ITT Rule IDL Version 7.0 User Manual download pdf (Page 365)

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Chapter 15: Creating a Custom iTool Widget Interface 365

iTool Developer’s Guide Example: a Custom iTool Interface

example2_wdtool_cleanup

The cleanup routine for our interface is simple; it frees the pointer used to hold the

widget interface’s state structure. The complete code for the cleanup routine is shown

below.

PRO example2_wdtool_cleanup, wChild

; Make sure we have a valid widget ID.

IF (~WIDGET_INFO(wChild, /VALID)) THEN $

RETURN

; Retrieve the pointer to the state structure, and

; free it.

WIDGET_CONTROL, wChild, GET_UVALUE = pState

IF (PTR_VALID(pState)) THEN $

PTR_FREE, pState

END

Discussion

Note that this routine is only called when the widget interface is actually destroyed,

not when the WIDGET_KILL_REQUEST event is processed. See “Handling

Shutdown Events” on page 356 for details.

example2_wdtool_event

The main event-handling routine for our widget interface handles three types of

events that might be generated by the top-level base widget:

• WIDGET_KILL_REQUEST (generated when the user requests that the

application be exited).

• WIDGET_KBRD_FOCUS (generated when the user selects the application).

• WIDGET_BASE (generated when the user resizes the top-level base widget.

A more complicated interface may handle additional events; the techniques used

would be similar to those illustrated here. The complete code for the main event-

handler routine is shown below.

PRO example2_wdtool_event, event

; Retrieve a pointer to the state structure.

wChild = WIDGET_INFO(event.handler, /CHILD)

WIDGET_CONTROL, wChild, GET_UVALUE = pState

CASE TAG_NAMES(event, /STRUCTURE_NAME) OF

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ITT Rule IDL Version 7.0 User Manual Page 365

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