PUBLIC oForm
oForm = CREATEOBJECT("Tform", SYS(2023)) && watching TEMP dir
oForm.Visible = .T.
* end of main
 
DEFINE CLASS Tform As Form
#DEFINE FILE_NOTIFY_CHANGE_FILE_NAME 1
#DEFINE FILE_NOTIFY_CHANGE_DIR_NAME 2
#DEFINE FILE_NOTIFY_CHANGE_ATTRIBUTES 4
#DEFINE FILE_NOTIFY_CHANGE_SIZE 8
#DEFINE FILE_NOTIFY_CHANGE_LAST_WRITE 16
#DEFINE FILE_NOTIFY_CHANGE_LAST_ACCESS 32
#DEFINE FILE_NOTIFY_CHANGE_CREATION 64
#DEFINE FILE_NOTIFY_CHANGE_SECURITY 128
#DEFINE INVALID_HANDLE_VALUE -1
#DEFINE WAIT_OBJECT_0 0
#DEFINE WATCHING_INTERVAL 1000  && milliseconds
 
PROTECTED hNotify, PathBeingWatched
 
    Width=400
    Height=150
    MaxButton=.F.
    BorderStyle=2
    AutoCenter=.T.
    Caption="Watching directory"
 
    hNotify=INVALID_HANDLE_VALUE
    PathBeingWatched=""
 
    ADD OBJECT lblTarget As Label WITH Left=10, Top=7, Autosize=.T.
    ADD OBJECT tm As Timer WITH Interval=0
 
    ADD OBJECT lblAlert As Label WITH Left=10, Top=30,;
    Autosize=.T., Caption="Notification:"
 
FUNCTION Init(cPath)
    THIS.declare
    THIS.PathBeingWatched = FULLPATH(m.cPath)
 
    IF Not THIS.StartWatching()
        = MESSAGEBOX("Notification handle error.")
        RETURN .F.
    ENDIF
 
PROCEDURE Destroy
    THIS.StopWatching
 
PROTECTED FUNCTION StartWatching
    LOCAL lResult
 
    * no subdirs watched
    THIS.hNotify = FindFirstChangeNotification(;
        THIS.PathBeingWatched, 0,;
        FILE_NOTIFY_CHANGE_FILE_NAME +;
        FILE_NOTIFY_CHANGE_LAST_WRITE )
 
    lResult = (THIS.hNotify <> INVALID_HANDLE_VALUE)
 
    IF lResult
        THIS.lblTarget.Caption = "Watched: " +;
            THIS.PathBeingWatched
        THIS.tm.Interval = WATCHING_INTERVAL
    ENDIF
RETURN  lResult
 
PROTECTED PROCEDURE ContinueWatching
    IF FindNextChangeNotification(THIS.hNotify) = 0
        THIS.StopWatching
        = MESSAGEBOX("Request error.")
        THIS.Release
    ENDIF
    THIS.tm.Interval = WATCHING_INTERVAL
 
PROTECTED FUNCTION StopWatching
    THIS.tm.Interval = 0
    IF THIS.hNotify <> INVALID_HANDLE_VALUE
        = FindCloseChangeNotification(THIS.hNotify)
    ENDIF
 
FUNCTION _signaled        && returns signaled state
RETURN (WaitForSingleObject(THIS.hNotify, 0) = WAIT_OBJECT_0)
 
PROCEDURE _notify        && triggered on event
    LOCAL cMessage
    cMessage = "Notification: " + TTOC(DATETIME())
    THIS.lblAlert.Caption = cMessage
    ACTIVATE SCREEN
    ? cMessage
    THIS.ContinueWatching
 
PROCEDURE tm.Timer
    IF ThisForm._signaled()
        ThisForm._notify
    ENDIF
 
PROTECTED PROCEDURE declare
    DECLARE SHORT FindNextChangeNotification IN kernel32;
        INTEGER hChangeHandle
 
    DECLARE SHORT FindCloseChangeNotification IN kernel32;
        INTEGER hChangeHandle
 
    DECLARE INTEGER FindFirstChangeNotification IN kernel32;
        STRING lpPathName, INTEGER bWatchSubtree,;
        INTEGER dwNotifyFilter
 
    DECLARE INTEGER WaitForSingleObject IN kernel32;
        INTEGER hHandle, INTEGER dwMilliseconds
 
ENDDEFINE