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Copyright (c) 1994 by NeXT Computer, Inc. All Rights Reserved.

**Single-Operator Functions**

Single-operator functions provide a C language interface to the
individual operators of the PostScript language. The specification for a
single-operator function is identical to that of the PostScript operator it
represents. The *PostScript Language Reference Manual*, *Second
Edition*, by Adobe Systems Incorporated, provides the specifications of all
standard PostScript operators. Also refer to the *Display PostScript System,
Client Library Reference Manual*, by Adobe Systems Incorporated. Listed
below are single-operator functions that correspond to operators found in
OpenStep but not in the standard implementation of the PostScript language.

These functions have either a PS or a DPS prefix. For every single-operator function with a PS prefix, there's a corresponding single-operator function with a DPS prefix. The PS and DPS functions are identical except that DPS functions take an additional (first) argument that represents the PostScript execution context.

Besides using standard C language types, some single-operator functions use
**userobject**an **int** that refers to the value returned by
**DPSDefineUserObject()**.

In the function descriptions below, *x* and *y* refer to the origin
of *source* rectangles, and *w *and *h* refer to the width and
height of the source rectangles. *gstateNum* refers to the graphics state
(gstate) of the source rectangle. *dx* and *dy* refer to the origin
of the *destination* for the compositing or dissolving operation.
*op* refers to the specific compositing operation. *a* or
*alpha* refers to the coverage component used for compositing operations.

**PS Prefix Functions**

void **PScomposite(**float *x*, float *y*, float *w*,
float *h*, int *gstateNum*, float *dx*, float *dy*, int
*op*)

void **PScompositerect(**float *x*, float *y*, float *w*,
float *h*, int *op*)

void **PScurrentalpha(**float **alpha*)

void **PSdissolve(**float *x*, float *y*, float *w*, float
*h*, int *gstateNum*, float *dx*, float *dy*, float
*delta*)

void **PSsetalpha(**float *a*)

DPS Prefix Functions

void **DPScomposite(**DPSContext *ctxt*,** **float *x*, float
*y*, float *w*, float *h*, int *gstateNum*, float
*dx*, float *dy*, int *op*)

void **DPScompositerect(**DPSContext *ctxt*, float *dx*, float
*dy*, float *w*, float *h*, int *op*)

void **DPScurrentalpha(**DPSContext *ctxt*, float **pcoverage*)

void **DPSdissolve(**DPSContext *ctxt*, float *x*, float *y*,
float *w*, float *h*, int *gstateNum*, float *dx*, float
*dy*, float *delta*)

void **DPSsetalpha(**DPSContext *ctxt*, float *a*)