'twittering-image-type' can find image type without invoking 'file'.

The function tries to find image type with 'image-type-from-data'.
If the try fails, the function invokes 'file' as in the past.

(twittering-image-type): Try to detect image type with
`image-type-from-data' at first.

ChangeLog

@@ -56,6 +56,11 @@
 	* twittering-mode.el (twittering-status-not-blank-p): bug fix:
 	always return nil with strings with trailing newline.
 
+2010-01-08  Tadashi MATSUO  <tad@mymail.twin.jp>
+
+	* twittering-mode.el (twittering-image-type): Try to detect image
+	type with `image-type-from-data' at first.
+
 2010-01-08  Yuto Hayamizu  <y.hayamizu@gmail.com>
 
 	* twittering-mode.el (twittering-tmp-dir): delete

twittering-mode.el

@@ -323,6 +323,7 @@ and its contents(BUFFER)"
 	(cdr type-cache)
       (let ((image-type
 	     (cond
+	      ((image-type-from-data (buffer-string)))
 	      ((executable-find "file")
 	       (with-temp-buffer
 		 (let ((res-buf (current-buffer)))