Image autodetection

Image autodetection

[Chong Yidong]

I have tried to digest the long and confusing thread on this subject.
I propose the following:

1. Make a new variable, auto-detect-image-type-p.  If non-nil, the
   function image-type-auto-detected-p (called from magic-mode-alist)
   performs content detection.  The default is nil.

2. Do not display images as images automatically in image-mode.
   Instead, the user sees "Type C-c C-c to view the image as an
   image".  This additional step should not be a major inconvenience.

The other changes proposed in that thread, such as using
image-minor-mode by default, are probably unnecessary.

Re: Image autodetection

[Juanma Barranquero]

On 1/29/07, Chong Yidong <cyd@stupidchicken.com> wrote:

> The other changes proposed in that thread, such as using
> image-minor-mode by default, are probably unnecessary.

The only advantage of the image-minor-mode method is that users would
receive a security warning when they first run image-toggle-display
(because it would be disabled).

But at this moment, I think any of the proposed fixes is good, as long
as we adopt one and can go forward with the release.

                    /L/e/k/t/u

Re: Image autodetection

[Jason Rumney]

Juanma Barranquero wrote:
> The only advantage of the image-minor-mode method is that users would
> receive a security warning when they first run image-toggle-display
> (because it would be disabled).

There's no reason that image-mode could not do the same.

Re: Image autodetection

[Juanma Barranquero]

On 1/30/07, Jason Rumney <jasonr@gnu.org> wrote:

> There's no reason that image-mode could not do the same.

You're right.

With image-mode, image-minor-mode, image-mode-maybe,
image-type-auto-detected-p, image-type-auto-detectable,
image-type-file-name-regexps, image-type-header-regexps,
image-file-name-extensions, image-file-name-regexps,
etc. we already have too much confusion regarding how and when to set
image-mode; so I like Richard's idea of bypassing #1 of Chong's
proposals (no more options, please!) and just implementing #2 (with
image-toggle-display disabled, as you note).

Either that, or we start scrapping all the above and rethink all this
stuff... which I think would be great, were not for the pretest.
(Though, to be honest, the "confusion" stems from the fact that we
started to teach Emacs to better auto-detect images, and then had to
switch tracks when the security issues came up, so we've finished
conflating two very different issues.)

                    /L/e/k/t/u

Re: Image autodetection

[Juanma Barranquero]

On 1/30/07, Juanma Barranquero <lekktu@gmail.com> wrote:

> so I like Richard's idea of bypassing #1 of Chong's
> proposals (no more options, please!) and just implementing #2 (with
> image-toggle-display disabled, as you note).

Something like the attached patch, which couldn't be simpler.

                    /L/e/k/t/u


Index: lisp/image-mode.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/image-mode.el,v
retrieving revision 1.16
diff -u -2 -r1.16 image-mode.el
--- lisp/image-mode.el	21 Jan 2007 03:53:11 -0000	1.16
+++ lisp/image-mode.el	30 Jan 2007 12:03:44 -0000
@@ -61,10 +61,5 @@
   (use-local-map image-mode-map)
   (add-hook 'change-major-mode-hook 'image-toggle-display-text nil t)
-  (if (and (display-images-p)
-	   (not (get-text-property (point-min) 'display)))
-      (image-toggle-display)
-    ;; Set next vars when image is already displayed but local
-    ;; variables were cleared by kill-all-local-variables
-    (setq cursor-type nil truncate-lines t))
+  (setq cursor-type nil truncate-lines t)
   (run-mode-hooks 'image-mode-hook)
   (if (display-images-p)
@@ -180,4 +175,10 @@
 	  (message "Repeat this command to go back to displaying the file as
text")))))

+(put 'image-toggle-display 'disabled "\
+
+WARNING: Displaying images can be a security risk.
+Please make sure you're using up-to-date image libraries
+and the images displayed come from a trusted source.")
+
 (provide 'image-mode)

Re: Image autodetection

[Stefan Monnier]

>> The other changes proposed in that thread, such as using
>> image-minor-mode by default, are probably unnecessary.

> The only advantage of the image-minor-mode method is that users would
> receive a security warning when they first run image-toggle-display

Actually, the way I see it the only real advantage of image-minor-mode is
that if a C file gets wrongly detected as a GIF file, it doesn't really
matter because the C mode is still activated and you just get a bunch of
spurious extra commands to display the "image".


        Stefan


>> so I like Richard's idea of bypassing #1 of Chong's
>> proposals (no more options, please!) and just implementing #2 (with
>> image-toggle-display disabled, as you note).

> Something like the attached patch, which couldn't be simpler.

Looks good to me.

