From c296de5778f040e5803326dbb74a7362ac0146fa Mon Sep 17 00:00:00 2001
From: Tim Ruffing <crypto@timruffing.de>
Date: Fri, 12 Nov 2021 20:37:39 +0100
Subject: [PATCH] Support setrgbb/setrgbf for setting 24-bit color

---
 src/term.c     | 28 ++++++++++++++++++++++------
 src/termchar.h | 10 ++++++----
 2 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/src/term.c b/src/term.c
index b4f3dfc25e..8022ca95f1 100644
--- a/src/term.c
+++ b/src/term.c
@@ -1945,7 +1945,10 @@ turn_on_face (struct frame *f, int face_id)
       ts = tty->standout_mode ? tty->TS_set_background : tty->TS_set_foreground;
       if (face_tty_specified_color (fg) && ts)
 	{
-          p = tparam (ts, NULL, 0, fg, 0, 0, 0);
+	  if (tty->TF_rgb_separate)
+	    p = tparam (ts, NULL, 0, fg >> 16, (fg >> 8) & 0xFF, fg & 0xFF, 0);
+	  else
+	    p = tparam (ts, NULL, 0, fg, 0, 0, 0);
 	  OUTPUT (tty, p);
 	  xfree (p);
 	}
@@ -1953,7 +1956,10 @@ turn_on_face (struct frame *f, int face_id)
       ts = tty->standout_mode ? tty->TS_set_foreground : tty->TS_set_background;
       if (face_tty_specified_color (bg) && ts)
 	{
-          p = tparam (ts, NULL, 0, bg, 0, 0, 0);
+	  if (tty->TF_rgb_separate)
+	    p = tparam (ts, NULL, 0, bg >> 16, (bg >> 8) & 0xFF, bg & 0xFF, 0);
+	  else
+	    p = tparam (ts, NULL, 0, bg, 0, 0, 0);
 	  OUTPUT (tty, p);
 	  xfree (p);
 	}
@@ -4133,10 +4139,10 @@ init_tty (const char *name, const char *terminal_type, bool must_succeed)
 
 #ifdef TERMINFO
       {
-	const char *fg = tigetstr ("setf24");
-	const char *bg = tigetstr ("setb24");
-	/* Non-standard support for 24-bit colors. */
-	if (fg && bg
+	const char *fg;
+	const char *bg;
+	/* Our own non-standard support for 24-bit colors. */
+	if ((fg = tigetstr ("setf24")) && (bg = tigetstr ("setb24"))
 	    && fg != (char *) (intptr_t) -1
 	    && bg != (char *) (intptr_t) -1)
 	  {
@@ -4144,6 +4150,16 @@ init_tty (const char *name, const char *terminal_type, bool must_succeed)
 	    tty->TS_set_background = bg;
 	    tty->TN_max_colors = 16777216;
 	  }
+	/* Other non-standard support for 24-bit colors. */
+	else if ((fg = tigetstr ("setrgbf")) && (bg = tigetstr ("setrgbb"))
+	    && fg != (char *) (intptr_t) -1
+	    && bg != (char *) (intptr_t) -1)
+	  {
+	    tty->TS_set_foreground = fg;
+	    tty->TS_set_background = bg;
+	    tty->TN_max_colors = 16777216;
+	    tty->TF_rgb_separate = 1;
+	  }
 	/* Standard support for 24-bit colors.  */
 	else if (tigetflag ("RGB") > 0)
 	  {
diff --git a/src/termchar.h b/src/termchar.h
index 7ab9337fbe..d266fd16f9 100644
--- a/src/termchar.h
+++ b/src/termchar.h
@@ -154,10 +154,12 @@ #define EMACS_TERMCHAR_H
   /* "op" -- SVr4 set default pair to its original value.  */
   const char *TS_orig_pair;
 
-  /* "AF"/"AB" or "Sf"/"Sb"-- set ANSI or SVr4 foreground/background color.
-     1 param, the color index.  */
-  const char *TS_set_foreground;
-  const char *TS_set_background;
+  const char *TS_set_foreground; /* "AF"/"Sf"/"setrgbf" -- set foreground color. */
+  const char *TS_set_background; /* "AB"/"Sb"/"setrgbb" -- set background color. */
+  /* If set, TS_set_foreground and TS_set_background take 3 separate
+     params for R, G, and B values ("setrgbf"/"setrgbb" -- non-standard).
+     If unset, they take 1 param ("AF"/"AB" or "Sf"/"Sb" -- ANSI or SVr4r). */
+  int TF_rgb_separate;
 
   int TF_hazeltine;             /* termcap hz flag. */
   int TF_insmode_motion;        /* termcap mi flag: can move while in insert mode. */
-- 
2.33.1