tests/org.eclipse.ui.tests.performance/src/org/eclipse/ui/tests/performance/layout/ConstantAreaLayout.java

/*******************************************************************************
 * Copyright (c) 2004 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.ui.tests.performance.layout;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Layout;

/**
 * A very efficient (but useless) layout with complicated preferred size behavior.
 * Its preferred size attempts to maintain a constant area. This can be used for 
 * performance testing other layouts (by attaching this to child Composites in the 
 * layout being tested). It will give a good estimate as to how the layout will
 * handle wrapping widgets.
 * 
 * @since 3.1
 */
public class ConstantAreaLayout extends Layout {

    private int area;
    private int preferredWidth;
    
    public ConstantAreaLayout(int area, int preferredWidth) {
        this.area = area;
        this.preferredWidth = preferredWidth;
    }
    
    /* (non-Javadoc)
     * @see org.eclipse.swt.widgets.Layout#computeSize(org.eclipse.swt.widgets.Composite, int, int, boolean)
     */
    protected Point computeSize(Composite composite, int wHint, int hHint,
            boolean flushCache) {
        
        if (wHint == 0 || hHint == 0) {
            return new Point(1,1);
        }
        
        if (wHint == SWT.DEFAULT) {
            if (hHint == SWT.DEFAULT) {
                wHint = preferredWidth;
            } else {
                wHint = area / hHint;
            }
        }
        
        if (hHint == SWT.DEFAULT) {
            hHint = area / wHint;
        }
        
        return new Point(wHint, hHint);
    }

    /* (non-Javadoc)
     * @see org.eclipse.swt.widgets.Layout#layout(org.eclipse.swt.widgets.Composite, boolean)
     */
    protected void layout(Composite composite, boolean flushCache) {

    }

}