24.0.92; (image-size ...) on "large" images

[Jambunathan K <kjambunathan@gmail.com>]

org-odt.el relies on (image-size ...) to determine pixel dimensions of
an image. For "large" images, this API returns "false" values. It would
be wonderful, if Emacs returns just the true value of the image or
nothing at all.

On a related note, IIRC, during batch export there is no way I can use
create-image + image-size to determine pixel dimensions of the image. Is
there a reliable and uniform way to determine size of images that are
*never* intended to be displayed.

Original issue:
http://www.mail-archive.com/emacs-orgmode@gnu.org/msg51014.html

My notes:
http://www.mail-archive.com/emacs-orgmode@gnu.org/msg51441.html

,---- http://www.mail-archive.com/emacs-orgmode@gnu.org/msg51441.html
| Re: [O] [ODT] image scaling overridden by long caption
| 
| Jambunathan K
| Mon, 30 Jan 2012 20:59:37 -0800
| 
| Andreas Leha <andreas.l...@med.uni-goettingen.de> writes:
| 
| 
| >>> #+label: fig:baz
| >>> #+name: baz
| >>> #+attr_odt: :scale 0.5
| >>> #+header: :file baz.png
| >>> #+header: :width 7200 :height 3600 :res 600
| >>> #+begin_src R :exports results :results graphics
| >>>   plot(1:10, 1:10)
| >>> #+end_src
| 
| Image that R outputs is 7200-by-3600.
| 
| >> #+begin_src emacs-lisp
| >>   (list (* max-image-size (frame-pixel-width)) 
| >>         (* max-image-size (frame-pixel-height)))
| >> #+end_src
| >
| > #+results:
| > | 3648.0 | 4320.0 |
| 
| Emacs will "refuse to load" images that cannot fit in 3640-by-4320
| area. Note that max-image dimensions is "tightly coupled" with the frame
| size.
| 
| >> #+begin_src emacs-lisp
| >>     (message "%S" (ignore-errors 
| >>                     (image-size (create-image "baz.png") 'pixels)))
| >> #+end_src
| >
| > #+results:
| > : (30 . 30)
| 
| Instead of loading a large image, Emacs tries to create a "safe"
| 30-by-30 pixel area (whatver it is).
| 
| The solution is to instruct Emacs to handle higher image sizes. Just
| bump the value of max-image-size. For example, add this to init file.
| 
| #+begin_src emacs-lisp
|   (setq max-image-size (* 2 max-image-size)) ;; modify scale 
| #+end_src
`----