Developing a Printing Extension(IM:XP)

Inside Macintosh: QuickDraw GX Printing Extensions and Drivers /: Chapter 2 - Printing Extensions

Developing a Printing Extension
The composition of your printing extension depends on the capabilities that you are adding to QuickDraw GX printing. Each printing extension must at least include a resource file, an assembly-language jump table, one or more files of code to implement the functions that your extension perform. The background picture printing extension is typical; it consists of four files, as shown in Table 2-1. The rest of this chapter describes the contents of each of these files. The complete files are found in the QuickDraw GX sample code.
Table 2-1 Files used to implement the background picture printing extension
Filename Contents
backwash.a The assembly-language jump table that QuickDraw GX uses to locate the message overrides for the background picture printing extension
backwash.h The C language header file that includes all of the other needed header files, defines the constants and data types used by the program, and references external items
backwash.c The C language code that implements the message overrides for the background picture printing extension
backwash.r The resources for the background picture printing extension

The background picture printing extension draws a background picture on each page as the page is despooled, just before it is imaged on the output device. A page printed while the background picture printing extension is active can have any picture printed on it. An example is shown in Figure 2-2.
Figure 2-2 A page printed while the background picture printing extension is active

The background picture printing extension also adds a panel to the Print dialog box. The panel allows the user to enable or disable the extension, to select which background picture to use, and to set an intensity level for drawing the picture on the page. The Print dialog box with the background picture panel added is shown in Figure 2-1 on page 2-5.

Subtopics

The Jump Table

The Printing Message Overrides

Implementing the Background Picture Extension Functions

**Table 2-1 Files used to implement the background picture printing extension**
Filename	Contents
backwash.a	The assembly-language jump table that QuickDraw GX uses to locate the message overrides for the background picture printing extension
backwash.h	The C language header file that includes all of the other needed header files, defines the constants and data types used by the program, and references external items
backwash.c	The C language code that implements the message overrides for the background picture printing extension
backwash.r	The resources for the background picture printing extension