ITT Rule IDL Version 7.0 User Manual download pdf (Page 315)

Chapter 14: Creating a User Interface Panel 315

iTool Developer’s Guide Creating a UI Panel Interface

Adding Observers

For notification messages to be passed to the correct callback routine, an

OnNotifyObserver must be established by calling the AddOnNotifyObserver method

of the IDLitUI object. The AddOnNotifyObserver method takes as its arguments the

ID created by the call to the RegisterWidget method (as discussed in the previous

section) and the component object identifier of the iTool component to observe. Once

the observer is created, each time the specified iTool component generates a message

(that is, when the component itself calls the DoOnNotify method), the registered

widget callback routine is called with the message as one of its arguments. The call to

the AddOnNotifyObserver method looks like:

oUI->AddOnNotifyObserver,

idObserver

idSubject

where idObserver is an identifier created by a call to the RegisterWidget method, and

idSubject is usually the component object identifier of the iTool component being

observed. See “IDLitUI::AddOnNotifyObserver” (IDL Reference Guide) for

additional details.

The idSubject argument to the AddOnNotifyObserver method is normally the object

identifier of an iTool component object, but it can be any string value. For example,

any time the selection within an iTool window changes, the DoOnNotify method is

called with its first parameter (idOriginator) set to the string value

'Visualization' rather than to the object identifier of a component. An observer

whose idSubject argument is set to the string

'Visualization' will be notified

each time the selection changes in the iTool window. For example, the following

statement specifies that the panel widget (as registered via the RegisterWidget

method) will receive notifications whenever a visualization changes in the iTool

window.

oUI->AddOnNotifyObserver, idObserver, 'Visualization'

Here, idObserver is the identifier created in the previous section. The second

argument (

'Visualization') specifies that messages will be generated whenever

a visualization is modified.

“Example: A Simple UI Panel” on page 322 provides examples of observers of both

types. See “iTool Messaging System” on page 41 for background information on

observers and messages.

Create the Widget Hierarchy

The widget hierarchy of a user interface panel looks like the following:

Panel widget

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ITT Rule IDL Version 7.0 User Manual Page 315