1 files changed, 146 insertions, 0 deletions
diff --git a/java/org/gnu/emacs/EmacsActivity.java b/java/org/gnu/emacs/EmacsActivity.java
new file mode 100644
index 00000000000..cacd5f13e60
--- /dev/null
+++ b/java/org/gnu/emacs/EmacsActivity.java
@@ -0,0 +1,146 @@
+/* Communication module for Android terminals.  -*- c-file-style: "GNU" -*-
+
+Copyright (C) 2023 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or (at
+your option) any later version.
+
+GNU Emacs is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
+
+package org.gnu.emacs;
+
+import java.lang.IllegalStateException;
+import java.util.List;
+import java.util.ArrayList;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.Intent;
+import android.os.Bundle;
+import android.util.Log;
+import android.widget.FrameLayout;
+import android.widget.FrameLayout.LayoutParams;
+
+public class EmacsActivity extends Activity
+{
+  public static final String TAG = "EmacsActivity";
+
+  /* List of all activities that do not have an associated
+     EmacsWindow.  */
+  public static List<EmacsActivity> availableActivities;
+
+  /* The currently attached EmacsWindow, or null if none.  */
+  private EmacsWindow window;
+
+  /* The frame layout associated with the activity.  */
+  private FrameLayout layout;
+
+  static
+  {
+    /* Set up the list of available activities.  */
+    availableActivities = new ArrayList<EmacsActivity> ();
+  };
+
+  public void
+  attachChild (EmacsWindow child)
+  {
+    if (window != null)
+      throw new IllegalStateException ("trying to attach window when one"
+				       + " already exists");
+
+    /* Record and attach the view.  */
+    window = child;
+    layout.addView (window.view);
+
+    /* Remove the objects from the lists of what is available.  */
+    EmacsService.availableChildren.remove (child);
+    availableActivities.remove (this);
+
+    /* Now set child->activity.  */
+    child.setActivity (this);
+  }
+
+  /* Make this activity available for future windows to attach
+     again.  */
+
+  public void
+  makeAvailable ()
+  {
+    window = null;
+
+    for (EmacsWindow iterWindow
+	   : EmacsService.availableChildren)
+      {
+	synchronized (iterWindow)
+	  {
+	    if (!iterWindow.isDestroyed ())
+	      attachChild (iterWindow);
+
+	    return;
+	  }
+      }
+
+    availableActivities.add (this);
+  }
+
+  @Override
+  public void
+  onCreate (Bundle savedInstanceState)
+  {
+    FrameLayout.LayoutParams params;
+
+    params = new FrameLayout.LayoutParams (LayoutParams.MATCH_PARENT,
+					   LayoutParams.MATCH_PARENT);
+
+    /* Make the frame layout.  */
+    layout = new FrameLayout (this);
+    layout.setLayoutParams (params);
+
+    /* Set it as the content view.  */
+    setContentView (layout);
+
+    /* Make the activity available before starting the
+       service.  */
+    makeAvailable ();
+
+    if (EmacsService.SERVICE == null)
+      /* Start the Emacs service now.  */
+      startService (new Intent (this, EmacsService.class));
+
+    super.onCreate (savedInstanceState);
+  }
+
+  @Override
+  public void
+  onStop ()
+  {
+    /* The activity is no longer visible.  If there is a window
+       attached, detach it.  */
+
+    if (window != null)
+      {
+	layout.removeView (window.view);
+
+	/* Notice that the window is already available too.  But do
+	   not call noticeAvailableChild; that might assign it to some
+	   other activity, which behaves badly.  */
+	EmacsService.availableChildren.add (window);
+	window = null;
+      }
+
+    /* Finally, remove this activity from the list of available
+       activities.  */
+    availableActivities.remove (this);
+    super.onStop ();
+  }
+};