X-Git-Url: http://git.chise.org/gitweb/?a=blobdiff_plain;ds=sidebyside;f=lisp%2Fmm-decode.el;h=e3578e8a5e388bacb1de08fb92557857ba69dae4;hb=cddb4672a1b8d0b3fb03dd1c5cad4b01f9fab219;hp=7090855ce5e2db6ae92e0289418869ab1903cf29;hpb=d48e99b2da1516da4277df6f6ada793a01b5c81e;p=elisp%2Fgnus.git-

diff --git a/lisp/mm-decode.el b/lisp/mm-decode.el
index 7090855..e3578e8 100644
--- a/lisp/mm-decode.el
+++ b/lisp/mm-decode.el
@@ -1,5 +1,5 @@
 ;;; mm-decode.el --- Functions for decoding MIME things
-;; Copyright (C) 1998 Free Software Foundation, Inc.
+;; Copyright (C) 1998,99 Free Software Foundation, Inc.
 
 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
 ;;	MORIOKA Tomohiko <morioka@jaist.ac.jp>
@@ -25,66 +25,110 @@
 ;;; Code:
 
 (require 'mail-parse)
-(require 'mailcap)
+(require 'gnus-mailcap)
 (require 'mm-bodies)
 
+;;; Convenience macros.
+
+(defmacro mm-handle-buffer (handle)
+  `(nth 0 ,handle))
+(defmacro mm-handle-type (handle)
+  `(nth 1 ,handle))
+(defmacro mm-handle-encoding (handle)
+  `(nth 2 ,handle))
+(defmacro mm-handle-undisplayer (handle)
+  `(nth 3 ,handle))
+(defmacro mm-handle-set-undisplayer (handle function)
+  `(setcar (nthcdr 3 ,handle) ,function))
+(defmacro mm-handle-disposition (handle)
+  `(nth 4 ,handle))
+(defmacro mm-handle-description (handle)
+  `(nth 5 ,handle))
+(defmacro mm-handle-cache (handle)
+  `(nth 6 ,handle))
+(defmacro mm-handle-set-cache (handle contents)
+  `(setcar (nthcdr 6 ,handle) ,contents))
+(defmacro mm-handle-id (handle)
+  `(nth 7 ,handle))
+(defmacro mm-make-handle (&optional buffer type encoding undisplayer
+				    disposition description cache
+				    id)
+  `(list ,buffer ,type ,encoding ,undisplayer
+	 ,disposition ,description ,cache ,id))
+
 (defvar mm-inline-media-tests
-  '(("image/jpeg" mm-inline-image (featurep 'jpeg))
-    ("image/png" mm-inline-image (featurep 'png))
-    ("image/gif" mm-inline-image (featurep 'gif))
-    ("image/tiff" mm-inline-image (featurep 'tiff))
-    ("image/xbm" mm-inline-image (eq (device-type) 'x))
-    ("image/xpm" mm-inline-image (featurep 'xpm))
-    ("image/bmp" mm-inline-image (featurep 'bmp))
+  '(("image/jpeg" mm-inline-image (mm-valid-and-fit-image-p 'jpeg handle))
+    ("image/png" mm-inline-image (mm-valid-and-fit-image-p 'png handle))
+    ("image/gif" mm-inline-image (mm-valid-and-fit-image-p 'gif handle))
+    ("image/tiff" mm-inline-image (mm-valid-and-fit-image-p 'tiff handle)) 
+    ("image/xbm" mm-inline-image (mm-valid-and-fit-image-p 'xbm handle))
+    ("image/x-xbitmap" mm-inline-image (mm-valid-and-fit-image-p 'xbm handle))
+    ("image/xpm" mm-inline-image (mm-valid-and-fit-image-p 'xpm handle))
+    ("image/x-pixmap" mm-inline-image (mm-valid-and-fit-image-p 'xpm handle))
+    ("image/bmp" mm-inline-image (mm-valid-and-fit-image-p 'bmp handle))
     ("text/plain" mm-inline-text t)
     ("text/enriched" mm-inline-text t)
     ("text/richtext" mm-inline-text t)
-    ("text/html" mm-inline-text (featurep 'w3))
+    ("text/html" mm-inline-text (locate-library "w3"))
+    ("text/x-vcard" mm-inline-text (locate-library "vcard"))
+    ("message/delivery-status" mm-inline-text t)
+    ("message/rfc822" mm-inline-message t)
+    ("text/.*" mm-inline-text t)
     ("audio/wav" mm-inline-audio
      (and (or (featurep 'nas-sound) (featurep 'native-sound))
 	  (device-sound-enabled-p)))
     ("audio/au" mm-inline-audio
      (and (or (featurep 'nas-sound) (featurep 'native-sound))
-	  (device-sound-enabled-p))))
+	  (device-sound-enabled-p)))
+    ("multipart/alternative" ignore t)
+    ("multipart/mixed" ignore t)
+    ("multipart/related" ignore t))
   "Alist of media types/test that say whether the media types can be displayed inline.")
 
