| /******************************************************************************* |
| * Copyright (c) 2004, 2010 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| |
| package org.eclipse.draw2d; |
| |
| /** |
| * Classes which implement this interface provide callback hooks for various |
| * layout related events. |
| * <P> |
| * Instances can be hooked to figures by calling |
| * {@link IFigure#addLayoutListener(LayoutListener)}. Listeners will be made |
| * aware of various steps of the layout mechanism, and even have the opportunity |
| * to prevent normal layout from occurring. |
| * |
| * @since 3.1 |
| */ |
| public interface LayoutListener { |
| |
| /** |
| * A stub implementation which implements all of the declared methods. |
| * |
| * @since 3.1 |
| */ |
| class Stub implements LayoutListener { |
| |
| /** |
| * Stub which does nothing. |
| * |
| * @see LayoutListener#invalidate(IFigure) |
| */ |
| public void invalidate(IFigure container) { |
| } |
| |
| /** |
| * Stub which does nothing. |
| * |
| * @see LayoutListener#layout(IFigure) |
| */ |
| public boolean layout(IFigure container) { |
| return false; |
| } |
| |
| /** |
| * Stub which does nothing. |
| * |
| * @see LayoutListener#postLayout(IFigure) |
| */ |
| public void postLayout(IFigure container) { |
| } |
| |
| /** |
| * Stub which does nothing. |
| * |
| * @see LayoutListener#remove(IFigure) |
| */ |
| public void remove(IFigure child) { |
| } |
| |
| /** |
| * Stub which does nothing. |
| * |
| * @see LayoutListener#setConstraint(IFigure, java.lang.Object) |
| */ |
| public void setConstraint(IFigure child, Object constraint) { |
| } |
| |
| } |
| |
| /** |
| * Called when a container has been invalidated. |
| * |
| * @param container |
| * the invalidated Figure |
| * @since 3.1 |
| */ |
| void invalidate(IFigure container); |
| |
| /** |
| * Called prior to layout occurring. A listener may intercept a layout by |
| * returning <code>true</code>. If the layout is intercepted, the |
| * container's <code>LayoutManager</code> will not receive a layout call. |
| * |
| * @param container |
| * the figure incurring a layout |
| * @return <code>true</code> if the layout has been intercepted by the |
| * listener |
| * @since 3.1 |
| */ |
| boolean layout(IFigure container); |
| |
| /** |
| * Called after layout has occurred. |
| * |
| * @since 3.1 |
| * @param container |
| * the figure incurring a layout |
| */ |
| void postLayout(IFigure container); |
| |
| /** |
| * Called when a child is about to be removed from its parent. |
| * |
| * @since 3.1 |
| * @param child |
| * the child being removed |
| */ |
| void remove(IFigure child); |
| |
| /** |
| * Called when a child's constraint is initialized or updated. |
| * |
| * @param child |
| * the child being updated |
| * @param constraint |
| * the child's new constraint |
| * @since 3.1 |
| */ |
| void setConstraint(IFigure child, Object constraint); |
| |
| } |