Keep track of whether or not anything was painted each frame and avoid the

extra effort of copying the back buffer to the screen if nothing actually
changed.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@2322 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/media/FrameManager.java

@@ -1,5 +1,5 @@
 //
-// $Id: FrameManager.java,v 1.32 2003/01/15 02:21:07 shaper Exp $
+// $Id: FrameManager.java,v 1.33 2003/03/25 19:06:54 mdb Exp $
 
 package com.threerings.media;
 
@@ -422,12 +422,18 @@ public class FrameManager
 
             // paint our frame participants (which want to be handled
             // specially)
-            _participantPaintOp.setGraphics(_bgfx);
+            _participantPaintOp.init(_bgfx);
             _participants.apply(_participantPaintOp);
+            boolean ppart = _participantPaintOp.paintedSomething();
 
             // repaint any widgets that have declared they need to be
             // repainted since the last tick
-            _remgr.paintComponents(_bgfx, this);
+            boolean pcomp = _remgr.paintComponents(_bgfx, this);
+
+            // if we didn't paint anything, get the fork out of dodge
+            if (!(ppart || pcomp)) {
+                return;
+            }
 
             if (_displayPerf && _perfLabel != null) {
                 // render the current performance status
@@ -683,9 +689,19 @@ public class FrameManager
          * Sets the graphics context to which the frame participants
          * render themselves.
          */
-        public void setGraphics (Graphics g)
+        public void init (Graphics g)
         {
             _g = g;
+            _painted = 0;
+        }
+
+        /**
+         * Returns true if we painted at least one component in our last
+         * application.
+         */
+        public boolean paintedSomething ()
+        {
+            return (_painted > 0);
         }
 
         // documentation inherited
@@ -693,7 +709,7 @@ public class FrameManager
         {
             FrameParticipant part = (FrameParticipant)observer;
             Component pcomp = part.getComponent();
-            if (pcomp == null) {
+            if (pcomp == null || !part.needsPaint()) {
                 return true;
             }
 
@@ -726,6 +742,7 @@ public class FrameManager
                 _g.translate(_bounds.x, _bounds.y);
                 pcomp.paint(_g);
                 _g.translate(-_bounds.x, -_bounds.y);
+                _painted++;
 
             } catch (Throwable t) {
                 String ptos = StringUtil.safeToString(part);
@@ -754,6 +771,9 @@ public class FrameManager
         /** The graphics context to which the participants render. */
         protected Graphics _g;
 
+        /** The number of participants that were actually painted. */
+        protected int _painted;
+
         /** A handy rectangle that we reuse time and again to avoid having
          * to instantiate a new rectangle in the midst of the core
          * rendering loop. */

src/java/com/threerings/media/FrameParticipant.java

@@ -1,5 +1,5 @@
 //
-// $Id: FrameParticipant.java,v 1.2 2002/06/18 22:25:33 mdb Exp $
+// $Id: FrameParticipant.java,v 1.3 2003/03/25 19:06:54 mdb Exp $
 
 package com.threerings.media;
 
@@ -20,6 +20,13 @@ public interface FrameParticipant
      */
     public void tick (long tickStamp);
 
+    /**
+     * Called immediately prior to {@link #getComponent} and then {@link
+     * Component#paint} on said component, to determine whether or not
+     * this frame participant needs to be painted.
+     */
+    public boolean needsPaint ();
+
     /**
      * If a frame participant wishes also to be actively rendered every
      * frame rather than use passive rendering (which for Swing, at least,

src/java/com/threerings/media/FrameRepaintManager.java

@@ -1,5 +1,5 @@
 //
-// $Id: FrameRepaintManager.java,v 1.16 2002/12/09 05:00:48 shaper Exp $
+// $Id: FrameRepaintManager.java,v 1.17 2003/03/25 19:06:54 mdb Exp $
 
 package com.threerings.media;
 
@@ -216,13 +216,15 @@ public class FrameRepaintManager extends RepaintManager
 
     /**
      * Paints the components that have become dirty since the last tick.
+     *
+     * @return true if any components were painted.
      */
-    public void paintComponents (Graphics g, FrameManager fmgr)
+    public boolean paintComponents (Graphics g, FrameManager fmgr)
     {
         synchronized (this) {
             // exit now if there are no dirty rectangles to paint
             if (_dirty.isEmpty()) {
-                return;
+                return false;
             }
 
             // otherwise, swap our hashmaps
@@ -416,6 +418,8 @@ public class FrameRepaintManager extends RepaintManager
 
         // clear out the mapping of dirty components
         _spare.clear();
+
+        return true;
     }
 
     /**

src/java/com/threerings/media/MediaPanel.java

@@ -1,5 +1,5 @@
 //
-// $Id: MediaPanel.java,v 1.28 2003/02/04 03:11:43 mdb Exp $
+// $Id: MediaPanel.java,v 1.29 2003/03/25 19:06:54 mdb Exp $
 
 package com.threerings.media;
 
@@ -223,9 +223,21 @@ public class MediaPanel extends JComponent
     {
     }
 
-    /**
+    // documentation inherited from interface
-     * Returns this component, as we want to be painted with the tick.
+    public boolean needsPaint ()
-     */
+    {
+        // compute our average dirty regions per tick
+        if (_tick++ == 99) {
+            _tick = 0;
+            int dirty = IntListUtil.sum(_dirty);
+            Arrays.fill(_dirty, 0);
+            _dirtyPerTick = (float)dirty/100;
+        }
+
+        return (!_tickPaintPending || _remgr.haveDirtyRegions());
+    }
+
+    // documentation inherited from interface
     public Component getComponent ()
     {
         return this;
@@ -271,14 +283,6 @@ public class MediaPanel extends JComponent
             _tickPaintPending = false;
         }
 
-        // compute our average dirty regions per tick
-        if (_tick++ == 99) {
-            _tick = 0;
-            int dirty = IntListUtil.sum(_dirty);
-            Arrays.fill(_dirty, 0);
-            _dirtyPerTick = (float)dirty/100;
-        }
-
         // if we have no invalid rects, there's no need to repaint
         if (!_remgr.haveDirtyRegions()) {
             return;