[Webinar] Streamline your web hosting managementRegister Today

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 2460
  • Last Modified:

Keyboard buffer

I would like to clear the keyboard buffer in VB. Is there an API that will examine the buffer contents and allow removal or manipulation of the buffer contents.
0
ashmore
Asked:
ashmore
  • 3
  • 2
  • 2
  • +1
1 Solution
 
bruintjeCommented:
Hi ashmore,

You can use SetKeyboardState and GetKeyboardState. Came across a good example at the microsoft site with a form and a button and this was the code

Private Declare Sub GetKeyboardState Lib "user32" (lpKeyState As Any)
Private Declare Sub SetKeyboardState Lib "user32" (lpKeyState As Any)
Const VK_CAPITAL = &H14
Const VK_NUMLOCK = &H90

Private Sub Command1_Click()
    ReDim KeyboardBuffer(256) As Byte

    GetKeyboardState KeyboardBuffer(0)

    If KeyboardBuffer(VK_CAPITAL) And 1 Then
        KeyboardBuffer(VK_CAPITAL) = 0
    Else
        KeyboardBuffer(VK_CAPITAL) = 1
    End If

    If KeyboardBuffer(VK_NUMLOCK) And 1 Then
        KeyboardBuffer(VK_NUMLOCK) = 0
    Else
        KeyboardBuffer(VK_NUMLOCK) = 1
    End If

    SetKeyboardState KeyboardBuffer(0)
End Sub

Bruintje.

Aah... found the link so you can check it for yourself

http://premium.microsoft.com/msdn/library/techart/msdn_msdn167.htm

0
 
amebaCommented:
If by 'buffer' you mean 'system queue' you can use:

GetInputState
- the return value is nonzero if the function detects a mouse click or keyboard event in the system queue. Otherwise, it is zero.

GetQueueStatus (fuFlags)
- returns a value that indicates the type of messages in the queue.
QS_KEY      WM_CHAR message is in the queue.

Both functions are very fast and typically used inside speed-critical loops.
---------
There is API SetMessageQueue, but I wouldn't try it in VB
(The function must be called before any windows are created and before any messages are sent)

0
 
ashmoreAuthor Commented:
Dear Bruintje
Thanks for your reply but I need to explain more.
The GetKeyboardstate lets you know the state of any of the 256 virtual keys. The problem I am trying to solve is that if for  example the <esc> or <enter> key has been pressed 6 times it only registers in  GetKeyboardstate as being pressed once, not how many times. What I need to do is to look at the the most recent unprocessed keystrokes, analyse what the user is doing and then set the buffer to null. It must be a feature that is used in writing games. It was easy in DOS but maybe thats showing my age.
0
The new generation of project management tools

With monday.com’s project management tool, you can see what everyone on your team is working in a single glance. Its intuitive dashboards are customizable, so you can create systems that work for you.

 
amebaCommented:
ameba wrote:
>by 'buffer' you mean 'system queue'
You do!
0
 
bruintjeCommented:
Hi Ashmore,

Well reject my answer and give ameba a chance. Thinks his comments are more of an solution to your problem.
0
 
amebaCommented:
I don't have solution. I suggest ashmore use
  If GetQueueStatus(QS_KEY)<>0 Then ' something new is in the queue
    If GetKeyState(VK_ENTER) < 0 Then
        ' set some public flags that indicate enter pressed
    ElseIf GetKeyState(VK_ESCAPE) < 0 Then
        ' set some other public flags
    End If
  End If

and use some logic that examines flags in key processing routine.

0
 
ashmoreAuthor Commented:
Rejected on  bruintje advice. Thank you for your help.
0
 
kishor33Commented:
You are not required to use a API call for clearing the content of the keyboard instead use the combination of doevent procedure and keydown event to clear the content of the keyboard buffer.

Hope it will help

Thank you,
Birendra
0

Featured Post

Hire Technology Freelancers with Gigs

Work with freelancers specializing in everything from database administration to programming, who have proven themselves as experts in their field. Hire the best, collaborate easily, pay securely, and get projects done right.

  • 3
  • 2
  • 2
  • +1
Tackle projects and never again get stuck behind a technical roadblock.
Join Now