[PATCH] Handle brightXXX color names in backgrounds

[S. Gilles]

A number of terminal emulators (xterm with TERM=xterm-256color and st,
off the top of my head), interpret the A_BLINK attribute by actually
blinking, not setting the background color to the bright version. A
quick way to test this is

    :color indicator black brightblack

which on some terms (urxvt) will cause black-on-gray text, and on
others (xterm) will cause an unreadable blinking line.

This patch changes that behavior by avoiding A_BLINK and directly
using the bright versions of colors if they are available. I've tested
it on urxvt, xterm (with TERM=xterm-256color), and st, and it behaves
as I expect. On xterm (with TERM=xterm), blinking still persists, but
it always did that anyway, so at least this patch doesn't seem to
break that case.

Please let me know if I have erred with style or submission.

-- 
S. Gilles

# HG changeset patch
# User S. Gilles <sgil...@math.umd.edu>
# Date 1451569185 18000
#      Thu Dec 31 08:39:45 2015 -0500
# Node ID bc242e89469b7443bc6126589dbdb2060f419844
# Parent  9480a363a68a7472d61c8e27a29fd2312cac8721
Prefer bright versions (8-15) of colors for brightXXX backgrounds.

When a bright color is specified as a background, try to use the
bright version of that color, falling back to the A_BLINK method only
on terms which do not support enough colors.

diff -r 9480a363a68a -r bc242e89469b color.c
--- a/color.c   Thu Dec 17 12:25:00 2015 -0800
+++ b/color.c   Thu Dec 31 08:39:45 2015 -0500
@@ -306,13 +306,14 @@
 #ifdef HAVE_COLOR
 
 static int
-parse_color_name (const char *s, int *col, int *attr, int brite, BUFFER *err)
+parse_color_name (const char *s, int *col, int *attr, int is_fg, BUFFER *err)
 {
   char *eptr;
+  int is_bright = 0;
 
   if (ascii_strncasecmp (s, "bright", 6) == 0)
   {
-    *attr |= brite;
+    is_bright = 1;
     s += 6;
   }
 
@@ -334,6 +335,24 @@
     return (-1);
   }
 
+  if (is_bright)
+  {
+    if (is_fg)
+    {
+      *attr |= A_BOLD;
+    }
+    else if (COLORS < 16)
+    {
+      /* A_BLINK turns the background color brite on some terms */
+      *attr |= A_BLINK;
+    }
+    else
+    {
+      /* Advance the color by 8 to get the bright version */
+      *col += 8;
+    }
+  }
+
   return 0;
 }
 
@@ -615,7 +634,7 @@
 
   mutt_extract_token (buf, s, 0);
 
-  if (parse_color_name (buf->data, fg, attr, A_BOLD, err) != 0)
+  if (parse_color_name (buf->data, fg, attr, 1, err) != 0)
     return (-1);
 
   if (! MoreArgs (s))
@@ -626,7 +645,7 @@
   
   mutt_extract_token (buf, s, 0);
 
-  if (parse_color_name (buf->data, bg, attr, A_BLINK, err) != 0)
+  if (parse_color_name (buf->data, bg, attr, 0, err) != 0)
     return (-1);
   
   return 0;