[mutter] MetaFrameBorders: Add invisible borders

[Jasper St. Pierre <jstpierre src gnome org>]

commit a1a2527c75ab0c135f89396ea036336fb67ac538
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Tue Jul 12 00:55:50 2011 -0400

    MetaFrameBorders: Add invisible borders
    
    This just adds the invisible border field and populates it with data
    but doesn't use it in any way.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=644930

 src/core/frame.c  |    8 ++++----
 src/meta/common.h |    5 +++++
 src/ui/theme.c    |   19 ++++++++++++++++++-
 3 files changed, 27 insertions(+), 5 deletions(-)
---
diff --git a/src/core/frame.c b/src/core/frame.c
index e42a13d..a203253 100644
--- a/src/core/frame.c
+++ b/src/core/frame.c
@@ -304,10 +304,10 @@ meta_frame_get_flags (MetaFrame *frame)
 void
 meta_frame_borders_clear (MetaFrameBorders *self)
 {
-  self->visible.top    = 0;
-  self->visible.bottom = 0;
-  self->visible.left   = 0;
-  self->visible.right  = 0;
+  self->visible.top    = self->invisible.top    = self->total.top    = 0;
+  self->visible.bottom = self->invisible.bottom = self->total.bottom = 0;
+  self->visible.left   = self->invisible.left   = self->total.left   = 0;
+  self->visible.right  = self->invisible.right  = self->total.right  = 0;
 }
 
 void
diff --git a/src/meta/common.h b/src/meta/common.h
index a78516d..3f31267 100644
--- a/src/meta/common.h
+++ b/src/meta/common.h
@@ -310,6 +310,11 @@ struct _MetaFrameBorders
    * and an outer portion that is invisible but responds to events.
    */
   GtkBorder visible;
+  GtkBorder invisible;
+
+  /* For convenience, we have a "total" border which is equal to the sum
+   * of the two borders above. */
+  GtkBorder total;
 };
 
 /* sets all dimensions to zero */
diff --git a/src/ui/theme.c b/src/ui/theme.c
index b878d92..bad8842 100644
--- a/src/ui/theme.c
+++ b/src/ui/theme.c
@@ -56,6 +56,7 @@
 #include "theme-private.h"
 #include <meta/util.h>
 #include <meta/gradient.h>
+#include <meta/prefs.h>
 #include <gtk/gtk.h>
 #include <string.h>
 #include <stdlib.h>
@@ -402,7 +403,7 @@ meta_frame_layout_get_borders (const MetaFrameLayout *layout,
                                MetaFrameFlags         flags,
                                MetaFrameBorders      *borders)
 {
-  int buttons_height, title_height;
+  int buttons_height, title_height, draggable_borders;
   
   g_return_if_fail (layout != NULL);
 
@@ -428,6 +429,22 @@ meta_frame_layout_get_borders (const MetaFrameLayout *layout,
       meta_frame_borders_clear (borders);
       return;
     }
+
+  draggable_borders = meta_prefs_get_draggable_border_width ();
+
+  borders->invisible.left   = MAX (0, draggable_borders - borders->visible.left);
+  borders->invisible.right  = MAX (0, draggable_borders - borders->visible.right);
+  borders->invisible.bottom = MAX (0, draggable_borders - borders->visible.bottom);
+
+  /* borders.visible is the height of the *title bar*. We can't do the same
+   * algorithm here, titlebars are expectedly much bigger. Just subtract a couple
+   * pixels to get a proper feel. */
+  borders->invisible.top    = MAX (0, draggable_borders - 2);
+
+  borders->total.left   = borders->invisible.left   + borders->visible.left;
+  borders->total.right  = borders->invisible.right  + borders->visible.right;
+  borders->total.bottom = borders->invisible.bottom + borders->visible.bottom;
+  borders->total.top    = borders->invisible.top    + borders->visible.top;
 }
 
 static MetaButtonType