support for true-color terminals

support for true-color terminals

[Charles Strahan]

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Hello,

A while back, there was an effort to add support for true-color
terminals (by which I mean terminals supporting 16777216 simultaneous
colors):

http://emacs.1067599.n5.nabble.com/RFC-Add-tty-True-Color-support-td299962.html

I've contacted Rüdiger, asking if he wouldn't mind if I pick up from
where he left off, and he said that was fine as he's been too busy to
work on this.

I've attached to this email the patch that I'm using, based on his work.
Any feedback would be greatly appreciated.

This is my first (attempted) contribution to Emacs, and I'm very new to
the code base, so there might be some silly mistakes that I'm unaware
of. If we can get this polished enough for inclusion, I'd be more than
happy to assign copyright.

This patch is based off of Emacs 24.5. If it would be easier to get this
merged into Emacs 25, I can rebase my changes and submit a new patch for
review.


Thanks,

Charles

[-- Attachment #2: emacs-24.5-tty-true-color.patch --]
[-- Type: text/plain, Size: 14651 bytes --]

diff --git a/lisp/term/tty-colors.el b/lisp/term/tty-colors.el
index 98108ce..21814a9 100644
--- a/lisp/term/tty-colors.el
+++ b/lisp/term/tty-colors.el
@@ -764,7 +764,8 @@
     (auto . 0)
     (ansi8 . 8)
     (always . 8)
-    (yes . 8))
+    (yes . 8)
+    (true-color . 16777216))
   "An alist of supported standard tty color modes and their aliases.")
 
 (defun tty-color-alist (&optional _frame)
diff --git a/lisp/term/xterm.el b/lisp/term/xterm.el
index c673749..244cf7f 100644
--- a/lisp/term/xterm.el
+++ b/lisp/term/xterm.el
@@ -674,6 +674,15 @@ versions of xterm."
     ;; are more colors to support, compute them now.
     (when (> ncolors 0)
       (cond
+       ((= (display-color-cells (selected-frame)) 16777216)	; 24-bit xterm
+        (let ((idx (length xterm-standard-colors)))
+          ;; Insert standard X colors after the standard xterm ones
+          (mapc (lambda (color)
+                       (if (not (assoc (car color) xterm-standard-colors))
+                           (progn
+                             (tty-color-define (car color) idx (cdr color))
+                             (setq idx (1+ idx)))))
+                color-name-rgb-alist)))
        ((= ncolors 240)	; 256-color xterm
 	;; 216 non-gray colors first
 	(let ((r 0) (g 0) (b 0))
diff --git a/src/dispextern.h b/src/dispextern.h
index 239c442..5760b84 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1739,9 +1739,15 @@ struct face
 INLINE bool
 face_tty_specified_color (unsigned long color)
 {
-  return color < FACE_TTY_DEFAULT_BG_COLOR;
+  return (color < FACE_TTY_DEFAULT_BG_COLOR);
 }
 
+INLINE bool
+face_tty_specified_24_bit_color (unsigned long color)
+{
+  /* 24 bit colors have 24th but not 25th bit set */
+  return ((color & (0x03 << 24)) == (0x01 << 24));
+}
 /* Non-zero if FACE was realized for unibyte use.  */
 
 #define FACE_UNIBYTE_P(FACE) ((FACE)->charset < 0)
diff --git a/src/term.c b/src/term.c
index 8312491..ce03cdb 100644
--- a/src/term.c
+++ b/src/term.c
@@ -1915,18 +1915,40 @@ turn_on_face (struct frame *f, int face_id)
       const char *ts;
       char *p;
 
-      ts = tty->standout_mode ? tty->TS_set_background : tty->TS_set_foreground;
+      if (face_tty_specified_24_bit_color(fg))
+        ts = tty->standout_mode ? tty->TS_set_rgb_background : tty->TS_set_rgb_foreground;
+      else
+        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 (!face_tty_specified_24_bit_color(fg))
+            p = tparam (ts, NULL, 0, fg, 0, 0, 0);
+          else
+            {
+              const unsigned char r = (fg >> 16) & 0xFF,
+                g = (fg >> 8) & 0xFF,
+                b = fg & 0xFF;
+              p = tparam (ts, NULL, 0, (int)r, (int)g, (int)b, 0);
+            }
 	  OUTPUT (tty, p);
 	  xfree (p);
 	}
 
