DOCUMENT:Q268771  03-APR-2002  [foxpro]
TITLE   :FIX: DOEVENTS Command Runs Slowly
PRODUCT :Microsoft FoxPro
PROD/VER::5.0,5.0a,6.0
OPER/SYS:
KEYWORDS:kbOOP kbvfp500 kbvfp500a kbvfp600 kbGrpDSFox kbDSupport kbCodeSnippet

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a, 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

The DOEVENTS command allows your program to yield time to process Windows
events. However, in tight loops, DOEVENTS waits for an excessive amount of time
for an event.

WORKAROUND
----------

Use the MOUSE command as shown in "More Information" to give DOEVENTS something
to read.

STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft products that are
listed at the beginning of this article.

This problem was corrected in Microsoft Visual FoxPro version 7.0.

MORE INFORMATION
================

In order to reduce the previously described waiting time, following these
steps:

1. Move the mouse while you're waiting. (This is not considered to be an optimum
   solution.)

2. Programmatically feed the app events for DOEVENTS to process.

The following code shows calling DOEVENTS in a tight loop, programmatically
feeding the app events for DOEVENTS to process, and displaying the resulting
times to perform the loops:

1. Copy the following code into a program file, and note the speed difference
   between the call to DOEVENTS and the call to FastDoEvents.

NOTE: This code works better if there is actually a window open. If there is no
window open, DOEVENTS and FastDoEvents have similar execution times, which fall
between the times recorded with a window open.

   lnSeconds = SECONDS()
   FOR i = 1 to 50
      DOEVENTS
   ENDfor
   ? "Total time: " + STR(SECONDS() - lnSeconds, 7, 4)

   lnSeconds = SECONDS()
   FOR i = 1 to 50
      FastDoEvents()
   ENDfor
   ? "Total time: " + STR(SECONDS() - lnSeconds, 7, 4)

   FUNCTION FastDoEvents
      LOCAL lnRow, lnCol, lcWindow

      lcWindow = WONTOP()

      lnRow = MROW(lcWindow)
      lnCol = MCOL(lcWindow)

      IF ( lnRow > 0 ) AND ( lnCol > 0 )
         IF NOT EMPTY(lcWindow)
            MOUSE AT lnRow, lnCol WINDOW (lcWindow)
         ELSE
            MOUSE AT lnRow, lnCol 
         ENDif
      ELSE
         KEYBOARD " "
         =INKEY()
      ENDif

      DOEVENTS
   RETURN

REFERENCES
==========

For more information on the DOEVENTS and MOUSE commands, please see the Visual
FoxPro Language Reference.

Additional query words:

======================================================================
Keywords          : kbOOP kbvfp500 kbvfp500a kbvfp600 kbGrpDSFox kbDSupport kbCodeSnippet 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP600 kbVFP500a
Version           : :5.0,5.0a,6.0
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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Copyright Microsoft Corporation 2002.