True color (24-bit) terminal support for tmux-2.1

tmux-2.1-24bit.diff

This diff is a modified version of a diff written by Arnis Lapsa.

[ The original can be found here: https://gist.github.com/ArnisL/6156593 ]

This diff adds support to tmux for 24-bit color CSI SRG sequences. This
allows terminal based programs that take advantage of it (e.g., vim or
emacs with https://gist.github.com/choppsv1/73d51cedd3e8ec72e1c1 patch)
to display 16 million colors while running in tmux.

The primary changes I've made were to support ":" as a delimeter as well
as the older ";" delimeter, as well as adapting to 2.1. The ":" delimiter
is defined by ITU T.416 which is apparently the correct way to do this;
however, many early implementations of 24 bit support in terminal
applications used ";" so both are supported. Tmux 2.1 added parsing
support for the 24 bit SGR code, but not output support, instead it
translated the colors.

In addition I removed the code to forceably disable italic if terminal
is screen or screen-* and instead pay attention to the advertised terminal
capability.

diff --git a/colour.c b/colour.c
index a56ddce..0b396b8 100644
--- a/colour.c
+++ b/colour.c
@@ -29,13 +29,6 @@
  * of the 256 colour palette.
  */
 
-struct colour_rgb {
-	u_char  i;
-	u_char	r;
-	u_char	g;
-	u_char	b;
-};
-
 const struct colour_rgb colour_from_256[] = {
 	{   0, 0x00, 0x00, 0x00 }, {   1, 0x00, 0x00, 0x5f },
 	{   2, 0x00, 0x00, 0x87 }, {   3, 0x00, 0x00, 0xaf },
diff --git a/input.c b/input.c
index ab56fc3..dad6f9f 100644
--- a/input.c
+++ b/input.c
@@ -505,8 +505,7 @@ const struct input_transition input_state_csi_enter_table[] = {
 	{ 0x1c, 0x1f, input_c0_dispatch,  NULL },
 	{ 0x20, 0x2f, input_intermediate, &input_state_csi_intermediate },
 	{ 0x30, 0x39, input_parameter,	  &input_state_csi_parameter },
-	{ 0x3a, 0x3a, NULL,		  &input_state_csi_ignore },
-	{ 0x3b, 0x3b, input_parameter,	  &input_state_csi_parameter },
+	{ 0x3a, 0x3b, input_parameter,	  &input_state_csi_parameter },
 	{ 0x3c, 0x3f, input_intermediate, &input_state_csi_parameter },
 	{ 0x40, 0x7e, input_csi_dispatch, &input_state_ground },
 	{ 0x7f, 0xff, NULL,		  NULL },
@@ -523,8 +522,7 @@ const struct input_transition input_state_csi_parameter_table[] = {
 	{ 0x1c, 0x1f, input_c0_dispatch,  NULL },
 	{ 0x20, 0x2f, input_intermediate, &input_state_csi_intermediate },
 	{ 0x30, 0x39, input_parameter,	  NULL },
-	{ 0x3a, 0x3a, NULL,		  &input_state_csi_ignore },
-	{ 0x3b, 0x3b, input_parameter,	  NULL },
+	{ 0x3a, 0x3b, input_parameter,	  NULL },
 	{ 0x3c, 0x3f, NULL,		  &input_state_csi_ignore },
 	{ 0x40, 0x7e, input_csi_dispatch, &input_state_ground },
 	{ 0x7f, 0xff, NULL,		  NULL },
@@ -917,7 +915,7 @@ input_split(struct input_ctx *ictx)
 		return (0);
 
 	ptr = ictx->param_buf;
-	while ((out = strsep(&ptr, ";")) != NULL) {
+	while ((out = strsep(&ptr, ":;")) != NULL) {
 		if (*out == '\0')
 			n = -1;
 		else {
@@ -1628,17 +1626,21 @@ input_csi_dispatch_sgr_256(struct input_ctx *ictx, int fgbg, u_int *i)
 	if (c == -1) {
 		if (fgbg == 38) {
 			gc->flags &= ~GRID_FLAG_FG256;
+			gc->flags &= ~GRID_FLAG_FG24;
 			gc->fg = 8;
 		} else if (fgbg == 48) {
 			gc->flags &= ~GRID_FLAG_BG256;
+			gc->flags &= ~GRID_FLAG_BG24;
 			gc->bg = 8;
 		}
 	} else {
 		if (fgbg == 38) {
 			gc->flags |= GRID_FLAG_FG256;
+			gc->flags &= ~GRID_FLAG_FG24;
 			gc->fg = c;
 		} else if (fgbg == 48) {
 			gc->flags |= GRID_FLAG_BG256;
+			gc->flags &= ~GRID_FLAG_BG24;
 			gc->bg = c;
 		}
 	}
@@ -1664,13 +1666,27 @@ input_csi_dispatch_sgr_rgb(struct input_ctx *ictx, int fgbg, u_int *i)
 	if (b == -1 || b > 255)
 		return;
 
