Implement frame restacking under Android

* java/org/gnu/emacs/EmacsActivity.java (invalidateFocus1):
Synchronize with window.children for iteration through it.

* java/org/gnu/emacs/EmacsService.java (queryTree): Synchronize
with windowList for iteration through it.

* java/org/gnu/emacs/EmacsView.java (moveChildToBack): Correct
formatting mistake.
(moveAbove, moveBelow): New functions.

* java/org/gnu/emacs/EmacsWindow.java (destroyHandle, reparentTo)
(raise, lower): Remedy synchronization blunders.
(reconfigure): New function.

* src/android.c (android_init_emacs_window): Link with
`reconfigure'.
(android_reconfigure_wm_window): New wrapper function.

* src/androidfns.c (android_frame_restack): New function.
(Fandroid_frame_restack): Properly implement this function and
expunge outdated comment.

* src/androidgui.h (enum android_stack_mode)
(enum android_window_changes): New enumerators.

4 files changed, 171 insertions, 23 deletions

diff --git a/java/org/gnu/emacs/EmacsActivity.java b/java/org/gnu/emacs/EmacsActivity.java
index cecd9c21d99..f9aa261e355 100644
--- a/java/org/gnu/emacs/EmacsActivity.java
+++ b/java/org/gnu/emacs/EmacsActivity.java
@@ -89,8 +89,11 @@ public class EmacsActivity extends Activity
     if (window.view.isFocused ())
       focusedWindow = window;
 
-    for (EmacsWindow child : window.children)
-      invalidateFocus1 (child);
+    synchronized (window.children)
+      {
+        for (EmacsWindow child : window.children)
+          invalidateFocus1 (child);
+      }
   }
 
   public static void
diff --git a/java/org/gnu/emacs/EmacsService.java b/java/org/gnu/emacs/EmacsService.java
index 28b725d0cd0..6fa2ebb3fdb 100644
--- a/java/org/gnu/emacs/EmacsService.java
+++ b/java/org/gnu/emacs/EmacsService.java
@@ -505,15 +505,18 @@ public final class EmacsService extends Service
     else
       windowList = window.children;
 
-    array = new short[windowList.size () + 1];
-    i = 1;
+    synchronized (windowList)
+      {
+        array = new short[windowList.size () + 1];
+        i = 1;
 
-    array[0] = (window == null
-                ? 0 : (window.parent != null
-                       ? window.parent.handle : 0));
+        array[0] = (window == null
+                    ? 0 : (window.parent != null
+                           ? window.parent.handle : 0));
 
-    for (EmacsWindow treeWindow : windowList)
-      array[i++] = treeWindow.handle;
+        for (EmacsWindow treeWindow : windowList)
+          array[i++] = treeWindow.handle;
+      }
 
     return array;
   }
diff --git a/java/org/gnu/emacs/EmacsView.java b/java/org/gnu/emacs/EmacsView.java
index d09dcc7e50d..877b1ce2429 100644
--- a/java/org/gnu/emacs/EmacsView.java
+++ b/java/org/gnu/emacs/EmacsView.java
@@ -581,12 +581,12 @@ public final class EmacsView extends ViewGroup
 
         /* The view at 0 is the surface view.  */
         attachViewToParent (child, 1,
-                            child.getLayoutParams());
+                            child.getLayoutParams ());
       }
   }
 
-  /* The following two functions must not be called if the view has no
-     parent, or is parented to an activity.  */
+  /* The following four functions must not be called if the view has
+     no parent, or is parented to an activity.  */
 
   public void
   raise ()
@@ -615,6 +615,40 @@ public final class EmacsView extends ViewGroup
     parent.moveChildToBack (this);
   }
 
+  public void
+  moveAbove (EmacsView view)
+  {
+    EmacsView parent;
+    int index;
+
+    parent = (EmacsView) getParent ();
+
+    if (parent != view.getParent ())
+      throw new IllegalStateException ("Moving view above non-sibling");
+
+    index = parent.indexOfChild (this);
+    parent.detachViewFromParent (index);
+    index = parent.indexOfChild (view);
+    parent.attachViewToParent (this, index + 1, getLayoutParams ());
+  }
+
+  public void
+  moveBelow (EmacsView view)
+  {
+    EmacsView parent;
+    int index;
+
+    parent = (EmacsView) getParent ();
+
+    if (parent != view.getParent ())
+      throw new IllegalStateException ("Moving view above non-sibling");
+
+    index = parent.indexOfChild (this);
+    parent.detachViewFromParent (index);
+    index = parent.indexOfChild (view);
+    parent.attachViewToParent (this, index, getLayoutParams ());
+  }
+
   @Override
   protected void
   onCreateContextMenu (ContextMenu menu)
diff --git a/java/org/gnu/emacs/EmacsWindow.java b/java/org/gnu/emacs/EmacsWindow.java
index 1f28d5f4f53..8d444aa27f5 100644
--- a/java/org/gnu/emacs/EmacsWindow.java
+++ b/java/org/gnu/emacs/EmacsWindow.java
@@ -22,6 +22,7 @@ package org.gnu.emacs;
 import java.lang.IllegalStateException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.ListIterator;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.Map;
@@ -93,7 +94,9 @@ public final class EmacsWindow extends EmacsHandleObject
   public EmacsWindow parent;
 