 (defvar mm-user-display-methods
   '(("image/.*" . inline)
-    ("text/.*" . inline)))
+    ("text/.*" . inline)
+    ("message/delivery-status" . inline)
+    ("message/rfc822" . inline)))
 
 (defvar mm-user-automatic-display
-  '("text/plain" "text/enriched" "text/richtext" "text/html" "image/gif"))
-
-(defvar mm-alternative-precedence
-  '("text/plain" "text/enriched" "text/richtext" "text/html")
-  "List that describes the precedence of alternative parts.")
-
-(defvar mm-tmp-directory "/tmp/"
+  '("text/plain" "text/enriched" "text/richtext" "text/html"
+    "text/x-vcard" "image/.*" "message/delivery-status" "multipart/.*"
+    "message/rfc822"))
+
+(defvar mm-attachment-override-types
+  '("text/plain" "text/x-vcard")
+  "Types that should have \"attachment\" ignored if they can be displayed inline.")
+
+(defvar mm-user-automatic-external-display nil
+  "List of MIME type regexps that will be displayed externally automatically.")
+
+(defvar mm-discouraged-alternatives nil
+  "List of MIME types that are discouraged when viewing multiapart/alternative.
+Viewing agents are supposed to view the last possible part of a message,
+as that is supposed to be the richest.  However, users may prefer other
+types instead, and this list says what types are most unwanted.  If,
+for instance, text/html parts are very unwanted, and text/richtech are
+somewhat unwanted, then the value of this variable should be set
+to:
+
+ (\"text/html\" \"text/richtext\")")
+
+(defvar mm-tmp-directory
+  (cond ((fboundp 'temp-directory) (temp-directory))
+	((boundp 'temporary-file-directory) temporary-file-directory)
+	("/tmp/"))
   "Where mm will store its temporary files.")
 
+(defvar mm-all-images-fit nil
+  "If non-nil, then all images fit in the buffer.")
+
 ;;; Internal variables.
 
 (defvar mm-dissection-list nil)
 (defvar mm-last-shell-command "")
 (defvar mm-content-id-alist nil)
 
-;;; Convenience macros.
-
-(defmacro mm-handle-buffer (handle)
-  `(nth 0 ,handle))
-(defmacro mm-handle-type (handle)
-  `(nth 1 ,handle))
-(defmacro mm-handle-encoding (handle)
-  `(nth 2 ,handle))
-(defmacro mm-handle-undisplayer (handle)
-  `(nth 3 ,handle))
-(defmacro mm-handle-set-undisplayer (handle function)
-  `(setcar (nthcdr 3 ,handle) ,function))
-(defmacro mm-handle-disposition (handle)
-  `(nth 4 ,handle))
-(defmacro mm-handle-description (handle)
-  `(nth 5 ,handle))
-
 ;;; The functions.
 
