bug#34138: 27.0.50; Delayed display of PDF file images

[martin rudalics]

> Since a recent commit, I'm seeing a delay in the display of PDF files as
> images (both with -Q and with my initializations).  I see this in both
> doc-view-mode and pdf-view-mode (from the pdf-tools package, available
> from MELPA).  In doc-view-mode, on visiting a PDF file, it at first
> appears as raw PDF, as when visiting it in fundamental-mode, and only
> after a few seconds does the image appear.

I cannot see how 'doc-view-mode' could be possibly affected by the
changes you identified below.  It doesn't run any of the affected
hooks.  Have you tried running 'doc-view-mode' without loading
'pdf-view-mode'?

> The same happens in
> pdf-view-mode but there the delay is much longer -- with some files it
> takes close to a minute on my machine before the image is displayed,
> unless I provide keyboard input, which makes the image appear
> immediately.

These might be related although going through the sources of
‘pdf-view-mode’ I cannot see any problem.  'pdf-util-window-attach'
uses a workaround for deleting a window after running
'window-configuration-change-hook' and there I see a different source
of trouble:

'display-buffer-split-below-and-attach' calls 'window--display-buffer'
with a fifth argument and that has been changed in another commit.
Please remove the display-buffer-mark-dedicated argument in that call
and see whether the problem persists.  CC-ing Andreas to make an
appropriate change in pdf-util.el.

> In addition, in pdf-view-mode this appears in *Message*:
> Error during redisplay: (eval (pdf-misc-size-indication)) signaled
> (error "Invalid image specification: nil").

This should come from the 'image-display-size' call in
'pdf-view-image-size'.  Could you get a backtrace for it?

> In doc-view-mode there is
> no such error message.  Git bisect pinpoints this commit:
>
> e567ac1495..: Martin Rudalics 2019-01-11 Run window change functions
> during redisplay

martin