bug#13887: 24.3; doc-view will render blurry images when image-magick is available

[Stefan Monnier <monnier@iro.umontreal.ca>]

> a) Is all the "window t" stuff necessary?
> Does anyone really care what is "shown" in a buffer unless it's
> displayed in a window?

It's not a question of caring: it's a mechanism.

If you "move to next page" before displaying the buffer, then yes, you
probably care.  In most cases you don't, but then this "window t stuff"
shouldn't hurt you one bit either.

> c) Does (image-get-display-property) have any business asking what buffer
> is currently selected in the window?

Good question.  It shouldn't hurt, but maybe it's a mistake.

> d) Why data is sometimes retrieved from the the buffer (as in (
> image-get-display-property)), and sometimes from image-mode-winprops-alist
> (as in (image-mode-winprops))? Is the complexity justified, or is one of
> the methods "legacy"?

Can't remember, sorry.  That's a good question, tho.

I do remember that part of the motivation behind the design was that:
- several windows need to be able to display different pages (or
  different parts of the same page) of the same doc-view buffer.
- "current page and page position" info needs to be preserved while the
  buffer is not shown, so that you can temporarily switch to some other
  buffer and then switch back to the doc-view buffer without finding
  yourself back at page 1.


        Stefan