Support 24-bit TrueColor on MS-Windows console

* src/w32console.c (DEFAULTP, SSPRINTF, w32con_write_vt_seq)
(w32con_get_cursor_coords): New functions and macros.
(w32con_write_glyphs): Hide cursor before writing to the console.
Add code for writing in virtual-terminal mode when
'w32_use_virtual_terminal' is non-zero.
(w32con_write_glyphs_with_face): Add code for writing in
virtual-terminal mode when 'w32_use_virtual_terminal' is non-zero.
(w32con_setup_virtual_terminal): New function.
(w32con_set_terminal_modes): Call it.
(turn_on_face, turn_off_face): New functions.
(initialize_w32_display): Save background and foreground, and the
current TTY.
(Fset_screen_color): Accept an additional optional argument VTP;
if non-nil, arrange for 24-bit display to use the specified
colors.
(Fget_screen_color): Accept an additional optional argument VTP;
if non-nil, return colors used by 24-bit display.
(Fw32_use_virtual_terminal, Fw32_use_virtual_terminal_p): New
functions.
* src/term.c (tty_setup_colors) [WINDOWSNT]: Set up
virtual-terminal sequences for colors.
(init_tty) [WINDOWSNT]: Set up terminfo capabilities for Windows
virtual-terminal.
* src/xdisp.c (redisplay_internal): Don't call set_tty_color_mode
for WINDOWSNT.

* lisp/term/w32console.el (w32-tty-set-base-colors)
(w32-tty-define-base-colors, w32-tty-define-8bit-colors)
(w32-tty-define-24bit-colors, w32-tty-get-pixel): New functions.
(terminal-init-w32console): Remove color setup.
(w32-tty-setup-colors): New function.
* lisp/term/tty-colors.el (tty-color-mode-alist): Add --color
modes for 256 and 24-bit color modes.
* lisp/startup.el (tty-handle-args): Fix --color handling.
* lisp/faces.el (tty-set-up-initial-frame-faces): Set up colors
for MS-Windows consoles.

* etc/NEWS:
* doc/emacs/msdos.texi (Windows Misc):
* doc/emacs/cmdargs.texi (Colors X): Document 24-bit color support
on MS-Windows.
(Bug#79298)

4 files changed, 339 insertions, 64 deletions

diff --git a/src/term.c b/src/term.c
index b5cf418450f..766eeebe5e8 100644
--- a/src/term.c
+++ b/src/term.c
@@ -2207,7 +2207,7 @@ TERMINAL does not refer to a text terminal.  */)
   return make_fixnum (t ? t->display_info.tty->TN_max_colors : 0);
 }
 
-#if !defined DOS_NT && !defined HAVE_ANDROID
+#if !defined MSDOS && !defined HAVE_ANDROID
 
 /* Declare here rather than in the function, as in the rest of Emacs,
    to work around an HPUX compiler bug (?). See
@@ -2246,7 +2246,7 @@ tty_default_color_capabilities (struct tty_display_info *tty, bool save)
    MODE's value is generally the number of colors which we want to
    support; zero means set up for the default capabilities, the ones
    we saw at init_tty time; -1 means turn off color support.  */
-static void
+void
 tty_setup_colors (struct tty_display_info *tty, int mode)
 {
   /* Canonicalize all negative values of MODE.  */
@@ -2269,6 +2269,10 @@ tty_setup_colors (struct tty_display_info *tty, int mode)
 #ifdef TERMINFO
         tty->TS_set_foreground = "\033[3%p1%dm";
         tty->TS_set_background = "\033[4%p1%dm";
+#elif WINDOWSNT
+        tty->TS_orig_pair = "\x1b[39m\x1b[49m";
+        tty->TS_set_foreground = "\x1b[%lum";
+        tty->TS_set_background = "\x1b[%lum";
 #else
         tty->TS_set_foreground = "\033[3%dm";
         tty->TS_set_background = "\033[4%dm";
@@ -2276,6 +2280,26 @@ tty_setup_colors (struct tty_display_info *tty, int mode)
         tty->TN_max_colors = 8;
         tty->TN_no_color_video = 0;
         break;
+#ifdef WINDOWSNT
+      case 16:
+        tty->TN_max_colors = 16;
+        tty->TS_set_foreground = "\x1b[%lum";
+        tty->TS_set_background = "\x1b[%lum";
+        tty->TN_no_color_video = 0;
+        break;
+      case 256:
+        tty->TN_max_colors = 256;
+        tty->TS_set_foreground = "\x1b[38;5;%lum";
+        tty->TS_set_background = "\x1b[48;5;%lum";
+        tty->TN_no_color_video = 0;
+        break;
+      case 16777216:
+        tty->TN_max_colors = 16777216;
+        tty->TS_set_foreground = "\x1b[38;2;%lu;%lu;%lum";
+        tty->TS_set_background = "\x1b[48;2;%lu;%lu;%lum";
+        tty->TN_no_color_video = 0;
+        break;
+#endif
     }
 }
 
