Handles events such as window updating and resizing.

typedef void(* NavEventProcPtr) (
    NavEventCallbackMessage callBackSelector, 
    NavCBRecPtr callBackParms, 
    void *callBackUD
);

You would declare your function like this if you were to name it MyNavEventCallback:

void MyNavEventCallback (
    NavEventCallbackMessage callBackSelector, 
    NavCBRecPtr callBackParms, 
    void *callBackUD
);

callBackSelector

One of the values specified by the NavEventCallbackMessage data type. These values indicate which type of event your function must respond to. For a description of the constants that represent these values, see “Event Message Constants”.

callBackParms

A pointer to a structure of type NavCBRec. Your application uses the data supplied in this structure to begin processing the event.

callBackUD

A pointer to a value set by your application when it calls a Navigation Services function such as NavGetFile. When Navigation Services calls your event-handling function, the callBackUD value is passed back to your application in this parameter.

DISCUSSION

Register your event-handling function by passing a Universal Procedure Pointer (UPP) in the eventProc parameter of a Navigation Services function such as NavGetFile. You obtain this UPP by calling the macro NewNavEventProc and passing a pointer to your event-handling function. If you determine that an event is appropriate for your event-handling function, you can call other functions to handle custom control drawing, object filtering, or custom previews. For more information, see “Creating Application-Defined Functions”.

When events involve controls, your event-handling function must respond to events only for your application-defined controls. To determine which control is affected by an event, pass the kNavCtlGetFirstControlID constant, described in “Custom Control Setting Constants”, in the selector parameter of the function NavCustomControl.

AVAILABILITY

Supported in Carbon.

© 2000 Apple Computer, Inc. — (Last Updated 4/17/2000)