Make `toggle-frame-maximized' respect the dock on OS X (bug#22988).

* src/nsterm.m (ns_screen_margins): New function.
(ns_screen_margins_ignoring_hidden_dock): New function.
(ns_menu_bar_height): Reimplement in terms of `ns_screen_margins'.
([EmacsWindow zoom:]): Take all screen margins (except those
originating from a hidden dock) into account.

src/nsterm.m

@@ -646,16 +646,118 @@ Free a pool and temporary objects it refers to (callable from C)
 }
 
 
-/* True, if the menu bar should be hidden.  */
-
 static BOOL
 ns_menu_bar_should_be_hidden (void)
+/* True, if the menu bar should be hidden.  */
 {
   return !NILP (ns_auto_hide_menu_bar)
     && [NSApp respondsToSelector:@selector(setPresentationOptions:)];
 }
 
 
+struct EmacsMargins
+{
+  CGFloat top;
+  CGFloat bottom;
+  CGFloat left;
+  CGFloat right;
+};
+
+
+static struct EmacsMargins
+ns_screen_margins (NSScreen *screen)
+/* The parts of SCREEN used by the operating system.  */
+{
+  NSTRACE ("ns_screen_margins");
+
+  struct EmacsMargins margins;
+
+  NSRect screenFrame = [screen frame];
+  NSRect screenVisibleFrame = [screen visibleFrame];
+
+  /* Sometimes, visibleFrame isn't up-to-date with respect to a hidden
+     menu bar, check this explicitly.  */
+  if (ns_menu_bar_should_be_hidden())
+    {
+      margins.top = 0;
+    }
+  else
+    {
+      CGFloat frameTop = screenFrame.origin.y + screenFrame.size.height;
+      CGFloat visibleFrameTop = (screenVisibleFrame.origin.y
+                                 + screenVisibleFrame.size.height);
+
+      margins.top = frameTop - visibleFrameTop;
+    }
+
+  {
+    CGFloat frameRight = screenFrame.origin.x + screenFrame.size.width;
+    CGFloat visibleFrameRight = (screenVisibleFrame.origin.x
+                                 + screenVisibleFrame.size.width);
+    margins.right = frameRight - visibleFrameRight;
+  }
+
+  margins.bottom = screenVisibleFrame.origin.y - screenFrame.origin.y;
+  margins.left   = screenVisibleFrame.origin.x - screenFrame.origin.x;
+
+  NSTRACE_MSG ("left:%g right:%g top:%g bottom:%g",
+               margins.left,
+               margins.right,
+               margins.top,
+               margins.bottom);
+
+  return margins;
+}
+
+
+/* A screen margin between 1 and DOCK_IGNORE_LIMIT (inclusive) is
+   assumed to contain a hidden dock.  OS X currently use 4 pixels for
+   this, however, to be future compatible, a larger value is used.  */
+#define DOCK_IGNORE_LIMIT 6
+
+static struct EmacsMargins
+ns_screen_margins_ignoring_hidden_dock (NSScreen *screen)
+/* The parts of SCREEN used by the operating system, excluding the parts
+reserved for an hidden dock.  */
+{
+  NSTRACE ("ns_screen_margins_ignoring_hidden_dock");
+
+  struct EmacsMargins margins = ns_screen_margins(screen);
+
+  /* OS X (currently) reserved 4 pixels along the edge where a hidden
+     dock is located.  Unfortunately, it's not possible to find the
+     location and information about if the dock is hidden.  Instead,
+     it is assumed that if the margin of an edge is less than
+     DOCK_IGNORE_LIMIT, it contains a hidden dock.  */
+  if (margins.left <= DOCK_IGNORE_LIMIT)
+    {
+      margins.left = 0;
+    }
+  if (margins.right <= DOCK_IGNORE_LIMIT)
+    {
+      margins.right = 0;
+    }
+  if (margins.top <= DOCK_IGNORE_LIMIT)
+    {
+      margins.top = 0;
+    }
+  /* Note: This doesn't occur in current versions of OS X, but
+     included for completeness and future compatibility.  */
+  if (margins.bottom <= DOCK_IGNORE_LIMIT)
+    {
+      margins.bottom = 0;
+    }
+
+  NSTRACE_MSG ("left:%g right:%g top:%g bottom:%g",
+               margins.left,
+               margins.right,
+               margins.top,
+               margins.bottom);
+
+  return margins;
+}
+
+
 static CGFloat
 ns_menu_bar_height (NSScreen *screen)
 /* The height of the menu bar, if visible.
@@ -663,24 +765,9 @@ Free a pool and temporary objects it refers to (callable from C)
    Note: Don't use this when fullscreen is enabled -- the screen
    sometimes includes, sometimes excludes the menu bar area.  */
 {
-  CGFloat res;
+  struct EmacsMargins margins = ns_screen_margins(screen);
 
