/*******************************************************************************
 * Copyright (c) 2000, 2006 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.pde.internal.ui.util;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.dialogs.Dialog;
import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.widgets.*;

/**
 * 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 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) {
		if (button.getFont().equals(JFaceResources.getDefaultFont()))
			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);
	}

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

	public static void setDialogSize(Dialog dialog, int width, int height) {
		Point computedSize = dialog.getShell().computeSize(SWT.DEFAULT, SWT.DEFAULT);
		width = Math.max(computedSize.x, width);
		height = Math.max(computedSize.y, height);
		dialog.getShell().setSize(width, height);
	}
}