@@ -2312,7 +2336,7 @@ set_tty_color_mode (struct tty_display_info *tty, struct frame *f)
     }
 }
 
-#endif /* !DOS_NT && !HAVE_ANDROID */
+#endif /* !MSDOS && !HAVE_ANDROID */
 
 char *
 tty_type_name (Lisp_Object terminal)
@@ -4644,6 +4668,22 @@ use the Bourne shell command 'TERM=...; export TERM' (C-shell:\n\
 
     initialize_w32_display (terminal, &width, &height);
 
+    tty->TN_no_color_video = 0;
+    tty->TN_max_colors = 16777216;
+    tty->TS_orig_pair = "\x1b[39m\x1b[49m";
+    tty->TS_set_foreground = "\x1b[38;2;%lu;%lu;%lum";
+    tty->TS_set_background = "\x1b[48;2;%lu;%lu;%lum";
+
+    /* Save default color capabilities */
+    tty_default_color_capabilities (tty, 1);
+
+    tty->TS_enter_bold_mode = "\x1b[1m";
+    tty->TS_enter_italic_mode = "\x1b[3m";
+    tty->TS_enter_strike_through_mode = "\x1b[9m";
+    tty->TS_enter_underline_mode = "\x1b[4m";
+    tty->TS_enter_reverse_mode = "\x1b[7m";
+    tty->TS_exit_attribute_mode = "\x1b[0m";
+
     FrameRows (tty) = height;
     FrameCols (tty) = width;
     tty->specified_window = height;
@@ -4689,7 +4729,6 @@ use the Bourne shell command 'TERM=...; export TERM' (C-shell:\n\
      don't think we're losing anything by turning it off.  */
   tty->line_ins_del_ok = 0;
 
-  tty->TN_max_colors = 16;  /* Must be non-zero for tty-display-color-p.  */
 #endif  /* DOS_NT */
 
 #ifdef HAVE_GPM
@@ -5205,11 +5244,11 @@ non-nil to enable this optimization.  */);
   defsubr (&Stty_display_pixel_width);
   defsubr (&Stty_display_pixel_height);
 
-#if !defined DOS_NT && !defined HAVE_ANDROID
+#if !defined MSDOS && !defined HAVE_ANDROID
   default_orig_pair = NULL;
   default_set_foreground = NULL;
   default_set_background = NULL;
-#endif /* !DOS_NT && !HAVE_ANDROID */
+#endif /* !MSDOS && !HAVE_ANDROID */
 
 #ifndef HAVE_ANDROID
   encode_terminal_src = NULL;
diff --git a/src/termchar.h b/src/termchar.h
index 9d7c3a2a555..9a9001d5cef 100644
--- a/src/termchar.h
+++ b/src/termchar.h
@@ -249,4 +249,6 @@ struct input_event;
 extern Lisp_Object tty_handle_tab_bar_click (struct frame *, int, int, bool,
                                              struct input_event *);
 
+extern void tty_setup_colors (struct tty_display_info *tty, int mode);
+
 #endif /* EMACS_TERMCHAR_H */
diff --git a/src/w32console.c b/src/w32console.c
index be5e0b92072..b0a2f0c1c0e 100644
--- a/src/w32console.c
+++ b/src/w32console.c
@@ -19,6 +19,9 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 /*
    Tim Fleehart (apollo@online.com)             1-17-92
    Geoff Voelker (voelker@cs.washington.edu)    9-12-93
+   Ewan Townshend (ewan@etown.dev)              2025-08
+   * c. ~ 2025: 24bit RGB support in Windows (10+) Terminal
+   * https://learn.microsoft.com/en-us/windows/console/console-virtual-terminal-sequences
 */
 
