From: Mark Walters <markwalters1009@gmail.com>
To: Austin Clements <amdragon@MIT.EDU>
Subject: Re: [PATCH 1/1] Make buttons for attachments allow viewing as well as
	saving
In-Reply-To: <20120117210158.GS16740@mit.edu>
References: <1326629796-11436-1-git-send-email-markwalters1009@gmail.com>
	<1326629796-11436-2-git-send-email-markwalters1009@gmail.com>
	<87wr8r5trv.fsf@servo.finestructure.net>
	<87lip7fhkc.fsf@qmul.ac.uk> <20120117022330.GE16740@mit.edu>
	<8739beitq4.fsf@qmul.ac.uk> <20120117202603.GP16740@mit.edu>
	<871uqy3vy4.fsf@qmul.ac.uk> <20120117210158.GS16740@mit.edu>
User-Agent: Notmuch/0.11~rc2+73~g1ea2b60 (http://notmuchmail.org) Emacs/23.2.1
	(i486-pc-linux-gnu)
Date: Tue, 17 Jan 2012 22:27:51 +0000
Message-ID: <87obu2q80o.fsf@qmul.ac.uk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: notmuch@notmuchmail.org
Precedence: list


> In general, yes, I think so.  A few comments on your draft below.

Ok I include a newer version which I am fairly happy with but I do have
some queries.

> > +(defvar notmuch-show-part-button-map
> > +  (let ((map (make-sparse-keymap)))
> > +       (set-keymap-parent map button-map)
> > +       (define-key map "s" 'notmuch-show-part-button-save)
> > +       (define-key map "v" 'notmuch-show-part-button-view)
> > +       (define-key map "o" 'notmuch-show-part-button-interactively-view)
> > +    map)
> > +  "Submap for button commands")
> > +(fset 'notmuch-show-part-button-map notmuch-show-part-button-map)
> 
> I don't think this fset is necessary.  Actually, I've never seen this
> outside of the notmuch code.  It looks like it does appear in code
> shipped with Emacs, but only in a handful of places.  All of those
> places look like very old code, so maybe this was necessary once upon
> a time?

I have no idea on this: at the moment I have left it in as fset for
keymaps seems to occur throughout notmuch (I have the fset because I
copied it from somewhere).

> (defmacro notmuch-with-temp-part-buffer (message-id nth &rest body)
>   (declare (indent 2))
>   (let ((process-crypto (make-symbol "process-crypto")))
>     `(let ((,process-crypto notmuch-show-process-crypto))
>        (with-temp-buffer
>          (setq notmuch-show-process-crypto ,process-crypto)
>          ;; Always acquires the part via `notmuch part', even if it is
>          ;; available in the JSON output.
>          (insert (notmuch-show-get-bodypart-internal message-id nth))
>          ,@body))))

I have followed the macro approach: since notmuch-show-save-part also
uses it (which doesn't appear in the diff as it was unchanged). I have
made all three functions use notmuch-with-temp-part-buffer. However, I
used the macro exactly as you wrote it (and it seems to work) but I
moderately understand why but could not justify it to someone! 

> (defun notmuch-show-interactively-view-part (message-id nth content-type)
>   (notmuch-with-temp-part-buffer message-id nth
>     (let ((handle (mm-make-handle (current-buffer) (list content-type))))
>       (mm-interactively-view-part handle)))))

Emacs wants to indent the (let line level with message-id in the line
above which looks odd (and makes the lines too long). Do I overrule
emacs, or put message-id and nth onto a separate line or is there
something better?

Also note that, because of the unification with notmuch-show-save-part
all three functions have to have the four arguments message-id, nth,
filename and content-type (even though currently each individual
function only uses three of them). However see below for another comment
on this.

> > +(defcustom notmuch-show-part-button-default-action 'notmuch-show-part-button-save
> > +  "Default part header button action (on ENTER or mouse click)."
> > +  :group 'notmuch
> > +  :type '(choice (const :tag "Save part"
> > +			notmuch-show-part-button-save)
> > +		 (const :tag "View part"
> > +			notmuch-show-part-button-view)
> > +		 (const :tag "View interactively"
> > +			notmuch-show-part-button-interactively-view)))
> 
> You probably want this to be the handler function, rather than the
> button function, since the interface to the button function is rather
> awkward.  That is, if someone wanted to plug in their own action, they
> would want to define it in terms of the high-level handler interface
> that you use above, rather than the low-level
> button-with-magic-properties interface that Emacs forces you to use
> below.

