org.eclipse.draw2d.AbstractHintLayout Maven / Gradle / Ivy
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/*******************************************************************************
* Copyright (c) 2000, 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;
import org.eclipse.draw2d.geometry.Dimension;
/**
* The foundation for layout managers which are sensitive to width and/or height
* hints. This class will cache preferred and minimum sizes for a given set of
* hints. If the hints change in a meaningful way, the cached size is thrown out
* and redetermined.
*
* Subclasses may be sensitive to one or both hints. By default, this class
* assumes both hints are important. Subclasses may override this behavior in
* {@link #isSensitiveHorizontally(IFigure)} and
* {@link #isSensitiveVertically(IFigure)}. At least one of these method should
* return true.
*
* @author hudsonr
* @since 2.0
*/
public abstract class AbstractHintLayout extends AbstractLayout {
private Dimension minimumSize = null;
private Dimension cachedPreferredHint = new Dimension(-1, -1);
private Dimension cachedMinimumHint = new Dimension(-1, -1);
/**
* Calculates the minimum size using the given width and height hints. This
* method is called from {@link #getMinimumSize(IFigure, int, int)} whenever
* the cached minimum size has been flushed.
*
* By default, this method just calls
* {@link #getPreferredSize(IFigure, int, int)}, meaning minimum and
* preferres sizes will be the same unless this method is overridden.
*
* @param container
* the Figure on which this layout is installed
* @param wHint
* the width hint
* @param hHint
* the height hint
*
* @return the layout's minimum size
*/
protected Dimension calculateMinimumSize(IFigure container, int wHint,
int hHint) {
return getPreferredSize(container, wHint, hHint);
}
/**
* @see org.eclipse.draw2d.LayoutManager#getMinimumSize(IFigure, int, int)
*/
public Dimension getMinimumSize(IFigure container, int w, int h) {
boolean flush = cachedMinimumHint.width != w
&& isSensitiveHorizontally(container);
flush |= cachedMinimumHint.height != h
&& isSensitiveVertically(container);
if (flush) {
minimumSize = null;
cachedMinimumHint.width = w;
cachedMinimumHint.height = h;
}
if (minimumSize == null)
minimumSize = calculateMinimumSize(container, w, h);
return minimumSize;
}
/**
* @see org.eclipse.draw2d.LayoutManager#getPreferredSize(IFigure, int, int)
*/
public final Dimension getPreferredSize(IFigure container, int w, int h) {
boolean flush = cachedPreferredHint.width != w
&& isSensitiveHorizontally(container);
flush |= cachedPreferredHint.height != h
&& isSensitiveVertically(container);
if (flush) {
preferredSize = null;
cachedPreferredHint.width = w;
cachedPreferredHint.height = h;
}
return super.getPreferredSize(container, w, h);
}
/**
* Extends the superclass implementation to flush the cached minimum size.
*
* @see org.eclipse.draw2d.LayoutManager#invalidate()
*/
public void invalidate() {
minimumSize = null;
super.invalidate();
}
/**
* Returns whether this layout manager is sensitive to changes in the
* horizontal hint. By default, this method returns true.
*
* @param container
* the layout's container
* @return true if this layout is sensite to horizontal hint
* changes
*/
protected boolean isSensitiveHorizontally(IFigure container) {
return true;
}
/**
* Returns whether this layout manager is sensitive to changes in the
* vertical hint. By default, this method returns true.
*
* @param container
* the layout's container
* @return true if this layout is sensite to vertical hint
* changes
*/
protected boolean isSensitiveVertically(IFigure container) {
return true;
}
}