-      ts = tty->standout_mode ? tty->TS_set_foreground : tty->TS_set_background;
+      if (face_tty_specified_24_bit_color(bg))
+        ts = tty->standout_mode ? tty->TS_set_rgb_foreground : tty->TS_set_rgb_background;
+      else
+        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 (!face_tty_specified_24_bit_color(bg))
+            p = tparam (ts, NULL, 0, bg, 0, 0, 0);
+          else
+            {
+              const unsigned char r = (bg >> 16) & 0xFF,
+                g = (bg >> 8) & 0xFF,
+                b = bg & 0xFF;
+              p = tparam (ts, NULL, 0, (int)r, (int)g, (int)b, 0);
+          }
 	  OUTPUT (tty, p);
 	  xfree (p);
 	}
@@ -2028,6 +2050,8 @@ TERMINAL does not refer to a text terminal.  */)
   struct terminal *t = get_tty_terminal (terminal, 0);
   if (!t)
     return make_number (0);
+  else if (t->display_info.tty->TS_set_rgb_foreground)
+    return make_number (16777216); /* 24 bit True Color */
   else
     return make_number (t->display_info.tty->TN_max_colors);
 }
@@ -2043,6 +2067,8 @@ static int default_no_color_video;
 static char *default_orig_pair;
 static char *default_set_foreground;
 static char *default_set_background;
+static char *default_set_rgb_foreground;
+static char *default_set_rgb_background;
 
 /* Save or restore the default color-related capabilities of this
    terminal.  */
@@ -2055,6 +2081,8 @@ tty_default_color_capabilities (struct tty_display_info *tty, bool save)
       dupstring (&default_orig_pair, tty->TS_orig_pair);
       dupstring (&default_set_foreground, tty->TS_set_foreground);
       dupstring (&default_set_background, tty->TS_set_background);
+      dupstring (&default_set_rgb_foreground, tty->TS_set_rgb_foreground);
+      dupstring (&default_set_rgb_background, tty->TS_set_rgb_background);
       default_max_colors = tty->TN_max_colors;
       default_max_pairs = tty->TN_max_pairs;
       default_no_color_video = tty->TN_no_color_video;
@@ -2064,6 +2092,8 @@ tty_default_color_capabilities (struct tty_display_info *tty, bool save)
       tty->TS_orig_pair = default_orig_pair;
       tty->TS_set_foreground = default_set_foreground;
       tty->TS_set_background = default_set_background;
+      tty->TS_set_rgb_foreground = default_set_rgb_foreground;
+      tty->TS_set_rgb_background = default_set_rgb_background;
       tty->TN_max_colors = default_max_colors;
       tty->TN_max_pairs = default_max_pairs;
       tty->TN_no_color_video = default_no_color_video;
@@ -2088,6 +2118,7 @@ tty_setup_colors (struct tty_display_info *tty, int mode)
 	tty->TN_max_pairs = 0;
 	tty->TN_no_color_video = 0;
 	tty->TS_set_foreground = tty->TS_set_background = tty->TS_orig_pair = NULL;
+        tty->TS_set_rgb_foreground = tty->TS_set_rgb_background = NULL;
 	break;
       case 0:	 /* default colors, if any */
       default:
@@ -2102,10 +2133,26 @@ tty_setup_colors (struct tty_display_info *tty, int mode)
 	tty->TS_set_foreground = "\033[3%dm";
 	tty->TS_set_background = "\033[4%dm";
 #endif
+	tty->TS_set_rgb_foreground = NULL;
+	tty->TS_set_rgb_background = NULL;
 	tty->TN_max_colors = 8;
 	tty->TN_max_pairs = 64;
 	tty->TN_no_color_video = 0;
 	break;
+      case 16777216: /* RGB colors */
+        tty->TS_orig_pair = "\033[0m";
+
+#ifdef TERMINFO
+        tty->TS_set_rgb_foreground = "\033[38;2;%p1%d;%p2%d;%p3%dm";
+        tty->TS_set_rgb_background = "\033[48;2;%p1%d;%p2%d;%p3%dm";
+#else
+        tty->TS_set_rgb_foreground = "\033[38;2;%d;%d;%dm";
+        tty->TS_set_rgb_background = "\033[48;2;%d;%d;%dm";
+#endif
+
+        tty->TN_max_colors = 16777216;
+        tty->TN_no_color_video = 0;
+        break;
     }
 }
 
