Add lighten/darken capability to colorset expansion.

  * Added expansion for appending .lighten<p> and .darken<p> to
    a color set expansion, such as $[fg.cs<n>.lighten<p>] or
    $[shadow.cs<n>.darken<p>].
  * Added missing $[fgsh.cs<n>] expansion to manpage.

NEWS

@@ -22,6 +22,10 @@ Changes in stable release 2.6.8 (UNRELEASED)
 
   - fvwm-menu-desktop(1) now requires python3 as an explicit
     dependency.
+  - The colorset expansion parameters, $[fg.cs<n>], $[bg.cs<n>],
+    etc, can now expand p percent lighter or darker colors by
+    appending .lighten<p> or .darken<p> to the parameter.
+    For example, $[fg.cs3.lighten15] or $[shadow.cs3.darken15].
 
 -------------------------------------------------------------------
 Changes in stable release 2.6.7 (06-Mar-2016)

doc/fvwm/expansion.xml

@@ -396,15 +396,27 @@ command can be used:</para>
       $[bg.cs&lt;n&gt;]
       $[hilight.cs&lt;n&gt;]
       $[shadow.cs&lt;n&gt;]
+      $[fgsh.cs&lt;n&gt;]
     </term>
     <listitem>
       <para>
 	These parameters are replaced with the name of the foreground
-	(fg), background (bg), hilight (hilight) or shadow (shadow) color
-	that is defined in colorset &lt;n&gt; (replace &lt;n&gt; with zero
-	or a positive integer).  For example "$[fg.cs3]" is expanded to the
-	name of the foreground color of colorset 3 (in rgb:rrrr/gggg/bbbb
-	form).  Please refer to the
+	(fg), background (bg), hilight (hilight), shadow (shadow), or
+        the font shadow (fgsh) color that is defined in colorset &lt;n&gt;
+        (replace &lt;n&gt; with zero or a positive integer).  For example
+        "$[fg.cs3]" is expanded to the name of the foreground color of
+        colorset 3 (in rgb:rrrr/gggg/bbbb form).
+      </para>
+      <para>
+        In addition if .lighten&lt;p&gt; or .darken&lt;p&gt; is appeneded
+        to the parameters, they are instead replaced with a color that is
+        lighter or darker than the one defined in colorset &lt;n&gt;
+        by a percentage value &lt;p&gt; (between 0 and 100). For example
+        "$[bg.cs3.lighten15]" is expanded to the background color of
+        colorset 3 and then lightened 15% (in rgb:rrrr/gggg/bbbb form).
+      </para>
+      <para>
+        Please refer to the
 	<fvwmref sect="colorsets" opt="colorsets" name="Colorsets"/>
 	section for details about colorsets.
       </para>

fvwm/expand.c

@@ -350,6 +350,8 @@ static signed int expand_vars_extended(
 	char dummy[64] = "\0";
 	char *target = (output) ? output : dummy;
 	int cs = -1;
+	int csadj = 0;
+	int nn = 0;
 	int n;
 	int i;
 	int l;
@@ -376,7 +378,7 @@ static signed int expand_vars_extended(
 	case VAR_HILIGHT_CS:
 	case VAR_SHADOW_CS:
 	case VAR_FGSH_CS:
-		if (!isdigit(*rest) || (*rest == '0' && *(rest + 1) != 0))
+		if (!isdigit(*rest) || (*rest == '0' && *(rest + 1) != 0 && *(rest + 1) != '.' ))
 		{
 			/* not a non-negative integer without leading zeros */
 			return -1;
@@ -386,6 +388,24 @@ static signed int expand_vars_extended(
 			return -1;
 		}
 		if (*(rest + n) != 0)
+		{
+			/* Check for .lightenN or .darkenN */
+			csadj = 101;
+			l = -1;
+			if (sscanf(rest + n, ".lighten%d%n", &l, &nn) && l >= 0 && l <= 100)
+			{
+				csadj = l;
+			}
+			if (sscanf(rest + n, ".darken%d%n", &l, &nn) && l >= 0 && l <= 100)
+			{
+				csadj = -l;
+			}
+			if (csadj == 101)
+			{
+				return -1;
+			}
+		}
+		if (*(rest + n + nn) != 0)
 		{
 			/* trailing characters */
 			return -1;
@@ -414,7 +434,7 @@ static signed int expand_vars_extended(
 			break;
 		}
 		is_target = True;
-		len = pixel_to_color_string(dpy, Pcmap, pixel, target, False);
+		len = pixel_to_color_string(dpy, Pcmap, pixel, target, False, csadj);
 		goto GOT_STRING;
 	case VAR_GT_:
 		if (rest == NULL)

libs/ColorUtils.c

@@ -392,7 +392,7 @@ Pixel GetTintedPixel(Pixel in, Pixel tint, int percent)
  * memory area pointed at by 'output' must be at least 64 bytes (in case of
  * future extensions and multibyte characters).*/
 int pixel_to_color_string(
-	Display *dpy, Colormap cmap, Pixel pixel, char *output, Bool use_hash)
+	Display *dpy, Colormap cmap, Pixel pixel, char *output, Bool use_hash, int adj)
 {
 	XColor color;
 	int n;
@@ -403,6 +403,22 @@ int pixel_to_color_string(
 	color.blue = 0;
 
 	XQueryColor(dpy, cmap, &color);
+
+	/* Lighten color */
+	if ( adj > 0 && adj <= 100 )
+	{
+		color.red = (int)( ((100 - adj)*color.red + adj*65535)/100 );
+		color.green = (int)( ((100 - adj)*color.green + adj*65535)/100 );
+		color.blue = (int)( ((100 - adj)*color.blue + adj*65535)/100 );
+	}
+	/* Darken color */
+	if ( adj >= -100 && adj < 0 )
+	{
+		color.red = (int)( (100 + adj)*color.red/100 );
+		color.green = (int)( (100 + adj)*color.green/100 );
+		color.blue = (int)( (100 + adj)*color.blue/100 );
+	}
+
 	if (!use_hash)
 	{
 		sprintf(

libs/ColorUtils.h

@@ -23,7 +23,7 @@ Pixel GetTintedPixel(Pixel in, Pixel tint, int percent);
  * memory area pointed at by 'output' must be at least 64 bytes (in case of
  * future extensions and multibyte characters).*/
 int pixel_to_color_string(
-	Display *dpy, Colormap cmap, Pixel pixel, char *output, Bool use_hash);
+	Display *dpy, Colormap cmap, Pixel pixel, char *output, Bool use_hash, int adj);
 
 Pixel GetSimpleColor(char *name);
 /* handles colorset color names too */