 
@@ -53,11 +56,17 @@ static void w32con_set_terminal_modes (struct terminal *t);
 static void w32con_update_begin (struct frame * f);
 static void w32con_update_end (struct frame * f);
 static WORD w32_face_attributes (struct frame *f, int face_id);
+static int  w32con_write_vt_seq (const char *);
+static void turn_on_face (struct frame *, int face_id);
+static void turn_off_face (struct frame *, int face_id);
+static COORD w32con_get_cursor_coords ();
 
 static COORD    cursor_coords;
 static HANDLE   prev_screen, cur_screen;
 static WORD     char_attr_normal;
 static DWORD    prev_console_mode;
+static int      bg_normal;
+static int      fg_normal;
 
 static CONSOLE_CURSOR_INFO console_cursor_info;
 #ifndef USE_SEPARATE_SCREEN
@@ -67,7 +76,10 @@ static CONSOLE_CURSOR_INFO prev_console_cursor;
 extern HANDLE  keyboard_handle;
 HANDLE  keyboard_handle;
 int w32_console_unicode_input;
-
+extern int w32_use_virtual_terminal;
+int w32_use_virtual_terminal = 1;
+extern struct tty_display_info *current_tty;
+struct tty_display_info *current_tty = NULL;
 
 /* Setting this as the ctrl handler prevents emacs from being killed when
    someone hits ^C in a 'suspended' session (child shell).
@@ -83,6 +95,38 @@ ctrl_c_handler (unsigned long type)
           && (type == CTRL_C_EVENT || type == CTRL_BREAK_EVENT));
 }
 
+#define DEFAULTP(p)                                                     \
+  (p == FACE_TTY_DEFAULT_COLOR                                          \
+   || p == FACE_TTY_DEFAULT_FG_COLOR                                    \
+   || p == FACE_TTY_DEFAULT_BG_COLOR)
+
+#define SEQMAX 256 /* Arbitrary upper limit on VT sequence size */
+
+#define SSPRINTF(buf, i, sz, fmt, ...)                                  \
+  do {                                                                  \
+    eassert (*i < sz && sz <= SEQMAX);                                  \
+    if (fmt && *i < sz && sz <= SEQMAX)                         \
+      *i += snprintf (buf + *i, sz - *i, fmt, __VA_ARGS__);             \
+  } while (0)
+
+/* Writes virtual terminal sequence to screen */
+static int
+w32con_write_vt_seq (const char *seq)
+{
+  char buf[SEQMAX];
+  DWORD n = 0, k = 0;
+  SSPRINTF (buf, &n, SEQMAX, seq, NULL);
+  if (n) WriteConsole (cur_screen, (LPCSTR) buf, n, &k, NULL);
+  return k;
+}
+
+static COORD
+w32con_get_cursor_coords ()
+{
+  CONSOLE_SCREEN_BUFFER_INFO info;
+  GetConsoleScreenBufferInfo (GetStdHandle (STD_OUTPUT_HANDLE), &info);
+  return info.dwCursorPosition;
+}
 
 /* Move the cursor to (ROW, COL) on FRAME.  */
 static void
@@ -309,10 +353,11 @@ w32con_write_glyphs (struct frame *f, register struct glyph *string,
                      register int len)
 {
   DWORD r;
-  WORD char_attr;
   LPCSTR conversion_buffer;
   struct coding_system *coding;
 
+  w32con_hide_cursor();
+
   if (len <= 0)
     return;
 
@@ -342,8 +387,6 @@ w32con_write_glyphs (struct frame *f, register struct glyph *string,
 