@@ -4201,6 +4248,9 @@ use the Bourne shell command `TERM=... export TERM' (C-shell:\n\
       tty->TN_no_color_video = tgetnum ("NC");
       if (tty->TN_no_color_video == -1)
         tty->TN_no_color_video = 0;
+
+      tty->TS_set_rgb_foreground = NULL;
+      tty->TS_set_rgb_background = NULL;
     }
 
   tty_default_color_capabilities (tty, 1);
diff --git a/src/termchar.h b/src/termchar.h
index d8066d7..e48d583 100644
--- a/src/termchar.h
+++ b/src/termchar.h
@@ -157,6 +157,10 @@ struct tty_display_info
   const char *TS_set_foreground;
   const char *TS_set_background;
 
+  /* Support for 24bit RGB color terminals. */
+  const char *TS_set_rgb_foreground;
+  const char *TS_set_rgb_background;
+
   int TF_hazeltine;             /* termcap hz flag. */
   int TF_insmode_motion;        /* termcap mi flag: can move while in insert mode. */
   int TF_standout_motion;       /* termcap mi flag: can move while in standout mode. */
diff --git a/src/xfaces.c b/src/xfaces.c
index 29c91f7..347ebf8 100644
--- a/src/xfaces.c
+++ b/src/xfaces.c
@@ -382,7 +382,7 @@ static ptrdiff_t lface_id_to_name_size;
 
 /* TTY color-related functions (defined in tty-colors.el).  */
 
-static Lisp_Object Qtty_color_desc, Qtty_color_by_index, Qtty_color_standard_values;
+static Lisp_Object Qtty_color_desc, Qtty_color_by_index, Qtty_color_standard_values, Qtty_color_canonicalize;
 
 /* The name of the function used to compute colors on TTYs.  */
 
@@ -943,54 +943,80 @@ tty_lookup_color (struct frame *f, Lisp_Object color, XColor *tty_color,
   if (!STRINGP (color) || NILP (Ffboundp (Qtty_color_desc)))
     return 0;
 
-  XSETFRAME (frame, f);
-
-  color_desc = call2 (Qtty_color_desc, color, frame);
-  if (CONSP (color_desc) && CONSP (XCDR (color_desc)))
+  if (f->output_method == output_termcap
+      && f->output_data.tty->display_info->TS_set_rgb_foreground
+      && !NILP (Ffboundp (Qtty_color_standard_values)))
     {
-      Lisp_Object rgb;
-
-      if (! INTEGERP (XCAR (XCDR (color_desc))))
-	return 0;
+      /* Terminal supports 3 byte RGB colors. */
+      if (!NILP (Ffboundp (Qtty_color_canonicalize)))
+        color = call1(Qtty_color_canonicalize, color);
 
-      tty_color->pixel = XINT (XCAR (XCDR (color_desc)));
+      color_desc = call1 (Qtty_color_standard_values, color);
+      if (! parse_rgb_list (color_desc, tty_color))
+        return 0;
 
-      rgb = XCDR (XCDR (color_desc));
-      if (! parse_rgb_list (rgb, tty_color))
-	return 0;
+      /* Map XColor to 3 byte values. */
+      tty_color->pixel = 1 << 24 /* Set bit 24 to mark RGB values. */
+        | (tty_color->red / 256) << 16
+        | (tty_color->green / 256) << 8
+        | (tty_color->blue / 256);
 
