130 lines
3.6 KiB
Java
130 lines
3.6 KiB
Java
/*
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* Copyright (c) 1999, 2008, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package javax.swing.text;
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import java.util.Vector;
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import sun.awt.AppContext;
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/**
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* A queue of text layout tasks.
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*
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* @author Timothy Prinzing
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* @see AsyncBoxView
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* @since 1.3
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*/
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public class LayoutQueue {
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private static final Object DEFAULT_QUEUE = new Object();
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private Vector<Runnable> tasks;
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private Thread worker;
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/**
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* Construct a layout queue.
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*/
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public LayoutQueue() {
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tasks = new Vector<Runnable>();
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}
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/**
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* Fetch the default layout queue.
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*/
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public static LayoutQueue getDefaultQueue() {
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AppContext ac = AppContext.getAppContext();
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synchronized (DEFAULT_QUEUE) {
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LayoutQueue defaultQueue = (LayoutQueue) ac.get(DEFAULT_QUEUE);
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if (defaultQueue == null) {
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defaultQueue = new LayoutQueue();
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ac.put(DEFAULT_QUEUE, defaultQueue);
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}
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return defaultQueue;
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}
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}
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/**
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* Set the default layout queue.
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*
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* @param q the new queue.
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*/
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public static void setDefaultQueue(LayoutQueue q) {
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synchronized (DEFAULT_QUEUE) {
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AppContext.getAppContext().put(DEFAULT_QUEUE, q);
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}
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}
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/**
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* Add a task that is not needed immediately because
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* the results are not believed to be visible.
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*/
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public synchronized void addTask(Runnable task) {
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if (worker == null) {
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worker = new LayoutThread();
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worker.start();
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}
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tasks.addElement(task);
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notifyAll();
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}
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/**
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* Used by the worker thread to get a new task to execute
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*/
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protected synchronized Runnable waitForWork() {
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while (tasks.size() == 0) {
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try {
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wait();
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} catch (InterruptedException ie) {
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return null;
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}
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}
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Runnable work = tasks.firstElement();
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tasks.removeElementAt(0);
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return work;
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}
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/**
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* low priority thread to perform layout work forever
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*/
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class LayoutThread extends Thread {
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LayoutThread() {
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super("text-layout");
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setPriority(Thread.MIN_PRIORITY);
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}
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public void run() {
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Runnable work;
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do {
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work = waitForWork();
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if (work != null) {
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work.run();
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}
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} while (work != null);
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}
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}
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}
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