andrewlalis.erme.view.DiagramPanel;
+
+import java.awt.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.InputEvent;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+
+public class DiagramMouseListener extends MouseAdapter {
+	private final MappingModel model;
+	private Point mouseDragStart;
+
+	public DiagramMouseListener(MappingModel model) {
+		this.model = model;
+	}
+
+	@Override
+	public void mousePressed(MouseEvent e) {
+		DiagramPanel panel = (DiagramPanel) e.getSource();
+		final Graphics2D g2d = panel.getGraphics2D();
+		this.mouseDragStart = e.getPoint();
+		if ((e.getModifiers() & ActionEvent.CTRL_MASK) == ActionEvent.CTRL_MASK) {
+			boolean hit = false;
+			for (Relation r : this.model.getRelations()) {
+				if (r.getViewModel().getBounds(g2d).contains(e.getX(), e.getY())) {
+					r.setSelected(!r.isSelected());
+					hit = true;
+				}
+			}
+			if (!hit) {
+				this.model.getRelations().forEach(r -> r.setSelected(false));
+			}
+		}
+	}
+
+	@Override
+	public void mouseEntered(MouseEvent e) {
+		super.mouseEntered(e);
+	}
+
+	@Override
+	public void mouseDragged(MouseEvent e) {
+		int dx = this.mouseDragStart.x - e.getX();
+		int dy = this.mouseDragStart.y - e.getY();
+		for (Relation r : this.model.getRelations()) {
+			if (r.isSelected()) {
+				r.setPosition(new Point(r.getPosition().x - dx, r.getPosition().y - dy));
+			}
+		}
+		this.mouseDragStart = e.getPoint();
+	}
+
+	@Override
+	public void mouseMoved(MouseEvent e) {
+	}
+}

src/main/java/nl/andrewlalis/erme/model/Attribute.java

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+package nl.andrewlalis.erme.model;
+
+import lombok.Getter;
+
+import java.util.Objects;
+
+/**
+ * A single value that belongs to a relation.
+ */
+@Getter
+public class Attribute {
+	private final Relation relation;
+	private AttributeType type;
+	private String name;
+
+	public Attribute(Relation relation, AttributeType type, String name) {
+		this.relation = relation;
+		this.type = type;
+		this.name = name;
+	}
+
+	public void setType(AttributeType type) {
+		this.type = type;
+		this.relation.getModel().fireChangedEvent();
+	}
+
+	public void setName(String name) {
+		this.name = name;
+		this.relation.getModel().fireChangedEvent();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o) return true;
+		if (o == null || getClass() != o.getClass()) return false;
+		Attribute attribute = (Attribute) o;
+		return type == attribute.type &&
+				name.equals(attribute.name);
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(type, name);
+	}
+}

src/main/java/nl/andrewlalis/erme/model/AttributeType.java

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+package nl.andrewlalis.erme.model;
+
+public enum AttributeType {
+	PLAIN,
+	ID_KEY,
+	PARTIAL_ID_KEY,
+	FOREIGN_KEY
+}

src/main/java/nl/andrewlalis/erme/model/MappingModel.java

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+package nl.andrewlalis.erme.model;
+
+import lombok.Getter;
+
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * This model contains all the information about a single mapping diagram,
+ * including each mapped table and the links between them.
+ */
+public class MappingModel {
+	@Getter
+	private final Set<Relation> relations;
+
+	private final Set<ModelChangeListener> changeListeners;
+
+	public MappingModel() {
+		this.relations = new HashSet<>();
+		this.changeListeners = new HashSet<>();
+	}
+
+	public void addRelation(Relation r) {
+		if (this.relations.add(r)) {
+			this.fireChangedEvent();
+		}
+	}
+
+	public void removeRelation(Relation r) {
+		if (this.relations.remove(r)) {
+			this.fireChangedEvent();
+		}
+	}
+
+	public void addChangeListener(ModelChangeListener listener) {
+		this.changeListeners.add(listener);
+		listener.onModelChanged();
+	}
+
+	protected final void fireChangedEvent() {
+		this.changeListeners.forEach(ModelChangeListener::onModelChanged);
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o) return true;
+		if (o == null || this.getClass() != o.getClass()) return false;
+		MappingModel that = (MappingModel) o;
+		return this.getRelations().equals(that.getRelations());
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(this.getRelations());
+	}
+}