 (defun mm-dissect-buffer (&optional no-strict-mime)
@@ -93,17 +137,20 @@
     (let (ct ctl type subtype cte cd description id result)
       (save-restriction
 	(mail-narrow-to-head)
-	(when (and (or no-strict-mime
-		       (mail-fetch-field "mime-version"))
-		   (setq ct (mail-fetch-field "content-type")))
-	  (setq ctl (condition-case () (mail-header-parse-content-type ct)
-		      (error nil))
+	(when (or no-strict-mime
+		  (mail-fetch-field "mime-version"))
+	  (setq ct (mail-fetch-field "content-type")
+		ctl (ignore-errors (mail-header-parse-content-type ct))
 		cte (mail-fetch-field "content-transfer-encoding")
 		cd (mail-fetch-field "content-disposition")
 		description (mail-fetch-field "content-description")
 		id (mail-fetch-field "content-id"))))
-      (if (not ctl)
-	  (mm-dissect-singlepart '("text/plain") nil no-strict-mime nil nil)
+      (if (or (not ctl)
+	      (not (string-match "/" (car ctl))))
+	  (mm-dissect-singlepart
+	   '("text/plain") nil no-strict-mime
+	   (and cd (ignore-errors (mail-header-parse-content-disposition cd)))
+	   description)
 	(setq type (split-string (car ctl) "/"))
 	(setq subtype (cadr type)
 	      type (pop type))
@@ -111,7 +158,7 @@
 	 result
 	 (cond
 	  ((equal type "multipart")
-	   (mm-dissect-multipart ctl))
+	   (cons (car ctl) (mm-dissect-multipart ctl)))
 	  (t
 	   (mm-dissect-singlepart
 	    ctl
@@ -119,17 +166,19 @@
 					(mail-header-remove-comments
 					 cte)))))
 	    no-strict-mime
-	    (and cd (condition-case ()
-			(mail-header-parse-content-disposition cd)
-		      (error nil)))))))
+	    (and cd (ignore-errors (mail-header-parse-content-disposition cd)))
+	    description id))))
 	(when id
+	  (when (string-match " *<\\(.*\\)> *" id)
+	    (setq id (match-string 1 id)))
 	  (push (cons id result) mm-content-id-alist))
 	result))))
 
-(defun mm-dissect-singlepart (ctl cte &optional force cdl description)
+(defun mm-dissect-singlepart (ctl cte &optional force cdl description id)
   (when (or force
 	    (not (equal "text/plain" (car ctl))))
-    (let ((res (list (list (mm-copy-to-buffer) ctl cte nil cdl description))))
+    (let ((res (mm-make-handle
+		(mm-copy-to-buffer) ctl cte nil cdl description nil id)))
       (push (car res) mm-dissection-list)
       res)))
 
@@ -142,9 +191,9 @@
 (defun mm-dissect-multipart (ctl)
   (goto-char (point-min))
   (let* ((boundary (concat "\n--" (mail-content-type-get ctl 'boundary)))
-	(close-delimiter (concat boundary "--[ \t]*$"))
-	start parts 
-	(end (save-excursion	
+	(close-delimiter (concat (regexp-quote boundary) "--[ \t]*$"))
+	start parts
+	(end (save-excursion
 	       (goto-char (point-max))
 	       (if (re-search-backward close-delimiter nil t)
 		   (match-beginning 0)
@@ -155,14 +204,14 @@
 	(save-excursion
 	  (save-restriction
 	    (narrow-to-region start (point))
-	    (setq parts (nconc (mm-dissect-buffer t) parts)))))
+	    (setq parts (nconc (list (mm-dissect-buffer t)) parts)))))
       (forward-line 2)
       (setq start (point)))
     (when start
       (save-excursion
 	(save-restriction
 	  (narrow-to-region start end)
-	  (setq parts (nconc (mm-dissect-buffer t) parts)))))
+	  (setq parts (nconc (list (mm-dissect-buffer t)) parts)))))
     (nreverse parts)))
 
 (defun mm-copy-to-buffer ()
@@ -171,17 +220,23 @@
     (let ((obuf (current-buffer))
 	  beg)
       (goto-char (point-min))
-      (search-forward "\n\n" nil t)
+      (search-forward-regexp "^\n" nil t)
       (setq beg (point))
       (set-buffer (generate-new-buffer " *mm*"))
       (insert-buffer-substring obuf beg)
       (current-buffer))))
 
