Capturing Carriage Return

[senfo]

Hello all,

To help alleviate human error, I'm developing an application that uses a
barcode reader to fill in a value in a TextBox control. The barcode
reader is connected to the PC through the PS2 keyboard jack, so to
Windows, it's essentially just a keyboard. After the reader has
finished reading the barcode, it sends out Ctrl + M (which I *think* is
a carriage return).

To capture the Ctrl + M, I configured an event handler for the
PreviewKeyDown event. In the event handler, I have tried the following:

private void MyTextBox_Previ ewKeyDown(objec t sender,
PreviewKeyDownE ventArgs e)
{
// First way I tried
if (e.Control && e.KeyCode == Keys.M)
{
ShowNewDialog() ;
}

// Second way I tried
if ((int) e.KeyData == (int) (Keys.M | Keys.Control))
{
ShowNewDialog() ;
}
}

Essentially, both of them do the same thing, but the first one is less
confusing to somebody that reads my code later.

At any rate, the code works --kind of. The problem is that after
ShowNewDialog() returns, the letter "m" shows up in the MyTextBox
control. If I comment out the call to ShowNewDialog() , the letter "m"
never shows up.

Short of an ugly "fix", such as removing the letter "m" after
ShowNewDialog() returns, I'm not sure what else to do. I was hoping
there was a better way of capturing the carriage return that I haven't
thought of.

Any suggestions?

Thank you in advance,

--
Sean

[Morten Wennevik]

Hi,

Any reason for using PreviewKeyDown instead of KeyDown?

If you are using KeyDown you can use the KeyEventArgs.Ha ndled = true to
suppress keys

On Fri, 03 Nov 2006 15:45:52 +0100, senfo
<en**********@y ahoo.comI-WANT-NO-SPAMwrote:

Hello all,

To help alleviate human error, I'm developing an application that usesa
barcode reader to fill in a value in a TextBox control. The barcode
reader is connected to the PC through the PS2 keyboard jack, so to
Windows, it's essentially just a keyboard. After the reader has
finished reading the barcode, it sends out Ctrl + M (which I *think* is
a carriage return).

To capture the Ctrl + M, I configured an event handler for the
PreviewKeyDown event. In the event handler, I have tried the following:

private void MyTextBox_Previ ewKeyDown(objec t sender,
PreviewKeyDownE ventArgs e)
{
// First way I tried
if (e.Control && e.KeyCode == Keys.M)
{
ShowNewDialog() ;
}

// Second way I tried
if ((int) e.KeyData == (int) (Keys.M | Keys.Control))
{
ShowNewDialog() ;
}
}

Essentially, both of them do the same thing, but the first one is less
confusing to somebody that reads my code later.

At any rate, the code works --kind of. The problem is that after
ShowNewDialog() returns, the letter "m" shows up in the MyTextBox
control. If I comment out the call to ShowNewDialog() , the letter "m"
never shows up.

Short of an ugly "fix", such as removing the letter "m" after
ShowNewDialog() returns, I'm not sure what else to do. I was hoping
there was a better way of capturing the carriage return that I haven't
thought of.

Any suggestions?

Thank you in advance,

--
Happy Coding!
Morten Wennevik [C# MVP]

[senfo]

Morten Wennevik wrote:

Any reason for using PreviewKeyDown instead of KeyDown?

If you are using KeyDown you can use the KeyEventArgs.Ha ndled = true to
suppress keys

Hi Morten,

That's a good question and I don't have an answer for you. Using the
KeyDown event fixed everything.

Thank you very much!

--
Sean