StackLayout.java

/*******************************************************************************
 * Copyright (c) 2000, 2010, 2012 IBM Corporation, Gerhardt Informatics Kft. 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
 *     Gerhardt Informatics Kft. - GEFGWT port
 *******************************************************************************/
package org.eclipse.swt.custom;

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

/**
 * This Layout stacks all the controls one on top of the other and resizes all
 * controls to have the same size and location. The control specified in
 * topControl is visible and all other controls are not visible. Users must set
 * the topControl value to flip between the visible items and then call layout()
 * on the composite which has the StackLayout.
 * 
 * <p>
 * Here is an example which places ten buttons in a stack layout and flips
 * between them:
 * 
 * <pre>
 * <code>
 * 	public static void main(String[] args) {
 * 		Display display = new Display();
 * 		Shell shell = new Shell(display);
 * 		shell.setLayout(new GridLayout());
 * 	
 * 		final Composite parent = new Composite(shell, SWT.NONE);
 * 		parent.setLayoutData(new GridData(GridData.FILL_BOTH));
 * 		final StackLayout layout = new StackLayout();
 * 		parent.setLayout(layout);
 * 		final Button[] bArray = new Button[10];
 * 		for (int i = 0; i < 10; i++) {
 * 			bArray[i] = new Button(parent, SWT.PUSH);
 * 			bArray[i].setText("Button "+i);
 * 		}
 * 		layout.topControl = bArray[0];
 * 	
 * 		Button b = new Button(shell, SWT.PUSH);
 * 		b.setText("Show Next Button");
 * 		final int[] index = new int[1];
 * 		b.addListener(SWT.Selection, new Listener(){
 * 			public void handleEvent(Event e) {
 * 				index[0] = (index[0] + 1) % 10;
 * 				layout.topControl = bArray[index[0]];
 * 				parent.layout();
 * 			}
 * 		});
 * 	
 * 		shell.open();
 * 		while (shell != null && !shell.isDisposed()) {
 * 			if (!display.readAndDispatch())
 * 				display.sleep(); 
 * 		} 	
 * 	}
 * </code>
 * </pre>
 * 
 * @see <a href="http://www.eclipse.org/swt/snippets/#stacklayout">StackLayout
 *      snippets</a>
 * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example:
 *      LayoutExample</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further
 *      information</a>
 */

public class StackLayout extends Layout {

	/**
	 * marginWidth specifies the number of pixels of horizontal margin that will
	 * be placed along the left and right edges of the layout.
	 * 
	 * The default value is 0.
	 */
	public int marginWidth = 0;
	/**
	 * marginHeight specifies the number of pixels of vertical margin that will
	 * be placed along the top and bottom edges of the layout.
	 * 
	 * The default value is 0.
	 */
	public int marginHeight = 0;

	/**
	 * topControl the Control that is displayed at the top of the stack. All
	 * other controls that are children of the parent composite will not be
	 * visible.
	 */
	public Control topControl;

	protected Point computeSize(Composite composite, int wHint, int hHint,
			boolean flushCache) {
		Control children[] = composite.getChildren();
		int maxWidth = 0;
		int maxHeight = 0;
		for (int i = 0; i < children.length; i++) {
			Point size = children[i].computeSize(wHint, hHint, flushCache);
			maxWidth = Math.max(size.x, maxWidth);
			maxHeight = Math.max(size.y, maxHeight);
		}
		int width = maxWidth + 2 * marginWidth;
		int height = maxHeight + 2 * marginHeight;
		if (wHint != SWT.DEFAULT)
			width = wHint;
		if (hHint != SWT.DEFAULT)
			height = hHint;
		return new Point(width, height);
	}

	protected boolean flushCache(Control control) {
		return true;
	}

	protected void layout(Composite composite, boolean flushCache) {
		Control children[] = composite.getChildren();
		Rectangle rect = composite.getClientArea();
		rect.x += marginWidth;
		rect.y += marginHeight;
		rect.width -= 2 * marginWidth;
		rect.height -= 2 * marginHeight;
		for (int i = 0; i < children.length; i++) {
			children[i].setBounds(rect);
			children[i].setVisible(children[i] == topControl);
		}
	}

	String getName() {
		String string = getClass().getName();
		int index = string.lastIndexOf('.');
		if (index == -1)
			return string;
		return string.substring(index + 1, string.length());
	}

	/**
	 * Returns a string containing a concise, human-readable description of the
	 * receiver.
	 * 
	 * @return a string representation of the layout
	 */
	public String toString() {
		String string = getName() + " {";
		if (marginWidth != 0)
			string += "marginWidth=" + marginWidth + " ";
		if (marginHeight != 0)
			string += "marginHeight=" + marginHeight + " ";
		if (topControl != null)
			string += "topControl=" + topControl + " ";
		string = string.trim();
		string += "}";
		return string;
	}
}