Changed RulerLayout to directly inherit from AbstractLayout eclipse-g…

…ef#418

RulerLayout inherited from XYLayout. The later assumed that children
constraint are rectangles. As this is not valid for RulerLayouts the
RulerLayout was changed to inherit from AstractLayout and use its own
constraint map with Integers.

Fixes eclipse-gef#418

org.eclipse.draw2d/src/org/eclipse/draw2d/XYLayout.java

@@ -136,9 +136,11 @@ public void remove(IFigure figure) {
 	@Override
 	public void setConstraint(IFigure figure, Object newConstraint) {
 		super.setConstraint(figure, newConstraint);
-		if (newConstraint instanceof Rectangle rect) {
-			constraints.put(figure, rect);
+		if (!(newConstraint instanceof Rectangle rect)) {
+			throw new IllegalArgumentException("XYLayout was given " + newConstraint.getClass().getName() //$NON-NLS-1$
+					+ " as constraint for Figure. Rectangle expected!"); //$NON-NLS-1$
 		}
+		constraints.put(figure, rect);
 	}
 
 }

org.eclipse.gef/src/org/eclipse/gef/internal/ui/rulers/RulerLayout.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2003, 2010 IBM Corporation and others.
+ * Copyright (c) 2003, 2024 IBM Corporation and others.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
@@ -12,8 +12,11 @@
  *******************************************************************************/
 package org.eclipse.gef.internal.ui.rulers;
 
+import java.util.HashMap;
+import java.util.Map;
+
+import org.eclipse.draw2d.AbstractLayout;
 import org.eclipse.draw2d.IFigure;
-import org.eclipse.draw2d.XYLayout;
 import org.eclipse.draw2d.geometry.Dimension;
 import org.eclipse.draw2d.geometry.Rectangle;
 
@@ -25,7 +28,9 @@
  * @author Pratik Shah
  * @since 3.0
  */
-public class RulerLayout extends XYLayout {
+public class RulerLayout extends AbstractLayout {
+
+	private final Map<IFigure, Integer> constraints = new HashMap<>();
 
 	/**
 	 * @see org.eclipse.draw2d.AbstractLayout#calculatePreferredSize(org.eclipse.draw2d.IFigure,
@@ -40,7 +45,7 @@ protected Dimension calculatePreferredSize(IFigure container, int wHint, int hHi
 	 * @see org.eclipse.draw2d.AbstractLayout#getConstraint(org.eclipse.draw2d.IFigure)
 	 */
 	@Override
-	public Object getConstraint(IFigure child) {
+	public Integer getConstraint(IFigure child) {
 		return constraints.get(child);
 	}
 
@@ -52,7 +57,13 @@ public void layout(IFigure container) {
 		Rectangle rulerSize = container.getClientArea();
 		for (IFigure child : container.getChildren()) {
 			Dimension childSize = child.getPreferredSize();
-			int position = ((Integer) getConstraint(child)).intValue();
+
+			Integer childPos = getConstraint(child);
+			if (childPos == null) {
+				continue;
+			}
+
+			int position = childPos.intValue();
 			if (((RulerFigure) container).isHorizontal()) {
 				childSize.height = rulerSize.height - 1;
 				Rectangle.SINGLETON.setLocation(position - (childSize.width / 2), rulerSize.y);
@@ -65,4 +76,29 @@ public void layout(IFigure container) {
 		}
 	}
 
+	/**
+	 * @see org.eclipse.draw2d.LayoutManager#remove(IFigure)
+	 */
+	@Override
+	public void remove(IFigure figure) {
+		super.remove(figure);
+		constraints.remove(figure);
+	}
+
+	/**
+	 * Sets the layout constraint of the given figure. The constraints can only be
+	 * of type {@link Integer}.
+	 *
+	 * @see org.eclipse.draw2d.LayoutManager#setConstraint(IFigure, Object)
+	 */
+	@Override
+	public void setConstraint(IFigure figure, Object newConstraint) {
+		super.setConstraint(figure, newConstraint);
+		if (!(newConstraint instanceof Integer intConstraint)) {
+			throw new IllegalArgumentException("RulerLayout was given " + newConstraint.getClass().getName() //$NON-NLS-1$
+					+ " as constraint for Figure. Integer expected!"); //$NON-NLS-1$
+		}
+		constraints.put(figure, intConstraint);
+	}
+
 }