+(defun mm-inlinable-part-p (type)
+  "Say whether TYPE can be displayed inline."
+  (eq (mm-user-method type) 'inline))
+
 (defun mm-display-part (handle &optional no-default)
-  "Display the MIME part represented by HANDLE."
+  "Display the MIME part represented by HANDLE.
+Returns nil if the part is removed; inline if displayed inline;
+external if displayed external."
   (save-excursion
     (mailcap-parse-mailcaps)
-    (if (mm-handle-undisplayer handle)
+    (if (mm-handle-displayed-p handle)
 	(mm-remove-part handle)
       (let* ((type (car (mm-handle-type handle)))
 	     (method (mailcap-mime-info type))
@@ -189,56 +244,123 @@
 	(if (eq user-method 'inline)
 	    (progn
 	      (forward-line 1)
-	      (mm-display-inline handle))
+	      (mm-display-inline handle)
+	      'inline)
 	  (when (or user-method
 		    method
 		    (not no-default))
-	    (mm-display-external
-	     handle (or user-method method 'mailcap-save-binary-file))))))))
+	    (if (and (not user-method)
+		     (not method)
+		     (equal "text" (car (split-string type))))
+		(progn
+		  (forward-line 1)
+		  (mm-insert-inline handle (mm-get-part handle))
+		  'inline)
+	      (mm-display-external
+	       handle (or user-method method
+			  'mailcap-save-binary-file))
+	      'external)))))))
 
 (defun mm-display-external (handle method)
   "Display HANDLE using METHOD."
   (mm-with-unibyte-buffer
-    (insert-buffer-substring (mm-handle-buffer handle))
-    (mm-decode-content-transfer-encoding (mm-handle-encoding handle))
     (if (functionp method)
 	(let ((cur (current-buffer)))
-	  (switch-to-buffer (generate-new-buffer "*mm*"))
+	  (if (eq method 'mailcap-save-binary-file)
+	      (progn
+		(set-buffer (generate-new-buffer "*mm*"))
+		(setq method nil))
+	    (mm-insert-part handle)
+	    (let ((win (get-buffer-window cur t)))
+	      (when win
+		(select-window win)))
+	    (switch-to-buffer (generate-new-buffer "*mm*")))
 	  (buffer-disable-undo)
-	  (mm-set-buffer-file-coding-system 'no-conversion)
+	  (mm-set-buffer-file-coding-system mm-binary-coding-system)
 	  (insert-buffer-substring cur)
-	  (funcall method)
-	  (mm-handle-set-undisplayer handle (current-buffer)))
+	  (message "Viewing with %s" method)
+	  (let ((mm (current-buffer))
+		(non-viewer (assoc "non-viewer"
+				   (mailcap-mime-info
+				    (car (mm-handle-type handle)) t))))
+	    (unwind-protect
+		(if method
+		    (funcall method)
+		  (mm-save-part handle))
+	      (when (and (not non-viewer)
+			 method)
+		(mm-handle-set-undisplayer handle mm)))))
+      ;; The function is a string to be executed.
+      (mm-insert-part handle)
       (let* ((dir (make-temp-name (expand-file-name "emm." mm-tmp-directory)))
 	     (filename (mail-content-type-get
 			(mm-handle-disposition handle) 'filename))
 	     (needsterm (assoc "needsterm"
 			       (mailcap-mime-info
 				(car (mm-handle-type handle)) t)))
-	     process file)
+	     process file buffer)
 	;; We create a private sub-directory where we store our files.
 	(make-directory dir)
 	(set-file-modes dir 448)
 	(if filename
-	    (setq file (expand-file-name (or filename "mm.") dir))
+	    (setq file (expand-file-name (file-name-nondirectory filename)
+					 dir))
 	  (setq file (make-temp-name (expand-file-name "mm." dir))))
-	(write-region (point-min) (point-max)
-		      file nil 'nomesg nil 'no-conversion)
-	(setq process
-	      (if needsterm
-		  (start-process "*display*" nil
-				 "xterm"
-				 "-e" (format method file))
-		(start-process "*display*" (generate-new-buffer "*mm*")
-			       shell-file-name
-			       "-c" (format method file))))
-	(mm-handle-set-undisplayer handle (cons file process))
+	(write-region (point-min) (point-max) file nil 'nomesg)
+	(message "Viewing with %s" method)
+	(unwind-protect
+	    (setq process
+		  (if needsterm
+		      (start-process "*display*" nil
+				     "xterm"
+				     "-e" shell-file-name "-c"
+				     (format method
+					     (mm-quote-arg file)))
+		    (start-process "*display*"
+				   (setq buffer (generate-new-buffer "*mm*"))
+				   shell-file-name
+				   "-c" (format method
+						(mm-quote-arg file)))))
+	  (mm-handle-set-undisplayer handle (cons file buffer)))
 	(message "Displaying %s..." (format method file))))))
 
