Trying to "display" control characters in a text box

I have a barcode scanner which uses a "keyboard wedge" program so that the
data it scans comes through as if it was typed on a keyboard. I am trying
to have the data in the barcode be displayed in a text box. I know that
there are certain control characters embedded in the data that I want to
display substitutions for in the text box, for instance I want to replace
ASCII character 04 with the string "<EOT>". I have tried doing a simple
replace in the TextChanged event, but it appears that the Textbox Control
strips out the control characters as they come in. I also tried catching
the "keystrokes" using the KeyUp event, but that seems to have done
something (and I can't figure out what) with some of the control characters
and added other characters that are not in the data. Does anyone have any
suggestions as to how I can accomplish this? I know what the data encoded
in the barcode is, and I can verify that the scanner is reading it
properly - I just can't get it into a VB.Net text box properly.

TIA
Ron L

re: Trying to "display" control characters in a text box

Try creating a simple Console Application and read in the keyboard buffer,
this should make it easier to 'Replace' non printable characters...

"Ron L" wrote:
[color=blue]
> I have a barcode scanner which uses a "keyboard wedge" program so that the
> data it scans comes through as if it was typed on a keyboard. I am trying
> to have the data in the barcode be displayed in a text box. I know that
> there are certain control characters embedded in the data that I want to
> display substitutions for in the text box, for instance I want to replace
> ASCII character 04 with the string "<EOT>". I have tried doing a simple
> replace in the TextChanged event, but it appears that the Textbox Control
> strips out the control characters as they come in. I also tried catching
> the "keystrokes" using the KeyUp event, but that seems to have done
> something (and I can't figure out what) with some of the control characters
> and added other characters that are not in the data. Does anyone have any
> suggestions as to how I can accomplish this? I know what the data encoded
> in the barcode is, and I can verify that the scanner is reading it
> properly - I just can't get it into a VB.Net text box properly.
>
> TIA
> Ron L
>
>
>[/color]

re: Trying to "display" control characters in a text box

Ron,

How the barcode scanner enters this ASCII (04)? Is it actully simulates
pressing Ctrl+D? If it does it is no surprise that the TextBox strips them
out - for the TextBox Ctrl+D is not defined shortcut so it just skips it
(probably it produces some beeping sound depending on the sound scheme). The
same way the TextBox will perfome copy operation if your barcode scanner is
trying to send ASCII(03) in this way.


--

Stoitcho Goutsev (100)

"Ron L" <ronl@bogus.Address.com> wrote in message
news:eBwaydxVGHA.2360@TK2MSFTNGP09.phx.gbl...[color=blue]
>I have a barcode scanner which uses a "keyboard wedge" program so that the
>data it scans comes through as if it was typed on a keyboard. I am trying
>to have the data in the barcode be displayed in a text box. I know that
>there are certain control characters embedded in the data that I want to
>display substitutions for in the text box, for instance I want to replace
>ASCII character 04 with the string "<EOT>". I have tried doing a simple
>replace in the TextChanged event, but it appears that the Textbox Control
>strips out the control characters as they come in. I also tried catching
>the "keystrokes" using the KeyUp event, but that seems to have done
>something (and I can't figure out what) with some of the control characters
>and added other characters that are not in the data. Does anyone have any
>suggestions as to how I can accomplish this? I know what the data encoded
>in the barcode is, and I can verify that the scanner is reading it
>properly - I just can't get it into a VB.Net text box properly.
>
> TIA
> Ron L
>
>[/color]

re: Trying to "display" control characters in a text box

Hello, Ron,

Is it possible that you can move the scanned input to a String variable
first. If so then you can just replace the control characters in the
string before you move it to the TextBox. Something like:

TextBox1.text = ReplaceCCs(strInput)

where ReplaceCCs is a function, in VB something like:

Private Function ReplaceCCs(ByVal Input As String) As String

' Fill in the "TBC"s with appropriate replacement strings:
Dim straSubs() As String = {"<Nul>", "<TBC>", "<TBC>", "<TBC>", _
"<TBC>", "<TBC>", "<TBC>", "<TBC>", _
"<TBC>", "<Tab>", "<LF>", "<VT>", _
"<FF>", "<CR>", "<TBC>", "<TBC>", _
"<TBC>", "<TBC>", "<TBC>", "<TBC>", _
"<TBC>", "<TBC>", "<TBC>", "<TBC>", _
"<TBC>", "<TBC>", "<TBC>", "<TBC>", _
"<TBC>", "<TBC>", "<TBC>", "<TBC>"}
Dim strOut As String = Input
For intChar As Integer = 0 To 31
strOut = strOut.Replace(Chr(intChar), straSubs(intChar))
Next intChar

strOut = strOut.Replace(Chr(127), "<Del>")

Return strOut

End Function

I've been a bit lazy, and not filled in all the appropriate substitution
codes -- just a few I could easily remember.