I have done this.

> This duplication is much worse, but also less necessary.
> 
> (defun notmuch-show-part-button-interactively-view (&optional button)
>   (interactive)
>   (notmuch-show-part-button-internal button #'notmuch-show-interactively-view-part))
> 
> (defun notmuch-show-part-button-internal (button handler)
>   (let ((button (or button (button-at (point)))))
>     (if button
> 	(let ((nth (button-get button :notmuch-part)))
> 	  (if nth
> 	      (funcall handler (notmuch-show-get-message-id) nth
> 			       (button-get button :notmuch-content-type))
> 	    (message "Not a valid part (is it a fake part?)."))))))

Yes this is much nicer and I have done this too (modulo the extra
argument mentioned above).

Finally, I have discovered one bug/misfeature. If you try to "view" an
attachment then it will offer to save it but will not offer a
filename. If you try and save it (or use the default action) it will
offer a filename as now. As far as I can see this is not fixable if I
use mm-display-part: however, I could include a slight tweaked version,
notmuch-show-mm-display-part say, which would fix this corner
case. (Essentially, it would call notmuch-show-save-part if it failed to
find a handler rather than mailcap-save-binary-file.) However, this is
about 50 lines of lisp so I am not sure it is worth it.

Best wishes

Mark

>From bda4bb7637fb7d09c50f95b6b76fd42a377e0dde Mon Sep 17 00:00:00 2001
From: Mark Walters <markwalters1009@gmail.com>
Date: Sat, 14 Jan 2012 18:04:22 +0000
Subject: [PATCH] Make buttons for attachments allow viewing as well as saving

Define a keymap for attachment buttons to allow multiple actions.
Define 3 possible actions:
    save attachment: exactly as currently,
    view attachment: uses mailcap entry,
    view attachment with user chosen program

Keymap on a button is: s for save, v for view and o for view with
other program. Default (i.e. enter or mouse button) is save but this
is configurable in notmuch customize.

One implementation detail: the view attachment function forces all
attachments to be "displayed" using mailcap even if emacs could
display them itself. Thus, for example, text/html appears in a browser
and text/plain asks whether to save (on a standard debian setup)
---
 emacs/notmuch-show.el |  105 +++++++++++++++++++++++++++++++++++++-----------
 1 files changed, 81 insertions(+), 24 deletions(-)

diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
index 03c1f6b..2e4fecd 100644
--- a/emacs/notmuch-show.el
+++ b/emacs/notmuch-show.el
@@ -281,10 +281,21 @@ message at DEPTH in the current thread."
 	(run-hooks 'notmuch-show-markup-headers-hook)))))
 
 (define-button-type 'notmuch-show-part-button-type
-  'action 'notmuch-show-part-button-action
+  'action 'notmuch-show-part-button-default
+  'keymap 'notmuch-show-part-button-map
   'follow-link t
   'face 'message-mml)
 
+(defvar notmuch-show-part-button-map
+  (let ((map (make-sparse-keymap)))
+       (set-keymap-parent map button-map)
+       (define-key map "s" 'notmuch-show-part-button-save)
+       (define-key map "v" 'notmuch-show-part-button-view)
+       (define-key map "o" 'notmuch-show-part-button-interactively-view)
+    map)
+  "Submap for button commands")
+(fset 'notmuch-show-part-button-map notmuch-show-part-button-map)
+
 (defun notmuch-show-insert-part-header (nth content-type declared-type &optional name comment)
   (let ((button))
     (setq button
@@ -299,29 +310,48 @@ message at DEPTH in the current thread."
 		   " ]")
 	   :type 'notmuch-show-part-button-type
 	   :notmuch-part nth
-	   :notmuch-filename name))
+	   :notmuch-filename name
+	   :notmuch-content-type content-type))
     (insert "\n")
     ;; return button
     button))
 
 ;; Functions handling particular MIME parts.
 
