DLI Implementation and Reference Guide - Datalogics

12.12 DLI Implementation and Reference Guide
Indexed
Indexed color spaces are most often used in images, but are by no means limited to
Concepts and Facilities: Guide to the DL Pager Composition System
images.
An indexed color space first selects a device color space in which it will be rendered.
This must be DeviceRGB, DeviceGray, DeviceCMYK, DeviceN or ICCBased.
It then supplies an array of from 1 to n entries, each entry having the value of a color
in the selected model. (For DeviceGray, there would be one entry per color; for
DeviceRGB, three; and so on).
Color is specified as a single channel, which must be an integer between zero and n-1.
This value is used as an index to the array of colors, and the selected entry is imaged
in the underlying color space.
This color space cannot be created with PDEColorSpaceCreateFromName. When
created with PDEColorSpaceCreate, its atom is Indexed and the color structure
must be a PDEIndexedColorData.
Patterned
A patterned color space is not really a color space at all. Rather, it is an image which
will fill or stroke an area or line. It may contain colors of its own, or it may be a
black-and-white image which is colored per the underlying color space.
Any valid PDF marking commands may be used to construct the pattern image. The
image itself is constructed as a rectangular space, which is overlaid on the area being
filled or stroked. Specification of how far apart each tile is to be placed (horizontally
and vertically) permits the appearance of non-rectangular areas.
DLI contains an interface (dlpdfpatterncreate) which will accept a container
and convert it into a patterned color space. This space may then be used within a
container via the interface’s dlpdfcontentusefillpattern or
dlpdfcontentusestrokepattern methods.