debug/org.eclipse.cdt.debug.ui/src/org/eclipse/cdt/debug/internal/ui/SWTUtil.java

/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved.
 */
package org.eclipse.cdt.debug.internal.ui;

import org.eclipse.jface.dialogs.IDialogConstants;
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.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).heightHint = getButtonHeigthHint( button );
			((GridData) gd).widthHint = getButtonWidthHint( button );
		}
	}
}