Re: Repeatedly including an EPS file

[Valeriy E. Ushakov]

On Sat, Feb 03, 2001 at 20:44:09 +0300, Valeriy E. Ushakov wrote:

> > Can anyone advise a technique for defining the logo once and
> > referencing it "symbolically".
> 
> See Adobe Technote #5144 "Using EPS Files in PostScript Language Forms"
> 
>     http://partners.adobe.com/asn/developer/pdfs/tn/5144.pdf

Ok, this seems interesting, so I've given it a try.  First of all you
need a Level 2 printer, that understands forms.  Section 3 of the
technote explains how you can use copypage with Level 1 interpreters
if you will use the EPS only once per page, but I haven't tried that
approach.


. Technote example defines its own code to bracket EPS files.   Lout
  also defines such code.

  It's possible to reuse Lout versions, but you need to patch Lout
  code for BeginEPSF and EndEPSF to match the one found in TN5144.
  Note that Lout code is taken from EPSF spec, apparently that code
  doesn't work well for forms.  I haven't looked close into it, I just
  changed the code to match the one found in the tech note:

    in BeginEPSF move "userdict begin" to the bery begining of the def
    in EndEPSF and "end" at the very end

  These are hardcoded in z49.c, so either tweak it and recompile or
  patch the produced output.

  Since that's a hassle, you can just ignore it and use a version from
  the technote.


. You have to know the BBox of the EPS and tell it to Lout.  When Lout
  includes EPS files it reads the BBox information for DSC comments,
  but since in this case Lout will *not* be reading the file, you have
  to tell it the size of the picture.


. There's a wart.  @PrependGraphic only adds things to prologue, and
  you want the form with your EPS to be in the setup.  Also, you
  probably want to end (pop) the form dictionary in the document
  trailer and Lout doesn't provide necessary hooks.


So you will need:

* the .lpg resource file with common code and @PrependGraphic for it

  The code is on pages 7-8 of TN 5144, it's the resource forms_ops
  starting with:

      %%BeginResource: procset forms_ops 1.0 0

  NB: If you modified Lout Begin/EndEPSF for reuse with forms, you
  can delete StartEPSF and EPSFCleanUp from this resource (but see
  warning below).

  NB: You will want to delete /ARRAY_SIZE definition from that
  resource.  It changes from file to file so you'd better define it on
  a per-EPS basis.


* an .lpg file with your EPS wrapped in a form and @PrependGraphic for it

  This is the setup code on page 8 of the tech note.  Copy the stuff
  between %%BeginSetup and %%EndSetup comments, change the form name.

  NB: You want to put the ARRAY_SIZE (that example code defines in
  prolog) into the form dictionary!

  NB: If you modified Lout Begin/EndEPSF for reuse with forms, you can
  use them instead.

  Update the BBbox entry and paste the EPS file at the indicated place.


* a Lout definition that invokes the form

  Now things are all set and you can do:

  # SU Crest logo from the User's Guide
  def @Crest {
    {
      20 dup scale      # undo Lout scaling to it's internal unit
      CrestForm execform
    } @Graphic
    # Tell Lout the size of the EPS picture
    60p @Wide 53p @High
  }



And then just use @Crest as any other Lout object.  BTW, if the form
is cached you will save rendering time as well as file size (see
section 7.2 of the tech note).

I guess that you can easily automate all this stuff with a script.

SY, Uwe
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