src/main/java/nl/andrewlalis/erme/model/ModelChangeListener.java

@@ -0,0 +1,5 @@
+package nl.andrewlalis.erme.model;
+
+public interface ModelChangeListener {
+	void onModelChanged();
+}

src/main/java/nl/andrewlalis/erme/model/Relation.java

@@ -0,0 +1,76 @@
+package nl.andrewlalis.erme.model;
+
+import lombok.Getter;
+import nl.andrewlalis.erme.view.view_models.RelationViewModel;
+
+import java.awt.*;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * Represents a single "relation" or table in the diagram.
+ */
+@Getter
+public class Relation {
+	private final MappingModel model;
+	private Point position;
+	private String name;
+	private final List<Attribute> attributes;
+
+	private transient boolean selected;
+	private final transient RelationViewModel viewModel;
+
+	public Relation(MappingModel model, Point position, String name) {
+		this.model = model;
+		this.position = position;
+		this.name = name;
+		this.attributes = new ArrayList<>();
+		this.viewModel = new RelationViewModel(this);
+	}
+
+	public void setPosition(Point position) {
+		if (!this.position.equals(position)) {
+			this.position = position;
+			this.model.fireChangedEvent();
+		}
+	}
+
+	public void setName(String name) {
+		if (!this.name.equals(name)) {
+			this.name = name;
+			this.model.fireChangedEvent();
+		}
+	}
+
+	public void setSelected(boolean selected) {
+		if (selected != this.selected) {
+			this.selected = selected;
+			this.model.fireChangedEvent();
+		}
+	}
+
+	public void addAttribute(Attribute attribute) {
+		this.attributes.add(attribute);
+		this.model.fireChangedEvent();
+	}
+
+	public void removeAttribute(Attribute attribute) {
+		if (this.attributes.remove(attribute)) {
+			this.model.fireChangedEvent();
+		}
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o) return true;
+		if (o == null || getClass() != o.getClass()) return false;
+		Relation relation = (Relation) o;
+		return Objects.equals(this.getName(), relation.getName());
+	}
+
+	@Override
+	public int hashCode() {
+		return this.getName().hashCode();
+	}
+}

src/main/java/nl/andrewlalis/erme/view/DiagramPanel.java

@@ -0,0 +1,64 @@
+package nl.andrewlalis.erme.view;
+
+import lombok.Getter;
+import nl.andrewlalis.erme.control.diagram.DiagramMouseListener;
+import nl.andrewlalis.erme.model.MappingModel;
+import nl.andrewlalis.erme.model.ModelChangeListener;
+import nl.andrewlalis.erme.view.view_models.MappingModelViewModel;
+
+import javax.swing.*;
+import java.awt.*;
+import java.awt.event.MouseListener;
+import java.awt.event.MouseMotionListener;
+
+/**
+ * The main panel in which the ER Mapping diagram is displayed.
+ */
+public class DiagramPanel extends JPanel implements ModelChangeListener {
+	@Getter
+	private MappingModel model;
+
+	public DiagramPanel(MappingModel model) {
+		super(true);
+		this.setModel(model);
+	}
+
+	public void setModel(MappingModel newModel) {
+		this.model = newModel;
+		newModel.addChangeListener(this);
+		for (MouseListener listener : this.getMouseListeners()) {
+			this.removeMouseListener(listener);
+		}
+		for (MouseMotionListener listener : this.getMouseMotionListeners()) {
+			this.removeMouseMotionListener(listener);
+		}
+		DiagramMouseListener listener = new DiagramMouseListener(newModel);
+		this.addMouseListener(listener);
+		this.addMouseMotionListener(listener);
+		this.repaint();
+	}
+
+	@Override
+	protected void paintComponent(Graphics g) {
+		super.paintComponent(g);
+		new MappingModelViewModel(this.model).draw(this.getGraphics2D(g));
+	}
+
+	public Graphics2D getGraphics2D(Graphics g) {
+		Graphics2D g2d = (Graphics2D) g;
+		g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+		g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+		g.setFont(g.getFont().deriveFont(14.0f));
+		return g2d;
+	}
+
+	public Graphics2D getGraphics2D() {
+		return this.getGraphics2D(this.getGraphics());
+	}
+
+	@Override
+	public void onModelChanged() {
+		this.revalidate();
+		this.repaint();
+	}
+}

