CheckUpdate

Generate update event if needed

#include <Windows.h> Window Manager

EventRecord *theEvent ; receives event data if return value is TRUE

returns Does any window need updating?

This low-level function is used by the Toolbox Event Manager to update

windows that have non-empty update regions.

theEvent is a pointer to an EventRecord. Upon return, it will be filled with

an update event, if one is needed.

Returns: a Boolean value indicating whether theEvent contains data. It will

be one of:

FALSE No windows needed updating

TRUE A window needed updating; theEvent contains the EventRecord.

Notes: This checks each window, starting at the front of the window list, looking

for a window that needs updating (its update region is not empty). For each

such window found:

• If the WindowRecord's windowPic field is not NIL (see SetWindowPic),

this function draws the picture.

• If the windowPic field is NIL (as with most windows), this function stores

an update event for that window in theEvent and returns a value of TRUE.

If no windows need updating, or if all windows that needed updating are

defined with a PicHandle, this function returns FALSE.

Referenced by (3):