Re: [Dev-luatex] Differences between PDF and DVI

12 Dec 2008


      On Tue, 9 Dec 2008, Taco Hoekwater wrote:
...
Hartmut Henkel wrote:
...
When you change \hoffset, the whole RL text moves in the DVI case, but
not in the PDF case.
In dvi mode there is a big difference between the actual dvi location
(dvi_h, moves r2l or l2r depending on text direction) and where tex
thinks the dvi location is (cur_h, always moves e2l). dvi output is
quite convoluted. In pdf mode, output is much more straightforward.
I think that it would be better to listen to \pagerightoffset in
both cases, but that is open for discussion.
...
Also there seems to be some inconsistent magic if
\pagerightoffset=0pt.
In that case, it defaults to 1inch (pdf) or 2inch (dvi). Yes, that is
a mess (see below). I can easily make the pdf do what the dvi does, but
which behaviour is right?
...
I have no idea how it should look like.
Me neither. And internally there are some more variables involved:
\pdfhorigin
  \pdfvorigin
  \pdfbottomoffset
Ok, \pdfbottomoffset can probably be ignored because luatex at the
moment doesn't do top-to-bottom scripts.  But what about those origin
things?
Initex defaults:
\pdfpagewidth 0pt
\pdfpageheight 0pt
\pdfbottomoffset 0pt
\pdfrightoffset 0pt
\hoffset 0pt
\voffset 0pt
\pdfhorigin 1in
\pdfvorigin 1in
Here is the current logic (in DVI):
cur_page_width    = (\pdfpagewidth > 0
                      ? \pdfpagewidth
                      : \wd255 +2*(\hoffset + 1in))
cur_right_offset  = (\pdfrightoffset != 0
                      ? \pdfrightoffset
                      : 2in )
cur_h             = \hoffset
       = (\pagedir TLT
                     ? cur_h
                     : cur_page_width-cur_right_offset - cur_h )
And in PDF, it looks like this:
cur_page_width    = (\pdfpagewidth > 0
                      ? \pdfpagewidth
                      : \wd255 +2*(\hoffset + \pdfhorigin))
cur_right_offset  = (\pdfrightoffset != 0
                      ? \pdfrightoffset
                      : 1in )
cur_h             = (\pagedir TLT
                      ? \hoffset + \pdfhorigin;
                      : cur_page_width-cur_right_offset )
       =  cur_h
regarding \pdfhorigin and \pdfvorigin, it just appeared (under the
shower :-) that these both should move _all_ stuff on the page
consistently and therefore _independently_ from the direction mode. They
are purely paper oriented parameters and only in use for PDF. So i guess
that these two can be factored out, and with 1in default PDF should look
like DVI. No idea about the others.

Regards, Hartmut