src/main/java/nl/andrewlalis/erme/view/EditorFrame.java

@@ -0,0 +1,38 @@
+package nl.andrewlalis.erme.view;
+
+import nl.andrewlalis.erme.model.Attribute;
+import nl.andrewlalis.erme.model.AttributeType;
+import nl.andrewlalis.erme.model.MappingModel;
+import nl.andrewlalis.erme.model.Relation;
+
+import javax.swing.*;
+import java.awt.*;
+
+/**
+ * The main JFrame for the editor.
+ */
+public class EditorFrame extends JFrame {
+	public EditorFrame() {
+		super("ER-Mapping Editor");
+		MappingModel model = new MappingModel();
+		Relation usersRelation = new Relation(model, new Point(50, 50), "Users");
+		usersRelation.addAttribute(new Attribute(usersRelation, AttributeType.ID_KEY, "username"));
+		usersRelation.addAttribute(new Attribute(usersRelation, AttributeType.PLAIN, "fullName"));
+		usersRelation.addAttribute(new Attribute(usersRelation, AttributeType.PLAIN, "language"));
+		usersRelation.addAttribute(new Attribute(usersRelation, AttributeType.PLAIN, "verified"));
+		usersRelation.addAttribute(new Attribute(usersRelation, AttributeType.PARTIAL_ID_KEY, "partialKey"));
+		model.addRelation(usersRelation);
+		Relation tokensRelation = new Relation(model, new Point(50, 120), "Tokens");
+		tokensRelation.addAttribute(new Attribute(tokensRelation, AttributeType.ID_KEY, "tokenCode"));
+		tokensRelation.addAttribute(new Attribute(tokensRelation, AttributeType.FOREIGN_KEY, "username"));
+		tokensRelation.addAttribute(new Attribute(tokensRelation, AttributeType.PLAIN, "expirationDate"));
+		model.addRelation(tokensRelation);
+
+		this.setContentPane(new DiagramPanel(model));
+		this.setJMenuBar(new EditorMenuBar());
+		this.setMinimumSize(new Dimension(500, 500));
+		this.pack();
+		this.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
+		this.setLocationRelativeTo(null);
+	}
+}

src/main/java/nl/andrewlalis/erme/view/EditorMenuBar.java

@@ -0,0 +1,36 @@
+package nl.andrewlalis.erme.view;
+
+import nl.andrewlalis.erme.control.actions.ExitAction;
+import nl.andrewlalis.erme.control.actions.ExportToImageAction;
+import nl.andrewlalis.erme.control.actions.RedoAction;
+import nl.andrewlalis.erme.control.actions.UndoAction;
+
+import javax.swing.*;
+
+/**
+ * The menu bar that's visible atop the application.
+ */
+public class EditorMenuBar extends JMenuBar {
+	public EditorMenuBar() {
+		this.add(this.buildFileMenu());
+		this.add(this.buildEditMenu());
+	}
+
+	private JMenu buildFileMenu() {
+		JMenu menu = new JMenu("File");
+		JMenuItem exportAsImageItem = new JMenuItem(ExportToImageAction.getInstance());
+		menu.add(exportAsImageItem);
+		JMenuItem exitItem = new JMenuItem(ExitAction.getInstance());
+		menu.add(exitItem);
+		return menu;
+	}
+
+	private JMenu buildEditMenu() {
+		JMenu menu = new JMenu("Edit");
+		JMenuItem undoItem = new JMenuItem(UndoAction.getInstance());
+		menu.add(undoItem);
+		JMenuItem redoItem = new JMenuItem(RedoAction.getInstance());
+		menu.add(redoItem);
+		return menu;
+	}
+}

