Support for X11 bitmap font.

This change will introduce support for fixed, bitmap fonts. Unlike in
outline fonts, amount of sizes for bitmap fonts is declared up front.
Because of that fact, increasing/decreasing bitmap font size might look
awkward or even have no effect at all, depending on used font face.

This patch was successfully used against font-misc-misc from X.Org
package.

font

@@ -20,8 +20,6 @@ use List::Util qw(first);
 # supports unicode in certain pixel sizes.  9, 10, 12, 14 are embedded
 # bitmaps, which means (Except for 10) that they lack certain unicode
 # charmaps.
-#
-# Note: the regexes will only work on xft xrdb entries
 
 #   For this script to work, ~/.Xdefauls should probably contain at
 #   least the following:
@@ -106,6 +104,37 @@ sub _resize_xft_string
       }
       $piece =~ s/pixelsize=$old_size/pixelsize=$new_size/;
     }
+
+    # Check for X11 bitmap font string
+    elsif ($piece =~ /(-[^-]+){7}-(\d+)(-[^-]+){6}/)
+    {
+      my ($old_size) =  $2;
+      my ($new_size) =  $old_size;
+      my (@fixed_sizes) = (20, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140,
+                           160, 180, 200, 220, 240, 280, 320);
+      my ($fixed_default_size) = &{ sub {  my @a = sort { $a <=> $b } @_;
+                                      return ($a[$#a/2] + $a[@a/2]) / 2;}
+                                  }(@fixed_sizes); # median ...
+      my ($old_size_index) = first {
+        $fixed_sizes[$_] eq $old_size } 0..$#fixed_sizes;
+
+      # old font size is valid
+      if (defined($old_size_index))
+      {
+        # Bounds checking (as in Monaco part)
+        if ($old_size_index > 0 || $delta > 0)
+        {
+          my ($new_size_index)  = $old_size_index + $delta; # +1, equivalently
+          # 2) avoid increment of largest to non-existent larger
+          $new_size = exists($fixed_sizes[$new_size_index])
+                                          ? $fixed_sizes[$new_size_index]
+                                          : $old_size;
+        }
+      }
+      $piece =~ s/(?<first>(-[^-]+){7}-)$old_size(?<last>(-[^-]+){6})
+          /$+{first}$new_size$+{last}/x;
+    }
+
     push @resized, $piece;
   }
   return join (":", @resized);