-	c = colour_find_rgb(r, g, b);
-	if (fgbg == 38) {
-		gc->flags |= GRID_FLAG_FG256;
-		gc->fg = c;
-	} else if (fgbg == 48) {
-		gc->flags |= GRID_FLAG_BG256;
-		gc->bg = c;
+	/* XXX chopps: This would be a good place to add a "translate" option */
+	if (0) {
+		c = colour_find_rgb(r, g, b);
+		if (fgbg == 38) {
+			gc->flags |= GRID_FLAG_FG256;
+			gc->fg = c;
+		} else if (fgbg == 48) {
+			gc->flags |= GRID_FLAG_BG256;
+			gc->bg = c;
+		}
+	} else {
+		struct colour_rgb rgb = {.i=0, .r=r, .g=g, .b=b};
+		if (fgbg == 38) {
+			gc->flags &= ~GRID_FLAG_FG256;
+			gc->flags |= GRID_FLAG_FG24;
+			gc->fg_rgb = rgb;
+		} else if (fgbg == 48) {
+			gc->flags &= ~GRID_FLAG_BG256;
+			gc->flags |= GRID_FLAG_BG24;
+			gc->bg_rgb = rgb;
+		}
 	}
 }
 
@@ -1753,10 +1769,12 @@ input_csi_dispatch_sgr(struct input_ctx *ictx)
 		case 36:
 		case 37:
 			gc->flags &= ~GRID_FLAG_FG256;
+			gc->flags &= ~GRID_FLAG_FG24;
 			gc->fg = n - 30;
 			break;
 		case 39:
 			gc->flags &= ~GRID_FLAG_FG256;
+			gc->flags &= ~GRID_FLAG_FG24;
 			gc->fg = 8;
 			break;
 		case 40:
@@ -1768,10 +1786,12 @@ input_csi_dispatch_sgr(struct input_ctx *ictx)
 		case 46:
 		case 47:
 			gc->flags &= ~GRID_FLAG_BG256;
+			gc->flags &= ~GRID_FLAG_BG24;
 			gc->bg = n - 40;
 			break;
 		case 49:
 			gc->flags &= ~GRID_FLAG_BG256;
+			gc->flags &= ~GRID_FLAG_BG24;
 			gc->bg = 8;
 			break;
 		case 90:
@@ -1794,6 +1814,7 @@ input_csi_dispatch_sgr(struct input_ctx *ictx)
 		case 106:
 		case 107:
 			gc->flags &= ~GRID_FLAG_BG256;
+			gc->flags &= ~GRID_FLAG_BG24;
 			gc->bg = n - 10;
 			break;
 		}
diff --git a/tmux.h b/tmux.h
index 4d19a5a..a36b03e 100644
--- a/tmux.h
+++ b/tmux.h
@@ -628,10 +628,20 @@ struct utf8_data {
 #define GRID_FLAG_FG256 0x1
 #define GRID_FLAG_BG256 0x2
 #define GRID_FLAG_PADDING 0x4
+#define GRID_FLAG_FG24 0x8
+#define GRID_FLAG_BG24 0x10
 
 /* Grid line flags. */
 #define GRID_LINE_WRAPPED 0x1
 
+/* An RGB colour. */
+struct colour_rgb {
+	u_char  i;
+	u_char	r;
+	u_char	g;
+	u_char	b;
+};
+
 /* Grid cell data. */
 struct grid_cell {
 	u_char	attr;
@@ -641,6 +651,8 @@ struct grid_cell {
 
 	u_char	xstate; /* top 4 bits width, bottom 4 bits size */
 	u_char	xdata[UTF8_SIZE];
+	struct colour_rgb fg_rgb;
+	struct colour_rgb bg_rgb;
 } __packed;
 
