bug#6981: create-animated-image doesn't animate

bug#6981: create-animated-image doesn't animate

[Juri Linkov]

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When looking at the attached animated image closer/farther to/from the screen,
the face appears/disappears.  When looking with/without glasses, the face
appears/disappears.  But when looking at it in Emacs, nothing changes.


[-- Attachment #2: oii.gif --]
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I believe imagemagick could help to fix this.

bug#6981: create-animated-image doesn't animate

[Stefan Monnier]

> When looking at the attached animated image closer/farther to/from the
> screen, the face appears/disappears.  When looking with/without
> glasses, the face appears/disappears.  But when looking at it in
> Emacs, nothing changes.

I'm not sure I understand: your image displayed in Gnus as a bunch of
lines, which (if I tilt the screen of my laptop enough) reveal a face.


        Stefan

bug#6981: create-animated-image doesn't animate

[Juri Linkov]

>> When looking at the attached animated image closer/farther to/from the
>> screen, the face appears/disappears.  When looking with/without
>> glasses, the face appears/disappears.  But when looking at it in
>> Emacs, nothing changes.
>
> I'm not sure I understand: your image displayed in Gnus as a bunch of
> lines, which (if I tilt the screen of my laptop enough) reveal a face.

In addition to the optical illusion, this image also contains animation
that can be seen in image viewers/web browsers.

bug#6981: create-animated-image doesn't animate

[Jason Rumney]

Juri Linkov <juri@jurta.org> writes:

> When looking at the attached animated image closer/farther to/from the screen,
> the face appears/disappears.  When looking with/without glasses, the face
> appears/disappears.  But when looking at it in Emacs, nothing changes.

Note the following limitation mentioned in the comment in image.c:

  /* Clear the part of the screen image that are not covered by
     the image from the GIF file.  Full animated GIF support
     requires more than can be done here (see the gif89 spec,
     disposal methods).  Let's simply assume that the part
     not covered by a sub-image is in the frame's background color.  */

The following seems to show the image animation with this limitation
(the black bars of the first frame disappear rather than remaining in
the transparent background of following frames):

(setq img (create-animated-image "~/oii.gif"))
(insert-image img)
(image-animate-start img)


The last line seems to be neccesary, even though create-animated-image
starts the animation itself. Other changes to the buffer contents seem
to stop the animation so that line needs to be evaluated again.

bug#6981: create-animated-image doesn't animate

[Juri Linkov]

> Note the following limitation mentioned in the comment in image.c:
>
>   /* Clear the part of the screen image that are not covered by
>      the image from the GIF file.  Full animated GIF support
>      requires more than can be done here (see the gif89 spec,
>      disposal methods).  Let's simply assume that the part
>      not covered by a sub-image is in the frame's background color.  */

So we have two separate problems.  The first problem is this limitation.
In Gimp I see animated image frames described as "combine".  It seems
this corresponds to the disposal method 1 ("do not dispose, the graphic
is to be left in place") in http://www.w3.org/Graphics/GIF/spec-gif89a.txt
I rememeber there was a function in imagemagick that can do this.

> (setq img (create-animated-image "~/oii.gif"))
> (insert-image img)
> (image-animate-start img)
>
> The last line seems to be neccesary, even though create-animated-image
> starts the animation itself. Other changes to the buffer contents seem
> to stop the animation so that line needs to be evaluated again.

Thanks for the hint.  Since animation works (with the limitation above)
when inserted by `insert-image', but doesn't work with `image-mode',
the bug is in `image-mode'.  And indeed, removing `append' with
`image-transform-properties' in `image-toggle-display-image' like

@@ -494,10 +494,7 @@ (defun image-toggle-display-image ()
 			    (buffer-substring-no-properties (point-min) (point-max)))
 			 filename))
 	 (type (image-type file-or-data nil data-p))
-         (image0 (create-animated-image file-or-data type data-p))
-	 (image (append image0
-                        (image-transform-properties image0)
-                        ))
+         (image (create-animated-image file-or-data type data-p))
 	 (props
 	  `(display ,image
 		    intangible ,image

fixes this bug and restores animation.  This means that the Lisp object of
the created image should not be changed.

Joakim, this suggests that the function `image-transform-properties'
you recently added should nconc display properties to the end
of the image spec.

bug#6981: create-animated-image doesn't animate

[Chong Yidong]

> When looking at the attached animated image closer/farther to/from the
> screen, the face appears/disappears.  When looking with/without
> glasses, the face appears/disappears.  But when looking at it in
> Emacs, nothing changes.

The introduction of image-transform-properties in August 10 broke the
animated gif code in image-mode.el.  I've committed a fix.