Cheers,
Randy


Ron L wrote:
[color=blue]
> I have a barcode scanner which uses a "keyboard wedge" program so that the
> data it scans comes through as if it was typed on a keyboard. I am trying
> to have the data in the barcode be displayed in a text box. I know that
> there are certain control characters embedded in the data that I want to
> display substitutions for in the text box, for instance I want to replace
> ASCII character 04 with the string "<EOT>". I have tried doing a simple
> replace in the TextChanged event, but it appears that the Textbox Control
> strips out the control characters as they come in. I also tried catching
> the "keystrokes" using the KeyUp event, but that seems to have done
> something (and I can't figure out what) with some of the control characters
> and added other characters that are not in the data. Does anyone have any
> suggestions as to how I can accomplish this? I know what the data encoded
> in the barcode is, and I can verify that the scanner is reading it
> properly - I just can't get it into a VB.Net text box properly.
>
> TIA
> Ron L
>
>[/color]

re: Trying to "display" control characters in a text box

Randy

Thanks for the response. My problem is that the scanner acts like a
keyboard, so I'm not sure how to get the original informaion into a string
in the first place. I have tried catching the key up event, but I haven't
figured out what to place in the string to get the control characters into
the string. I have printed out the key values, and can't find a correlation
between the key value or key code and the control character I am expecting
to see.

Ron L


"R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
news:44323655$0$10561$dbd43001@news.wanadoo.nl...[color=blue]
> Hello, Ron,
>
> Is it possible that you can move the scanned input to a String variable
> first. If so then you can just replace the control characters in the
> string before you move it to the TextBox. Something like:
>
> TextBox1.text = ReplaceCCs(strInput)
>
> where ReplaceCCs is a function, in VB something like:
>
> Private Function ReplaceCCs(ByVal Input As String) As String
>
> ' Fill in the "TBC"s with appropriate replacement strings:
> Dim straSubs() As String = {"<Nul>", "<TBC>", "<TBC>", "<TBC>", _
> "<TBC>", "<TBC>", "<TBC>", "<TBC>", _
> "<TBC>", "<Tab>", "<LF>", "<VT>", _
> "<FF>", "<CR>", "<TBC>", "<TBC>", _
> "<TBC>", "<TBC>", "<TBC>", "<TBC>", _
> "<TBC>", "<TBC>", "<TBC>", "<TBC>", _
> "<TBC>", "<TBC>", "<TBC>", "<TBC>", _
> "<TBC>", "<TBC>", "<TBC>", "<TBC>"}
> Dim strOut As String = Input
> For intChar As Integer = 0 To 31
> strOut = strOut.Replace(Chr(intChar), straSubs(intChar))
> Next intChar
>
> strOut = strOut.Replace(Chr(127), "<Del>")
>
> Return strOut
>
> End Function
>
> I've been a bit lazy, and not filled in all the appropriate substitution
> codes -- just a few I could easily remember.
>
> Cheers,
> Randy
>
>
> Ron L wrote:
>[color=green]
>> I have a barcode scanner which uses a "keyboard wedge" program so that
>> the data it scans comes through as if it was typed on a keyboard. I am
>> trying to have the data in the barcode be displayed in a text box. I
>> know that there are certain control characters embedded in the data that
>> I want to display substitutions for in the text box, for instance I want
>> to replace ASCII character 04 with the string "<EOT>". I have tried
>> doing a simple replace in the TextChanged event, but it appears that the
>> Textbox Control strips out the control characters as they come in. I
>> also tried catching the "keystrokes" using the KeyUp event, but that
>> seems to have done something (and I can't figure out what) with some of
>> the control characters and added other characters that are not in the
>> data. Does anyone have any suggestions as to how I can accomplish this?
>> I know what the data encoded in the barcode is, and I can verify that the
>> scanner is reading it properly - I just can't get it into a VB.Net text
>> box properly.
>>
>> TIA
>> Ron L
>>[/color][/color]

re: Trying to "display" control characters in a text box

Hello, Ron,

I've never worked with a scanner, so please excuse my ignorance. What
kind of control is it that receives the input? (I had assumed it would
be something akin to a TextBox and you could just use the Text property
after completion of the input.)

