DLI Implementation and Reference Guide - Datalogics

Image Display 11.3
Pointers to images become invalid on document destruction and must not be used
after that time.
A document may contain any number of images. Each image will be included in the
document only once, but may be referenced within that document many times.
The image is considered to be a part of the document, and may not be used in any
document other than the one in which it was created. Images need not be directly
destroyed, since they will be destroyed automatically when the document that
contains them is destroyed.
Images are tracked and reused via the ImageName value. The same image data with a
different Image Name is considered a different image. Image data is passed into the
creation routines via strings in memory. These strings may be freed after the call to
create the image.
Implementations of DLI on UNIX and Windows include public-domain libraries to
convert a number of common graphic forms into bitmaps usable by PDF.
NOTE: The public-domain graphic-conversion libraries used on Unix and Windows
are not available on OS/390 and OS/400 platforms. Consequently some image
creation procedures are not available under OS/390 and OS/400.
Graphic Image Forms
Predefined images typically fall into one of two major varieties:
• Bitmap Graphic Forms
• Graphical Language Forms
Bitmap Graphic Forms
This is the most basic form of image. It consists of a stream of bits; indications of the
number of samples per line, and the number of lines; a description of the samples
(color model, sample size); and a description of ordering. It may also contain a