fix for flicker in JAVA2D mode (issue #558)

core/src/processing/core/PApplet.java

@@ -1445,10 +1445,18 @@ public class PApplet extends Applet
 
     // make sure the screen is visible and usable
     // (also prevents over-drawing when using PGraphicsOpenGL)
-    if ((g != null) && (g.image != null)) {
+    if (g != null) {
-//      println("inside paint(), screen.drawImage()");
+      // added synchronization for 0194 because of flicker issues with JAVA2D
-      screen.drawImage(g.image, 0, 0, null);
+      // 
+      synchronized (g) {
+        if (g.image != null) {
+          screen.drawImage(g.image, 0, 0, null);
+        }
+      }
     }
+//    if ((g != null) && (g.image != null)) {
+//      screen.drawImage(g.image, 0, 0, null);
+//    }
   }
 
 
@@ -1565,6 +1573,7 @@ public class PApplet extends Applet
 
       //System.out.println("handleDraw() " + frameCount);
 
+      synchronized (g) {
       g.beginDraw();
       if (recorder != null) {
         recorder.beginDraw();
@@ -1620,12 +1629,14 @@ public class PApplet extends Applet
       }
 
       g.endDraw();
+      
       if (recorder != null) {
         recorder.endDraw();
       }
 
       frameRateLastNanos = now;
       frameCount++;
+      }
 
       repaint();
       getToolkit().sync();  // force repaint now (proper method)

core/todo.txt

@@ -1,4 +1,6 @@
 0194 core
+X flicker between background and rest with JAVA2D
+X   http://code.google.com/p/processing/issues/detail?id=558
 
 
 _ bug: textAlign(RIGHT) is shutting off native fonts