On Sat 22 Jun 2019 at 22:31:48 (-0400), Celejar wrote:
> On Fri, 21 Jun 2019 20:53:52 -0500 David Wright <deb...@lionunicorn.co.uk>
> wrote:
> > But what eliminates it for me as a general viewer is the lack of key-
> > binding configuration file. Quoting Archwiki,
> > "Navigation within a document works with standard keyboard shortcuts
> > and mouse interaction. For example, B and Space scroll up and down."
> > they don't look like standard bindings to me. Or is there some
> > external DE configuration that's handling all this for DE-users?
>
> My understanding is that the key bindings are generally vi-like, e.g.,
> hjkl pan left, down, up, and right. You can also use the more intuitive
> key bindings that work in vi (at least in Vim, as per the standard
> (Debian?) configuration: PgUp, PgDn, and the cursor arrow keys do pretty
> much what you'd expect.
On the contrary, that's where I have problems. Compare if you will
xpdf and mupdf with a typical portrait PDF displayed on a landscape
screen, with xpdf in its default paginated (non-continuous) mode.
On opening the document, you would see the top ~two-thirds of the
first page displayed ("top1").
Pressing PgDn repeatedly in xpdf will display bottom1, top2, bottom2,
top3, etc, and PgUp will reverse that all the way back to top1 again.
Not so with mupdf where you will never see the last part of the
file (bottomLast) displayed, because PgDn gives you top2, top3,
top4, … topLast and PgUp gives you bottomLast-1, bottomLast-2,
bottomLast-3, … bottom1.
In xpdf, the Up/Down/Left/Right arrows pan/scroll the page without
leaving it (continuous mode will scroll over page boundaries as if
the document was on fan-folded paper).
In mupdf, Up/Down moves through the document in small steps, jumping
over page boundaries (reasonable), but Left/Right changes pages,
staying in the same vertical position on each new page (like gv
does, but at least gv has a thumbnail picture in the margin of where
you are on the page).²
> > One place mupdf scores is viewing very very tall PNGs and JPGs.¹
> > However, it's let down by the fact that scrolling must be done using
> > the mouse: the keyboard shortcuts move the image much too far.
> > It appears to segment (virtually) the image into still very tall
> > "pages" which are larger than the area being displayed. So I prefer
> > to use xzgv for this task.
>
> Are you using the panning or page Up/Down keys? I find the panning keys
> to be pretty useful in viewing tall documents, although the fact that
> they'll turn to the next page when you're already at the bottom of a
> page (instead of just doing nothing) can be annoying.
In xpdf's continuous mode, you have the benefit of seeing the
page-join going past, which makes it more obvious how the document
is scrolling by.
But the PNG/JPG modes of mupdf introduce a new set of navigation problems.
PgDn, PgUp, Left and Right do nothing. Down and Up do the same as j and k,
and the problem is as described above: the panning increment is far too
large. AFAICT it's dividing the images into 11 "virtual pages" and so
you only ever see the top of these 11 chunks.
² The difference between PgDn/Right and PgUp/Left is not mentioned in
the man page.
Cheers,
David.
