Add a couple of format c/f and c/b to emit colours.

cmd-list-keys.c

@@ -232,7 +232,7 @@ cmd_list_keys_exec(struct cmd *self, struct cmdq_item *item)
 		n = 1;
 
 	ft = format_create(cmdq_get_client(item), item, FORMAT_NONE, 0);
-	format_defaults(ft, NULL, NULL, NULL, NULL);
+	format_defaults(ft, tc, NULL, NULL, NULL);
 	format_add(ft, "notes_only", "%d", notes_only);
 	format_add(ft, "key_has_repeat", "%d", key_bindings_has_repeat(l, n));
 	format_add(ft, "key_string_width", "%u", cmd_list_keys_get_width(l, n));

colour.c

@@ -290,6 +290,58 @@ colour_tostring(int c)
 	return ("invalid");
 }
 
+/* Convert colour to an SGR escape sequence. */
+const char *
+colour_toescape(struct client *c, int colour, int bg)
+{
+	static char	s[32];
+	u_char		r, g, b;
+	int		n, flags = (TERM_256COLOURS|TERM_RGBCOLOURS);
+	u_int		o = (bg ? 40 : 30);
+
+	if (c != NULL && (c->tty.flags & TTY_OPENED) && c->tty.term != NULL)
+		flags = c->tty.term->flags;
+
+	if (colour & COLOUR_FLAG_THEME) {
+		n = colour & 0xff;
+		if (c != NULL && (u_int)n < COLOUR_THEME_COUNT)
+			colour = c->theme_colours[n];
+		else
+			colour = colour_theme_terminal_colour(n);
+	}
+
+	if (colour == 8 || colour == 9) {
+		xsnprintf(s, sizeof s, "\033[%dm", o + 9);
+		return (s);
+	}
+
+	if ((~flags & TERM_RGBCOLOURS) & (colour & COLOUR_FLAG_RGB)) {
+		colour_split_rgb(colour, &r, &g, &b);
+		colour = colour_find_rgb(r, g, b);
+	}
+	if ((~flags & TERM_256COLOURS) & (colour & COLOUR_FLAG_256))
+		colour = colour_256to16(colour);
+
+	if (colour & COLOUR_FLAG_RGB) {
+		colour_split_rgb(colour, &r, &g, &b);
+		xsnprintf(s, sizeof s, "\033[%d;2;%u;%u;%um", o + 8, r, g, b);
+		return (s);
+	}
+	if (colour & COLOUR_FLAG_256) {
+		xsnprintf(s, sizeof s, "\033[%d;5;%um", o + 8, colour & 0xff);
+		return (s);
+	}
+	if (colour >= 0 && colour <= 7) {
+		xsnprintf(s, sizeof s, "\033[%dm", colour + o);
+		return (s);
+	}
+	if (colour >= 90 && colour <= 97) {
+		xsnprintf(s, sizeof s, "\033[%dm", colour + o - 30);
+		return (s);
+	}
+	return (NULL);
+}
+
 /* Convert background colour to theme. */
 enum client_theme
 colour_totheme(int c)

format.c

@@ -121,6 +121,8 @@ format_job_cmp(struct format_job *fj1, struct format_job *fj2)
 #define FORMAT_CLIENT_TERMCAP 0x1000000
 #define FORMAT_CLIENT_TERMFEAT 0x2000000
 #define FORMAT_CLIENT_ENVIRON 0x4000000
+#define FORMAT_COLOUR_ESC_FG 0x8000000
+#define FORMAT_COLOUR_ESC_BG 0x10000000
 
 /* Limit on recursion. */
 #define FORMAT_LOOP_LIMIT 100
@@ -4454,7 +4456,7 @@ format_build_modifiers(struct format_expand_state *es, const char **s,
 			break;
 
 		/* Check single character modifiers with no arguments. */
-		if (strchr("labcdnwETSWPL!<>", cp[0]) != NULL &&
+		if (strchr("labdnwETSWPL!<>", cp[0]) != NULL &&
 		    format_is_end(cp[1])) {
 			format_add_modifier(&list, count, cp, 1, NULL, 0);
 			cp++;
@@ -4476,7 +4478,7 @@ format_build_modifiers(struct format_expand_state *es, const char **s,
 		}
 
 		/* Now try single character with arguments. */
-		if (strchr("ImCLNPSst=pReqW", cp[0]) == NULL)
+		if (strchr("ImCLNPSst=pReqWc", cp[0]) == NULL)
 			break;
 		c = cp[0];
 
@@ -5254,6 +5256,12 @@ format_replace(struct format_expand_state *es, const char *key, size_t keylen,
 				break;
 			case 'c':
 				modifiers |= FORMAT_COLOUR;
+				if (fm->argc < 1)
+					break;
+				if (strchr(fm->argv[0], 'f') != NULL)
+					modifiers |= FORMAT_COLOUR_ESC_FG;
+				if (strchr(fm->argv[0], 'b') != NULL)
+					modifiers |= FORMAT_COLOUR_ESC_BG;
 				break;
 			case 'd':
 				modifiers |= FORMAT_DIRNAME;
@@ -5452,11 +5460,28 @@ format_replace(struct format_expand_state *es, const char *key, size_t keylen,
 	/* Is this a colour? */
 	if (modifiers & FORMAT_COLOUR) {
 		new = format_expand1(es, copy);
+		if (modifiers & (FORMAT_COLOUR_ESC_FG|FORMAT_COLOUR_ESC_BG)) {
+			if (strcasecmp(new, "none") == 0)
+				value = xstrdup("\033[0m");
+			else if ((c = colour_fromstring(new)) == -1)
+				value = xstrdup("");
+			else {
+				if (modifiers & FORMAT_COLOUR_ESC_BG)
+					cp = colour_toescape(ft->c, c, 1);
+				else
+					cp = colour_toescape(ft->c, c, 0);
+				if (cp == NULL)
+					value = xstrdup("");
+				else
+					value = xstrdup(cp);
+			}
+		} else {
 			c = colour_fromstring(new);
 			if (c == -1 || (c = colour_force_rgb(c)) == -1)
 				value = xstrdup("");
 			else
 				xasprintf(&value, "%06x", c & 0xffffff);
+		}
 		free(new);
 		goto done;
 	}

tmux.1

@@ -6694,6 +6694,12 @@ results in
 replaces a
 .Nm
 colour by its six-digit hexadecimal RGB value.
+If an argument of
+.Ql f
+or
+.Ql b
+is given, it will instead produce the SGR escape sequence to set the foreground
+or background colour respectively.
 .Pp
 A limit may be placed on the length of the resultant string by prefixing it
 by an

tmux.h

@@ -3254,6 +3254,7 @@ void	 colour_split_rgb(int, u_char *, u_char *, u_char *);
 int	 colour_force_rgb(int);
 int	 colour_dim(int, u_int);
 const char *colour_tostring(int);
+const char *colour_toescape(struct client *, int, int);
 enum client_theme colour_totheme(int);
 int	 colour_fromstring(const char *);
 const char *colour_theme_option(u_int, enum client_theme);