Inside Macintosh: Macintosh Toolbox Essentials /

Chapter 5 - Control Manager

This chapter describes how your application can use the Control Manager to create
and manage controls. Controls are onscreen objects that the user can manipulate with the mouse. By manipulating controls, the user can take an immediate action or change settings to modify a future action. For example, a scroll bar control allows a user to immediately change the portion of the document that your application displays, whereas a pop-up menu control for baud rate might allow the user to change the rate by which your application handles subsequent data transmissions.

Read this chapter to learn how and when to implement controls. Virtually all applications need to implement controls, at least in the form of scroll bars for document
windows. You use Control Manager routines, resources, and data structures to implement scroll bars in your application's document windows.

The other standard Macintosh controls are buttons, checkboxes, radio buttons, and pop-up menus. You can use the Control Manager to create and manage these controls, too. Alternatively, you can use the Dialog Manager to implement these controls in alert boxes and dialog boxes more easily. (You typically use an alert box to warn a user of
an unusual situation, and you typically use a dialog box to ask the user for information necessary to carry out a command.) The chapter "Dialog Manager" in this book describes in detail how to implement controls in alert and dialog boxes. However, in certain situations--for instance, when you need to implement highly complex dialog boxes--you may want to use Control Manager routines to manage these types of controls directly; read this chapter for information on how to do so.

For scrolling lists of graphic or textual information (similar to the list of files that system software presents after the user chooses the Open command from the File menu), your application can use the List Manager to implement the scroll bars. See the chapter "List Manager" in Inside Macintosh: More Macintosh Toolbox for more information.

The Control Manager offers routines for automatically handling user-generated
mouse events in controls and redrawing controls in response to update events. For further information about events and event handling, see the chapter "Event Manager" in this book.

You typically use a control resource--a resource of type 'CNTL'--to specify the type, size, location, and other attributes of a control. See the chapter "Introduction to the Macintosh Toolbox" in this book for general information about resources; detailed information about the Resource Manager and its routines is provided in the chapter "Resource Manager" in Inside Macintosh: More Macintosh Toolbox.

Every control you create must be associated with a particular window. All of the controls for a window are stored in a control list referenced by the window's window record. See the chapter "Window Manager" in this book for general information about windows. (When you use the Dialog Manager to implement a control, the Dialog Manager associates it with its respective dialog box or alert box, as described in the chapter "Dialog Manager.")

This chapter provides an introduction to the use of controls, and then discusses how
you can

• create and display controls
• determine whether mouse-down events have occurred in controls
• respond to mouse-down events in controls
• change the settings in controls
• use scroll bars to move a document in a window
• move and resize controls for a window
• define your own control definition function to create nonstandard controls

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Chapter Contents

Introduction to Controls

Buttons

Checkboxes

Radio Buttons

Pop-Up Menus

Scroll Bars

Other Controls

Active and Inactive Controls

The Control Definition Function

About the Control Manager

Using the Control Manager

Creating and Displaying a Control

Creating a Button, Checkbox, or Radio Button

Creating Scroll Bars

Creating a Pop-Up Menu

Updating a Control

Responding to Mouse Events in a Control

Determining a Mouse-Down Event in a Control

Tracking the Cursor in a Control

Determining and Changing Control Settings

Scrolling Through a Document

Scrolling in Response to Events in the Scroll Box

Scrolling in Response to Events in Scroll Arrows and Gray Areas

Drawing a Scrolled Document Inside a Window

Moving and Resizing Scroll Bars

Defining Your Own Control Definition Function

Control Manager Reference

Data Structures

The Control Record

The Auxiliary Control Record

The Pop-Up Menu Private Data Record

The Control Color Table Record

Control Manager Routines

Creating Controls

Drawing Controls

Handling Mouse Events in Controls

Changing Control Settings and Display

Determining Control Values

Removing Controls

Application-Defined Routines

Defining Your Own Control Definition Function

Defining Your Own Action Procedures

Resources

The Control Resource

The Control Color Table Resource

The Control Definition Function

Summary of the Control Manager

Pascal Summary

Constants

Data Types

Control Manager Routines

Application-Defined Routines

C Summary

Constants

Data Types

Control Manager Routines

Application-Defined Routines

Assembly-Language Summary

Data Structures

Global Variables