1 /*******************************************************************************

     2  * Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).

     3  * All rights reserved. This program and the accompanying materials

     4  * are made available under the terms of the Eclipse Public License v1.0

     5  * which accompanies this distribution, and is available at

     6  * http://www.eclipse.org/legal/epl-v10.html

     7  *

     8  * Contributors:

     9  *     Nokia Corporation - initial implementation

    10  *******************************************************************************/

    11 

    12 package org.eclipse.swt.internal.extension;

    13 

    14 import org.eclipse.swt.internal.qt.midp.UIThreadLauncher;

    15 import org.eclipse.swt.widgets.Display;

    16 import org.eclipse.swt.widgets.Internal_PackageSupport;

    17 

    18 /**

    19  * A class that encapsulates services that enable the use of eSWT UI before the

    20  * application has initialized its UI. This is achieved by utilizing an

    21  * 'internal' instance of the Display class. I.e. an instance that is not

    22  * revealed to the application but is only used internally within the API

    23  * implementation.

    24  * 

    25  * The same rules apply to the internal Display instance that apply to the

    26  * Display normally. When the Display is created then the creating thread

    27  * becomes the UI thread of the process. The application needs to be able to

    28  * obtain control of the UI thread. The services for interfacing with the

    29  * application are provided by the class ApplicationUI.

    30  * 

    31  * @see ApplicationUI

    32  */

    33 public final class InternalUI {

    34 	/**

    35 	 * Obtains the platform specific UI thread where SWT UI APIs can be accessed

    36 	 * in and calls the provided Runnable in it. This method instantly returns

    37 	 * leaving two threads running concurrently: the calling thread and the UI

    38 	 * thread. Only one UI thread can exist per process and this method can be

    39 	 * called only once to obtain it. Subsequent calls will result in an

    40 	 * exception being thrown. This method can be called by any thread.

    41 	 * 

    42 	 * @param runnable

    43 	 *            A Runnable to call back in the UI thread.

    44 	 * @exception RuntimeException

    45 	 *                If starting the UI thread fails

    46 	 */

    47 	public static void startInUIThread(Runnable runnable) {

    48 		if(!UIThreadLauncher.startInUIThread(runnable)) {

    49 			throw new RuntimeException("Failed to start the UI thread");

    50 		}

    51 	}

    52 	

    53 	/**

    54 	 * Creates the internal instance of Display. Must be called only once.

    55 	 * 

    56 	 * This means that the native resources required by the eSWT UI will be

    57 	 * initialized and a Display instance is returned that can be used to access

    58 	 * them normally via the public eSWT APIs. 

    59 	 * 

    60 	 * @return The internal Display instance

    61 	 * @see getInternalDisplayInstance

    62 	 */

    63 	public synchronized static Display createInternalDisplay() {

    64 		if(getInternalDisplayInstance() != null) {

    65 			throw new RuntimeException("Display already exists");

    66 		}

    67 		return Internal_PackageSupport.internalInstance();

    68 	}

    69 	

    70 	/**

    71 	 * Returns the internal Display instance or null if it doesn't exist. 

    72 	 * @return The internal Display instance or null

    73 	 */

    74 	public synchronized static Display getInternalDisplayInstance() {

    75 		return Internal_PackageSupport.getInternalDisplayInstance();

    76 	}

    77 }