-      /* Should we fill in STD_COLOR too?  */
       if (std_color)
-	{
-	  /* Default STD_COLOR to the same as TTY_COLOR.  */
-	  *std_color = *tty_color;
-
-	  /* Do a quick check to see if the returned descriptor is
-	     actually _exactly_ equal to COLOR, otherwise we have to
-	     lookup STD_COLOR separately.  If it's impossible to lookup
-	     a standard color, we just give up and use TTY_COLOR.  */
-	  if ((!STRINGP (XCAR (color_desc))
-	       || NILP (Fstring_equal (color, XCAR (color_desc))))
-	      && !NILP (Ffboundp (Qtty_color_standard_values)))
-	    {
-	      /* Look up STD_COLOR separately.  */
-	      rgb = call1 (Qtty_color_standard_values, color);
-	      if (! parse_rgb_list (rgb, std_color))
-		return 0;
-	    }
-	}
+        *std_color = *tty_color;
 
       return 1;
     }
-  else if (NILP (Fsymbol_value (intern ("tty-defined-color-alist"))))
-    /* We were called early during startup, and the colors are not
-       yet set up in tty-defined-color-alist.  Don't return a failure
-       indication, since this produces the annoying "Unable to
-       load color" messages in the *Messages* buffer.  */
-    return 1;
   else
-    /* tty-color-desc seems to have returned a bad value.  */
-    return 0;
+    {
+      XSETFRAME (frame, f);
+
+      color_desc = call2 (Qtty_color_desc, color, frame);
+      if (CONSP (color_desc) && CONSP (XCDR (color_desc)))
+        {
+          Lisp_Object rgb;
+
+          if (! INTEGERP (XCAR (XCDR (color_desc))))
+            return 0;
+
+          tty_color->pixel = XINT (XCAR (XCDR (color_desc)));
+
+          rgb = XCDR (XCDR (color_desc));
+          if (! parse_rgb_list (rgb, tty_color))
+            return 0;
+
+          /* Should we fill in STD_COLOR too?  */
+          if (std_color)
+            {
+              /* Default STD_COLOR to the same as TTY_COLOR.  */
+              *std_color = *tty_color;
+
+              /* Do a quick check to see if the returned descriptor is
+                 actually _exactly_ equal to COLOR, otherwise we have to
+                 lookup STD_COLOR separately.  If it's impossible to lookup
+                 a standard color, we just give up and use TTY_COLOR.  */
+              if ((!STRINGP (XCAR (color_desc))
+                   || NILP (Fstring_equal (color, XCAR (color_desc))))
+                  && !NILP (Ffboundp (Qtty_color_standard_values)))
+                {
+                  /* Look up STD_COLOR separately.  */
+                  rgb = call1 (Qtty_color_standard_values, color);
+                  if (! parse_rgb_list (rgb, std_color))
+                    return 0;
+                }
+            }
+
+          return 1;
+        }
+      else if (NILP (Fsymbol_value (intern ("tty-defined-color-alist"))))
+        /* We were called early during startup, and the colors are not
+           yet set up in tty-defined-color-alist.  Don't return a failure
+           indication, since this produces the annoying "Unable to
+           load color" messages in the *Messages* buffer.  */
+        return 1;
+      else
+        /* tty-color-desc seems to have returned a bad value.  */
+        return 0;
+    }
 }
 
