2003/11/05 10:25:00

[org.ibex.core.git] / src / org / xwt / Scheduler.java

diff --git a/src/org/xwt/Scheduler.java b/src/org/xwt/Scheduler.java
index 2cb7892..a46c75c 100644 (file)
--- a/src/org/xwt/Scheduler.java
+++ b/src/org/xwt/Scheduler.java
@@ -8,21 +8,37 @@ import org.xwt.util.*;
 /** Implements cooperative multitasking */
 public class Scheduler {
 
-    public static final Scheduler singleton = Platform.getScheduler();
-    protected Scheduler() { }
+    // Public API Exposed to org.xwt /////////////////////////////////////////////////
 
     public static abstract class Task { public abstract void perform(); }
+    public static void add(Task t) { singleton.runnable.append(t); }
+    public static void init() { singleton.run(); }
+
+
+    // API which must be supported by subclasses /////////////////////////////////////
+
+    protected Scheduler() { }
+
+    /**
+     *  INVARIANT: all scheduler implementations MUST invoke
+     *  Surface.renderAll() after performing a Task if no tasks remain
+     *  in the queue.  A scheduler may choose to invoke
+     *  Surface.renderAll() more often than that if it so chooses.
+     */
+    public void run() { defaultRun(); }
+
+
+    // Default Implementation /////////////////////////////////////
 
     protected static Queue runnable = new Queue(50);
-    public static void add(Task t) { singleton.runnable.append(t); }
-    public void run() {
+    private static final Scheduler singleton = Platform.getScheduler();
+    public void defaultRun() {
         while(true) {
             Task t = (Task)runnable.remove(true);
             try {
                 t.perform();
                 // FIXME: be smarter about this
-                for(int i=0; i<Surface.allSurfaces.size(); i++)
-                    ((Surface)Surface.allSurfaces.elementAt(i)).render();
+                Surface.renderAll();
             } catch (Exception e) {
                 Log.log(Scheduler.class, "Task threw an exception: " + e);
                 Log.log(Scheduler.class, e);