some fixes of loop handing in GL renderers

core/src/processing/android/PFragment.java

@@ -254,12 +254,6 @@ public void requestDraw() {
 
 
   public boolean canDraw() {
-    if (sketch == null) return false;
-    return sketch.isLooping();
+    return sketch != null && sketch.isLooping();
   }
-
-
-//public void onBackPressed() {
-//  sketch.exit();
-//}
 }

core/src/processing/core/PApplet.java

@@ -315,14 +315,6 @@ public class PApplet extends Object implements ActivityAPI, PConstants {
 
   protected boolean looping;
 
-  // This auxiliary variable is used to implement a little hack that fixes
-  // https://github.com/processing/processing-android/issues/147
-  // on older devices where the last frame cannot be maintained after ending
-  // the rendering in GL. The trick consists in running one more frame after the
-  // noLoop() call, which ensures that the FBO layer is properly initialized
-  // and drawn with the contents of the previous frame.
-  protected boolean requestedNoLoop = false;
-
   /** flag set to true when a redraw is asked for by the user */
   protected boolean redraw;
 
@@ -1908,7 +1900,7 @@ protected boolean handleSpecialDraw() {
       g.endDraw();
 
       handled = true;
-    } else if (requestedNoLoop) {
+    } else if (g.requestedNoLoop) {
       // noLoop() was called sometime in the previous frame with a GL renderer, but only now
       // we are sure that the frame is properly displayed.
       looping = false;
@@ -1918,7 +1910,7 @@ protected boolean handleSpecialDraw() {
       g.beginDraw();
       g.endDraw();
 
-      requestedNoLoop = false;
+      g.requestedNoLoop = false;
       handled = true;
     }
 
@@ -1930,8 +1922,8 @@ protected boolean handleSpecialDraw() {
     }
   }
 
-  //////////////////////////////////////////////////////////////
 
+  //////////////////////////////////////////////////////////////
 
 
   synchronized public void redraw() {
@@ -1961,8 +1953,8 @@ synchronized public void loop() {
 
   synchronized public void noLoop() {
     if (looping) {
-      if (g instanceof PGraphicsOpenGL) {
-        requestedNoLoop = true;
+      if (g.requestNoLoop()) {
+        g.requestedNoLoop = true;
       } else {
         looping = false;
       }

core/src/processing/core/PGraphics.java

@@ -649,6 +649,14 @@ public class PGraphics extends PImage implements PConstants {
   protected boolean restartedLoopingAfterResume = false;
   protected boolean restoredSurface = true;
 
+  // This auxiliary variable is used to implement a little hack that fixes
+  // https://github.com/processing/processing-android/issues/147
+  // on older devices where the last frame cannot be maintained after ending
+  // the rendering in GL. The trick consists in running one more frame after the
+  // noLoop() call, which ensures that the FBO layer is properly initialized
+  // and drawn with the contents of the previous frame.
+  protected boolean requestedNoLoop = false;
+
   //////////////////////////////////////////////////////////////
 
   // INTERNAL
@@ -996,7 +1004,7 @@ protected void restoreState() {  // ignore
     // This method probably does not need to be re-implemented in the subclasses. All we need to
     // do is to check for the resume in no-loop state situation:
     restoredSurface = false;
-    if (!parent.isLooping()) {
+    if (!parent.looping) {
       // The sketch needs to draw a few frames after resuming so it has the chance to restore the
       // screen contents:
       // https://github.com/processing/processing-android/issues/492
@@ -1023,6 +1031,19 @@ protected void restoreSurface() { // ignore
     }
   }
 
+
+  protected boolean requestNoLoop() { // ignore
+    // Some renderers (OpenGL) cannot be set to no-loop right away, it has to be requested so
+    // any pending frames are properly rendered. Override as needed.
+    return false;
+  }
+
+
+  protected boolean isLooping() { // ignore
+    return parent.isLooping() && (!requestNoLoop() || !requestedNoLoop);
+  }
+
+
   //////////////////////////////////////////////////////////////
 
   // HINTS

core/src/processing/opengl/PGL.java

@@ -760,9 +760,9 @@ protected void beginRender() {
         float bb = ((argb) & 0xff) / 255.0f;
         clearColor(br, bg, bb, ba);
         clear(COLOR_BUFFER_BIT);
-      } else if (!pclearColor || !sketch.isLooping()) {
-        // Render previous back texture (now is the front) as background,
-        // because no background() is being used ("incremental drawing")
+      } else if (!pclearColor || !graphics.isLooping()) {
+        // Render previous back texture (now is the front) as background, because no background()
+        // is being used ("incremental drawing")
         int x = 0;
         int y = 0;
         if (presentMode) {
@@ -869,7 +869,7 @@ protected void endRender(int windowColor) {
         saveFirstFrame();
       }
 
-      if (!clearColor && 0 < sketch.frameCount || !sketch.isLooping()) {
+      if (!clearColor && 0 < sketch.frameCount || !graphics.isLooping()) {
         enableFBOLayer();
         if (SINGLE_BUFFERED) {
           createFBOLayer();

core/src/processing/opengl/PGraphicsOpenGL.java

@@ -735,7 +735,7 @@ protected void updatePixelSize() {
 
 
   // Factory method
-  protected PGL createPGL(PGraphicsOpenGL pg) {
+  protected PGL createPGL(PGraphicsOpenGL pg) { // ignore
 //    return new PJOGL(pg);
     return new PGLES(pg);
   }
@@ -764,6 +764,12 @@ public void setFrameRate(float frameRate) {
   }
 
 
+  @Override
+  protected boolean isLooping() { // ignore
+    return super.isLooping();
+  }
+
+
   public boolean saveImpl(String filename) {
     return super.save(filename); // ASYNC save frame using PBOs not yet available on Android
 
@@ -5798,6 +5804,12 @@ protected void restoreSurface() {
     super.restoreSurface();
   }
 
+
+  @Override
+  protected boolean requestNoLoop() {
+    return true;
+  }
+
   //////////////////////////////////////////////////////////////
 
   // GET/SET PIXELS