Fix bug #8597 with setting frame background mode on w32 console.

src/w32console.c (Fset_screen_color): Doc fix.
 (Fget_screen_color): New function.
 (syms_of_ntterm): Defsubr it.
 lisp/term/w32console.el (terminal-init-w32console): Call
 get-screen-color and use its output to set the frame
 background-mode.

lisp/ChangeLog

@@ -1,3 +1,9 @@
+2011-05-07  Eli Zaretskii  <eliz@gnu.org>
+
+	* term/w32console.el (terminal-init-w32console): Call
+	get-screen-color and use its output to set the frame
+	background-mode.  (Bug#8597)
+
 2011-05-07  Stefan Monnier  <monnier@iro.umontreal.ca>
 
 	Make bytecomp.el understand that defmethod defines funs (bug#8631).

lisp/term/w32console.el

@@ -59,6 +59,19 @@
       (setq colors (cdr colors)
             color (car colors))))
   (clear-face-cache)
+  ;; Figure out what are the colors of the console window, and set up
+  ;; the background-mode correspondingly.
+  (let* ((screen-color (get-screen-color))
+	 (bg (cadr screen-color))
+	 (descr (tty-color-by-index bg))
+	 r g b bg-mode)
+    (setq r (nth 2 descr)
+	  g (nth 3 descr)
+	  b (nth 4 descr))
+    (if (< (+ r g b) (* .6 (+ 65535 65535 65535)))
+	(setq bg-mode 'dark)
+      (setq bg-mode 'light))
+    (set-terminal-parameter nil 'background-mode bg-mode))
   (tty-set-up-initial-frame-faces)
   (run-hooks 'terminal-init-w32-hook))
 

src/ChangeLog

@@ -1,5 +1,9 @@
 2011-05-07  Eli Zaretskii  <eliz@gnu.org>
 
+	* w32console.c (Fset_screen_color): Doc fix.
+	(Fget_screen_color): New function.
+	(syms_of_ntterm): Defsubr it.
+
 	* callproc.c (call_process_cleanup): Don't close and unlink the
 	temporary file if Fcall_process didn't create it in the first
 	place.

src/w32console.c

@@ -705,7 +705,9 @@ initialize_w32_display (struct terminal *term)
 
 
 DEFUN ("set-screen-color", Fset_screen_color, Sset_screen_color, 2, 2, 0,
-       doc: /* Set screen colors.  */)
+       doc: /* Set screen foreground and background colors.
+
+Arguments should be indices between 0 and 15, see w32console.el.  */)
   (Lisp_Object foreground, Lisp_Object background)
 {
   char_attr_normal = XFASTINT (foreground) + (XFASTINT (background) << 4);
@@ -714,6 +716,18 @@ DEFUN ("set-screen-color", Fset_screen_color, Sset_screen_color, 2, 2, 0,
   return Qt;
 }
 
+DEFUN ("get-screen-color", Fget_screen_color, Sget_screen_color, 0, 0, 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.  */)
+  (void)
+{
+  return Fcons (make_number (char_attr_normal & 0x000f),
+		Fcons (make_number ((char_attr_normal >> 4) & 0x000f), Qnil));
+}
+
 DEFUN ("set-cursor-size", Fset_cursor_size, Sset_cursor_size, 1, 1, 0,
        doc: /* Set cursor size.  */)
   (Lisp_Object size)
@@ -739,6 +753,7 @@ scroll-back buffer.  */);
   w32_use_full_screen_buffer = 0;
 
   defsubr (&Sset_screen_color);
+  defsubr (&Sget_screen_color);
   defsubr (&Sset_cursor_size);
   defsubr (&Sset_message_beep);
 }