How clear the input buffer

[twgonder]

Another dumb question, not knowing its name in VBA.
I have a form where the user can just hold down the Enter key and various sequential procedures run based on the proximate command button that gets focus.
The problem is, something gets messed up and the procedures don't always run in the order they should.


I'm guessing it's some problem with the input buffer for keystrokes that craps itself.

I never had this kind of problem on other computer systems, maybe it's Windows caused or by using an API?
In any case, I'm looking for a command that will clear the input buffer, so that all the extra keystrokes are discarded before returning control to the form.

Does VBA have such a thing? Or am I barking up the wrong tree?

Read the textbox from the bottom up.

[orange]

What code is behind your buttons?

[twgonder]

@orange #2 The only thing kinda out of the norm are these statements:

Private Declare PtrSafe Function GetTickCount64 Lib "kernel32" () As LongPtr
...
arStrCnt(1, aPos) = GetTickCount64

These are well documented by IslaDogs, and if there is a problem with them, I'm surprised he hasn't reported it (as far as I've seen).

[orange]

OK you're familiar with the Timing info from Colin. I'm not sure what is causing the sequencing variation. I haven't experienced that.
I haven't toyed with GetTickCount64.
I use this api

#If VBA7 Then
Private Declare PtrSafe Function apiGetTime Lib "winmm.dll" _
                                    Alias "timeGetTime" () As Long
 #Else
Private Declare Function apiGetTime Lib "winmm.dll" _
                                    Alias "timeGetTime" () As Long
#End If

[twgonder]

@orange #4 I've got to get permission to post the .accdb. Maybe tomorrow. Then we can see if it's problematic on different machines.

[isladogs]

I have never seen issues with GetTickCount64 or GetTickCount but I normally use the latter.

There is no advantage in using GetTickCount64 for this kind of test. In case it helps, you could try replacing with GetTickCount which will do the same job

Declare PtrSafe Function GetTickCount Lib "kernel32" () As Long

For a discussion about why the two functions exist, see the GetTickCount/GetTickCount64 section of my article: 32 to 64-bit: Conditional Compilation (isladogs.co.uk)

Or try another timer such as GetSystemTime

However, I suspect any issues are to do with your code rather than the API used for timing.

[twgonder]

@ IslaDogs #6 I read your great article, a few times. You mentioned GetTickCount64 pretty extensively, so I went with that.

I've been testing to see if there's a difference in delays between Sleep 1 and Sleep 15, and it may be my imagination that Sleep 15 runs a bit slower. Is this just my imagination based on the system clock being no finer than 16 ms or has anything changed in Windows or hardware lately?

[isladogs]

I doubt that GetTickCount64 is the issue but I don't use it myself. I do use GetTickCount

I also only use the Sleep API to cause delays of at least 100 milliseconds and have never tested it for anything less than the system clock interval
I don't know whether modern PCs have a faster system clock - my main workstation is 12 years old and is still subject to a precision of +-16 milliseconds

If that isn't precise enough for you, try using the high resolution timer which can measure to <1 microsecond. For most purposes, this is overkill in my opinion.

[twgonder]

@ All I still haven't heard back from my contact about sharing the db, but I isolated the problem a bit better.
In the status area of the form (see post #1) there is a procedure that adds text to the textbox.
At the end of the procedure is a DoEvents. Normally this is there for large status messages that get built for testing, to show immediately.

It seems that holding down the Enter key and with the DoEvents running allows the command buttons to run out of order.
Commenting out the 'DoEvents allows the command buttons (and procedures) to run in proper order.

I haven't fully wrapped my brain around it yet. I'm guessing it's something like the input buffer is filled with Enters while a procedure is running,
and then the DoEvents skips what's waiting and goes to the next key press.

If not for this problem, I would still like to know a way to clear an input buffer if possible.
Let's say an impatient user starts clicking/typing all over a form while a long procedure is running,
I want to delete all the clicks and keystrokes to start fresh for the next input.
Make sense?

[twgonder]

Okay, nothing about clearing user actions from the peanut gallery.

How about a way to stop all user actions while still allowing DoEvents to run?
(I think this is not a great solution in some cases, like if the user might need to press a cancel button during a big process.)

[Welshgasman]

Just thought I would ask Google as that is always my first point of call.
https://www.mrexcel.com/board/thread...buffer.254206/

[CJ_London]

perhaps lock keyboard and mouse so the buffer doesn't fill in the first place
https://www.mrexcel.com/board/thread...yboard.410739/

[twgonder]

@ Welshgasman & CJ_London #11 & #12
Thanks for those links. I do search Google first, but I'm often at a disadvantage because I'm not sure what vernacular to use or the name of some MS feature, as MS often changes it from a name that served in other systems for decades. In this case it seems to be an API that might affect all of Windows, and not just Access. Hmmm, not so sure about that.

Some of the samples look a bit complicated, so I'll have to get into them next chance I get.

[Welshgasman]

@ Welshgasman & CJ_London #11 & #12
Thanks for those links. I do search Google first, but I'm often at a disadvantage because I'm not sure what vernacular to use or the name of some MS feature, as MS often changes it from a name that served in other systems for decades. In this case it seems to be an API that might affect all of Windows, and not just Access. Hmmm, not so sure about that.

Some of the samples look a bit complicated, so I'll have to get into them next chance I get.

My search was 'clear input buffer vba'