src/main/java/nl/andrewlalis/erme/view/view_models/AttributeViewModel.java

@@ -0,0 +1,65 @@
+package nl.andrewlalis.erme.view.view_models;
+
+import nl.andrewlalis.erme.model.Attribute;
+import nl.andrewlalis.erme.model.AttributeType;
+
+import java.awt.*;
+import java.awt.font.TextAttribute;
+import java.awt.geom.Rectangle2D;
+import java.text.AttributedString;
+
+public class AttributeViewModel implements ViewModel {
+	public static final int PADDING_X = 5;
+	public static final int PADDING_Y = 5;
+	public static final Color BACKGROUND_COLOR = Color.LIGHT_GRAY;
+	public static final Color FONT_COLOR = Color.BLACK;
+
+	private final Attribute attribute;
+
+	public AttributeViewModel(Attribute attribute) {
+		this.attribute = attribute;
+	}
+
+	@Override
+	public void draw(Graphics2D g) {
+		AttributedString as = this.getAttributedString(g);
+		Rectangle r = this.getBounds(g, as);
+		g.setColor(BACKGROUND_COLOR);
+		g.fillRect(r.x, r.y, r.width, r.height);
+		g.setColor(FONT_COLOR);
+		g.drawRect(r.x, r.y, r.width, r.height);
+		g.drawString(as.getIterator(), r.x + PADDING_X, r.y + (r.height - PADDING_Y));
+	}
+
+	private Rectangle getBounds(Graphics2D g, AttributedString as) {
+		int x = this.attribute.getRelation().getPosition().x + RelationViewModel.PADDING_X;
+		int y = this.attribute.getRelation().getPosition().y + this.attribute.getRelation().getViewModel().getNameBounds(g).height + PADDING_Y;
+		int i = 0;
+		while (!this.attribute.getRelation().getAttributes().get(i).equals(this.attribute)) {
+			x += g.getFontMetrics().stringWidth(this.attribute.getRelation().getAttributes().get(i).getName()) + (2 * PADDING_X);
+			i++;
+		}
+		Rectangle2D rect = g.getFontMetrics().getStringBounds(as.getIterator(), 0, this.attribute.getName().length(), g);
+		return new Rectangle(
+				x,
+				y,
+				(int) rect.getWidth() + (2 * PADDING_X),
+				(int) rect.getHeight() + (2 * PADDING_Y)
+		);
+	}
+
+	public Rectangle getBounds(Graphics2D g) {
+		return this.getBounds(g, this.getAttributedString(g));
+	}
+
+	private AttributedString getAttributedString(Graphics2D g) {
+		AttributedString as = new AttributedString(this.attribute.getName());
+		as.addAttribute(TextAttribute.FONT, g.getFont());
+		if (this.attribute.getType().equals(AttributeType.ID_KEY)) {
+			as.addAttribute(TextAttribute.UNDERLINE, TextAttribute.UNDERLINE_ON);
+		} else if (this.attribute.getType().equals(AttributeType.PARTIAL_ID_KEY)) {
+			as.addAttribute(TextAttribute.UNDERLINE, TextAttribute.UNDERLINE_LOW_DASHED);
+		}
+		return as;
+	}
+}