       /* w32con_clear_end_of_line sets frame of glyphs to NULL.  */
       struct frame *attr_frame = face_id_frame ? face_id_frame : f;
-      /* Turn appearance modes of the face of the run on.  */
-      char_attr = w32_face_attributes (attr_frame, face_id);
 
       if (n == len)
         /* This is the last run.  */
@@ -351,31 +394,45 @@ w32con_write_glyphs (struct frame *f, register struct glyph *string,
       conversion_buffer = (LPCSTR) encode_terminal_code (string, n, coding);
       if (coding->produced > 0)
         {
-          /* Compute the string's width on display by accounting for
-             character's width.  FIXME: this doesn't handle character
-             compositions.  */
-          ptrdiff_t ncols = strwidth (coding->source, coding->src_bytes);
-          /* Set the attribute for these characters.  */
-          if (!FillConsoleOutputAttribute (cur_screen, char_attr, ncols,
-                                           cursor_coords, &r))
+          if (w32_use_virtual_terminal)
             {
-              printf ("Failed writing console attributes: %lu\n",
-                      GetLastError ());
-              fflush (stdout);
+              turn_on_face (f, face_id);
+              WriteConsole (cur_screen, conversion_buffer,
+                            coding->produced, &r, NULL);
+              turn_off_face (f, face_id);
+              cursor_coords = w32con_get_cursor_coords ();
             }
-
-          /* Write the characters.  */
-          if (!WriteConsoleOutputCharacter (cur_screen, conversion_buffer,
-                                            coding->produced, cursor_coords,
-                                            &r))
+          else
             {
-              printf ("Failed writing console characters: %lu\n",
-                      GetLastError ());
-              fflush (stdout);
-            }
+              /* Account for character width.
+                 FIXME: this doesn't handle character compositions.  */
+              ptrdiff_t ncols = strwidth (coding->source, coding->src_bytes);
+
+              /* Turn appearance modes of the face of the run on.  */
+              WORD char_attr = w32_face_attributes (attr_frame, face_id);
 
-          cursor_coords.X += ncols;
-          w32con_move_cursor (f, cursor_coords.Y, cursor_coords.X);
+              /* Set the attribute for these characters.  */
+              if (!FillConsoleOutputAttribute (cur_screen, char_attr, ncols,
+                                               cursor_coords, &r))
+                {
+                  printf ("Failed writing console attributes: %lu\n",
+                          GetLastError ());
+                  fflush (stdout);
+                }
+
+              /* Write the characters.  */
+              if (!WriteConsoleOutputCharacter (cur_screen, conversion_buffer,
+                                                coding->produced, cursor_coords,
+                                                &r))
+                {
+                  printf ("Failed writing console characters: %lu\n",
+                          GetLastError ());
+                  fflush (stdout);
+                }
+
+              cursor_coords.X += ncols;
+              w32con_move_cursor (f, cursor_coords.Y, cursor_coords.X);
+            }
         }
       len -= n;
       string += n;
@@ -391,6 +448,8 @@ w32con_write_glyphs_with_face (struct frame *f, register int x, register int y,
   LPCSTR conversion_buffer;
   struct coding_system *coding;
 
+  w32con_hide_cursor();
+
   if (len <= 0)
     return;
 
@@ -407,28 +466,42 @@ w32con_write_glyphs_with_face (struct frame *f, register int x, register int y,
   if (coding->produced > 0)
     {
       DWORD filled, written;
-      /* Compute the character attributes corresponding to the face.  */
-      DWORD char_attr = w32_face_attributes (f, face_id);
-      COORD start_coords;
-      /* Compute the string's width on display by accounting for
-         character's width.  FIXME: this doesn't handle character
-         compositions.  */
-      ptrdiff_t ncols = strwidth (coding->source, coding->src_bytes);
-
-      start_coords.X = x;
-      start_coords.Y = y;
-      /* Set the attribute for these characters.  */
-      if (!FillConsoleOutputAttribute (cur_screen, char_attr, ncols,
-                                       start_coords, &filled))
-        DebPrint (("Failed writing console attributes: %d\n", GetLastError ()));
+      if (w32_use_virtual_terminal)
+        {
+          COORD saved_coords = cursor_coords;
+          w32con_move_cursor(f, y, x);
+          turn_on_face (f, face_id);
+          WriteConsole (cur_screen, conversion_buffer,
+                        coding->produced, &written, NULL);
+          turn_off_face (f, face_id);
+          w32con_move_cursor(f, saved_coords.Y, saved_coords.X);
+        }
       else
         {
-          /* Write the characters.  */
-          if (!WriteConsoleOutputCharacter (cur_screen, conversion_buffer,
-                                            coding->produced, start_coords,
-                                            &written))
-            DebPrint (("Failed writing console characters: %d\n",
-                       GetLastError ()));
+          /* Compute the character attributes corresponding to the face.  */
+          DWORD char_attr = w32_face_attributes (f, face_id);
+          COORD start_coords;
+
+          start_coords.X = x;
+          start_coords.Y = y;
+
+          /* Account for character width.
+             FIXME: this doesn't handle character compositions.  */
+          ptrdiff_t ncols = strwidth (coding->source, coding->src_bytes);
+
+          /* Set the attribute for these characters.  */
+          if (!FillConsoleOutputAttribute (cur_screen, char_attr, ncols,
+                                           start_coords, &filled))
+            DebPrint (("Failed writing console attributes: %d\n", GetLastError ()));
+          else
+            {
+              /* Write the characters.  */
+              if (!WriteConsoleOutputCharacter (cur_screen, conversion_buffer,
+                                                coding->produced, start_coords,
+                                                &written))
+                DebPrint (("Failed writing console characters: %d\n",
+                           GetLastError ()));
+            }
         }
     }
 }
@@ -529,6 +602,33 @@ w32con_delete_glyphs (struct frame *f, int n)
   scroll_line (f, n, LEFT);
 }
 
