Add :distant-foreground to faces.

* doc/lispref/display.texi (Face Attributes): Document :distant-foreground.

* etc/NEWS: Mention :distant-foreground.

* lisp/faces.el (face-x-resources): Add :distant-foreground.
(region): Use :distant-foreground for gtk and ns.

* src/dispextern.h (lface_attribute_index): Add
LFACE_DISTANT_FOREGROUND_INDEX.

* src/xfaces.c: Declare color_distance.
(QCdistant_foreground): New variable.
(NEAR_SAME_COLOR_THRESHOLD): New define.
(load_color2): New function.
(load_color): Call load_color2.
(load_face_colors): Call load_color2 and if distant-color is specified
calculate distant and use distant-color if colors are near.
(LFACE_DISTANT_FOREGROUND): New define.
(merge_face_ref, Finternal_set_lisp_face_attribute)
(Finternal_get_lisp_face_attribute)
(x_supports_face_attributes_p): Handle distant-foreground similar to
foreground.
(syms_of_xfaces): DEFSYM QCdistant_foreground.

2 files changed, 13 insertions, 0 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index fa081f1e7aa..cc214aa6dfa 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,7 @@
+2013-11-01  Jan Djärv  <jan.h.d@swipnet.se>
+
+        * display.texi (Face Attributes): Document :distant-foreground.
+
 2013-10-30  Xue Fuqiao  <xfq.free@gmail.com>
 
         * display.texi (Abstract Display): Improve indexing.
diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 07ab2c6745f..ebb61a76b59 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -2036,6 +2036,15 @@ name, or a hexadecimal color specification.  @xref{Color Names}.  On
 black-and-white displays, certain shades of gray are implemented by
 stipple patterns.
 
+@item :distant-foreground
+Alternative foreground color, a string.  This is like @code{:foreground}
+but the color is only used as a foreground when the background color is
+near to the foreground that would have been used.  This is useful for
+example when marking text (i.e. the region face).  If the text has a foreground 
+that is visible with the region face, that foreground is used.
+If the foreground is near the region face background,
+@code{:distant-foreground} is used instead so the text is readable.
+
 @item :background
 Background color, a string.  The value can be a system-defined color
 name, or a hexadecimal color specification.  @xref{Color Names}.