Function keys not firing

Question

0.00/5 (No votes)

See more:

Dear all,

I am trying to fire ESC,F1 and F2 keys from code, Only "ESC" is getting fired not F1 and F2. Is there any mistake in the following code?

VB

If e.KeyChar = Microsoft.VisualBasic.ChrW(27) Then
       Panel7.Visible = True
       Panel7.Location = New Point(1, 1)
       txtsub.Focus()
End If
If e.KeyChar = Microsoft.VisualBasic.ChrW(112) Then
       Panel8.Visible = True
       Panel8.Location = New Point(1, 1)
       txtsub.Focus()
End If
If e.KeyChar = Microsoft.VisualBasic.ChrW(113) Then
       Panel9.Visible = True
       Panel9.Location = New Point(1, 1)
       txtsub.Focus()
End If

Posted 13-Sep-10 5:35am

Jatinder Gupta

Updated 13-Sep-10 5:44am

HimanshuJoshi

v3

Add a Solution

Comments

Dalek Dave 13-Sep-10 11:42am

Edited for Code Block.

HimanshuJoshi 13-Sep-10 11:44am

Edited for grammar and spelling

Kschuler 13-Sep-10 16:49pm

what event is this code in?

William Winner 13-Sep-10 17:54pm

@Kschuler...e.KeyChar is only available in the KeyPress event...

2 solutions

Solution 2

As far as your new question (from the comment left on my last answer), the user should always press ctrl, shift, or alt first. That's the way it works everywhere.

If I am in Word, highlight some text, and hold "c" and then hit ctrl to initiate a copy event, it won't work. What will happen is that the highlighted text will first become the letter "c", then "c" will be repeated until control is pressed. At that point, no text will be highlighted, so nothing will be copied.

It should always be assumed that ctrl, alt, and shift should be pressed first.

If, however, you are pressing Ctrl first and then F1 and you are getting duplicate messages, the problem is in your code. Let's say, you have written

VB

If e.KeyCode = Keys.F1 Then
  MessageBox.Show("F1")
End If
If e.KeyCode = Keys.F1 and e.Control Then
  MessageBox.Show("F1 + Ctrl")
End If

you will get two messages. Do you see why?

Also, just a few little tips since you appear to be new to .Net.

First, MsgBox shouldn't be used anymore. That's an old VB6 structure. You should be using MessageBox.Show("some text").

Secondly, you don't need to test boolean values against true or false. That is just added steps the application will have to take.

VB

If e.Control Then
'...
'
'is the same as
If e.Control = True

The difference is that e.Control = True has to first test that condition and then check whether that test returned true or false.

Finally, if you are testing a lot of possibilities for e.KeyCode, you would be better off using the Select Case structure. It would look like:

VB

Dim output as String = ""

Select Case e.KeyCode
  Case Keys.F1
    output = "F1"
  Case Keys.F2
    output = "F2"
End Select

If e.Control Then
  output = output & "+Ctrl"
End If

MessageBox.Show(output)

Posted 14-Sep-10 4:55am

William Winner

Updated 14-Sep-10 5:22am

v2

Comments

Dalek Dave 14-Sep-10 11:19am

Good answer.

Jatinder Gupta 14-Sep-10 20:56pm

Thanks sir, good solution.....

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

William Winner · Accepted Answer · 2010-09-13T12:01:00

Your problem is that you've trapped this through the KeyPress event.

You need to look up the documentation on the code when you're having an issue. From MSDN:

"The KeyPress event is not raised by noncharacter keys; however, the noncharacter keys do raise the KeyDown and KeyUp events."

So, you need to use the KeyUp event instead of the KeyPress event. Also, the KeyUp event is more readable and provides more options. For example, instead of writing

VB

If e.KeyChar = Chr(112) Then

you can write

VB

If e.KeyCode = Keys.F1 Then

It's a lot easier for someone debugging your code to read the second.

Also, as a grammatical note, when you say that you're trying to "fire" a key from code, it means that you're trying to tell the computer that that key was pressed. You're tying to "trap" the key.