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diff --git a/src/net/sourceforge/plantuml/swing/ScrollablePicture.java b/src/net/sourceforge/plantuml/swing/ScrollablePicture.java
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+/* ========================================================================
+ * PlantUML : a free UML diagram generator
+ * ========================================================================
+ *
+ * (C) Copyright 2009-2014, Arnaud Roques
+ *
+ * Project Info:  http://plantuml.sourceforge.net
+ * 
+ * This file is part of PlantUML.
+ *
+ * Licensed under The MIT License (Massachusetts Institute of Technology License)
+ * 
+ * See http://opensource.org/licenses/MIT
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+ * IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ * 
+ *
+ * Original Author:  Arnaud Roques
+ */
+package net.sourceforge.plantuml.swing;
+
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.Rectangle;
+import java.awt.event.MouseEvent;
+import java.awt.event.MouseMotionListener;
+
+import javax.swing.ImageIcon;
+import javax.swing.JLabel;
+import javax.swing.Scrollable;
+import javax.swing.SwingConstants;
+
+class ScrollablePicture extends JLabel implements Scrollable, MouseMotionListener {
+
+	private int maxUnitIncrement = 1;
+	private boolean missingPicture = false;
+
+	public ScrollablePicture(ImageIcon i, int m) {
+		super(i);
+		if (i == null) {
+			missingPicture = true;
+			setText("No picture found.");
+			setHorizontalAlignment(CENTER);
+			setOpaque(true);
+			setBackground(Color.white);
+		}
+		maxUnitIncrement = m;
+
+		// Let the user scroll by dragging to outside the window.
+		setAutoscrolls(true); // enable synthetic drag events
+		addMouseMotionListener(this); // handle mouse drags
+	}
+
+	// Methods required by the MouseMotionListener interface:
+	public void mouseMoved(MouseEvent e) {
+	}
+
+	public void mouseDragged(MouseEvent e) {
+		// The user is dragging us, so scroll!
+		Rectangle r = new Rectangle(e.getX(), e.getY(), 1, 1);
+		scrollRectToVisible(r);
+	}
+
+	@Override
+	public Dimension getPreferredSize() {
+		if (missingPicture) {
+			return new Dimension(320, 480);
+		} else {
+			return super.getPreferredSize();
+		}
+	}
+
+	public Dimension getPreferredScrollableViewportSize() {
+		return getPreferredSize();
+	}
+
+	public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
+		// Get the current position.
+		int currentPosition = 0;
+		if (orientation == SwingConstants.HORIZONTAL) {
+			currentPosition = visibleRect.x;
+		} else {
+			currentPosition = visibleRect.y;
+		}
+
+		// Return the number of pixels between currentPosition
+		// and the nearest tick mark in the indicated direction.
+		if (direction < 0) {
+			int newPosition = currentPosition - (currentPosition / maxUnitIncrement) * maxUnitIncrement;
+			return (newPosition == 0) ? maxUnitIncrement : newPosition;
+		} else {
+			return ((currentPosition / maxUnitIncrement) + 1) * maxUnitIncrement - currentPosition;
+		}
+	}
+
+	public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
+		if (orientation == SwingConstants.HORIZONTAL) {
+			return visibleRect.width - maxUnitIncrement;
+		} else {
+			return visibleRect.height - maxUnitIncrement;
+		}
+	}
+
+	public boolean getScrollableTracksViewportWidth() {
+		return false;
+	}
+
+	public boolean getScrollableTracksViewportHeight() {
+		return false;
+	}
+
+	public void setMaxUnitIncrement(int pixels) {
+		maxUnitIncrement = pixels;
+	}
+}