1 files changed, 127 insertions, 0 deletions
diff --git a/src/main/java/com/lowagie/tools/SwingWorker.java b/src/main/java/com/lowagie/tools/SwingWorker.java
new file mode 100644
index 0000000..634a61a
--- /dev/null
+++ b/src/main/java/com/lowagie/tools/SwingWorker.java
@@ -0,0 +1,127 @@
+package com.lowagie.tools;
+import javax.swing.SwingUtilities;
+
+/**
+ * This is the 3rd version of SwingWorker (also known as
+ * SwingWorker 3), an abstract class that you subclass to
+ * perform GUI-related work in a dedicated thread.  For
+ * instructions on using this class, see:
+ *
+ * http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html
+ */
+public abstract class SwingWorker {
+    private Object value;  // see getValue(), setValue()
+    private Thread thread;
+
+    /**
+     * Class to maintain reference to current worker thread
+     * under separate synchronization control.
+     */
+    private static class ThreadVar {
+        private Thread thread;
+        ThreadVar(Thread t) { thread = t; }
+        synchronized Thread get() { return thread; }
+        synchronized void clear() { thread = null; }
+    }
+
+    private ThreadVar threadVar;
+
+    /**
+     * Get the value produced by the worker thread, or null if it
+     * hasn't been constructed yet.
+     */
+    protected synchronized Object getValueX() {
+        return value;
+    }
+
+    /**
+     * Set the value produced by worker thread
+     */
+    private synchronized void setValueX(Object x) {
+        value = x;
+    }
+
+    /**
+     * Compute the value to be returned by the <code>get</code> method.
+     */
+    public abstract Object construct();
+
+    /**
+     * Called on the event dispatching thread (not on the worker thread)
+     * after the <code>construct</code> method has returned.
+     */
+    public void finished() {
+    }
+
+    /**
+     * A new method that interrupts the worker thread.  Call this method
+     * to force the worker to stop what it's doing.
+     */
+    public void interrupt() {
+        Thread t = threadVar.get();
+        if (t != null) {
+            t.interrupt();
+        }
+        threadVar.clear();
+    }
+
+    /**
+     * Return the value created by the <code>construct</code> method.
+     * Returns null if either the constructing thread or the current
+     * thread was interrupted before a value was produced.
+     *
+     * @return the value created by the <code>construct</code> method
+     */
+    public Object get() {
+        while (true) {
+            Thread t = threadVar.get();
+            if (t == null) {
+                return getValueX();
+            }
+            try {
+                t.join();
+            }
+            catch (InterruptedException e) {
+                Thread.currentThread().interrupt(); // propagate
+                return null;
+            }
+        }
+    }
+
+
+    /**
+     * Start a thread that will call the <code>construct</code> method
+     * and then exit.
+     */
+    public SwingWorker() {
+        final Runnable doFinished = new Runnable() {
+           public void run() { finished(); }
+        };
+
+        Runnable doConstruct = new Runnable() {
+            public void run() {
+                try {
+                    setValueX(construct());
+                }
+                finally {
+                    threadVar.clear();
+                }
+
+                SwingUtilities.invokeLater(doFinished);
+            }
+        };
+
+        Thread t = new Thread(doConstruct);
+        threadVar = new ThreadVar(t);
+    }
+
+    /**
+     * Start the worker thread.
+     */
+    public void start() {
+        Thread t = threadVar.get();
+        if (t != null) {
+            t.start();
+        }
+    }
+}