bundles/org.eclipse.swt.win32.win32.x86_64/src/org/eclipse/swt/custom/BusyIndicator.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2011 IBM Corporation and others.
   3  *
   4  * This program and the accompanying materials
   5  * are made available under the terms of the Eclipse Public License 2.0
   6  * which accompanies this distribution, and is available at
   7  * https://www.eclipse.org/legal/epl-2.0/
   8  *
   9  * SPDX-License-Identifier: EPL-2.0
  10  *
  11  * Contributors:
  12  *     IBM Corporation - initial API and implementation
  13  *******************************************************************************/
  14 package org.eclipse.swt.custom;
  15
  16
  17 import org.eclipse.swt.*;
  18 import org.eclipse.swt.graphics.*;
  19 import org.eclipse.swt.widgets.*;
  20
  21 /**
  22  * Support for showing a Busy Cursor during a long running process.
  23  *
  24  * @see <a href="http://www.eclipse.org/swt/snippets/#busyindicator">BusyIndicator snippets</a>
  25  * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
  26  */
  27 public class BusyIndicator {
  28
  29         static int nextBusyId = 1;
  30         static final String BUSYID_NAME = "SWT BusyIndicator"; //$NON-NLS-1$
  31         static final String BUSY_CURSOR = "SWT BusyIndicator Cursor"; //$NON-NLS-1$
  32
  33         /**
  34          * Runs the given <code>Runnable</code> while providing
  35          * busy feedback using this busy indicator.
  36          *
  37          * @param display the display on which the busy feedback should be
  38          *        displayed.  If the display is null, the Display for the current
  39          *        thread will be used.  If there is no Display for the current thread,
  40          *        the runnable code will be executed and no busy feedback will be displayed.
  41          * @param runnable the runnable for which busy feedback is to be shown.
  42          *        Must not be null.
  43          *
  44          * @exception IllegalArgumentException <ul>
  45          *    <li>ERROR_NULL_ARGUMENT - if the runnable is null</li>
  46          * </ul>
  47          */
  48
  49         public static void showWhile(Display display, Runnable runnable) {
  50                 if (runnable == null)
  51                         SWT.error(SWT.ERROR_NULL_ARGUMENT);
  52                 if (display == null) {
  53                         display = Display.getCurrent();
  54                         if (display == null) {
  55                                 runnable.run();
  56                                 return;
  57                         }
  58                 }
  59
  60                 Integer busyId = Integer.valueOf(nextBusyId);
  61                 nextBusyId++;
  62                 Cursor cursor = display.getSystemCursor(SWT.CURSOR_WAIT);
  63                 Shell[] shells = display.getShells();
  64                 for (Shell shell : shells) {
  65                         Integer id = (Integer)shell.getData(BUSYID_NAME);
  66                         if (id == null) {
  67                                 setCursorAndId(shell, cursor, busyId);
  68                         }
  69                 }
  70
  71                 try {
  72                         runnable.run();
  73                 } finally {
  74                         shells = display.getShells();
  75                         for (Shell shell : shells) {
  76                                 Integer id = (Integer)shell.getData(BUSYID_NAME);
  77                                 if (id == busyId) {
  78                                         setCursorAndId(shell, null, null);
  79                                 }
  80                         }
  81                 }
  82         }
  83
  84         /**
  85          * Paranoia code to make sure we don't break UI because of one shell disposed, see bug 532632 comment 20
  86          */
  87         private static void setCursorAndId(Shell shell, Cursor cursor, Integer busyId) {
  88                 if (!shell.isDisposed()) {
  89                         shell.setCursor(cursor);
  90                 }
  91                 if (!shell.isDisposed()) {
  92                         shell.setData(BUSYID_NAME, busyId);
  93                 }
  94         }
  95 }