-(defun notmuch-show-save-part (message-id nth &optional filename)
-  (let ((process-crypto notmuch-show-process-crypto))
-    (with-temp-buffer
-      (setq notmuch-show-process-crypto process-crypto)
-      ;; Always acquires the part via `notmuch part', even if it is
-      ;; available in the JSON output.
-      (insert (notmuch-show-get-bodypart-internal message-id nth))
-      (let ((file (read-file-name
-		   "Filename to save as: "
-		   (or mailcap-download-directory "~/")
-		   nil nil
-		   filename)))
-	;; Don't re-compress .gz & al.  Arguably we should make
-	;; `file-name-handler-alist' nil, but that would chop
-	;; ange-ftp, which is reasonable to use here.
-	(mm-write-region (point-min) (point-max) file nil nil nil 'no-conversion t)))))
+(defmacro notmuch-with-temp-part-buffer (message-id nth &rest body)
+  (declare (indent 2))
+  (let ((process-crypto (make-symbol "process-crypto")))
+    `(let ((,process-crypto notmuch-show-process-crypto))
+       (with-temp-buffer
+	 (setq notmuch-show-process-crypto ,process-crypto)
+	 ;; Always acquires the part via `notmuch part', even if it is
+	 ;; available in the JSON output.
+	 (insert (notmuch-show-get-bodypart-internal message-id nth))
+	 ,@body))))
+
+(defun notmuch-show-save-part (message-id nth &optional filename content-type)
+  (notmuch-with-temp-part-buffer message-id nth
+     (let ((file (read-file-name
+		  "Filename to save as: "
+		  (or mailcap-download-directory "~/")
+		  nil nil
+		  filename)))
+       ;; Don't re-compress .gz & al.  Arguably we should make
+       ;; `file-name-handler-alist' nil, but that would chop
+       ;; ange-ftp, which is reasonable to use here.
+       (mm-write-region (point-min) (point-max) file nil nil nil 'no-conversion t))))
+
+(defun notmuch-show-view-part (message-id nth &optional filename content-type )
+  (notmuch-with-temp-part-buffer message-id nth
+   ;; set mm-inlined-types to nil to force an external viewer
+    (let ((handle (mm-make-handle (current-buffer) (list content-type)))
+	  (mm-inlined-types nil))
+      (mm-display-part handle t))))
+
+(defun notmuch-show-interactively-view-part (message-id nth &optional filename content-type)
+  (notmuch-with-temp-part-buffer message-id nth
+   (let ((handle (mm-make-handle (current-buffer) (list content-type))))
+     (mm-interactively-view-part handle))))
 
 (defun notmuch-show-mm-display-part-inline (msg part nth content-type)
   "Use the mm-decode/mm-view functions to display a part in the
@@ -1502,13 +1532,40 @@ buffer."
 
 ;; Commands typically bound to buttons.
 
-(defun notmuch-show-part-button-action (button)
-  (let ((nth (button-get button :notmuch-part)))
-    (if nth
-	(notmuch-show-save-part (notmuch-show-get-message-id) nth
-				(button-get button :notmuch-filename))
-      (message "Not a valid part (is it a fake part?)."))))
+(defcustom notmuch-show-part-button-default-action 'notmuch-show-save-part
+  "Default part header button action (on ENTER or mouse click)."
+  :group 'notmuch
+  :type '(choice (const :tag "Save part"
+			notmuch-show-save-part)
+		 (const :tag "View part"
+			notmuch-show-view-part)
+		 (const :tag "View interactively"
+			notmuch-show-interactively-view-part)))
+
+(defun notmuch-show-part-button-default (&optional button)
+  (interactive)
+  (notmuch-show-part-button-internal button notmuch-show-part-button-default-action))
 
+(defun notmuch-show-part-button-save (&optional button)
+  (interactive)
+  (notmuch-show-part-button-internal button #'notmuch-show-save-part))
+
+(defun notmuch-show-part-button-view (&optional button)
+  (interactive)
+  (notmuch-show-part-button-internal button #'notmuch-show-view-part))
+
+(defun notmuch-show-part-button-interactively-view (&optional button)
+  (interactive)
+  (notmuch-show-part-button-internal button #'notmuch-show-interactively-view-part))
+
+(defun notmuch-show-part-button-internal (button handler)
+  (let ((button (or button (button-at (point)))))
+    (if button
+	(let ((nth (button-get button :notmuch-part)))
+	  (if nth
+	      (funcall handler (notmuch-show-get-message-id) nth
+		       (button-get button :notmuch-filename)
+		       (button-get button :notmuch-content-type)))))))
 ;;
 
 (provide 'notmuch-show)
-- 
1.7.2.3