Avert race condition between window attachment and buffer swap

* java/org/gnu/emacs/EmacsView.java (swapBuffers): Synchronize
such that code cannot execute between the bitmap's being loaded
and being transferred to surfaceView.
(onDetachedFromWindow): Recycle bitmap after the surface view is
reset.

* java/org/gnu/emacs/EmacsWindow.java (recreateActivity):

* src/android.c (android_init_emacs_window)
(android_recreate_activity):

* src/androidfns.c (Fandroid_recreate_activity)
(syms_of_androidfns): New functions for debugging window
attachment.

* src/androidgui.h: Update prototypes.

2 files changed, 43 insertions, 12 deletions

diff --git a/java/org/gnu/emacs/EmacsView.java b/java/org/gnu/emacs/EmacsView.java
index 136d8abc713..8398e4b784c 100644
--- a/java/org/gnu/emacs/EmacsView.java
+++ b/java/org/gnu/emacs/EmacsView.java
@@ -456,7 +456,6 @@ public final class EmacsView extends ViewGroup
   {
     Canvas canvas;
     Rect damageRect;
-    Bitmap bitmap;
 
     /* Make sure this function is called only from the Emacs
        thread.  */
@@ -474,11 +473,12 @@ public final class EmacsView extends ViewGroup
     damageRect = damageRegion.getBounds ();
     damageRegion.setEmpty ();
 
-    bitmap = getBitmap ();
-
-    /* Transfer the bitmap to the surface view, then invalidate
-       it.  */
-    surfaceView.setBitmap (bitmap, damageRect);
+    synchronized (this)
+      {
+        /* Transfer the bitmap to the surface view, then invalidate
+           it.  */
+        surfaceView.setBitmap (bitmap, damageRect);
+      }
   }
 
   @Override
@@ -724,17 +724,20 @@ public final class EmacsView extends ViewGroup
   public synchronized void
   onDetachedFromWindow ()
   {
-    isAttachedToWindow = false;
-
-    /* Recycle the bitmap and call GC.  */
-
-    if (bitmap != null)
-      bitmap.recycle ();
+    Bitmap savedBitmap;
 
+    savedBitmap = bitmap;
+    isAttachedToWindow = false;
     bitmap = null;
     canvas = null;
+
     surfaceView.setBitmap (null, null);
 
+    /* Recycle the bitmap and call GC.  */
+
+    if (savedBitmap != null)
+      savedBitmap.recycle ();
+
     /* Collect the bitmap storage; it could be large.  */
     Runtime.getRuntime ().gc ();
 
diff --git a/java/org/gnu/emacs/EmacsWindow.java b/java/org/gnu/emacs/EmacsWindow.java
index 207bd22c538..304304a328b 100644
--- a/java/org/gnu/emacs/EmacsWindow.java
+++ b/java/org/gnu/emacs/EmacsWindow.java
@@ -1784,4 +1784,32 @@ public final class EmacsWindow extends EmacsHandleObject
 
     return true;
   }
+
+
+
+  /* Miscellaneous functions for debugging graphics code.  */
+
+  /* Recreate the activity to which this window is attached, if any.
+     This is nonfunctional on Android 2.3.7 and earlier.  */
+
+  public void
+  recreateActivity ()
+  {
+    final EmacsWindowAttachmentManager.WindowConsumer attached;
+
+    attached = this.attached;
+
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB)
+      return;
+
+    view.post (new Runnable () {
+        @Override
+        public void
+        run ()
+        {
+          if (attached instanceof EmacsActivity)
+            ((EmacsActivity) attached).recreate ();
+        }
+      });
+  }
 };