+(defun mm-remove-parts (handles)
+  "Remove the displayed MIME parts represented by HANDLE."
+  (if (and (listp handles)
+	   (bufferp (car handles)))
+      (mm-remove-part handles)
+    (let (handle)
+      (while (setq handle (pop handles))
+	(cond
+	 ((stringp handle)
+	  )
+	 ((and (listp handle)
+	       (stringp (car handle)))
+	  (mm-remove-parts (cdr handle)))
+	 (t
+	  (mm-remove-part handle)))))))
+
+(defun mm-destroy-parts (handles)
+  "Remove the displayed MIME parts represented by HANDLE."
+  (if (and (listp handles)
+	   (bufferp (car handles)))
+      (mm-destroy-part handles)
+    (let (handle)
+      (while (setq handle (pop handles))
+	(cond
+	 ((stringp handle)
+	  )
+	 ((and (listp handle)
+	       (stringp (car handle)))
+	  (mm-destroy-parts (cdr handle)))
+	 (t
+	  (mm-destroy-part handle)))))))
+
 (defun mm-remove-part (handle)
   "Remove the displayed MIME part represented by HANDLE."
-  (let ((object (mm-handle-undisplayer handle)))
-    (condition-case ()
+  (when (listp handle)
+    (let ((object (mm-handle-undisplayer handle)))
+      (ignore-errors
 	(cond
 	 ;; Internally displayed part.
 	 ((mm-annotationp object)
@@ -249,25 +371,19 @@
 	  (funcall object))
 	 ;; Externally displayed part.
 	 ((consp object)
-	  (condition-case ()
-	      (delete-file (car object))
-	    (error nil))
-	  (condition-case ()
-	      (delete-directory (file-name-directory (car object)))
-	    (error nil))
-	  (condition-case ()
-	      (kill-process (cdr object))
-	    (error nil)))
+	  (ignore-errors (delete-file (car object)))
+	  (ignore-errors (delete-directory (file-name-directory (car object))))
+	  (ignore-errors (kill-buffer (cdr object))))
 	 ((bufferp object)
 	  (when (buffer-live-p object)
-	    (kill-buffer object))))
-      (error nil))
-    (mm-handle-set-undisplayer handle nil)))
+	    (kill-buffer object)))))
+      (mm-handle-set-undisplayer handle nil))))
 
 (defun mm-display-inline (handle)
   (let* ((type (car (mm-handle-type handle)))
 	 (function (cadr (assoc type mm-inline-media-tests))))
-    (funcall function handle)))
+    (funcall function handle)
+    (goto-char (point-min))))
 
 (defun mm-inlinable-p (type)
   "Say whether TYPE can be displayed inline."
@@ -298,6 +414,27 @@
   (let ((methods mm-user-automatic-display)
 	method result)
     (while (setq method (pop methods))
+      (when (and (string-match method type)
+		 (mm-inlinable-p type))
+	(setq result t
+	      methods nil)))
+    result))
+
+(defun mm-attachment-override-p (type)
+  "Say whether TYPE should have attachment behavior overridden."
+  (let ((types mm-attachment-override-types)
+	ty)
+    (catch 'found
+      (while (setq ty (pop types))
+	(when (and (string-match ty type)
+		   (mm-inlinable-p type))
+	  (throw 'found t))))))
+
+(defun mm-automatic-external-display-p (type)
+  "Return the user-defined method for TYPE."
+  (let ((methods mm-user-automatic-external-display)
+	method result)
+    (while (setq method (pop methods))
       (when (string-match method type)
 	(setq result t
 	      methods nil)))
@@ -310,15 +447,20 @@ This overrides entries in the mailcap file."
 
