PATHMac OS 8 and 9 Developer Documentation > Human Interface Toolbox > Window Manager >

Programming With the Mac OS 8.5 Window Manager

IsValidWindowPtr

Reports whether a pointer is a valid window pointer.

pascal Boolean IsValidWindowPtr (GrafPtr grafPort);
grafPort
A pointer to a graphics port. You pass the pointer to be examined.
function result
A value of type Boolean . The function returns true if the specified pointer is a valid window pointer; otherwise, false .
DISCUSSION

A custom control definition may use the IsValidWindowPtr function to determine whether it is being asked to draw onscreen or offscreen.

This function is primarily intended for use with debugging your application.

SPECIAL CONSIDERATIONS

The IsValidWindowPtr function is a processor-intensive call.

VERSION NOTES

Available with Mac OS 8.5 and later.

© 1999 Apple Computer, Inc. – (Last Updated 18 March 99)