 /* A version of defined_color for non-X frames.  */
@@ -1008,7 +1034,9 @@ tty_defined_color (struct frame *f, const char *color_name,
   color_def->green = 0;
 
   if (*color_name)
-    status = tty_lookup_color (f, build_string (color_name), color_def, NULL);
+    {
+      status = tty_lookup_color (f, build_string (color_name), color_def, NULL);
+    }
 
   if (color_def->pixel == FACE_TTY_DEFAULT_COLOR && *color_name)
     {
@@ -5780,6 +5808,7 @@ map_tty_color (struct frame *f, struct face *face,
   unsigned long default_pixel =
     foreground_p ? FACE_TTY_DEFAULT_FG_COLOR : FACE_TTY_DEFAULT_BG_COLOR;
   unsigned long pixel = default_pixel;
+  XColor true_color;
 #ifdef MSDOS
   unsigned long default_other_pixel =
     foreground_p ? FACE_TTY_DEFAULT_BG_COLOR : FACE_TTY_DEFAULT_FG_COLOR;
@@ -5798,7 +5827,18 @@ map_tty_color (struct frame *f, struct face *face,
     {
       /* Associations in tty-defined-color-alist are of the form
 	 (NAME INDEX R G B).  We need the INDEX part.  */
-      pixel = XINT (XCAR (XCDR (def)));
+      if (f->output_method == output_termcap
+          && f->output_data.tty->display_info->TS_set_rgb_foreground
+          && parse_rgb_list (XCDR (XCDR(def)), &true_color))
+        {
+          /* Map XColor to 3 byte values. */
+          pixel = 1 << 24 /* Set bit 24 to mark RGB values. */
+            | (true_color.red / 256) << 16
+            | (true_color.green / 256) << 8
+            | (true_color.blue / 256);
+        }
+       else
+         pixel = XINT (XCAR (XCDR (def)));
     }
 
   if (pixel == default_pixel && STRINGP (color))
@@ -6460,6 +6500,7 @@ syms_of_xfaces (void)
   DEFSYM (Qwindow_divider, "window-divider");
   DEFSYM (Qwindow_divider_first_pixel, "window-divider-first-pixel");
   DEFSYM (Qwindow_divider_last_pixel, "window-divider-last-pixel");
+  DEFSYM (Qtty_color_canonicalize, "tty-color-canonicalize");
   DEFSYM (Qtty_color_desc, "tty-color-desc");
   DEFSYM (Qtty_color_standard_values, "tty-color-standard-values");
   DEFSYM (Qtty_color_by_index, "tty-color-by-index");

Re: support for true-color terminals

[Eli Zaretskii]

> From: Charles Strahan <charles@cstrahan.com>
> Date: Thu, 10 Mar 2016 20:48:54 -0500
> 
> A while back, there was an effort to add support for true-color
> terminals (by which I mean terminals supporting 16777216 simultaneous
> colors):
> 
> http://emacs.1067599.n5.nabble.com/RFC-Add-tty-True-Color-support-td299962.html
> 
> I've contacted Rüdiger, asking if he wouldn't mind if I pick up from
> where he left off, and he said that was fine as he's been too busy to
> work on this.
> 
> I've attached to this email the patch that I'm using, based on his work.
> Any feedback would be greatly appreciated.
> 
> This is my first (attempted) contribution to Emacs, and I'm very new to
> the code base, so there might be some silly mistakes that I'm unaware
> of. If we can get this polished enough for inclusion, I'd be more than
> happy to assign copyright.

Thanks.

First, I suggest that you start the legal paperwork rolling right now,
because without that, discussing such a non-trivial change would be
rather pointless.  If you agree, I will send you the form off-list.

As for the patch: my first comment is about the changes in
tty_look_up_color and in map_tty_color -- why are these needed?  The
sheer number of the supported colors doesn't necessarily require any
changes in the basic design of TTY color support, so I'm not sure what
was the motivation for these changes.

Also, why do we need the 'true-color' option introduced in
tty-colors.el? why isn't 'auto' enough for supporting this terminal?