> Index: lisp/image-mode.el
> ===================================================================
> RCS file: /cvsroot/emacs/emacs/lisp/image-mode.el,v
> retrieving revision 1.16
> diff -u -2 -r1.16 image-mode.el
> --- lisp/image-mode.el	21 Jan 2007 03:53:11 -0000	1.16
> +++ lisp/image-mode.el	30 Jan 2007 12:03:44 -0000
> @@ -61,10 +61,5 @@
>   (use-local-map image-mode-map)
>   (add-hook 'change-major-mode-hook 'image-toggle-display-text nil t)
> -  (if (and (display-images-p)
> -	   (not (get-text-property (point-min) 'display)))
> -      (image-toggle-display)
> -    ;; Set next vars when image is already displayed but local
> -    ;; variables were cleared by kill-all-local-variables
> -    (setq cursor-type nil truncate-lines t))
> +  (setq cursor-type nil truncate-lines t)
>   (run-mode-hooks 'image-mode-hook)
>   (if (display-images-p)
> @@ -180,4 +175,10 @@
> 	  (message "Repeat this command to go back to displaying the file as
> text")))))

> +(put 'image-toggle-display 'disabled "\
> +
> +WARNING: Displaying images can be a security risk.
> +Please make sure you're using up-to-date image libraries
> +and the images displayed come from a trusted source.")
> +
> (provide 'image-mode)


> _______________________________________________
> Emacs-devel mailing list
> Emacs-devel@gnu.org
> http://lists.gnu.org/mailman/listinfo/emacs-devel

Re: Image autodetection

[Juanma Barranquero]

On 1/30/07, Stefan Monnier <monnier@iro.umontreal.ca> wrote:

> Actually, the way I see it the only real advantage of image-minor-mode is
> that if a C file gets wrongly detected as a GIF file, it doesn't really
> matter because the C mode is still activated and you just get a bunch of
> spurious extra commands to display the "image".

That would be a different change. As it is now, if we just change
`image-mode' to `image-minor-mode' in `magic-mode-alist' (as was done
in a previous proposed patch, now rejected), image files would be
opened in fundamental mode + image minor mode, because as soon as a
non-nil mode is returned when searching in `magic-mode-alist' the
detection of major mode is finished (and so `auto-mode-alist' is
bypassed). At least, that's what I remember from a test I did.

> Looks good to me.

Great.

                    /L/e/k/t/u

Re: Image autodetection

[Jason Rumney]

Juanma Barranquero wrote:
> That would be a different change. As it is now, if we just change
> `image-mode' to `image-minor-mode' in `magic-mode-alist' (as was done
> in a previous proposed patch, now rejected), image files would be
> opened in fundamental mode + image minor mode, because as soon as a
> non-nil mode is returned when searching in `magic-mode-alist' the
> detection of major mode is finished (and so `auto-mode-alist' is
> bypassed). At least, that's what I remember from a test I did.

We have image-mode-maybe that uses image-mode for files that are 
unambiguously images, and image-minor-mode for files where there may be 
another appropriate mode. With some minor changes, it could be used in 
magic-mode-alist.

Re: Image autodetection

[Juanma Barranquero]

On 1/30/07, Jason Rumney <jasonr@gnu.org> wrote:

> With some minor changes, it could be used in magic-mode-alist.

I see `image-mode-maybe' more as a user command, but if you can make
it work and the changes are really minor it could be a good option
(additionally to the changes already installed by Chong).

                    /L/e/k/t/u

Re: Image autodetection

[Chong Yidong]

"Juanma Barranquero" <lekktu@gmail.com> writes:

> On 1/30/07, Juanma Barranquero <lekktu@gmail.com> wrote:
>
>> so I like Richard's idea of bypassing #1 of Chong's
>> proposals (no more options, please!) and just implementing #2 (with
>> image-toggle-display disabled, as you note).
>
> Something like the attached patch, which couldn't be simpler.

> -  (if (and (display-images-p)
> -	   (not (get-text-property (point-min) 'display)))
> -      (image-toggle-display)
> -    ;; Set next vars when image is already displayed but local
> -    ;; variables were cleared by kill-all-local-variables
> -    (setq cursor-type nil truncate-lines t))
> +  (setq cursor-type nil truncate-lines t)

This last line should not be present; its purpose was to hide the
cursor in case we are already displaying as an image and run
image-mode again.  I've checked in the patch, with this additional
correction.

Re: Image autodetection

[Richard Stallman]

    1. Make a new variable, auto-detect-image-type-p.  If non-nil, the
       function image-type-auto-detected-p (called from magic-mode-alist)
       performs content detection.  The default is nil.

    2. Do not display images as images automatically in image-mode.
       Instead, the user sees "Type C-c C-c to view the image as an
       image".  This additional step should not be a major inconvenience.

If we do #2, I see no need for #1.

Re: Image autodetection

[Miles Bader]

Chong Yidong <cyd@stupidchicken.com> writes:
> 1. Make a new variable, auto-detect-image-type-p.  If non-nil, the
>    function image-type-auto-detected-p (called from magic-mode-alist)
>    performs content detection.  The default is nil.

Don't use a "-p" suffix on variables.

-Miles

-- 
What the fuck do white people have to be blue about!?  Banana Republic ran
out of Khakis?  The Espresso Machine is jammed?  Hootie and The Blowfish are
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people the blues, not to get them!    -- George Carlin