+static void
+w32con_setup_virtual_terminal (void)
+{
+  /* Disable unless 24bit color is supported (v. > 10.0.15063).  */
+  w32_use_virtual_terminal = w32_use_virtual_terminal
+    && (w32_major_version > 10
+        || (w32_major_version == 10
+            && (w32_minor_version > 0 || w32_build_number > 15063)));
+
+  DWORD out_mode;
+  GetConsoleMode (cur_screen, &out_mode);
+  out_mode |= ENABLE_PROCESSED_OUTPUT;
+  out_mode |= DISABLE_NEWLINE_AUTO_RETURN;
+
+  if (w32_use_virtual_terminal)
+    out_mode |= ENABLE_VIRTUAL_TERMINAL_PROCESSING;
+  else
+    out_mode &= ~ENABLE_VIRTUAL_TERMINAL_PROCESSING;
+
+  int out_mode_set = SetConsoleMode (cur_screen, out_mode);
+  w32_use_virtual_terminal = w32_use_virtual_terminal && out_mode_set;
+
+  int max_colors = w32_use_virtual_terminal ? 16777216 : 16;
+  tty_setup_colors (current_tty, max_colors);
+
+  safe_calln (Qtty_set_up_initial_frame_faces);
+}
 
 static void
 w32con_reset_terminal_modes (struct terminal *t)
@@ -585,6 +685,7 @@ w32con_set_terminal_modes (struct terminal *t)
   /* Initialize input mode: interrupt_input off, no flow control, allow
      8 bit character input, standard quit char.  */
   Fset_input_mode (Qnil, Qnil, make_fixnum (2), Qnil);
+  w32con_setup_virtual_terminal ();
 }
 
 /* hmmm... perhaps these let us bracket screen changes so that we can flush
@@ -631,8 +732,6 @@ sys_tgetstr (char *cap, char **area)
                         stubs from cm.c
  ***********************************************************************/
 
-extern struct tty_display_info *current_tty;
-struct tty_display_info *current_tty = NULL;
 extern int cost;
 int cost = 0;
 
@@ -736,6 +835,87 @@ w32_face_attributes (struct frame *f, int face_id)
   return char_attr;
 }
 