But when you say that you're catching the key-up event, perhaps the
processing required is more sophisticated than I realized.

Can you provide any additional information, or perhaps an example of the
code that you are trying to make work?

Cheers,
Randy


Ron L wrote:[color=blue]
> Randy
>
> Thanks for the response. My problem is that the scanner acts like a
> keyboard, so I'm not sure how to get the original informaion into a string
> in the first place. I have tried catching the key up event, but I haven't
> figured out what to place in the string to get the control characters into
> the string. I have printed out the key values, and can't find a correlation
> between the key value or key code and the control character I am expecting
> to see.
>
> Ron L[/color]

re: Trying to "display" control characters in a text box

Randy

I am using a text box control, but apparently there is logic in that control
that strips out most of the control characters (ASCII values < 32) before
entering them into the Text property. I had hoped that by catching the
Key-up event I could somehow "bypass" the code that removes the control
characters.

As far as the scanner is concerned, it is simply acting as if it is a
keyboard and is sending on the characters that were "typed".

Thanks,

Ron L

"R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
news:44336a01$0$3998$dbd41001@news.wanadoo.nl...[color=blue]
> Hello, Ron,
>
> I've never worked with a scanner, so please excuse my ignorance. What
> kind of control is it that receives the input? (I had assumed it would be
> something akin to a TextBox and you could just use the Text property after
> completion of the input.)
>
> But when you say that you're catching the key-up event, perhaps the
> processing required is more sophisticated than I realized.
>
> Can you provide any additional information, or perhaps an example of the
> code that you are trying to make work?
>
> Cheers,
> Randy
>
>
> Ron L wrote:[color=green]
>> Randy
>>
>> Thanks for the response. My problem is that the scanner acts like a
>> keyboard, so I'm not sure how to get the original informaion into a
>> string in the first place. I have tried catching the key up event, but I
>> haven't figured out what to place in the string to get the control
>> characters into the string. I have printed out the key values, and can't
>> find a correlation between the key value or key code and the control
>> character I am expecting to see.
>>
>> Ron L[/color][/color]

re: Trying to "display" control characters in a text box

Hello, Ron,

I'm not aware of any logic that strips out control characters from a
TextBox. For example, when I type into a multiline textBox using a
keyboard I can easily insert new line characters (<CR><LF>) by typing
<CNTL><Enter>, or other control characters by using Copy/Paste. These
are returned in the Text property.

Also, almost all keystrokes (including the Control keys) are available
via the Key-up events. (As I recall there are a few "navigation" keys
that do not normally appear there, but I think that even these can be
persuaded to appear with a little extra work.)

I wonder if there is something between the scanner driver and the
TextBox that is swallowing the characters you are expecting to see. Do
you have KeyPreview enabled for the Form that contains the TextBox? Or
is there possibly something more sophisticated such as an override of
WndProc interfering?

Anyway, I'm rather doubtful that the problem is with the TextBox.

Cheers,
Randy


Ron L wrote:
[color=blue]
> Randy
>
> I am using a text box control, but apparently there is logic in that control
> that strips out most of the control characters (ASCII values < 32) before
> entering them into the Text property. I had hoped that by catching the
> Key-up event I could somehow "bypass" the code that removes the control
> characters.
>
> As far as the scanner is concerned, it is simply acting as if it is a
> keyboard and is sending on the characters that were "typed".
>
> Thanks,
>
> Ron L
>
> "R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
> news:44336a01$0$3998$dbd41001@news.wanadoo.nl...
>[color=green]
>>Hello, Ron,
>>
>>I've never worked with a scanner, so please excuse my ignorance. What
>>kind of control is it that receives the input? (I had assumed it would be
>>something akin to a TextBox and you could just use the Text property after
>>completion of the input.)
>>
>>But when you say that you're catching the key-up event, perhaps the
>>processing required is more sophisticated than I realized.
>>
>>Can you provide any additional information, or perhaps an example of the
>>code that you are trying to make work?
>>
>>Cheers,
>>Randy
>>
>>
>>Ron L wrote:
>>[color=darkred]
>>>Randy
>>>
>>>Thanks for the response. My problem is that the scanner acts like a
>>>keyboard, so I'm not sure how to get the original informaion into a
>>>string in the first place. I have tried catching the key up event, but I
>>>haven't figured out what to place in the string to get the control
>>>characters into the string. I have printed out the key values, and can't
>>>find a correlation between the key value or key code and the control
>>>character I am expecting to see.
>>>
>>>Ron L[/color][/color]
>
>
>[/color]

