XBM images sometimes inverted on Windows

[Neil Roberts <bpeeluk@yahoo.co.uk>]

Hi,

I've noticed that when running Emacs under Windows, if you create an
XBM image where the :data keyword is set to a string containing the
actual bits of the bitmap then the foreground and background colours
are swapped. If you use the same image but set the :data keyword to an
XBM image string then the swapping does not occur. The swapping
doesn't occur either way under X. Is this a bug?

Please eval the following code snippet to demonstrate. Under X, both
smilies look the same, but under Windows the bottom smiley is
white-on-black, and the top smiley is black-on-white.

(defconst smiley-data '(#x00 #x00 #x24 #x00 #x00 #x24 #x18 #x00))

(defun smiley-from-xbm-data ()
  ;; Make an XBM image from the smiley data
  (list 'image :type 'xbm :ascent 100 :data
	(concat "#define smiley_width 8\n"
		"#define smiley_height 8\n"
		"static unsigned char smiley_bits[] = {\n"
		"   "
		(mapconcat (lambda (byte) (format "0x%02x" byte))
			   smiley-data ", ")
		" };")))

(defun smiley-from-xbm-bytes ()
  ;; Make an image using the bytes directly in a string
  (list 'image :type 'xbm :ascent 100 :width 8 :height 8
	:data (apply 'string smiley-data)))

(save-excursion
  (set-buffer (get-buffer-create "*Smiley demo*"))
  (erase-buffer)
  (insert "Smiley created from XBM image: "
	  (propertize ":)" 'display (smiley-from-xbm-data)) "\n"
	  "Smiley created from the actual bytes: "
	  (propertize ":)" 'display (smiley-from-xbm-bytes)) "\n")
  (pop-to-buffer (current-buffer)))

Thanks,
- Neil