 /* Grid line. */
diff --git a/tty.c b/tty.c
index 7be952c..607ff33 100644
--- a/tty.c
+++ b/tty.c
@@ -36,6 +36,7 @@ void	tty_error_callback(struct bufferevent *, short, void *);
 
 void	tty_set_italics(struct tty *);
 int	tty_try_256(struct tty *, u_char, const char *);
+int	tty_try_24(struct tty *, struct colour_rgb, const char *);
 
 void	tty_colours(struct tty *, const struct grid_cell *);
 void	tty_check_fg(struct tty *, struct grid_cell *);
@@ -459,11 +460,8 @@ tty_set_italics(struct tty *tty)
 	const char	*s;
 
 	if (tty_term_has(tty->term, TTYC_SITM)) {
-		s = options_get_string(&global_options, "default-terminal");
-		if (strcmp(s, "screen") != 0 && strncmp(s, "screen-", 7) != 0) {
-			tty_putcode(tty, TTYC_SITM);
-			return;
-		}
+		tty_putcode(tty, TTYC_SITM);
+		return;
 	}
 	tty_putcode(tty, TTYC_SMSO);
 }
@@ -1444,14 +1442,23 @@ tty_attributes(struct tty *tty, const struct grid_cell *gc,
 
 void
 tty_colours(struct tty *tty, const struct grid_cell *gc)
-{
+{	
 	struct grid_cell	*tc = &tty->cell;
 	u_char			 fg = gc->fg, bg = gc->bg, flags = gc->flags;
 	int			 have_ax, fg_default, bg_default;
 
 	/* No changes? Nothing is necessary. */
 	if (fg == tc->fg && bg == tc->bg &&
-	    ((flags ^ tc->flags) & (GRID_FLAG_FG256|GRID_FLAG_BG256)) == 0)
+	    tc->fg_rgb.r == gc->fg_rgb.r &&
+	    tc->fg_rgb.g == gc->fg_rgb.g &&
+	    tc->fg_rgb.b == gc->fg_rgb.b &&
+
+	    tc->bg_rgb.r == gc->bg_rgb.r &&
+	    tc->bg_rgb.g == gc->bg_rgb.g &&
+	    tc->bg_rgb.b == gc->bg_rgb.b &&
+	    ((flags ^ tc->flags) & (GRID_FLAG_FG256|GRID_FLAG_BG256|GRID_FLAG_FG24|GRID_FLAG_BG24)) == 0
+	    
+	    )
 		return;
 
 	/*
@@ -1460,8 +1467,8 @@ tty_colours(struct tty *tty, const struct grid_cell *gc)
 	 * case if only one is default need to fall onward to set the other
 	 * colour.
 	 */
-	fg_default = (fg == 8 && !(flags & GRID_FLAG_FG256));
-	bg_default = (bg == 8 && !(flags & GRID_FLAG_BG256));
+	fg_default = (fg == 8 && !(flags & GRID_FLAG_FG256) && !(flags & GRID_FLAG_FG24));
+	bg_default = (bg == 8 && !(flags & GRID_FLAG_BG256) && !(flags & GRID_FLAG_BG24));
 	if (fg_default || bg_default) {
 		/*
 		 * If don't have AX but do have op, send sgr0 (op can't
@@ -1475,39 +1482,49 @@ tty_colours(struct tty *tty, const struct grid_cell *gc)
 			tty_reset(tty);
 		else {
 			if (fg_default &&
-			    (tc->fg != 8 || tc->flags & GRID_FLAG_FG256)) {
+			    (tc->fg != 8 || tc->flags & GRID_FLAG_FG256 || tc->flags & GRID_FLAG_FG24)) {
 				if (have_ax)
 					tty_puts(tty, "\033[39m");
 				else if (tc->fg != 7 ||
-				    tc->flags & GRID_FLAG_FG256)
+				    tc->flags & GRID_FLAG_FG256 ||
+				    tc->flags & GRID_FLAG_FG24)
 					tty_putcode1(tty, TTYC_SETAF, 7);
 				tc->fg = 8;
 				tc->flags &= ~GRID_FLAG_FG256;
+				tc->flags &= ~GRID_FLAG_FG24;
 			}
 			if (bg_default &&
-			    (tc->bg != 8 || tc->flags & GRID_FLAG_BG256)) {
+			    (tc->bg != 8 || tc->flags & GRID_FLAG_BG256 || tc->flags & GRID_FLAG_BG24)) {
 				if (have_ax)
 					tty_puts(tty, "\033[49m");
 				else if (tc->bg != 0 ||
-				    tc->flags & GRID_FLAG_BG256)
+				    tc->flags & GRID_FLAG_BG256 ||
+				    tc->flags & GRID_FLAG_BG24)
 					tty_putcode1(tty, TTYC_SETAB, 0);
 				tc->bg = 8;
 				tc->flags &= ~GRID_FLAG_BG256;
+				tc->flags &= ~GRID_FLAG_BG24;
 			}
 		}
 	}
 