re: Trying to "display" control characters in a text box

Randy

Sorry, I should have been more specific. The text box removes *some* of the
control characters. My string has the RS (ASCII 30), GS (ASCII 29), and EOT
(ASCII 4) embedded in it. These are commonly represented as ctl-^, ctl-],
and ctl-D, respectively. If I open a command prompt and scan the label I
see all the expected control characters on the entered line, but in the text
box the GS and EOT have been stripped out! Given that, I am reasonably that
either the TextBox or some portion of the windows key event handling is
removing the GS and EOT characters from my input string.

Arrggghhhh!


Ron L


"R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
news:44341f25$0$84976$dbd49001@news.wanadoo.nl...[color=blue]
> Hello, Ron,
>
> I'm not aware of any logic that strips out control characters from a
> TextBox. For example, when I type into a multiline textBox using a
> keyboard I can easily insert new line characters (<CR><LF>) by typing
> <CNTL><Enter>, or other control characters by using Copy/Paste. These are
> returned in the Text property.
>
> Also, almost all keystrokes (including the Control keys) are available via
> the Key-up events. (As I recall there are a few "navigation" keys that do
> not normally appear there, but I think that even these can be persuaded to
> appear with a little extra work.)
>
> I wonder if there is something between the scanner driver and the TextBox
> that is swallowing the characters you are expecting to see. Do you have
> KeyPreview enabled for the Form that contains the TextBox? Or is there
> possibly something more sophisticated such as an override of WndProc
> interfering?
>
> Anyway, I'm rather doubtful that the problem is with the TextBox.
>
> Cheers,
> Randy
>
>
> Ron L wrote:
>[color=green]
>> Randy
>>
>> I am using a text box control, but apparently there is logic in that
>> control that strips out most of the control characters (ASCII values <
>> 32) before entering them into the Text property. I had hoped that by
>> catching the Key-up event I could somehow "bypass" the code that removes
>> the control characters.
>>
>> As far as the scanner is concerned, it is simply acting as if it is a
>> keyboard and is sending on the characters that were "typed".
>>
>> Thanks,
>>
>> Ron L
>>
>> "R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
>> news:44336a01$0$3998$dbd41001@news.wanadoo.nl...
>>[color=darkred]
>>>Hello, Ron,
>>>
>>>I've never worked with a scanner, so please excuse my ignorance. What
>>>kind of control is it that receives the input? (I had assumed it would
>>>be something akin to a TextBox and you could just use the Text property
>>>after completion of the input.)
>>>
>>>But when you say that you're catching the key-up event, perhaps the
>>>processing required is more sophisticated than I realized.
>>>
>>>Can you provide any additional information, or perhaps an example of the
>>>code that you are trying to make work?
>>>
>>>Cheers,
>>>Randy
>>>
>>>
>>>Ron L wrote:
>>>
>>>>Randy
>>>>
>>>>Thanks for the response. My problem is that the scanner acts like a
>>>>keyboard, so I'm not sure how to get the original informaion into a
>>>>string in the first place. I have tried catching the key up event, but
>>>>I haven't figured out what to place in the string to get the control
>>>>characters into the string. I have printed out the key values, and
>>>>can't find a correlation between the key value or key code and the
>>>>control character I am expecting to see.
>>>>
>>>>Ron L[/color]
>>
>>[/color][/color]

re: Trying to "display" control characters in a text box

Hello, Ron,

Perhaps these keys are being swallowed by some preprocessing on the
form. Have a look at the help for the "IsInputKey" (and possibly the
"IsInputChar") function. Perhaps they will help you out. I have
previously used the former in order to "capture" some of the navigation
keys. Here is an example of IsInputKey:

Protected Overrides _
Function IsInputKey(ByVal keyData As Keys) As Boolean
' Inhibit pre-processing for selected "special" keys
' that are handled directly by the control.
Select Case keyData
Case Keys.Down, Keys.Left, Keys.Right, Keys.Up
Return (Me.UserMode = aenmUserMode.Design)
Case Else
Return False
End Select

