(v13) Example of inspecting PDF files

This page applies to Harlequin v13.1r0 and later; and to Harlequin Core but not Harlequin MultiRIP.

This code listing gives a simple example of how to use the PDF inspection operators to obtain a page count from a PDF file.

As customary in examples, there is limited error handling, and some assumptions are made. For example, /Count might be indirect. This possibility is remote, but should be anticipated in production code, by checking the type of object returned.

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% Example of use for the getPDFtrailer and getPDFobject
% routines in the RIP. Reports the total number of pages
% in the PDF file "example.pdf", without customary error checks.
            
2 dict begin

% Open the file
(example.pdf) (r) file /PDFFile exch def

% Create the PDF execution context
PDFFile << >> pdfopen /PDFContextID exch def

% Get the trailer object
PDFContextID 1183615869 internaldict /getPDFtrailer get exec

% Should have a /Root object
/Root get

PDFContextID exch 1183615869 internaldict /getPDFobject get exec

% Got the Catalog object, now look for /Pages
/Pages get

PDFContextID exch 1183615869 internaldict /getPDFobject get exec

% This top-level Pages object has the page count for
% the entire PDF file
/Count get
(PDF contains ) print 128 string cvs print ( pages) =

% Be sure to close the execution context and the physical file 
PDFContextID pdfclose PDFFile closefile
currentdict end