Inside Macintosh: Operating System Utilities /

Chapter 1 - Gestalt Manager

This chapter describes how you can use the Gestalt Manager and other system software facilities to investigate the operating environment. You need to know about the operating environment if your application takes advantage of hardware (such as a floating-point unit) or software (such as Color QuickDraw) that is not available on all Macintosh computers. You can also use the Gestalt Manager to inform the Operating System that your software is present and to find out about other software registered with the Gestalt Manager.

The Gestalt Manager is available in system software versions 6.0.4 and later. The MPW software development system and some other development environments supply code that allows you to use the Gestalt Manager on earlier system software versions; check the documentation provided with your development system.

In system software versions earlier than 6.0.4, you can retrieve a limited description of the operating environment with the SysEnvirons function, also described in this chapter.

You need to read this chapter if you take advantage of specific hardware or software features that may not be present on all versions of the Macintosh, or if you wish to inform other software that your software is present in the operating environment.

This chapter describes how the Gestalt Manager works and then explains how you can

• determine whether the Gestalt Manager is available
• call the Gestalt function to investigate the operating environment
• make information about your own hardware or software available to other applications
• retrieve a limited description of the operating environment even if the Gestalt Manager is not available

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Chapter Contents

About the Gestalt Manager

Using the Gestalt Manager

Determining Whether the Gestalt Manager Is Available

Getting Information About the Operating Environment

Interpreting Gestalt Responses

Adding a New Selector Code

Modifying a Selector Function

Getting Environmental Information Without the Gestalt Manager

Gestalt Manager Reference

Constants

Data Structures

The System Environment Record

Gestalt Manager Routines

Getting Information About the Operating Environment

Adding a Selector Code

Modifying a Selector Function

Application-Defined Routines

The Selector Function

Summary of the Gestalt Manager

Pascal Summary

Constants

Data Types

Gestalt Manager Routines

Application-Defined Routines

C Summary

Constants

Data Types

Gestalt Manager Routines

Application-Defined Routines

Assembly-Language Summary

Data Structures

Result Codes