End Function

Cheers,
Randy


Ron L wrote:
[color=blue]
> Randy
>
> Sorry, I should have been more specific. The text box removes *some* of the
> control characters. My string has the RS (ASCII 30), GS (ASCII 29), and EOT
> (ASCII 4) embedded in it. These are commonly represented as ctl-^, ctl-],
> and ctl-D, respectively. If I open a command prompt and scan the label I
> see all the expected control characters on the entered line, but in the text
> box the GS and EOT have been stripped out! Given that, I am reasonably that
> either the TextBox or some portion of the windows key event handling is
> removing the GS and EOT characters from my input string.
>
> Arrggghhhh!
>
>
> Ron L
>
>
> "R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
> news:44341f25$0$84976$dbd49001@news.wanadoo.nl...
>[color=green]
>>Hello, Ron,
>>
>>I'm not aware of any logic that strips out control characters from a
>>TextBox. For example, when I type into a multiline textBox using a
>>keyboard I can easily insert new line characters (<CR><LF>) by typing
>><CNTL><Enter>, or other control characters by using Copy/Paste. These are
>>returned in the Text property.
>>
>>Also, almost all keystrokes (including the Control keys) are available via
>>the Key-up events. (As I recall there are a few "navigation" keys that do
>>not normally appear there, but I think that even these can be persuaded to
>>appear with a little extra work.)
>>
>>I wonder if there is something between the scanner driver and the TextBox
>>that is swallowing the characters you are expecting to see. Do you have
>>KeyPreview enabled for the Form that contains the TextBox? Or is there
>>possibly something more sophisticated such as an override of WndProc
>>interfering?
>>
>>Anyway, I'm rather doubtful that the problem is with the TextBox.
>>
>>Cheers,
>>Randy
>>
>>
>>Ron L wrote:
>>
>>[color=darkred]
>>>Randy
>>>
>>>I am using a text box control, but apparently there is logic in that
>>>control that strips out most of the control characters (ASCII values <
>>>32) before entering them into the Text property. I had hoped that by
>>>catching the Key-up event I could somehow "bypass" the code that removes
>>>the control characters.
>>>
>>>As far as the scanner is concerned, it is simply acting as if it is a
>>>keyboard and is sending on the characters that were "typed".
>>>
>>>Thanks,
>>>
>>>Ron L
>>>
>>>"R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
>>>news:44336a01$0$3998$dbd41001@news.wanadoo.nl.. .
>>>
>>>
>>>>Hello, Ron,
>>>>
>>>>I've never worked with a scanner, so please excuse my ignorance. What
>>>>kind of control is it that receives the input? (I had assumed it would
>>>>be something akin to a TextBox and you could just use the Text property
>>>>after completion of the input.)
>>>>
>>>>But when you say that you're catching the key-up event, perhaps the
>>>>processing required is more sophisticated than I realized.
>>>>
>>>>Can you provide any additional information, or perhaps an example of the
>>>>code that you are trying to make work?
>>>>
>>>>Cheers,
>>>>Randy
>>>>
>>>>
>>>>Ron L wrote:
>>>>
>>>>
>>>>>Randy
>>>>>
>>>>>Thanks for the response. My problem is that the scanner acts like a
>>>>>keyboard, so I'm not sure how to get the original informaion into a
>>>>>string in the first place. I have tried catching the key up event, but
>>>>>I haven't figured out what to place in the string to get the control
>>>>>characters into the string. I have printed out the key values, and
>>>>>can't find a correlation between the key value or key code and the
>>>>>control character I am expecting to see.
>>>>>
>>>>>Ron L
>>>
>>>[/color][/color]
>[/color]

re: Trying to "display" control characters in a text box

Randy

Thanks, that definitely was a step in the right direction. I put in both
the IsInputKey and IsInputChar routines (included below) and I now get the
RS character in the final output. I still don't get the GS and EOT
characters, though, even though they are handled in the IsInputChar routine
(I see the debug printouts). I suspect that this is due to a problem with
how I am handling them in the IsInputKey routine. Do you have any other
suggestions?

Thanks again,
Ron L


'********************* ControlCharactersTextBox Class
********************************
Imports System.Windows.Forms

Public Class CtlCharTextBox
Inherits System.Windows.Forms.TextBox

Protected Overrides Function IsInputKey(ByVal keyData As
System.Windows.Forms.Keys) As Boolean
If (keyData And Keys.Control) And (keyData And Keys.D) Then
Debug.WriteLine("IsInputKey: <EOT>")
Return True
ElseIf (keyData And Keys.Control) And (keyData And
Keys.OemCloseBrackets) Then
Debug.WriteLine("IsInputKey: <GS>")
Return True
ElseIf (keyData And Keys.Control) And (keyData And Keys.D6) Then
Debug.WriteLine("IsInputKey: <RS>")
Return True
Else
Return MyBase.IsInputKey(keyData)
End If
End Function