+static void
+turn_on_face (struct frame *f, int face_id)
+{
+  struct face *face = FACE_FROM_ID (f, face_id);
+  struct tty_display_info *tty = FRAME_TTY (f);
+  unsigned long fg = face->foreground;
+  unsigned long bg = face->background;
+
+  /* construct combined VT sequence for face attributes */
+  DWORD n = 0;
+  size_t sz = SEQMAX;
+  char seq[sz];
+  sz--;
+
+  if (face->tty_bold_p)
+    SSPRINTF (seq, &n, sz, tty->TS_enter_bold_mode, NULL);
+  if (face->tty_italic_p)
+    SSPRINTF (seq, &n, sz, tty->TS_enter_italic_mode, NULL);
+  if (face->tty_strike_through_p)
+    SSPRINTF (seq, &n, sz, tty->TS_enter_strike_through_mode, NULL);
+  if (face->underline != 0)
+    SSPRINTF (seq, &n, sz, tty->TS_enter_underline_mode, NULL);
+  /* Note: when face->tty_reverse_p != 0 and fg and bg are specified,
+     their values are already swapped and reversing them here would swap
+     them back, but we need to handle the reversal when unspecified.  */
+  if (face->tty_reverse_p && DEFAULTP (fg) && DEFAULTP (bg))
+    SSPRINTF (seq, &n, sz, tty->TS_enter_reverse_mode, NULL);
+
+  if (DEFAULTP (fg)) fg = fg_normal;
+  if (DEFAULTP (bg)) bg = bg_normal;
+
+  const char *set_fg = tty->TS_set_foreground;
+  const char *set_bg = tty->TS_set_background;
+  if (tty->TN_max_colors == 8  || tty->TN_max_colors == 16)
+    {
+      /* fg and bg are indices into 16 base colors (see link at top).  */
+      unsigned long fgi = 0, bgi = 0;
+
+      fgi = (fg >= 0  && fg < 8)
+            ? fg + 30
+            : (fg >= 8  && fg < 16)
+              ? fg - 8 + 90
+              : 0;
+      if (fgi)
+        SSPRINTF (seq, &n, sz, set_fg, fgi);
+
+      bgi = (bg >= 0  && bg < 8)
+            ? bg + 40
+            : (bg >= 8  && bg < 16)
+              ? bg - 8 + 100
+              : 0;
+      if (bgi)
+        SSPRINTF (seq, &n, sz, set_bg, bgi);
+    }
+  else if (tty->TN_max_colors == 256)
+    {
+      /* fg and bg are xterm indices.  */
+      if (fg >= 0 && fg < 256)
+        SSPRINTF (seq, &n, sz, set_fg, fg);
+
+      if (bg >= 0 && bg < 256)
+        SSPRINTF (seq, &n, sz, set_bg, bg);
+    }
+  else if (tty->TN_max_colors == 16777216)
+    {
+      /* fg and bg are pixel values -- decompose to rgb triples.  */
+      unsigned long rf = fg/65536, gf = (fg/256)&255, bf = fg&255;
+      unsigned long rb = bg/65536, gb = (bg/256)&255, bb = bg&255;
+      SSPRINTF (seq, &n, sz, set_fg, rf, gf, bf);
+      SSPRINTF (seq, &n, sz, set_bg, rb, gb, bb);
+    }
+  w32con_write_vt_seq ((const char *) seq);
+}
+
+static void
+turn_off_face (struct frame *f, int face_id)
+{
+  struct tty_display_info *tty = FRAME_TTY (f);
+  w32con_write_vt_seq (tty->TS_exit_attribute_mode);
+}
+
 /* The IME window is needed to receive the session notifications
    required to reset the low level keyboard hook state.  */
 
@@ -868,6 +1048,8 @@ initialize_w32_display (struct terminal *term, int *width, int *height)
     }
 
   char_attr_normal = info.wAttributes;
+  fg_normal = char_attr_normal & 0x000f;
+  bg_normal = (char_attr_normal >> 4) & 0x000f;
 
   /* Determine if the info returned by GetConsoleScreenBufferInfo
      is realistic.  Old MS Telnet servers used to only fill out
@@ -921,31 +1103,81 @@ initialize_w32_display (struct terminal *term, int *width, int *height)
 
   /* Set up the keyboard hook.  */
   setup_w32_kbdhook (hwnd);
+
+  /* Set current_tty to the tty of this terminal */
+  current_tty = term->display_info.tty;
 }
 
 
-DEFUN ("set-screen-color", Fset_screen_color, Sset_screen_color, 2, 2, 0,
+DEFUN ("set-screen-color", Fset_screen_color, Sset_screen_color, 2, 3, 0,
        doc: /* Set screen foreground and background colors.
 
