| /* |
| * Copyright 1999 Sun Microsystems, Inc. All Rights Reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Sun designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Sun in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| */ |
| package javax.swing.text; |
| |
| import java.util.Vector; |
| |
| /** |
| * A queue of text layout tasks. |
| * |
| * @author Timothy Prinzing |
| * @see AsyncBoxView |
| * @since 1.3 |
| */ |
| public class LayoutQueue { |
| |
| Vector<Runnable> tasks; |
| Thread worker; |
| |
| static LayoutQueue defaultQueue; |
| |
| /** |
| * Construct a layout queue. |
| */ |
| public LayoutQueue() { |
| tasks = new Vector<Runnable>(); |
| } |
| |
| /** |
| * Fetch the default layout queue. |
| */ |
| public static LayoutQueue getDefaultQueue() { |
| if (defaultQueue == null) { |
| defaultQueue = new LayoutQueue(); |
| } |
| return defaultQueue; |
| } |
| |
| /** |
| * Set the default layout queue. |
| * |
| * @param q the new queue. |
| */ |
| public static void setDefaultQueue(LayoutQueue q) { |
| defaultQueue = q; |
| } |
| |
| /** |
| * Add a task that is not needed immediately because |
| * the results are not believed to be visible. |
| */ |
| public synchronized void addTask(Runnable task) { |
| if (worker == null) { |
| worker = new LayoutThread(); |
| worker.start(); |
| } |
| tasks.addElement(task); |
| notifyAll(); |
| } |
| |
| /** |
| * Used by the worker thread to get a new task to execute |
| */ |
| protected synchronized Runnable waitForWork() { |
| while (tasks.size() == 0) { |
| try { |
| wait(); |
| } catch (InterruptedException ie) { |
| return null; |
| } |
| } |
| Runnable work = tasks.firstElement(); |
| tasks.removeElementAt(0); |
| return work; |
| } |
| |
| /** |
| * low priority thread to perform layout work forever |
| */ |
| class LayoutThread extends Thread { |
| |
| LayoutThread() { |
| super("text-layout"); |
| setPriority(Thread.MIN_PRIORITY); |
| } |
| |
| public void run() { |
| Runnable work; |
| do { |
| work = waitForWork(); |
| if (work != null) { |
| work.run(); |
| } |
| } while (work != null); |
| } |
| |
| |
| } |
| |
| } |