Protected Overrides Function IsInputChar(ByVal charCode As Char) As
Boolean
'Return MyBase.IsInputChar(charCode)
Select Case Asc(charCode)
Case 4 ' EOT character
'Debug.Write(Asc(charCode) & ", " & "<EOT> ")
Return True
Case 29 ' GS character
'Debug.Write(Asc(charCode) & ", " & "<GS> ")
Return True
Case 30 ' RS character
'Debug.Write(Asc(charCode) & ", " & "<RS> ")
Return True
Case Else
'Debug.Write(Asc(charCode) & ", " & charCode & " ")
Return MyBase.IsInputChar(charCode)
End Select
End Function
End Class


"R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
news:44357177$0$7330$dbd43001@news.wanadoo.nl...[color=blue]
> Hello, Ron,
>
> Perhaps these keys are being swallowed by some preprocessing on the form.
> Have a look at the help for the "IsInputKey" (and possibly the
> "IsInputChar") function. Perhaps they will help you out. I have
> previously used the former in order to "capture" some of the navigation
> keys. Here is an example of IsInputKey:
>
> Protected Overrides _
> Function IsInputKey(ByVal keyData As Keys) As Boolean
> ' Inhibit pre-processing for selected "special" keys
> ' that are handled directly by the control.
> Select Case keyData
> Case Keys.Down, Keys.Left, Keys.Right, Keys.Up
> Return (Me.UserMode = aenmUserMode.Design)
> Case Else
> Return False
> End Select
>
> End Function
>
> Cheers,
> Randy
>
>
> Ron L wrote:
>[color=green]
>> Randy
>>
>> Sorry, I should have been more specific. The text box removes *some* of
>> the control characters. My string has the RS (ASCII 30), GS (ASCII 29),
>> and EOT (ASCII 4) embedded in it. These are commonly represented as
>> ctl-^, ctl-], and ctl-D, respectively. If I open a command prompt and
>> scan the label I see all the expected control characters on the entered
>> line, but in the text box the GS and EOT have been stripped out! Given
>> that, I am reasonably that either the TextBox or some portion of the
>> windows key event handling is removing the GS and EOT characters from my
>> input string.
>>
>> Arrggghhhh!
>>
>>
>> Ron L
>>
>>
>> "R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
>> news:44341f25$0$84976$dbd49001@news.wanadoo.nl...
>>[color=darkred]
>>>Hello, Ron,
>>>
>>>I'm not aware of any logic that strips out control characters from a
>>>TextBox. For example, when I type into a multiline textBox using a
>>>keyboard I can easily insert new line characters (<CR><LF>) by typing
>>><CNTL><Enter>, or other control characters by using Copy/Paste. These
>>>are returned in the Text property.
>>>
>>>Also, almost all keystrokes (including the Control keys) are available
>>>via the Key-up events. (As I recall there are a few "navigation" keys
>>>that do not normally appear there, but I think that even these can be
>>>persuaded to appear with a little extra work.)
>>>
>>>I wonder if there is something between the scanner driver and the TextBox
>>>that is swallowing the characters you are expecting to see. Do you have
>>>KeyPreview enabled for the Form that contains the TextBox? Or is there
>>>possibly something more sophisticated such as an override of WndProc
>>>interfering?
>>>
>>>Anyway, I'm rather doubtful that the problem is with the TextBox.
>>>
>>>Cheers,
>>>Randy
>>>
>>>
>>>Ron L wrote:
>>>
>>>
>>>>Randy
>>>>
>>>>I am using a text box control, but apparently there is logic in that
>>>>control that strips out most of the control characters (ASCII values <
>>>>32) before entering them into the Text property. I had hoped that by
>>>>catching the Key-up event I could somehow "bypass" the code that removes
>>>>the control characters.
>>>>
>>>>As far as the scanner is concerned, it is simply acting as if it is a
>>>>keyboard and is sending on the characters that were "typed".
>>>>
>>>>Thanks,
>>>>
>>>>Ron L
>>>>
>>>>"R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
>>>>news:44336a01$0$3998$dbd41001@news.wanadoo.nl. ..
>>>>
>>>>
>>>>>Hello, Ron,
>>>>>
>>>>>I've never worked with a scanner, so please excuse my ignorance. What
>>>>>kind of control is it that receives the input? (I had assumed it would
>>>>>be something akin to a TextBox and you could just use the Text property
>>>>>after completion of the input.)
>>>>>
>>>>>But when you say that you're catching the key-up event, perhaps the
>>>>>processing required is more sophisticated than I realized.
>>>>>
>>>>>Can you provide any additional information, or perhaps an example of
>>>>>the code that you are trying to make work?
>>>>>
>>>>>Cheers,
>>>>>Randy
>>>>>
>>>>>
>>>>>Ron L wrote:
>>>>>
>>>>>
>>>>>>Randy
>>>>>>
>>>>>>Thanks for the response. My problem is that the scanner acts like a
>>>>>>keyboard, so I'm not sure how to get the original informaion into a
>>>>>>string in the first place. I have tried catching the key up event,
>>>>>>but I haven't figured out what to place in the string to get the
>>>>>>control characters into the string. I have printed out the key
>>>>>>values, and can't find a correlation between the key value or key code
>>>>>>and the control character I am expecting to see.
>>>>>>
>>>>>>Ron L
>>>>
>>>>[/color]
>>[/color][/color]