Re: support for true-color terminals

[Charles Strahan]

On Fri, Mar 11, 2016, at 04:26 AM, Eli Zaretskii wrote:
> > From: Charles Strahan <charles@cstrahan.com>
> > Date: Thu, 10 Mar 2016 20:48:54 -0500
> > 
> > A while back, there was an effort to add support for true-color
> > terminals (by which I mean terminals supporting 16777216 simultaneous
> > colors):
> > 
> > http://emacs.1067599.n5.nabble.com/RFC-Add-tty-True-Color-support-td299962.html
> > 
> > I've contacted Rüdiger, asking if he wouldn't mind if I pick up from
> > where he left off, and he said that was fine as he's been too busy to
> > work on this.
> > 
> > I've attached to this email the patch that I'm using, based on his work.
> > Any feedback would be greatly appreciated.
> > 
> > This is my first (attempted) contribution to Emacs, and I'm very new to
> > the code base, so there might be some silly mistakes that I'm unaware
> > of. If we can get this polished enough for inclusion, I'd be more than
> > happy to assign copyright.
> 
> Thanks.
> 
> First, I suggest that you start the legal paperwork rolling right now,
> because without that, discussing such a non-trivial change would be
> rather pointless.  If you agree, I will send you the form off-list.

Yes, I agree - thank you. I'll get the paperwork filled out as soon as I
can.

> As for the patch: my first comment is about the changes in
> tty_look_up_color and in map_tty_color -- why are these needed?  The
> sheer number of the supported colors doesn't necessarily require any
> changes in the basic design of TTY color support, so I'm not sure what
> was the motivation for these changes.
> 
> Also, why do we need the 'true-color' option introduced in
> tty-colors.el? why isn't 'auto' enough for supporting this terminal?

I'll try to answer your questions in the next day or two when my
schedule frees up.

-Charles

Re: support for true-color terminals

[Charles Strahan]

Hello,

Unless I've missed it, I don't think I've received an email regarding
copyright assignment. Could you point me at the requisite paperwork,
please?

Thanks!
-Charles

On Fri, Mar 18, 2016, at 04:05 AM, Charles Strahan wrote:
> On Fri, Mar 11, 2016, at 04:26 AM, Eli Zaretskii wrote:
> > > From: Charles Strahan <charles@cstrahan.com>
> > > Date: Thu, 10 Mar 2016 20:48:54 -0500
> > > 
> > > A while back, there was an effort to add support for true-color
> > > terminals (by which I mean terminals supporting 16777216 simultaneous
> > > colors):
> > > 
> > > http://emacs.1067599.n5.nabble.com/RFC-Add-tty-True-Color-support-td299962.html
> > > 
> > > I've contacted Rüdiger, asking if he wouldn't mind if I pick up from
> > > where he left off, and he said that was fine as he's been too busy to
> > > work on this.
> > > 
> > > I've attached to this email the patch that I'm using, based on his work.
> > > Any feedback would be greatly appreciated.
> > > 
> > > This is my first (attempted) contribution to Emacs, and I'm very new to
> > > the code base, so there might be some silly mistakes that I'm unaware
> > > of. If we can get this polished enough for inclusion, I'd be more than
> > > happy to assign copyright.
> > 
> > Thanks.
> > 
> > First, I suggest that you start the legal paperwork rolling right now,
> > because without that, discussing such a non-trivial change would be
> > rather pointless.  If you agree, I will send you the form off-list.
> 
> Yes, I agree - thank you. I'll get the paperwork filled out as soon as I
> can.
> 
> > As for the patch: my first comment is about the changes in
> > tty_look_up_color and in map_tty_color -- why are these needed?  The
> > sheer number of the supported colors doesn't necessarily require any
> > changes in the basic design of TTY color support, so I'm not sure what
> > was the motivation for these changes.
> > 
> > Also, why do we need the 'true-color' option introduced in
> > tty-colors.el? why isn't 'auto' enough for supporting this terminal?
> 
> I'll try to answer your questions in the next day or two when my
> schedule frees up.
> 
> -Charles
> 

Re: support for true-color terminals

[Eli Zaretskii]

> From: Charles Strahan <charles@cstrahan.com>
> Date: Sun, 10 Apr 2016 22:16:24 -0400
> 
> Hello,
> 
> Unless I've missed it, I don't think I've received an email regarding
> copyright assignment. Could you point me at the requisite paperwork,
> please?

Form sent off-list.