/*******************************************************************************
 * Copyright (c) 2002, 2011 Innoopract Informationssysteme GmbH 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:
 *    Innoopract Informationssysteme GmbH - initial API and implementation
 *    EclipseSource - ongoing development
 ******************************************************************************/
package org.eclipse.swt.widgets;

import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.graphics.Point;


/**
 * Instances of the receiver represent a selectable user interface object
 * that allows the user to drag a rubber banded outline of the sash within
 * the parent control.
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>HORIZONTAL, VERTICAL, SMOOTH</dd>
 * <dt><b>Events:</b></dt>
 * <dd>Selection</dd>
 * </dl>
 * <p>
 * Note: Only one of the styles HORIZONTAL and VERTICAL may be specified.
 * </p><p>
 * IMPORTANT: This class is intended to be subclassed <em>only</em>
 * within the SWT implementation.
 * </p>
 * 
 * @since 1.0
 */
public class Sash extends Control {

  /**
	 * Constructs a new instance of this class given its parent and a style
	 * value describing its behavior and appearance.
	 * <p>
	 * The style value is either one of the style constants defined in class
	 * <code>SWT</code> which is applicable to instances of this class, or
	 * must be built by <em>bitwise OR</em>'ing together (that is, using the
	 * <code>int</code> "|" operator) two or more of those <code>SWT</code>
	 * style constants. The class description lists the style constants that are
	 * applicable to the class. Style bits are also inherited from superclasses.
	 * </p>
	 *
	 * @param parent
	 *            a composite control which will be the parent of the new
	 *            instance (cannot be null)
	 * @param style
	 *            the style of control to construct
	 *
	 * @exception IllegalArgumentException
	 *                <ul>
	 *                <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
	 *                </ul>
	 * @exception SWTException
	 *                <ul>
	 *                <li>ERROR_THREAD_INVALID_ACCESS - if not called from the
	 *                thread that created the parent</li>
	 *                <li>ERROR_INVALID_SUBCLASS - if this class is not an
	 *                allowed subclass</li>
	 *                </ul>
	 *
	 * @see SWT#HORIZONTAL
	 * @see SWT#VERTICAL
	 * @see Widget#checkSubclass
	 * @see Widget#getStyle
	 */
  public Sash( Composite parent, int style ) {
    super( parent, checkStyle( style ) );
  }

  void initState() {
    state |= THEME_BACKGROUND;
  }

  public Point computeSize( int wHint, int hHint, boolean changed ) {
    checkWidget();
    int border = getBorderWidth();
    int width = border * 2, height = border * 2;
    if( ( style & SWT.HORIZONTAL ) != 0 ) {
      width += DEFAULT_WIDTH;
      height += 3;
    } else {
      width += 3;
      height += DEFAULT_HEIGHT;
    }
    if( wHint != SWT.DEFAULT ) {
      width = wHint + ( border * 2 );
    }
    if( hHint != SWT.DEFAULT ) {
      height = hHint + ( border * 2 );
    }
    return new Point( width, height );
  }


  /**
   * Adds the listener to the collection of listeners who will
   * be notified when the control is selected, by sending
   * it one of the messages defined in the <code>SelectionListener</code>
   * interface.
   * <p>
   * When <code>widgetSelected</code> is called, the x, y, width, and height fields of the event object are valid.
   * If the receiver is being dragged, the event object detail field contains the value <code>SWT.DRAG</code>.
   * <code>widgetDefaultSelected</code> is not called.
   * </p>
   *
   * @param listener the listener which should be notified
   *
   * @exception IllegalArgumentException <ul>
   *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
   * </ul>
   * @exception SWTException <ul>
   *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
   *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
   * </ul>
   *
   * @see SelectionListener
   * @see #removeSelectionListener
   * @see SelectionEvent
   */
  public void addSelectionListener( SelectionListener listener ) {
    checkWidget();
    SelectionEvent.addListener( this, listener );
  }

  /**
   * Removes the listener from the collection of listeners who will
   * be notified when the control is selected.
   *
   * @param listener the listener which should no longer be notified
   *
   * @exception IllegalArgumentException <ul>
   *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
   * </ul>
   * @exception SWTException <ul>
   *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
   *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
   * </ul>
   *
   * @see SelectionListener
   * @see #addSelectionListener
   */
  public void removeSelectionListener( SelectionListener listener ) {
    checkWidget();
    SelectionEvent.removeListener( this, listener );
  }

  //////////////////
  // Helping methods

  private static int checkStyle( int style ) {
    int result = SWT.NONE;
    if( style > 0 ) {
      result = style;
    }
    return result;
  }
}