Introduce ns-auto-hide-menu-bar to hide menubar for Emacs frames.

Code by Anders Lindgren.

* nsterm.m (ns_menu_bar_is_hidden): New variable.
(ns_constrain_all_frames, ns_menu_bar_should_be_hidden)
(ns_update_auto_hide_menu_bar): New functions.
(ns_update_begin): Call ns_update_auto_hide_menu_bar.
(applicationDidBecomeActive): Call ns_update_auto_hide_menu_bar and
ns_constrain_all_frames.
(constrainFrameRect): Return at once if ns_menu_bar_should_be_hidden.
(syms_of_nsterm): DEFVAR ns-auto-hide-menu-bar, init to Qnil.

2 files changed, 140 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index eb03806b33a..96f60877fce 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,14 @@
+2011-03-27  Anders Lindgren <andlind@gmail.com>
+
+        * nsterm.m (ns_menu_bar_is_hidden): New variable.
+        (ns_constrain_all_frames, ns_menu_bar_should_be_hidden)
+        (ns_update_auto_hide_menu_bar): New functions.
+        (ns_update_begin): Call ns_update_auto_hide_menu_bar.
+        (applicationDidBecomeActive): Call ns_update_auto_hide_menu_bar and
+        ns_constrain_all_frames.
+        (constrainFrameRect): Return at once if ns_menu_bar_should_be_hidden.
+        (syms_of_nsterm): DEFVAR ns-auto-hide-menu-bar, init to Qnil.
+
 2011-03-27  Jan Djärv  <jan.h.d@swipnet.se>
 
         * nsmenu.m (runDialogAt): Remove argument to timer_check.
diff --git a/src/nsterm.m b/src/nsterm.m
index c7cd411c614..ebfa875ae0e 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -170,6 +170,7 @@ BOOL ns_in_resize = NO;
 static BOOL ns_fake_keydown = NO;
 int ns_tmp_flags; /* FIXME */
 struct nsfont_info *ns_tmp_font; /* FIXME */
+static BOOL ns_menu_bar_is_hidden = NO;
 /*static int debug_lock = 0; */
 
 /* event loop */
@@ -505,6 +506,118 @@ ns_resize_handle_rect (NSWindow *window)
 }
 
 
+//
+// Window constraining
+// -------------------
+//
+// To ensure that the windows are not placed under the menu bar, they
+// are typically moved by the call-back constrainFrameRect. However,
+// by overriding it, it's possible to inhibit this, leaving the window
+// in it's original position.
+//
+// It's possible to hide the menu bar. However, technically, it's only
+// possible to hide it when the application is active. To ensure that
+// this work properly, the menu bar and window constraining are
+// deferred until the application becomes active.
+//
+// Even though it's not possible to manually move a window above the
+// top of the screen, it is allowed if it's done programmatically,
+// when the menu is hidden. This allows the editable area to cover the
+// full screen height.
+//
+// Test cases
+// ----------
+//
+// Use the following extra files:
+//
+//    init.el:
+//       ;; Hide menu and place frame slightly above the top of the screen.
+//       (setq ns-auto-hide-menu-bar t)
+//       (set-frame-position (selected-frame) 0 -20)
+//
+// Test 1:
+//
+//    emacs -Q -l init.el
+//
+//    Result: No menu bar, and the title bar should be above the screen.
+//
+// Test 2:
+//
+//    emacs -Q
+//
+//    Result: Menu bar visible, frame placed immediately below the menu.
+//
+
+static void
+ns_constrain_all_frames (void)
+{
+  Lisp_Object tail, frame;
+
+  FOR_EACH_FRAME (tail, frame)
+    {
+      struct frame *f = XFRAME (frame);
+      if (FRAME_NS_P (f))
+        {
+          NSView *view = FRAME_NS_VIEW (f);
+          /* This no-op will trigger the default window placing
+           * constriant system. */
+          f->output_data.ns->dont_constrain = 0;
+          [[view window] setFrameOrigin:[[view window] frame].origin];
+        }
+    }
+}
+
+
+/* True, if the menu bar should be hidden.  */
+
+static BOOL
+ns_menu_bar_should_be_hidden (void)
+{
+  return !NILP (ns_auto_hide_menu_bar)
+    && [NSApp respondsToSelector:@selector(setPresentationOptions:)];
+}
+
+
+/* Show or hide the menu bar, based on user setting.  */
+
+static void
+ns_update_auto_hide_menu_bar (void)
+{
+  BLOCK_INPUT;
+
+  NSTRACE (ns_update_auto_hide_menu_bar);
+
+  if (NSApp != nil
+      && [NSApp isActive]
+      && [NSApp respondsToSelector:@selector(setPresentationOptions:)])
+    {
+      // Note, "setPresentationOptions" triggers an error unless the
+      // application is active.
+      BOOL menu_bar_should_be_hidden = ns_menu_bar_should_be_hidden ();
+
+      if (menu_bar_should_be_hidden != ns_menu_bar_is_hidden)
+        {
+          NSApplicationPresentationOptions options
+            = NSApplicationPresentationAutoHideDock;
+
+          if (menu_bar_should_be_hidden)
+            options |= NSApplicationPresentationAutoHideMenuBar;
+
+          [NSApp setPresentationOptions: options];
+
+          ns_menu_bar_is_hidden = menu_bar_should_be_hidden;
+
+          if (!ns_menu_bar_is_hidden)
+            {
+              ns_constrain_all_frames ();
+            }
+        }
+    }
+
+  UNBLOCK_INPUT;
+}
+
+
 static void
 ns_update_begin (struct frame *f)
 /* --------------------------------------------------------------------------
@@ -515,6 +628,8 @@ ns_update_begin (struct frame *f)
   NSView *view = FRAME_NS_VIEW (f);
   NSTRACE (ns_update_begin);
 
+  ns_update_auto_hide_menu_bar ();
+
   ns_updating_frame = f;
   [view lockFocus];
 
@@ -4205,7 +4320,13 @@ ns_term_shutdown (int sig)
 }
 - (void)applicationDidBecomeActive: (NSNotification *)notification
 {
+  NSTRACE (applicationDidBecomeActive);
+
   //ns_app_active=YES;
+
+  ns_update_auto_hide_menu_bar ();
+  // No constrining takes place when the application is not active.
+  ns_constrain_all_frames ();
 }
 - (void)applicationDidResignActive: (NSNotification *)notification
 {
@@ -5689,7 +5810,10 @@ ns_term_shutdown (int sig)
   /* When making the frame visible for the first time, we want to
      constrain.  Other times not.  */
   struct frame *f = ((EmacsView *)[self delegate])->emacsframe;
-  if (f->output_data.ns->dont_constrain)
+  NSTRACE (constrainFrameRect);
+
+  if (f->output_data.ns->dont_constrain
+      || ns_menu_bar_should_be_hidden ())
     return frameRect;
 
   f->output_data.ns->dont_constrain = 1;
@@ -6361,6 +6485,10 @@ allowing it to be used at a lower level for accented character entry.");
   staticpro (&last_mouse_motion_frame);
   last_mouse_motion_frame = Qnil;
 
+  DEFVAR_LISP ("ns-auto-hide-menu-bar", ns_auto_hide_menu_bar,
+               "Non-nil means that the menu bar is hidden, but appears when the mouse is near.  Only works on OSX 10.6 or later.");
+  ns_auto_hide_menu_bar = Qnil;
+
   /* TODO: move to common code */
   DEFVAR_LISP ("x-toolkit-scroll-bars", Vx_toolkit_scroll_bars,
                doc: /* If not nil, Emacs uses toolkit scroll bars.  */);