 (defun mm-destroy-part (handle)
   "Destroy the data structures connected to HANDLE."
-  (mm-remove-part handle)
-  (when (buffer-live-p (mm-handle-buffer handle))
-    (kill-buffer (mm-handle-buffer handle))))
+  (when (listp handle)
+    (mm-remove-part handle)
+    (when (buffer-live-p (mm-handle-buffer handle))
+      (kill-buffer (mm-handle-buffer handle)))))
+
+(defun mm-handle-displayed-p (handle)
+  "Say whether HANDLE is displayed or not."
+  (mm-handle-undisplayer handle))
 
 (defun mm-quote-arg (arg)
   "Return a version of ARG that is safe to evaluate in a shell."
   (let ((pos 0) new-pos accum)
     ;; *** bug: we don't handle newline characters properly
-    (while (setq new-pos (string-match "[!`\"$\\& \t{}]" arg pos))
+    (while (setq new-pos (string-match "[;!'`\"$\\& \t{} |()<>]" arg pos))
       (push (substring arg pos new-pos) accum)
       (push "\\" accum)
       (push (list (aref arg new-pos)) accum)
@@ -334,10 +476,32 @@ This overrides entries in the mailcap file."
 (defun mm-get-part (handle)
   "Return the contents of HANDLE as a string."
   (mm-with-unibyte-buffer
-    (insert-buffer-substring (mm-handle-buffer handle))
-    (mm-decode-content-transfer-encoding (mm-handle-encoding handle))
+    (mm-insert-part handle)
     (buffer-string)))
 
+(defun mm-insert-part (handle)
+  "Insert the contents of HANDLE in the current buffer."
+  (let ((cur (current-buffer)))
+    (save-excursion
+      (if (member (car (split-string (car (mm-handle-type handle)) "/"))
+		  '("text" "message"))
+	  (with-temp-buffer
+	    (insert-buffer-substring (mm-handle-buffer handle))
+	    (mm-decode-content-transfer-encoding
+	     (mm-handle-encoding handle)
+	     (car (mm-handle-type handle)))
+	    (let ((temp (current-buffer)))
+	      (set-buffer cur)
+	      (insert-buffer-substring temp)))
+	(mm-with-unibyte-buffer
+	  (insert-buffer-substring (mm-handle-buffer handle))
+	  (mm-decode-content-transfer-encoding
+	   (mm-handle-encoding handle)
+	   (car (mm-handle-type handle)))
+	  (let ((temp (current-buffer)))
+	    (set-buffer cur)
+	    (insert-buffer-substring temp)))))))
+
 (defvar mm-default-directory nil)
 
 (defun mm-save-part (handle)
@@ -355,12 +519,27 @@ This overrides entries in the mailcap file."
 			   (or mm-default-directory default-directory))))
     (setq mm-default-directory (file-name-directory file))
     (mm-with-unibyte-buffer
-      (insert-buffer-substring (mm-handle-buffer handle))
-      (mm-decode-content-transfer-encoding (mm-handle-encoding handle))
+      (mm-insert-part handle)
       (when (or (not (file-exists-p file))
 		(yes-or-no-p (format "File %s already exists; overwrite? "
 				     file)))
-	(write-region (point-min) (point-max) file)))))
+	;; Now every coding system is 100% binary within mm-with-unibyte-buffer
+	;; Is text still special?
+	(let ((coding-system-for-write
+	       (if (equal "text" (car (split-string
+				       (car (mm-handle-type handle)) "/")))
+		   buffer-file-coding-system
+		 'binary))
+	      ;; Don't re-compress .gz & al.  Arguably we should make
+	      ;; `file-name-handler-alist' nil, but that would chop
+	      ;; ange-ftp which it's reasonable to use here.
+	      (inhibit-file-name-operation 'write-region)
+	      (inhibit-file-name-handlers
+	       (if (equal (car (mm-handle-type handle))
+			  "application/octet-stream")
+		   (cons 'jka-compr-handler inhibit-file-name-handlers)
+		 inhibit-file-name-handlers)))
+	  (write-region (point-min) (point-max) file))))))
 
 (defun mm-pipe-part (handle)
   "Pipe HANDLE to a process."
@@ -368,8 +547,7 @@ This overrides entries in the mailcap file."
 	 (command
 	  (read-string "Shell command on MIME part: " mm-last-shell-command)))
     (mm-with-unibyte-buffer
-      (insert-buffer-substring (mm-handle-buffer handle))
-      (mm-decode-content-transfer-encoding (mm-handle-encoding handle))
+      (mm-insert-part handle)
       (shell-command-on-region (point-min) (point-max) command nil))))
 
 (defun mm-interactively-view-part (handle)
@@ -383,15 +561,21 @@ This overrides entries in the mailcap file."
 
