DLI Implementation and Reference Guide - Datalogics

Displaying Line Drawings 10.7.
Path Drawing Methods
The directly-drawn shapes are useful for a great number of graphics, but they do not
permit filling of complex arbitrary shapes without the construction of a path. For that
reason, a second set of drawing operators was added. These operators simply
construct and draw a path, which may be arbitrarily complex. It may also be
disjointed.
The DLPDFPATH structure will contain a path of any size, allocating additional
memory as needed. Path construction is via methods which add segments to the
existing path. These methods seek to include both the PDF and PostScript graphics
operators. When completed, the path may be added to a content area. The path is not
destroyed when imaged and may be reused any number of times. The DLPDFPATH
structure also includes a provision for a CTM Matrix, which may be used to
transform the position and appearance of the path.
Within the path, a current point is maintained. This will be undefined initially, or after
a dlpdfpathaddclose, and will be the end point of the segment added at all other
times. Some operators require that the current point be established prior to adding a
segment of that type. Others will add a straight line segment drawn from the current
position to the start of the defined segment prior to a segment. This behavior mimics
the drawing mechanism in PostScript.
The first parameter of all of these methods, except dlpdfpathcreate and
dlpdfcontentdrawpath, is a pointer to a valid DLPDFPATH structure.
dlpdfpathcreate
This method will return a pointer to a new DLPDFPATH structure. The path’s contents
will be empty, its current position will be undefined, and its matrix will be set to the
unity matrix. This structure will persist until specifically deleted by the
dlpdfpathdestroy method.
The DLPDFPATH is not specific to a document or content structure. It may be shared
across many documents and placed within any number of content structures.