re: Trying to "display" control characters in a text box

Hello, Ron,

I'm at a bit of a loss here. But I'm thinking that the TextBox control
might not be your best solution. I'm afraid that I'm out of my depth
here, and so can't give you much good advice, but here are some
"under-processed" thoughts:

Perhaps you can simply capture the characters that you need in the
IsInputKey or IsCharKey routine and build the "text" string yourself.
You probably don't even need the text box then, just a control of your
own, inherited from Control.

Maybe you'll have to spawn a batch file to capture the input into a text
file and then read that.

Or perhaps you can use something like WndProc to capture the keys at
some lower level.

Have you consulted with the vendor/manufacturer of the barcode scanner
to see if they have any suggestions?

Good luck,
Randy


Ron L wrote:
[color=blue]
> Randy
>
> Thanks, that definitely was a step in the right direction. I put in both
> the IsInputKey and IsInputChar routines (included below) and I now get the
> RS character in the final output. I still don't get the GS and EOT
> characters, though, even though they are handled in the IsInputChar routine
> (I see the debug printouts). I suspect that this is due to a problem with
> how I am handling them in the IsInputKey routine. Do you have any other
> suggestions?
>
> Thanks again,
> Ron L
>
>
> '********************* ControlCharactersTextBox Class
> ********************************
> Imports System.Windows.Forms
>
> Public Class CtlCharTextBox
> Inherits System.Windows.Forms.TextBox
>
> Protected Overrides Function IsInputKey(ByVal keyData As
> System.Windows.Forms.Keys) As Boolean
> If (keyData And Keys.Control) And (keyData And Keys.D) Then
> Debug.WriteLine("IsInputKey: <EOT>")
> Return True
> ElseIf (keyData And Keys.Control) And (keyData And
> Keys.OemCloseBrackets) Then
> Debug.WriteLine("IsInputKey: <GS>")
> Return True
> ElseIf (keyData And Keys.Control) And (keyData And Keys.D6) Then
> Debug.WriteLine("IsInputKey: <RS>")
> Return True
> Else
> Return MyBase.IsInputKey(keyData)
> End If
> End Function
>
> Protected Overrides Function IsInputChar(ByVal charCode As Char) As
> Boolean
> 'Return MyBase.IsInputChar(charCode)
> Select Case Asc(charCode)
> Case 4 ' EOT character
> 'Debug.Write(Asc(charCode) & ", " & "<EOT> ")
> Return True
> Case 29 ' GS character
> 'Debug.Write(Asc(charCode) & ", " & "<GS> ")
> Return True
> Case 30 ' RS character
> 'Debug.Write(Asc(charCode) & ", " & "<RS> ")
> Return True
> Case Else
> 'Debug.Write(Asc(charCode) & ", " & charCode & " ")
> Return MyBase.IsInputChar(charCode)
> End Select
> End Function
> End Class
>
>
> "R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
> news:44357177$0$7330$dbd43001@news.wanadoo.nl...
>[color=green]
>>Hello, Ron,
>>
>>Perhaps these keys are being swallowed by some preprocessing on the form.
>>Have a look at the help for the "IsInputKey" (and possibly the
>>"IsInputChar") function. Perhaps they will help you out. I have
>>previously used the former in order to "capture" some of the navigation
>>keys. Here is an example of IsInputKey:
>>
>> Protected Overrides _
>> Function IsInputKey(ByVal keyData As Keys) As Boolean
>> ' Inhibit pre-processing for selected "special" keys
>> ' that are handled directly by the control.
>> Select Case keyData
>> Case Keys.Down, Keys.Left, Keys.Right, Keys.Up
>> Return (Me.UserMode = aenmUserMode.Design)
>> Case Else
>> Return False
>> End Select
>>
>> End Function
>>
>>Cheers,
>>Randy
>>
>>
>>Ron L wrote:
>>
>>[color=darkred]
>>>Randy
>>>
>>>Sorry, I should have been more specific. The text box removes *some* of
