Inside Macintosh: Programmer's Guide to MacApp / Part 2 - Working With MacApp

Chapter 19 - Working With Dialog Boxes and Controls

Overview

A dialog box is a special type of window used in Macintosh applications to display information and receive input from the user. A control is a user interface item, such as a radio button or checkbox, that commonly appears on a dialog box.

In MacApp, a dialog box is just another type of window, with its own hierarchy of views. MacApp supplies the TDialogView class for building a dialog, as well as a number of view subclasses to represent Macintosh Control Manager controls, such as buttons and checkboxes.

The TDialogView class automatically creates a TDialogBehavior object to supply dialog-box behavior. The dialog behavior object works with the dialog view to validate view data when the dialog box is closed.

MacApp provides a behavior class that supports tabbing between fields in a dialog box. The tabbing support gives a data-entry view a chance to validate its data when a user tabs to another field. Tabbing is described in "Tabbing Between Views," beginning on page 243.

You can use a view template to define a window and view hierarchy for a dialog box. You can then create the window with NewTemplateWindow and display it as either a modal or a modeless dialog box. These terms are described in "Modal Versus Modeless Dialog Boxes," beginning on page 240.

Figure 19-1 shows the classes and methods used with dialog boxes.

IMPORTANT

If you define a custom view class and use it in a view resource, don't forget to register the class, using the MA_REGISTER_CLASS macro (as described on page 30). Otherwise, you'll get an error message when your application tries to create the view hierarchy. (In a nodebug version, the message includes the words "Please contact the developer." In a debug version, you'll see the famous "Call Apple for a secret decoder ring.")

Figure 19-1 Dialog-box classes and methods