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130 lines
2.6 KiB
130 lines
2.6 KiB
/*
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* Copyright (c) 1999, 2008, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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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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