-Arguments should be indices between 0 and 15, see w32console.el.  */)
-  (Lisp_Object foreground, Lisp_Object background)
+Arguments should be indices for colors in the list returned by `tty-color-alist'.
+If VTP is non-nil, settings affect virtual terminal processing only.
+Otherwise, arguments should be between 0 and 15, and settings will
+be effective only when virtual terminal processing is disabled.
+
+See w32console.el and the documentation for `w32-use-virtual-terminal'.  */)
+  (Lisp_Object foreground, Lisp_Object background, Lisp_Object vtp)
 {
-  char_attr_normal = XFIXNAT (foreground) + (XFIXNAT (background) << 4);
+  int fg = XFIXNAT (foreground);
+  int bg = XFIXNAT (background);
+
+  if (NILP (vtp))
+    {
+      char_attr_normal = fg + (bg << 4);
+    }
+  else
+    {
+      fg_normal = fg;
+      bg_normal = bg;
+    }
 
   Frecenter (Qnil, Qt);
   return Qt;
 }
 
-DEFUN ("get-screen-color", Fget_screen_color, Sget_screen_color, 0, 0, 0,
+DEFUN ("get-screen-color", Fget_screen_color, Sget_screen_color, 0, 1, 0,
        doc: /* Get color indices of the current screen foreground and background.
 
-The colors are returned as a list of 2 indices (FOREGROUND BACKGROUND).
-See w32console.el and `tty-defined-color-alist' for mapping of indices
-to colors.  */)
+The colors are returned as a list of 2 indices (FOREGROUND BACKGROUND) for
+colors in the list returned by `tty-color-alist`.
+
+If VTP is non-nil, returns settings effective when virtual terminal
+processing is enabled.  Otherwise, returns settings effective when
+virtual terminal processing is disabled.
+
+See w32console.el and the documentation for `w32-use-virtual-terminal'.  */)
+  (Lisp_Object vtp)
+{
+  int fg = NILP (vtp) ? char_attr_normal & 0x000f : fg_normal;
+  int bg = NILP (vtp) ? (char_attr_normal >> 4) & 0x000f : bg_normal;
+
+  return Fcons (make_fixnum (fg), Fcons (make_fixnum (bg), Qnil));
+}
+
+DEFUN ("w32-use-virtual-terminal", Fw32_use_virtual_terminal, Sw32_use_virtual_terminal, 1, 1, 0,
+       doc: /* Enables (disables) virtual terminal sequence processing if argument is t (nil).  */)
+  (Lisp_Object arg)
+{
+  if (EQ (arg, Qt))
+    w32_use_virtual_terminal = 1;
+  else if (EQ (arg, Qnil))
+    w32_use_virtual_terminal = 0;
+  else {
+    error ("Invalid argument: expects t or nil.");
+    return Qnil;
+  }
+
+  w32con_setup_virtual_terminal ();
+  return Qt;
+}
+
+DEFUN ("w32-use-virtual-terminal-p", Fw32_use_virtual_terminal_p, Sw32_use_virtual_terminal_p, 0, 0, 0,
+       doc: /* Returns t (nil) if virtual terminal sequence processing is enabled (disabled).  */)
   (void)
 {
-  return Fcons (make_fixnum (char_attr_normal & 0x000f),
-                Fcons (make_fixnum ((char_attr_normal >> 4) & 0x000f), Qnil));
+  return w32_use_virtual_terminal ? Qt : Qnil;
 }
 
 DEFUN ("set-cursor-size", Fset_cursor_size, Sset_cursor_size, 1, 1, 0,
@@ -974,5 +1206,7 @@ scroll-back buffer.  */);
 
   defsubr (&Sset_screen_color);
   defsubr (&Sget_screen_color);
+  defsubr (&Sw32_use_virtual_terminal);
+  defsubr (&Sw32_use_virtual_terminal_p);
   defsubr (&Sset_cursor_size);
 }
diff --git a/src/xdisp.c b/src/xdisp.c
index 6f06206b43e..99474d7abdc 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -17387,7 +17387,7 @@ redisplay_internal (void)
              area, displaying a different frame means redisplay the
              whole thing.  */
           SET_FRAME_GARBAGED (sf);
-#if !defined DOS_NT && !defined HAVE_ANDROID
+#if !defined MSDOS && !defined HAVE_ANDROID
           set_tty_color_mode (FRAME_TTY (sf), sf);
 #endif
         }