Disable hardware acceleration on Android

It serves no purpose and causes tearing.  Uploading the bitmap
to the GPU takes about as long as it does to incrementally
update the surface in software.

* java/AndroidManifest.xml.in: Disable hardware acceleration.
* java/org/gnu/emacs/EmacsActivity.java (EmacsActivity): Make
lastClosedMenu static.
* java/org/gnu/emacs/EmacsDialog.java (toAlertDialog): Enable
hardware acceleration within alert dialogs.
* java/org/gnu/emacs/EmacsSurfaceView.java (onDraw): Describe
why hardware acceleration is disabled.
* java/org/gnu/emacs/EmacsWindow.java (run): Remove redundant
call.

java/AndroidManifest.xml.in

@@ -77,10 +77,14 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>. -->
 	       @ANDROID_SHARED_USER_ID@
 	       android:extractNativeLibs="true">
 
+    <!-- See EmacsSurfaceView.onDraw for why hardware acceleration is
+         disabled.  -->
+
     <activity android:name="org.gnu.emacs.EmacsActivity"
 	      android:launchMode="singleInstance"
 	      android:windowSoftInputMode="adjustResize"
 	      android:exported="true"
+	      android:hardwareAccelerated="false"
 	      android:configChanges="orientation|screenSize|screenLayout|keyboardHidden">
       <intent-filter>
         <action android:name="android.intent.action.MAIN" />
@@ -173,6 +177,7 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>. -->
     <activity android:name="org.gnu.emacs.EmacsMultitaskActivity"
 	      android:windowSoftInputMode="adjustResize"
 	      android:exported="true"
+	      android:hardwareAccelerated="false"
 	      android:configChanges="orientation|screenSize|screenLayout|keyboardHidden"/>
 
     <activity android:autoRemoveFromRecents="true"

java/org/gnu/emacs/EmacsActivity.java

@@ -70,7 +70,7 @@ public class EmacsActivity extends Activity
   private boolean isFullscreen;
 
   /* The last context menu to be closed.  */
-  private Menu lastClosedMenu;
+  private static Menu lastClosedMenu;
 
   static
   {

java/org/gnu/emacs/EmacsDialog.java

@@ -152,7 +152,7 @@ private final class EmacsButton implements View.OnClickListener,
   toAlertDialog (Context context)
   {
     AlertDialog dialog;
-    int size, styleId;
+    int size, styleId, flag;
     int[] attrs;
     EmacsButton button;
     EmacsDialogButtonLayout layout;
@@ -160,6 +160,7 @@ private final class EmacsButton implements View.OnClickListener,
     ViewGroup.LayoutParams layoutParams;
     Theme theme;
     TypedArray attributes;
+    Window window;
 
     size = buttons.size ();
     styleId = -1;
@@ -273,6 +274,17 @@ private final class EmacsButton implements View.OnClickListener,
 	  }
       }
 
+    /* Make sure the dialog is hardware accelerated.  Hardware
+       acceleration is disabled for dialogs by default, because they
+       aren't enabled in EmacsActivity either.  */
+
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB)
+      {
+	flag = WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED;
+	window = dialog.getWindow ();
+	window.addFlags (flag);
+      }
+
     return dialog;
   }
 

java/org/gnu/emacs/EmacsSurfaceView.java

@@ -176,7 +176,25 @@ else if (bitmap != null)
   onDraw (Canvas canvas)
   {
     /* Paint the view's bitmap; the bitmap might be recycled right
-       now.  */
+       now.
+
+       Hardware acceleration is disabled in AndroidManifest.xml to
+       prevent Android from uploading the front buffer to the GPU from
+       a separate thread.  This is important for two reasons: first,
+       the GPU command queue uses a massive amount of memory (dozens
+       of MiB) to upload bitmaps to the GPU, regardless of how much of
+       the bitmap has actually changed.
+
+       Secondly, asynchronous texturization leads to race conditions
+       when a buffer swap occurs before the front buffer is fully
+       uploaded to the GPU.  Normally, only slight and tolerable
+       tearing should result from this behavior, but Android does not
+       properly interlock the ``generation ID'' used to avoid
+       texturizing unchanged bitmaps with the bitmap contents,
+       consequentially leading to textures in an incomplete state
+       remaining in use to the GPU if a buffer swap happens between
+       the image data being uploaded and the ``generation ID'' being
+       read.  */
 
     if (frontBuffer != null)
       canvas.drawBitmap (frontBuffer, 0f, 0f, uiThreadPaint);

java/org/gnu/emacs/EmacsWindow.java

@@ -1377,7 +1377,7 @@ else if (EmacsWindow.this.isMapped)
 
 	  if (tem != null)
 	    {
-	      activity = (EmacsActivity) getAttachedConsumer ();
+	      activity = (EmacsActivity) tem;
 	      activity.syncFullscreenWith (EmacsWindow.this);
 	    }
 	}