Re: There should be an option to set the display size of an image to zero

[Eli Zaretskii <eliz@gnu.org>]

> From: "Stephen J. Turnbull" <stephen@xemacs.org>
> Date: Tue, 17 Sep 2013 16:19:48 +0900
> Cc: Marc Feeley <feeley@iro.umontreal.ca>, emacs-devel@gnu.org
> 
> As he phrased it, yes.  But the use-case he described could be
> accomodated fairly simply by blitting the image to the *background*
> rather than treating it as a (more or less) giant character in the
> foreground.

I'm not sure we have that capability.  I may be wrong, though.

> I think Emacs allows background pixmaps, doesn't it?

I don't think so.  We only support :stipple.  Again, I know almost
nothing about this.

> What I do (in XEmacs) when translating or inputting from a
> photographed page image is to make that image the background pixmap,
> then just type right over the text I'm working on.
> 
> Of course it wouldn't be particularly robust to scrolling and such.

Right.  The Emacs redisplay never redraws the background, except when
it completely erases the frame.

> To get a relatively robust version, you'd just need to be able to
> "pin" rectangular objects to the background canvas, which shouldn't be
> too hard.  Allowing you to pin those things relative to a particular
> marker in text might be quite a bit more complex, though.

We don't have a canvas in Emacs, I think.