(default-frame-background-mode): New internal variable.

(frame-set-background-mode): Use it.

1 files changed, 10 insertions, 3 deletions

diff --git a/lisp/faces.el b/lisp/faces.el
index b7d06513fd8..c28cbc5d84f 100644
--- a/lisp/faces.el
+++ b/lisp/faces.el
@@ -1575,6 +1575,13 @@ this won't have the expected effect."
                  (choice-item light)
                  (choice-item :tag "default" nil)))
 
+(defvar default-frame-background-mode nil
+  "Internal variable for the default brightness of the background.
+Emacs sets it automatically depending on the terminal type.
+The value `nil' means `dark'.  If Emacs runs in non-windowed
+mode from `xterm' or a similar terminal emulator, the value is
+`light'.  On rxvt terminals, the value depends on the environment
+variable COLORFGBG.")
 
 (defun frame-set-background-mode (frame)
   "Set up display-dependent faces on FRAME.
@@ -1590,13 +1597,13 @@ according to the `background-mode' and `display-type' frame parameters."
                  (intern (downcase bg-resource)))
                 ((and (null window-system) (null bg-color))
                  ;; No way to determine this automatically (?).
-                 'dark)
+                 (or default-frame-background-mode 'dark))
                 ;; Unspecified frame background color can only happen
                 ;; on tty's.
                 ((member bg-color '(unspecified "unspecified-bg"))
-                 'dark)
+                 (or default-frame-background-mode 'dark))
                 ((equal bg-color "unspecified-fg") ; inverted colors
-                 'light)
+                 (if (eq default-frame-background-mode 'light) 'dark 'light))
                 ((>= (apply '+ (x-color-values bg-color frame))
                     ;; Just looking at the screen, colors whose
                     ;; values add up to .6 of the white total