Implement `fullscreen' on Android 4.0 and later

* doc/emacs/android.texi (Android Windowing): Document what new
frame parameters are now supported.
* java/org/gnu/emacs/EmacsActivity.java (EmacsActivity): New
field `isFullscreen'.
(detachWindow, attachWindow): Sync fullscreen state.
(onWindowFocusChanged): Add more logging.
(onResume): Restore previous fullscreen state.
(syncFullscreen): New function.
* java/org/gnu/emacs/EmacsWindow.java (EmacsWindow)
(setFullscreen): New function.
* src/android.c (struct android_emacs_window): Add new method.
(android_init_emacs_window): Look up new method.
(android_set_fullscreen): New function.
* src/androidgui.h:
* src/androidterm.c (android_fullscreen_hook): Implement
accordingly.

3 files changed, 54 insertions, 3 deletions

diff --git a/src/android.c b/src/android.c
index d21aaabc1ac..fc5e6d278ed 100644
--- a/src/android.c
+++ b/src/android.c
@@ -136,6 +136,7 @@ struct android_emacs_window
   jmethodID swap_buffers;
   jmethodID toggle_on_screen_keyboard;
   jmethodID lookup_string;
+  jmethodID set_fullscreen;
 };
 
 /* The API level of the current device.  */
@@ -1920,6 +1921,7 @@ android_init_emacs_window (void)
   FIND_METHOD (toggle_on_screen_keyboard,
                "toggleOnScreenKeyboard", "(Z)V");
   FIND_METHOD (lookup_string, "lookupString", "(I)Ljava/lang/String;");
+  FIND_METHOD (set_fullscreen, "setFullscreen", "(Z)V");
 #undef FIND_METHOD
 }
 
@@ -5475,6 +5477,36 @@ android_reset_ic (android_window window, enum android_ic_mode mode)
 
 
 
+/* Window decoration management functions.  */
+
+/* Make the specified WINDOW fullscreen, i.e. obscure all of the
+   system navigation and status bars.  If not FULLSCREEN, make it
+   maximized instead.
+
+   Value is 1 if the system does not support this, else 0.  */
+
+int
+android_set_fullscreen (android_window window, bool fullscreen)
+{
+  jobject object;
+
+  /* Android 4.0 and earlier don't support fullscreen windows.  */
+
+  if (android_api_level < 16)
+    return 1;
+
+  object = android_resolve_handle (window, ANDROID_HANDLE_WINDOW);
+
+  (*android_java_env)->CallVoidMethod (android_java_env,
+                                       object,
+                                       window_class.set_fullscreen,
+                                       (jboolean) fullscreen);
+  android_exception_check ();
+  return 0;
+}
+
+
+
 #else /* ANDROID_STUBIFY */
 
 /* X emulation functions for Android.  */
diff --git a/src/androidgui.h b/src/androidgui.h
index 25dc6754fff..84419457a8a 100644
--- a/src/androidgui.h
+++ b/src/androidgui.h
@@ -614,6 +614,7 @@ extern int android_wc_lookup_string (android_key_pressed_event *,
 extern void android_update_ic (android_window, ptrdiff_t, ptrdiff_t,
                                ptrdiff_t, ptrdiff_t);
 extern void android_reset_ic (android_window, enum android_ic_mode);
+extern int android_set_fullscreen (android_window, bool);
 
 #endif
 
diff --git a/src/androidterm.c b/src/androidterm.c
index 0fbee1e9867..62a8d5d12b3 100644
--- a/src/androidterm.c
+++ b/src/androidterm.c
@@ -1792,12 +1792,30 @@ android_make_frame_visible_invisible (struct frame *f, bool visible)
 static void
 android_fullscreen_hook (struct frame *f)
 {
-  /* Explicitly setting fullscreen is not supported on Android.  */
+  Lisp_Object wanted;
 
   if (!FRAME_PARENT_FRAME (f))
-    store_frame_param (f, Qfullscreen, Qmaximized);
+    {
+      /* Explicitly setting fullscreen is not supported on older
+         Android versions.  */
+
+      wanted = (f->want_fullscreen == FULLSCREEN_BOTH
+                ? Qfullscreen : Qmaximized);
+
+      if (android_set_fullscreen (FRAME_ANDROID_WINDOW (f),
+                                  EQ (wanted, Qfullscreen)))
+        store_frame_param (f, Qfullscreen, Qmaximized);
+      else
+        store_frame_param (f, Qfullscreen, wanted);
+    }
   else
-    store_frame_param (f, Qfullscreen, Qnil);
+    {
+      store_frame_param (f, Qfullscreen, Qnil);
+
+      /* If this is a child frame, don't keep it fullscreen
+         anymore.  */
+      android_set_fullscreen (FRAME_ANDROID_WINDOW (f), false);
+    }
 }
 
 void