   /* List of all children in stacking order.  This must be kept
-     consistent with their Z order!  */
+     consistent with their Z order!
+
+     Synchronize access to this list with itself.  */
   public ArrayList<EmacsWindow> children;
 
   /* Map between pointer identifiers and last known position.  Used to
@@ -165,7 +168,11 @@ public final class EmacsWindow extends EmacsHandleObject
 
     if (parent != null)
       {
-        parent.children.add (this);
+        synchronized (parent.children)
+          {
+            parent.children.add (this);
+          }
+
         EmacsService.SERVICE.runOnUiThread (new Runnable () {
             @Override
             public void
@@ -214,7 +221,12 @@ public final class EmacsWindow extends EmacsHandleObject
   destroyHandle () throws IllegalStateException
   {
     if (parent != null)
-      parent.children.remove (this);
+      {
+        synchronized (parent.children)
+          {
+            parent.children.remove (this);
+          }
+      }
 
     EmacsActivity.invalidateFocus ();
 
@@ -1163,10 +1175,20 @@ public final class EmacsWindow extends EmacsHandleObject
     /* Reparent this window to the other window.  */
 
     if (parent != null)
-      parent.children.remove (this);
+      {
+        synchronized (parent.children)
+          {
+            parent.children.remove (this);
+          }
+      }
 
     if (otherWindow != null)
-      otherWindow.children.add (this);
+      {
+        synchronized (otherWindow.children)
+          {
+            otherWindow.children.add (this);
+          }
+      }
 
     parent = otherWindow;
 
@@ -1239,9 +1261,12 @@ public final class EmacsWindow extends EmacsHandleObject
     if (parent == null)
       return;
 
-    /* Remove and add this view again.  */
-    parent.children.remove (this);
-    parent.children.add (this);
+    synchronized (parent.children)
+      {
+        /* Remove and add this view again.  */
+        parent.children.remove (this);
+        parent.children.add (this);
+      }
 
     /* Request a relayout.  */
     EmacsService.SERVICE.runOnUiThread (new Runnable () {
@@ -1261,9 +1286,12 @@ public final class EmacsWindow extends EmacsHandleObject
     if (parent == null)
       return;
 
-    /* Remove and add this view again.  */
-    parent.children.remove (this);
-    parent.children.add (this);
+    synchronized (parent.children)
+      {
+        /* Remove and add this view again.  */
+        parent.children.remove (this);
+        parent.children.add (this);
+      }
 
     /* Request a relayout.  */
     EmacsService.SERVICE.runOnUiThread (new Runnable () {
@@ -1276,6 +1304,86 @@ public final class EmacsWindow extends EmacsHandleObject
       });
   }
 
+  public synchronized void
+  reconfigure (final EmacsWindow window, final int stackMode)
+  {
+    ListIterator<EmacsWindow> iterator;
+    EmacsWindow object;
+
+    /* This does nothing here.  */
+    if (parent == null)
+      return;
+
+    /* If window is NULL, call lower or upper subject to
+       stackMode.  */
+
+    if (window == null)
+      {
+        if (stackMode == 1) /* ANDROID_BELOW */
+          lower ();
+        else
+          raise ();
+
+        return;
+      }
+
+    /* Otherwise, if window.parent is distinct from this, return.  */
+    if (window.parent != this.parent)
+      return;
+
+    /* Synchronize with the parent's child list.  Iterate over each
+       item until WINDOW is encountered, before moving this window to
+       the location prescribed by STACKMODE.  */
+
+    synchronized (parent.children)
+      {
+        /* Remove this window from parent.children, for it will be
+           reinserted before or after WINDOW.  */
+        parent.children.remove (this);
+
+        /* Create an iterator.  */
+        iterator = parent.children.listIterator ();
+
+        while (iterator.hasNext ())
+          {
+            object = iterator.next ();
+
+            if (object == window)
+              {
+                /* Now place this before or after the cursor of the
+                   iterator.  */
+
+                if (stackMode == 0) /* ANDROID_ABOVE */
+                  iterator.add (this);
+                else
+                  {
+                    iterator.previous ();
+                    iterator.add (this);
+                  }
+
+                /* Effect the same adjustment upon the view
+                   hiearchy.  */
+
+                EmacsService.SERVICE.runOnUiThread (new Runnable () {
+                    @Override
+                    public void
+                    run ()
+                    {
+                      if (stackMode == 0)
+                        view.moveAbove (window.view);
+                      else
+                        view.moveBelow (window.view);
+                    }
+                  });
+              }
+          }
+
+        /* parent.children does not list WINDOW, which should never
+           transpire.  */
+        EmacsNative.emacsAbort ();
+      }
+  }
+
   public synchronized int[]
   getWindowGeometry ()
   {