[Bug-AUCTeX] preview, wrong scaling of preview images

[Gregor.Thalhammer]

Hi all,

On my system (WinXP, emacs 22.50 + auctex 11.83, from auctex homepage) I 
observe a wrong scaling of preview images, more precisely, the horizontal and 
vertical resolution of the images does not fit to the physical resolution of 
my display, so the images look stretched in the horizontal direction. I use a 
somewhat unusual resolution of 1680x1050 with 16:10 aspect ratio.

I can locate the problem down to the function preview-get-geometry in 
preview.el,

...
(list (preview-hook-enquiry preview-scale-function)
                    (cons (/ (* 25.4 (display-pixel-width))
                             (display-mm-width))
                          (/ (* 25.4 (display-pixel-height))
                             (display-mm-height)))
...

Obviously the problem is, that 'display-mm-width' (and also ...-height) 
returns a wrong size. These functions are not part of auctex, and to my 
knowledge they cannot give correct results, since in Windows the physical size 
of a display is not available.

So this problem is not really a bug of auctex.

I would propose to make these values customizable or perhaps use instead the 
screen resolution that Windows assumes. I am sorry, I am not an expert in 
Emacs/Lisp programming.

Gregor