src/main/java/nl/andrewlalis/erme/view/view_models/MappingModelViewModel.java

@@ -0,0 +1,21 @@
+package nl.andrewlalis.erme.view.view_models;
+
+import nl.andrewlalis.erme.model.MappingModel;
+import nl.andrewlalis.erme.model.Relation;
+
+import java.awt.*;
+
+public class MappingModelViewModel implements ViewModel {
+	private final MappingModel model;
+
+	public MappingModelViewModel(MappingModel model) {
+		this.model = model;
+	}
+
+	@Override
+	public void draw(Graphics2D g) {
+		for (Relation r : this.model.getRelations()) {
+			r.getViewModel().draw(g);
+		}
+	}
+}

src/main/java/nl/andrewlalis/erme/view/view_models/RelationViewModel.java

@@ -0,0 +1,67 @@
+package nl.andrewlalis.erme.view.view_models;
+
+import nl.andrewlalis.erme.model.Attribute;
+import nl.andrewlalis.erme.model.Relation;
+
+import java.awt.*;
+import java.awt.font.TextAttribute;
+import java.awt.geom.Rectangle2D;
+import java.text.AttributedString;
+
+public class RelationViewModel implements ViewModel {
+	public static final int PADDING_X = 5;
+	public static final int PADDING_Y = 5;
+
+	private final Relation relation;
+
+	public RelationViewModel(Relation relation) {
+		this.relation = relation;
+	}
+
+	@Override
+	public void draw(Graphics2D g) {
+		AttributedString as = this.getAttributedString(g);
+		Rectangle bounds = this.getBounds(g);
+		g.setColor(Color.BLACK);
+		g.drawString(as.getIterator(), bounds.x + PADDING_X, bounds.y + this.getNameBounds(g).height - PADDING_Y);
+		for (Attribute a : this.relation.getAttributes()) {
+			new AttributeViewModel(a).draw(g);
+		}
+		if (this.relation.isSelected()) {
+			g.setColor(Color.BLUE);
+		} else {
+			g.setColor(Color.CYAN);
+		}
+		g.drawRect(bounds.x, bounds.y, bounds.width, bounds.height);
+	}
+
+	public Rectangle getBounds(Graphics2D g) {
+		Rectangle rect = new Rectangle();
+		rect.x = this.relation.getPosition().x;
+		rect.y = this.relation.getPosition().y;
+		int totalAttributeWidth = 0;
+		int maxAttributeHeight = 0;
+		for (Attribute a : this.relation.getAttributes()) {
+			Rectangle attributeBounds = new AttributeViewModel(a).getBounds(g);
+			totalAttributeWidth += attributeBounds.width;
+			maxAttributeHeight = Math.max(maxAttributeHeight, attributeBounds.height);
+		}
+		Rectangle nameBounds = this.getNameBounds(g);
+		rect.width = Math.max(totalAttributeWidth, nameBounds.width) + (2 * PADDING_X);
+		rect.height = nameBounds.height + maxAttributeHeight + (2 * PADDING_Y);
+		return rect;
+	}
+
+	public Rectangle getNameBounds(Graphics2D g) {
+		AttributedString as = this.getAttributedString(g);
+		Rectangle2D nameBounds = g.getFontMetrics().getStringBounds(as.getIterator(), 0, this.relation.getName().length(), g);
+		return nameBounds.getBounds();
+	}
+
+	private AttributedString getAttributedString(Graphics2D g) {
+		AttributedString as = new AttributedString(this.relation.getName());
+		as.addAttribute(TextAttribute.FONT, g.getFont());
+		as.addAttribute(TextAttribute.WEIGHT, TextAttribute.WEIGHT_BOLD);
+		return as;
+	}
+}

src/main/java/nl/andrewlalis/erme/view/view_models/ViewModel.java

@@ -0,0 +1,7 @@
+package nl.andrewlalis.erme.view.view_models;
+
+import java.awt.*;
+
+public interface ViewModel {
+	void draw(Graphics2D g);
+}