ITT Rule IDL Version 7.0 User Manual download pdf (Page 342)

342 Chapter 15: Creating a Custom iTool Widget Interface

Creating the Interface Routine iTool Developer’s Guide

compound widgets, we include the following statement after creating our top level

base widget:

oUI = OBJ_NEW('IDLitUI', oTool, GROUP_LEADER = wBase)

Note that we need the iTool object that was the argument to our interface creation

routine to create the user interface object. Note also that we specify our top level base

as the GROUP_LEADER of the interface object; this will ensure that any floating or

modal dialogs displayed by the interface appear in the correct place.

Widget Creation and Layout

Your custom iTool interface can include both iTool compound widgets and

traditional IDL widgets. These are created in the same way as in a traditional widget

application. The finer points of creating iTool compound widgets are discussed in

later sections of this chapter.

User Interface Registration

Near the end of the widget creation routine, after the widget hierarchy has been

realized, we must register the top-level base with the user interface object:

myID = oUI->RegisterWidget(wBase, 'Example 2 Tool', $

'example2_wdtool_callback')

Here we specify the name of the callback routine that will handle messages from the

iTool components. The return value from the RegisterWidget method is the iTool full

identifier of the widget interface. We next use the identifier to specify that the

interface is an observer (that is, that it can receive messages generated by iTool

components) for the associated iTool:

oUI->AddOnNotifyObserver, myID, oTool->GetFullIdentifier()

This ensures that messages generated by the iTool are handled by the specified

callback routine.

Handling Widget Destruction

Many complex interfaces rely on a state structure containing information about the

widgets in the interface. If you pass a reference to this state structure between

routines in your user interface code using one or more pointers, free the pointers

when the widget interface is destroyed. In our example interface, a pointer to the state

structure is stored in the user value of the first child widget of the top level base

widget. The following statement specifies a routine to be called when the widgets are

destroyed:

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ITT Rule IDL Version 7.0 User Manual Page 342