DLI Implementation and Reference Guide - Datalogics

3.2 DLI Implementation and Reference Guide
Overview
Concepts and Facilities: Guide to the DL Pager Composition System
DLI provides a simple interface to create and write documents. It uses a document
structure (DLPDFDOC) to differentiate between documents, allowing for the
simultaneous creation of a number of documents. DLPDFDOC reflects the current
status of the document at all times and is required input to most other DLI calls. As
the document is created with Adobe PDF Library support, a CosDoc and a PDDoc
are created within the Library, and these may be obtained from this structure for use
in calls outside of DLI.
The Adobe PDF Library establishes the name and many of the attributes of a
document when it is completed, rather than when it is begun. Many existing
composition engines do not do this. For this reason, the document structure has a
convenient set of handles to permit the specification of such attributes at document
creation time, rather than at document write time.
There are a number of calls available at the Document Interface. Multiple documents
may be created and maintained at one time.
Required Use of Exception Handlers
Except for dlpdfinit and dlpdfterm, all calls to the Document Interface must be
within an exception handler (i.e. DURING/HANDLER/END_HANDLER statements) and
all DLI documents should be destroyed prior to closing the Adobe PDF Library. This
can be done all at once or one step at a time. Both DLI and the Adobe PDF Library
may raise exceptions in the form of escapes.
dlpdfinit and dlpdfterm must not be enclosed in these handlers because they
are not set up before initialization, and are freed during termination.
dlpdfdoccreate
This method will create and return a pointer to a new document, as a DLPDFDOC
pointer. There are two parameters to this method, an ASBool and a pointer to a
string, which are generally TRUE and NULL respectively. The first parameter, if