 	/* Set the foreground colour. */
-	if (!fg_default && (fg != tc->fg ||
-	    ((flags & GRID_FLAG_FG256) != (tc->flags & GRID_FLAG_FG256))))
+	if (!fg_default && (fg != tc->fg || ((flags & GRID_FLAG_FG256) != (tc->flags & GRID_FLAG_FG256)) || 
+	    (
+		    ( tc->fg_rgb.r!=gc->fg_rgb.r || tc->fg_rgb.g!=gc->fg_rgb.g || tc->fg_rgb.b!=gc->fg_rgb.b ) ||
+		    ((flags & GRID_FLAG_FG24) != (tc->flags & GRID_FLAG_FG24))
+	    )))
 		tty_colours_fg(tty, gc);
 
 	/*
 	 * Set the background colour. This must come after the foreground as
 	 * tty_colour_fg() can call tty_reset().
 	 */
-	if (!bg_default && (bg != tc->bg ||
-	    ((flags & GRID_FLAG_BG256) != (tc->flags & GRID_FLAG_BG256))))
+	if (!bg_default && (bg != tc->bg || ((flags & GRID_FLAG_BG256) != (tc->flags & GRID_FLAG_BG256)) || 
+	    (
+		    ( tc->bg_rgb.r!=gc->bg_rgb.r || tc->bg_rgb.g!=gc->bg_rgb.g || tc->bg_rgb.b!=gc->bg_rgb.b ) ||
+		    ((flags & GRID_FLAG_BG24) != (tc->flags & GRID_FLAG_BG24))
+	    )))
 		tty_colours_bg(tty, gc);
 }
 
@@ -1519,7 +1536,7 @@ tty_check_fg(struct tty *tty, struct grid_cell *gc)
 	colours = tty_term_number(tty->term, TTYC_COLORS);
 
 	/* Is this a 256-colour colour? */
-	if (gc->flags & GRID_FLAG_FG256) {
+	if (gc->flags & GRID_FLAG_FG256 && !(gc->flags & GRID_FLAG_BG24)) {
 		/* And not a 256 colour mode? */
 		if (!(tty->term->flags & TERM_256COLOURS) &&
 		    !(tty->term_flags & TERM_256COLOURS)) {
@@ -1552,7 +1569,7 @@ tty_check_bg(struct tty *tty, struct grid_cell *gc)
 	colours = tty_term_number(tty->term, TTYC_COLORS);
 
 	/* Is this a 256-colour colour? */
-	if (gc->flags & GRID_FLAG_BG256) {
+	if (gc->flags & GRID_FLAG_BG256 && !(gc->flags & GRID_FLAG_BG24)) {
 		/*
 		 * And not a 256 colour mode? Translate to 16-colour
 		 * palette. Bold background doesn't exist portably, so just
@@ -1580,15 +1597,29 @@ void
 tty_colours_fg(struct tty *tty, const struct grid_cell *gc)
 {
 	struct grid_cell	*tc = &tty->cell;
+	struct colour_rgb	 rgb= gc->fg_rgb;
 	u_char			 fg = gc->fg;
 	char			 s[32];
 
+	tc->flags &= ~GRID_FLAG_FG256;
+	tc->flags &= ~GRID_FLAG_FG24;
+
+	/* Is this a 24-colour colour? */
+	if (gc->flags & GRID_FLAG_FG24) {
+//log_debug("trying to output 24bit fg");
+		if (tty_try_24(tty, rgb, "38") == 0){
+			tc->fg_rgb = rgb;
+			tc->flags |= gc->flags & GRID_FLAG_FG24;
+		}
+		return;
+	}
+
 	/* Is this a 256-colour colour? */
 	if (gc->flags & GRID_FLAG_FG256) {
-		/* Try as 256 colours. */
-		if (tty_try_256(tty, fg, "38") == 0)
-			goto save_fg;
-		/* Else already handled by tty_check_fg. */
+		if (tty_try_256(tty, fg, "38") == 0){
+			tc->fg = fg;
+			tc->flags |= gc->flags & GRID_FLAG_FG256;
+		}
 		return;
 	}
 
