/******************************************************************************* * Copyright (c) 2000, 2003 IBM Corporation and others. * All rights reserved. This program and the accompanying materials  * are made available under the terms of the Common Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/cpl-v10.html *  * Contributors: *     IBM Corporation - initial API and implementation *******************************************************************************/package org.eclipse.swt.layout; import org.eclipse.swt.*;import org.eclipse.swt.widgets.*;/** * Instances of this class are used to define the attachments  * of a control in a <code>FormLayout</code>.  * <p> * To set a <code>FormData</code> object into a control, you use the  * <code>setLayoutData ()</code> method. To define attachments for the  * <code>FormData</code>, set the fields directly, like this: * <pre> * 		FormData data = new FormData(); * 		data.left = new FormAttachment(0,5); * 		data.right = new FormAttachment(100,-5); * 		button.setLayoutData(formData); * </pre> * </p> * <p> * <code>FormData</code> contains the <code>FormAttachments</code> for  * each edge of the control that the <code>FormLayout</code> uses to * determine the size and position of the control. <code>FormData</code> * objects also allow you to set the width and height of controls within * a <code>FormLayout</code>.  * </p> *  * @see FormLayout * @see FormAttachment *  * @since 2.0 */public final class FormData {	/**	 * height specifies the desired height in pixels	 */	public int height;	/**	 * width specifies the desired width in pixels	 */	public int width;	/**	 * left specifies the attachment of the left side of 	 * the control.	 */	public FormAttachment left;	/**	 * right specifies the attachment of the right side of	 * the control.	 */	public FormAttachment right;	/**	 * top specifies the attachment of the top of the control.	 */	public FormAttachment top;	/**	 * bottom specifies the attachment of the bottom of the	 * control.	 */	public FormAttachment bottom;		int cacheHeight, cacheWidth;	FormAttachment cacheLeft, cacheRight, cacheTop, cacheBottom;	boolean isVisited;	public FormData () {	this (SWT.DEFAULT, SWT.DEFAULT);}	public FormData (int width, int height) {	this.width = width;	this.height = height;}FormAttachment getBottomAttachment (int spacing) {	if (cacheBottom != null) return cacheBottom;	if (isVisited) return cacheBottom = new FormAttachment (0, cacheHeight);	if (bottom == null) {		if (top == null) return cacheBottom = new FormAttachment (0, cacheHeight);		return cacheBottom = getTopAttachment (spacing).plus (cacheHeight);	}	Control control = bottom.control;	if (control != null && control.isDisposed ()) bottom.control = control = null;	if (control == null) return cacheBottom = bottom;	isVisited = true;	FormData formData = (FormData) control.getLayoutData ();	FormAttachment bottomAttachment = formData.getBottomAttachment (spacing);	switch (bottom.alignment) {		case SWT.BOTTOM: 			cacheBottom = bottomAttachment.plus (bottom.offset);			break;		case SWT.CENTER: {			FormAttachment topAttachment = formData.getTopAttachment (spacing);			FormAttachment bottomHeight = bottomAttachment.minus (topAttachment);			cacheBottom = bottomAttachment.minus (bottomHeight.minus (cacheHeight).divide (2));			break;		}//		case SWT.TOP://		case SWT.DEFAULT:		default: {			FormAttachment topAttachment = formData.getTopAttachment (spacing);			cacheBottom = topAttachment.plus (bottom.offset - spacing);				break;		}	}	isVisited = false;	return cacheBottom;}FormAttachment getLeftAttachment (int spacing) {	if (cacheLeft != null) return cacheLeft;	if (isVisited) return cacheLeft = new FormAttachment (0, 0);	if (left == null) {		if (right == null) return cacheLeft = new FormAttachment (0, 0);		return cacheLeft = getRightAttachment (spacing).minus (cacheWidth);	}	Control control = left.control;	if (control != null && control.isDisposed ()) left.control = control = null;	if (control == null) return cacheLeft = left;	isVisited = true;	FormData formData = (FormData) control.getLayoutData ();	FormAttachment leftAttachment = formData.getLeftAttachment (spacing);	switch (left.alignment) {		case SWT.LEFT:			cacheLeft = leftAttachment.plus (left.offset);			break;		case SWT.CENTER: {			FormAttachment rightAttachment = formData.getRightAttachment (spacing);			FormAttachment leftWidth = rightAttachment.minus (leftAttachment);			cacheLeft = leftAttachment.plus (leftWidth.minus (cacheWidth).divide (2));			break;		}//		case SWT.RIGHT://		case SWT.DEFAULT:		default: {			FormAttachment rightAttachment = formData.getRightAttachment (spacing);			cacheLeft = rightAttachment.plus (left.offset + spacing); 		}	}	isVisited = false; 	return cacheLeft;}	FormAttachment getRightAttachment (int spacing) {	if (cacheRight != null) return cacheRight;	if (isVisited) return cacheRight = new FormAttachment (0, cacheWidth);	if (right == null) {		if (left == null) return cacheRight = new FormAttachment (0, cacheWidth);		return cacheRight = getLeftAttachment (spacing).plus (cacheWidth);	}	Control control = right.control;	if (control != null && control.isDisposed ()) right.control = control = null;	if (control == null) return cacheRight = right;	isVisited = true;	FormData formData = (FormData) control.getLayoutData ();	FormAttachment rightAttachment = formData.getRightAttachment (spacing);	switch (right.alignment) {		case SWT.RIGHT: 			cacheRight = rightAttachment.plus (right.offset);			break;		case SWT.CENTER: {			FormAttachment leftAttachment = formData.getLeftAttachment (spacing);			FormAttachment rightWidth = rightAttachment.minus (leftAttachment);			cacheRight = rightAttachment.minus (rightWidth.minus (cacheWidth).divide (2));			break;		}//		case SWT.LEFT://		case SWT.DEFAULT:		default: {			FormAttachment leftAttachment = formData.getLeftAttachment (spacing);			cacheRight = leftAttachment.plus (right.offset - spacing);			break;		}	}	isVisited = false;	return cacheRight;}FormAttachment getTopAttachment (int spacing) {	if (cacheTop != null) return cacheTop;	if (isVisited) return cacheTop = new FormAttachment (0, 0);	if (top == null) {		if (bottom == null) return cacheTop = new FormAttachment (0, 0);		return cacheTop = getBottomAttachment (spacing).minus (cacheHeight);	}	Control control = top.control;	if (control != null && control.isDisposed ()) top.control = control = null;	if (control == null) return cacheTop = top;	isVisited = true;	FormData formData = (FormData) control.getLayoutData ();	FormAttachment topAttachment = formData.getTopAttachment (spacing);	switch (top.alignment) {		case SWT.TOP:			cacheTop = topAttachment.plus (top.offset);			break;		case SWT.CENTER: {			FormAttachment bottomAttachment = formData.getBottomAttachment (spacing);			FormAttachment topHeight = bottomAttachment.minus (topAttachment);			cacheTop = topAttachment.plus (topHeight.minus (cacheHeight).divide (2));			break;		}//		case SWT.BOTTOM://		case SWT.DEFAULT:		default: {			FormAttachment bottomAttachment = formData.getBottomAttachment (spacing);			cacheTop = bottomAttachment.plus (top.offset + spacing);			break;		}	}	isVisited = false;	return cacheTop;}}