C# or .NET Flushing Keyboard Buffer

Question

How do I flush the keyboard buffer in C# using Windows Forms?

I have a barcode scanner which acts like a keyboard. If a really long barcode is scanned and the cancel

Answer 1

@Chris:

Console.KeyAvailable threw an exception on me because the Console did not have focus.

The exception message was helpful, though. It suggested using Console.In.Peek() to read in that instance.

I thought it would be worth noting here as an alternate solution and for posterity.

 if (-1 < Console.In.Peek()) {
     Console.In.ReadToEnd();
 }

Answer 2

You could do BIOS level flushing (http://support.microsoft.com/?scid=kb%3Ben-us%3B43993&x=22&y=10) but I would advise against this low level approach since Windows also does keyboard buffering on a higher level.

The best way seems to be to eat any arriving char while a specific flag is set. As SLaks suggests I would set KeyPreview to true and set e.Handled to true either in KeyPress or in KeyDown.. should make no difference.

Answer 3

Disable the form, and force all processing to occur with DoEvents whilst it's disabled. The Controls should reject any keystokes because they are disabled. Then re-enable the form.

this.Enabled = false;
Application.DoEvents();
this.Enabled = true;

Answer 4

while (Console.KeyAvailable) { Console.ReadKey(true); }

Answer 5

It's a old question but I got the same issue and I found a good way to do it...
When Application.DoEvent() is called, the keystoke buffer call the KeyPress event but _keypress is set to false, so it'll skip all them, after that _keypress return to true to be ready for another keypress event !

Public _keypress As Boolean
Private Sub Form1_KeyPress(sender As Object, e As KeyPressEventArgs) Handles Form1.KeyPress
    If Not _keypress Then
        _keypress = True
        //instructions
    End If
    Application.DoEvents()
    _keypress = False
End Sub

Answer 6

Set KeyPreview on the Form to true, then catch the KeyPress event and set e.Handled to true if cancel was clicked.

EDIT: Catch the Form's KeyPress event