@@ -1596,32 +1627,41 @@ tty_colours_fg(struct tty *tty, const struct grid_cell *gc)
 	if (fg >= 90 && fg <= 97) {
 		xsnprintf(s, sizeof s, "\033[%dm", fg);
 		tty_puts(tty, s);
-		goto save_fg;
+		tc->fg = fg;
+		return;
 	}
 
 	/* Otherwise set the foreground colour. */
 	tty_putcode1(tty, TTYC_SETAF, fg);
-
-save_fg:
-	/* Save the new values in the terminal current cell. */
 	tc->fg = fg;
-	tc->flags &= ~GRID_FLAG_FG256;
-	tc->flags |= gc->flags & GRID_FLAG_FG256;
 }
 
 void
 tty_colours_bg(struct tty *tty, const struct grid_cell *gc)
 {
 	struct grid_cell	*tc = &tty->cell;
+	struct colour_rgb	 rgb= gc->bg_rgb;
 	u_char			 bg = gc->bg;
 	char			 s[32];
 
+	tc->flags &= ~GRID_FLAG_BG256;
+	tc->flags &= ~GRID_FLAG_BG24;
+
+	/* Is this a 24-colour colour? */
+	if (gc->flags & GRID_FLAG_BG24) {
+		if (tty_try_24(tty, rgb, "48") == 0){
+			tc->bg_rgb = rgb;
+			tc->flags |= gc->flags & GRID_FLAG_BG24;
+		}
+		return;
+	}
+
 	/* Is this a 256-colour colour? */
 	if (gc->flags & GRID_FLAG_BG256) {
-		/* Try as 256 colours. */
-		if (tty_try_256(tty, bg, "48") == 0)
-			goto save_bg;
-		/* Else already handled by tty_check_bg. */
+		if (tty_try_256(tty, bg, "48") == 0){
+			tc->bg = bg;
+			tc->flags |= gc->flags & GRID_FLAG_BG256;
+		}
 		return;
 	}
 
@@ -1629,17 +1669,15 @@ tty_colours_bg(struct tty *tty, const struct grid_cell *gc)
 	if (bg >= 90 && bg <= 97) {
 		xsnprintf(s, sizeof s, "\033[%dm", bg + 10);
 		tty_puts(tty, s);
-		goto save_bg;
+                tc->bg = bg;
+                return;
 	}
 
 	/* Otherwise set the background colour. */
 	tty_putcode1(tty, TTYC_SETAB, bg);
 
-save_bg:
 	/* Save the new values in the terminal current cell. */
 	tc->bg = bg;
-	tc->flags &= ~GRID_FLAG_BG256;
-	tc->flags |= gc->flags & GRID_FLAG_BG256;
 }
 
 int
@@ -1679,6 +1717,23 @@ fallback:
 	return (0);
 }
 
+
+int
+tty_try_24(struct tty *tty, struct colour_rgb rgb, const char *type)
+{
+	char	s[32];
+
+	//if (!(tty->term->flags & TERM_256COLOURS) &&
+	//    !(tty->term_flags & TERM_256COLOURS))
+	//	return (-1);
+
+	//xsnprintf(s, sizeof s, "\033[%s;5;%hhum", type, colour);
+	xsnprintf(s, sizeof s, "\033[%s;2;%hhu;%hhu;%hhum", type, rgb.r, rgb.g, rgb.b);
+//log_debug("24bit output: %s",s);
+	tty_puts(tty, s);
+	return (0);
+}
+
 void
 tty_default_colours(struct grid_cell *gc, const struct window_pane *wp)
 {

This worked great! For what it's worth, I patched it via home-brew. Just brew edit tmux, then right before def install paste:

  option "with-truecolor", "Build with truecolor patch enabled"
  patch do
    url "https://gist.githubusercontent.com/choppsv1/352421a9f49262ad5c93/raw/be0211bcf518bbf90d578454a03a2a52245ca6c0/tmux-2.1-24bit.diff"
    sha1 "0a1f4b72bac9f0a8f49935dbced61d0a1bac8016"
  end if build.with? "truecolor"

Then brew install tmux --with-truecolor. Just be sure to restart your tmux server!