-  if (ns_menu_bar_should_be_hidden())
+  CGFloat res = margins.top;
-    {
-      res = 0;
-    }
-  else
-    {
-      NSRect screenFrame = [screen frame];
-      NSRect screenVisibleFrame = [screen visibleFrame];
-
-      CGFloat frameTop = screenFrame.origin.y + screenFrame.size.height;
-      CGFloat visibleFrameTop = (screenVisibleFrame.origin.y
-                                 + screenVisibleFrame.size.height);
-
-      res = frameTop - visibleFrameTop;
-
-    }
 
   NSTRACE ("ns_menu_bar_height " NSTRACE_FMT_RETURN " %.0f", res);
 
@@ -7867,9 +7954,10 @@ - (void)zoom:(id)sender
   // the menu-bar.
   [super zoom:sender];
 
-#elsif 0
+#elif 0
   // Native zoom done using the standard zoom animation, plus an
-  // explicit resize to cover the full screen.
+  // explicit resize to cover the full screen, except the menu-bar and
+  // dock, if present.
   [super zoom:sender];
 
   // After the native zoom, resize the resulting frame to fill the
@@ -7889,6 +7977,9 @@ - (void)zoom:(id)sender
       NSTRACE_FSTYPE ("fullscreenState", fs_state);
 
       NSRect sr = [screen frame];
+      struct EmacsMargins margins
+        = ns_screen_margins_ignoring_hidden_dock(screen);
+
       NSRect wr = [self frame];
       NSTRACE_RECT ("Rect after zoom", wr);
 
@@ -7897,15 +7988,15 @@ - (void)zoom:(id)sender
       if (fs_state == FULLSCREEN_MAXIMIZED
           || fs_state == FULLSCREEN_HEIGHT)
         {
-          newWr.origin.x = 0;
+          newWr.origin.y = sr.origin.y + margins.bottom;
-          newWr.size.height = sr.size.height - ns_menu_bar_height(screen);
+          newWr.size.height = sr.size.height - margins.top - margins.bottom;
         }
 
       if (fs_state == FULLSCREEN_MAXIMIZED
           || fs_state == FULLSCREEN_WIDTH)
         {
-          newWr.origin.y = 0;
+          newWr.origin.x = sr.origin.x + margins.left;
-          newWr.size.width = sr.size.width;
+          newWr.size.width = sr.size.width - margins.right - margins.left;
         }
 
       if (newWr.size.width     != wr.size.width
@@ -7918,13 +8009,20 @@ - (void)zoom:(id)sender
         }
     }
 #else
-  // Non-native zoom which is done instantaneously.  The resulting frame
+  // Non-native zoom which is done instantaneously.  The resulting
-  // covers the entire screen, except the menu-bar, if present.
+  // frame covers the entire screen, except the menu-bar and dock, if
+  // present.
   NSScreen * screen = [self screen];
   if (screen != nil)
     {
       NSRect sr = [screen frame];
-      sr.size.height -= ns_menu_bar_height (screen);
+      struct EmacsMargins margins
+        = ns_screen_margins_ignoring_hidden_dock(screen);
+
+      sr.size.height -= (margins.top + margins.bottom);
+      sr.size.width  -= (margins.left + margins.right);
+      sr.origin.x += margins.left;
+      sr.origin.y += margins.bottom;
 
       sr = [[self delegate] windowWillUseStandardFrame:self
                                           defaultFrame:sr];