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The Question is:
Can escape and control codes be generated directly from OpenVMS to an HP
printer? And if so, how?
Thanks, Wiz.
The Answer is :
Escape and control codes are simply characters, and characters can
be sent to printers. The question then becomes one of interpretation
and printer state, as most printers have constraints on the expected
file and data stream contents -- what you need to do depends greatly
on what you want to do, and on which printer is involved.
If you wish a particular action on a target device (eg: bold, etc)
rather than a particular character or character sequence, you can
retrieve various associated character sequences from SMG using (or
potentially extending) its existing dictionary contents and
capabilities. See the SMG$GET_TERM_DATA, and the SMG terminal
device data file. Directly embeding sequences within applications
tends to cause problems when devices change or additional devices
are added, as specific devices can have specific requirements in
this area.
That said, most folks will use an application or particularly a print
file format (eg: Postscript) which will effectively locate and embed
the appropriate sequence(s) into the data stream for the particular
target device -- use of Postscript-format files, for instance, avoids
having to code device-specific knowledge into the application. Again,
most folks will prefer to avoid embedding escape or control sequences
directly into the file or directly into the printer data stream.
For details on device control libraries, please see existing printing
discussions here starting with (1020).
If you inject characters directly in the data stream, you will have
to be familiar with the character set and command requirements of
the printer. (eg: with the PCL language for many printers, or with
Postscript for printers or hosts with Postscript printing support.)
For details on generating Postscript output directly from within an
application, please see the Postscript "Red Book" or other such
documentation.
Related topics: (7715), (102), (436), (2840), (3795), (4641), (5968).
Also please see the information on escape and control sequences in
the OpenVMS Frequently Asked Questions (FAQ).
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