>>>the control characters. My string has the RS (ASCII 30), GS (ASCII 29),
>>>and EOT (ASCII 4) embedded in it. These are commonly represented as
>>>ctl-^, ctl-], and ctl-D, respectively. If I open a command prompt and
>>>scan the label I see all the expected control characters on the entered
>>>line, but in the text box the GS and EOT have been stripped out! Given
>>>that, I am reasonably that either the TextBox or some portion of the
>>>windows key event handling is removing the GS and EOT characters from my
>>>input string.
>>>
>>>Arrggghhhh!
>>>
>>>
>>>Ron L
>>>
>>>
>>>"R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
>>>news:44341f25$0$84976$dbd49001@news.wanadoo.nl. ..
>>>
>>>
>>>>Hello, Ron,
>>>>
>>>>I'm not aware of any logic that strips out control characters from a
>>>>TextBox. For example, when I type into a multiline textBox using a
>>>>keyboard I can easily insert new line characters (<CR><LF>) by typing
>>>><CNTL><Enter>, or other control characters by using Copy/Paste. These
>>>>are returned in the Text property.
>>>>
>>>>Also, almost all keystrokes (including the Control keys) are available
>>>>via the Key-up events. (As I recall there are a few "navigation" keys
>>>>that do not normally appear there, but I think that even these can be
>>>>persuaded to appear with a little extra work.)
>>>>
>>>>I wonder if there is something between the scanner driver and the TextBox
>>>>that is swallowing the characters you are expecting to see. Do you have
>>>>KeyPreview enabled for the Form that contains the TextBox? Or is there
>>>>possibly something more sophisticated such as an override of WndProc
>>>>interfering?
>>>>
>>>>Anyway, I'm rather doubtful that the problem is with the TextBox.
>>>>
>>>>Cheers,
>>>>Randy
>>>>
>>>>
>>>>Ron L wrote:
>>>>
>>>>
>>>>
>>>>>Randy
>>>>>
>>>>>I am using a text box control, but apparently there is logic in that
>>>>>control that strips out most of the control characters (ASCII values <
>>>>>32) before entering them into the Text property. I had hoped that by
>>>>>catching the Key-up event I could somehow "bypass" the code that removes
>>>>>the control characters.
>>>>>
>>>>>As far as the scanner is concerned, it is simply acting as if it is a
>>>>>keyboard and is sending on the characters that were "typed".
>>>>>
>>>>>Thanks,
>>>>>
>>>>>Ron L
>>>>>
>>>>>"R. MacDonald" <scitec@NO-SP-AMcips.ca> wrote in message
>>>>>news:44336a01$0$3998$dbd41001@news.wanadoo.nl ...
>>>>>
>>>>>
>>>>>
>>>>>>Hello, Ron,
>>>>>>
>>>>>>I've never worked with a scanner, so please excuse my ignorance. What
>>>>>>kind of control is it that receives the input? (I had assumed it would
>>>>>>be something akin to a TextBox and you could just use the Text property
>>>>>>after completion of the input.)
>>>>>>
>>>>>>But when you say that you're catching the key-up event, perhaps the
>>>>>>processing required is more sophisticated than I realized.
>>>>>>
>>>>>>Can you provide any additional information, or perhaps an example of
>>>>>>the code that you are trying to make work?
>>>>>>
>>>>>>Cheers,
>>>>>>Randy
>>>>>>
>>>>>>
>>>>>>Ron L wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>>Randy
>>>>>>>
>>>>>>>Thanks for the response. My problem is that the scanner acts like a
>>>>>>>keyboard, so I'm not sure how to get the original informaion into a
>>>>>>>string in the first place. I have tried catching the key up event,
>>>>>>>but I haven't figured out what to place in the string to get the
>>>>>>>control characters into the string. I have printed out the key
>>>>>>>values, and can't find a correlation between the key value or key code
>>>>>>>and the control character I am expecting to see.
>>>>>>>
>>>>>>>Ron L
>>>>>
>>>>>[/color][/color]
>
>[/color]