For Xft and X font backends, set omitted max_width font fields.

* src/xfont.c (xfont_open):
* src/xftfont.c (xftfont_open): Set the font's max_width field.

* src/font.h (struct font): Update comments.

src/ChangeLog

+2012-08-16  Chong Yidong  <cyd@gnu.org>
+
+	* xfont.c (xfont_open):
+	* xftfont.c (xftfont_open): Set the font's max_width field.
+
+	* nsfont.m (nsfont_open): Similar to the Xft backend, set
+	min_width to space_width and average_width to the average over
+	printable ASCII characters.
+	(ns_char_width): Code cleanup.
+	(ns_ascii_average_width): New utility function.
+
+	* font.h (struct font): Update comments.
+
 2012-08-16  Dmitry Antipov  <dmantipov@yandex.ru>
 
-	Simple interface to set Lisp_Object fields of chararcter tables.
+	Simple interface to set Lisp_Object fields of character tables.
 	* lisp.h (CSET): New macro.
 	(char_table_set_extras, char_table_set_contents)
 	(sub_char_table_set_contents): New function.

src/font.h

@@ -284,8 +284,11 @@ struct font
 
   /* Beyond here, there should be no more Lisp_Object components.  */
 
-  /* Maximum bound width over all existing characters of the font.  On
-     X window, this is same as (font->max_bounds.width).  */
+  /* Minimum and maximum glyph widths, in pixels.  Some font backends,
+     such as xft, lack the information to easily compute minimum and
+     maximum widths over all characters; in that case, these values
+     are approximate.  */
+  int min_width;
   int max_width;
 
   /* By which pixel size the font is opened.  */
@@ -301,13 +304,10 @@ struct font
 
   /* Average width of glyphs in the font.  If the font itself doesn't
      have that information but has glyphs of ASCII characters, the
-     value is the average with of those glyphs.  Otherwise, the value
+     value is the average width of those glyphs.  Otherwise, the value
      is 0.  */
   int average_width;
 
-  /* Minimum glyph width (in pixels).  */
-  int min_width;
-
   /* Ascent and descent of the font (in pixels).  */
   int ascent, descent;
 

src/xfont.c

@@ -823,6 +823,7 @@ xfont_open (FRAME_PTR f, Lisp_Object entity, int pixel_size)
   font->descent = xfont->descent;
   font->height = font->ascent + font->descent;
   font->min_width = xfont->min_bounds.width;
+  font->max_width = xfont->max_bounds.width;
   if (xfont->min_bounds.width == xfont->max_bounds.width)
     {
       /* Fixed width font.  */

src/xftfont.c

@@ -414,20 +414,25 @@ xftfont_open (FRAME_PTR f, Lisp_Object entity, int pixel_size)
 	ascii_printable[ch] = ' ' + ch;
     }
   BLOCK_INPUT;
+
+  /* Unfortunately Xft doesn't provide a way to get minimum char
+     width.  So, we set min_width to space_width.  */
+
   if (spacing != FC_PROPORTIONAL
 #ifdef FC_DUAL
       && spacing != FC_DUAL
 #endif	/* FC_DUAL */
       )
     {
-      font->min_width = font->average_width = font->space_width
-	= xftfont->max_advance_width;
+      font->min_width = font->max_width = font->average_width
+	= font->space_width = xftfont->max_advance_width;
       XftTextExtents8 (display, xftfont, ascii_printable + 1, 94, &extents);
     }
   else
     {
       XftTextExtents8 (display, xftfont, ascii_printable, 1, &extents);
-      font->space_width = extents.xOff;
+      font->min_width = font->max_width = font->space_width
+	= extents.xOff;
       if (font->space_width <= 0)
 	/* dirty workaround */
 	font->space_width = pixel_size;
@@ -470,10 +475,6 @@ xftfont_open (FRAME_PTR f, Lisp_Object entity, int pixel_size)
 #endif	/* HAVE_LIBOTF */
   xftfont_info->ft_size = ft_face->size;
 
-  /* Unfortunately Xft doesn't provide a way to get minimum char
-     width.  So, we use space_width instead.  */
-  font->min_width = font->space_width;
-
   font->baseline_offset = 0;
   font->relative_compose = 0;
   font->default_ascent = 0;
@@ -764,6 +765,8 @@ syms_of_xftfont (void)
   DEFSYM (QCembolden, ":embolden");
   DEFSYM (QClcdfilter, ":lcdfilter");
 
+  ascii_printable[0] = 0;
+
   xftfont_driver = ftfont_driver;
   xftfont_driver.type = Qxft;
   xftfont_driver.get_cache = xfont_driver.get_cache;