 (defun mm-preferred-alternative (handles &optional preferred)
   "Say which of HANDLES are preferred."
-  (let ((prec (if preferred (list preferred) mm-alternative-precedence))
-	p h result type)
+  (let ((prec (if preferred (list preferred)
+		(mm-preferred-alternative-precedence handles)))
+	p h result type handle)
     (while (setq p (pop prec))
       (setq h handles)
       (while h
-	(setq type (car (mm-handle-type (car h))))
+	(setq type
+	      (if (stringp (caar h))
+		  (caar h)
+		(car (mm-handle-type (car h)))))
+	(setq handle (car h))
 	(when (and (equal p type)
 		   (mm-automatic-display-p type)
-		   (or (not (mm-handle-disposition (car h)))
+		   (or (stringp (caar h))
+		       (not (mm-handle-disposition (car h)))
 		       (equal (car (mm-handle-disposition (car h)))
 			      "inline")))
 	  (setq result (car h)
@@ -400,10 +584,76 @@ This overrides entries in the mailcap file."
 	(pop h)))
     result))
 
+(defun mm-preferred-alternative-precedence (handles)
+  "Return the precedence based on HANDLES and mm-discouraged-alternatives."
+  (let ((seq (mapcar (lambda (h) (car (mm-handle-type h))) handles)))
+    (dolist (disc (reverse mm-discouraged-alternatives))
+      (dolist (elem (copy-sequence seq))
+	(when (string-match disc elem)
+	  (setq seq (nconc (delete elem seq) (list elem))))))
+    seq))
+
 (defun mm-get-content-id (id)
   "Return the handle(s) referred to by ID."
   (cdr (assoc id mm-content-id-alist)))
 
+(defun mm-get-image (handle)
+  "Return an image instance based on HANDLE."
+  (let ((type (cadr (split-string (car (mm-handle-type handle)) "/")))
+	spec)
+    ;; Allow some common translations.
+    (setq type
+	  (cond
+	   ((equal type "x-pixmap")
+	    "xpm")
+	   ((equal type "x-xbitmap")
+	    "xbm")
+	   (t type)))
+    (or (mm-handle-cache handle)
+	(mm-with-unibyte-buffer
+	  (mm-insert-part handle)
+	  (prog1
+	      (setq spec
+		    (ignore-errors
+		      (cond
+		       ((equal type "xbm")
+			;; xbm images require special handling, since
+			;; the only way to create glyphs from these
+			;; (without a ton of work) is to write them
+			;; out to a file, and then create a file
+			;; specifier.
+			(let ((file (make-temp-name
+				     (expand-file-name "emm.xbm"
+						       mm-tmp-directory))))
+			  (unwind-protect
+			      (progn
+				(write-region (point-min) (point-max) file)
+				(make-glyph (list (cons 'x file))))
+			    (ignore-errors
+			      (delete-file file)))))
+		       (t
+			(make-glyph
+			 (vector (intern type) :data (buffer-string)))))))
+	    (mm-handle-set-cache handle spec))))))
+
+(defun mm-image-fit-p (handle)
+  "Say whether the image in HANDLE will fit the current window."
+  (let ((image (mm-get-image handle)))
+    (or mm-all-images-fit
+	(and (< (glyph-width image) (window-pixel-width))
+	     (< (glyph-height image) (window-pixel-height))))))
+
+(defun mm-valid-image-format-p (format)
+  "Say whether FORMAT can be displayed natively by Emacs."
+  (and (fboundp 'valid-image-instantiator-format-p)
+       (valid-image-instantiator-format-p format)))
+
+(defun mm-valid-and-fit-image-p (format handle)
+  "Say whether FORMAT can be displayed natively and HANDLE fits the window."
+  (and window-system
+       (mm-valid-image-format-p format)
+       (mm-image-fit-p handle)))
+
 (provide 'mm-decode)
 
 ;; mm-decode.el ends here