/*******************************************************************************
 * Copyright (c) 2005, 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.cdt.debug.internal.ui;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.jface.layout.PixelConverter;
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Caret;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.ScrollBar;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Widget;

/**
 * Utility class to simplify access to some SWT resources.
 */
public class SWTUtil {

	/**
	 * Returns the standard display to be used. The method first checks, if the
	 * thread calling this method has an associated disaply. If so, this
	 * display is returned. Otherwise the method returns the default display.
	 */
	public static Display getStandardDisplay() {
		Display display;
		display = Display.getCurrent();
		if ( display == null )
			display = Display.getDefault();
		return display;
	}

	/**
	 * Returns the shell for the given widget. If the widget doesn't represent
	 * a SWT object that manage a shell, <code>null</code> is returned.
	 * 
	 * @return the shell for the given widget
	 */
	public static Shell getShell(Widget widget) {
		if ( widget instanceof Control )
			return ((Control)widget).getShell();
		if ( widget instanceof Caret )
			return ((Caret)widget).getParent().getShell();
		if ( widget instanceof DragSource )
			return ((DragSource)widget).getControl().getShell();
		if ( widget instanceof DropTarget )
			return ((DropTarget)widget).getControl().getShell();
		if ( widget instanceof Menu )
			return ((Menu)widget).getParent().getShell();
		if ( widget instanceof ScrollBar )
			return ((ScrollBar)widget).getParent().getShell();
		return null;
	}

	/**
	 * Returns a width hint for a button control.
	 */
	public static int getButtonWidthHint( Button button ) {
		PixelConverter converter = new PixelConverter( button );
		int widthHint = converter.convertHorizontalDLUsToPixels( IDialogConstants.BUTTON_WIDTH );
		return Math.max( widthHint, button.computeSize( SWT.DEFAULT, SWT.DEFAULT, true ).x );
	}

	/**
	 * Returns a height hint for a button control.
	 */
//	public static int getButtonHeigthHint( Button button ) {
//		PixelConverter converter = new PixelConverter( button );
//		return converter.convertVerticalDLUsToPixels( IDialogConstants.BUTTON_HEIGHT );
//	}

	/**
	 * Sets width and height hint for the button control. <b>Note:</b> This
	 * is a NOP if the button's layout data is not an instance of <code>GridData</code>.
	 * 
	 * @param the button for which to set the dimension hint
	 */
	public static void setButtonDimensionHint( Button button ) {
		Assert.isNotNull( button );
		Object gd = button.getLayoutData();
		if ( gd instanceof GridData ) {
			((GridData)gd).widthHint = getButtonWidthHint( button );
			((GridData)gd).horizontalAlignment = GridData.FILL;	 
		}
	}
}
