/*******************************************************************************
 * Copyright (c) 2000, 2004 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 net.sourceforge.phpdt.internal.ui.util;

import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.jface.util.Assert;
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.Table;
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) {
		button.setFont(JFaceResources.getDialogFont());
		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 getButtonHeightHint(Button button) {
		button.setFont(JFaceResources.getDialogFont());
		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 button
	 *            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).heightHint = getButtonHeightHint(button);
			((GridData) gd).widthHint = getButtonWidthHint(button);
			((GridData) gd).horizontalAlignment = GridData.FILL;
		}
	}

	public static int getTableHeightHint(Table table, int rows) {
		if (table.getFont().equals(JFaceResources.getDefaultFont()))
			table.setFont(JFaceResources.getDialogFont());
		int result = table.getItemHeight() * rows + table.getHeaderHeight();
		if (table.getLinesVisible())
			result += table.getGridLineWidth() * (rows - 1);
		return result;
	}

}
