System beep on keyDown

Question

3.40/5 (2 votes)

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hi all. why this code make beep when buttons clicked?

C#

void SearchFeild_KeyDown(object sender, KeyEventArgs e)
       {

           //when user fill search fields and press Enter the curent button search will be clicked
           if (e.KeyCode == Keys.Enter && btnBack.Visible == false)
           {
               btnSearcch.PerformClick();
               e.Handled = true;
           }
           else if (e.KeyCode == Keys.Enter && btnBack.Visible == true)
           {
               btnBack.PerformClick();
               e.Handled = true;
           }

       }

thanks in advance.

Posted 30-Jan-14 5:41am

mit62

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Comments

ZurdoDev 30-Jan-14 12:55pm

Your windows theme says so?

Sergey Alexandrovich Kryukov 30-Jan-14 12:58pm

A side note: comparison a Boolean with true or false is pointless and clearly indicates that you have no idea what you are comparing. A literal code would be


if (e.KeyCode == Keys.Enter && btnBack.Visible)
    //...

—SA

ZurdoDev 31-Jan-14 12:54pm

That's harsh. It doesn't mean they don't understand, it's just a simple shortcut but nothing wrong with it.

Sergey Alexandrovich Kryukov 31-Jan-14 13:05pm

Well, I forgot to mention that this is equivalent, but about "harsh"... You see, I still think that such code is not just too long version. I never argue against some longer code. I still think the only reason to write such condition would be lack of understanding of what is compared with what, or how Boolean works.
If it would be bool? property, this OP's code would be perfect, but with bool this is just lack of understanding. Can you see my point?..
—SA

3 solutions

Solution 1

This code does not perform any beep, I can assure you. It's somewhere else. You are not showing any code related to the beep. Moreover, you are not showing any code related to the problem. This is because you are asking about clicking on the button, but showing some method which could be used as an event handler you added to some keyboard event of some control. Also, using PerformClick is not the best idea. Normally, when you want to have same effect as you would have on the click on a button (or something), quite simply, make it a separate method. It would like this:

C#

void BackHandler() { // no need to use those irrelevant sender or event args
     //...
}

//...

myBackButton.Click += (sender, eventArgs) => { BackHandler(); };

void SomewhereElse(/* ... */) { // or in some other event handler, does not matter where...
    //...
    BackHandler();
    //...
}

I hope the idea is clear.

OS can beep it if "thinks" you are clicking something non-existing. To check it up, you can change sound scheme to "No sound" (in Control Panel) and see what happens.

—SA

Posted 30-Jan-14 7:08am

Sergey Alexandrovich Kryukov

Comments

Sergey Alexandrovich Kryukov 31-Jan-14 2:05am

Use the debugger and see if this line with += is reached. And then see what happens in the handler. Debugger, that's all.
—SA

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TnTinMn · Accepted Answer · 2014-01-30T11:25:00

Solution 2

Based on you description, "SearchFeild" is some control that is or incorporates a TextBox for input. The TextBox will generate a beep when you input the Enter key if it is not set up for multiline input.

The "e.Handled = true;" statement is not doing what you think here. The documentation [^]for this is confusing, and one could interpret it the way you have. However, you need to realize that they are talking about setting "Handled" in the KeyPress Event. To make matters worse, the KeyPressed event uses KeyPressEventArgs not KeyEventArgs. In short the documentation stinks!

Instead use e.SuppressKeyPress = true;

Posted 30-Jan-14 11:25am

TnTinMn

Comments

BillWoodruff 30-Jan-14 23:47pm

Setting the e.SuppressKeyPress Property in a KeyDown EventHandlers in a WinForm TextBox will not suppress the beep if 'MultiLine is 'false, independent of the value of 'AcceptsReturn.

I don't have a problem with the documentation, since, in my view, a KeyDown EventHandler is a very different "animal" than a "KeyPress" EventHandler, and the two are designed to offer different functionality.

However, as implied in my response below, I find the various interactions of TextBox settings with whether a beep is played or not, kind of strange.

mit62 31-Jan-14 1:24am

I set MultiLine=true and it works without SuppressKeyPress = true;
I set MultiLine=false and it works again with SuppressKeyPress = true;

thanks.

BillWoodruff 31-Jan-14 1:45am

My tests show identical results if you are setting 'SuppressPress to 'true in the KeyDown Event, or not setting it to 'true, but you certainly don't want to allow multi-line entry if your TextBox is only vertically sized so it will contain only one line of Text !

acceptsreturn multiline

false false beep
true false beep
false true no beep
true true no beep

So, I believe you must handle the KeyPress Event in order to avoid the beep.

BillWoodruff 31-Jan-14 1:50am

If you get different results in testing, please let me know: always time to learn something new :)

mit62 31-Jan-14 2:17am

AcceptReturn Multiline SuppressPress Result
False False False beep
False False True nobeep
False True False nobeep
False true True nobeep
True False False beep
True False True nobeep
True True False nobeep
True True True nobeep

BillWoodruff 31-Jan-14 2:38am

Okay, I see that my getting the beep when SuppressKeyPress is 'true and 'AcceptsReturn and 'MultiLine are both 'false is an artifact of my using MessageBox.Show() in my test code.

I will test further in a few hours since I need to go out for a while, and either remove my solution, or modify it.

So, you can use 'SuppressKeyPress in the KeyDown Event as long as you don't use MessageBox.Show() in the Button's Click EventHandler you are invoking.

Meanwhile, I suggest you un-accept my answer and accept TnTinMan's answer.

TnTinMn 31-Jan-14 14:33pm

While for most users, the answer I posted will work it does have a weakness. Please see my response to Bill below.

Also, if you are the one who down-voted his answer, please modify your vote to a five.

Also please accept his answer.

BillWoodruff 31-Jan-14 2:55am

TnTinMan, I have voted your answer 5, and suggested the OP accept your answer since his testing has caused me to question the results of my testing. Sorry about that !

TnTinMn 31-Jan-14 14:26pm

Bill, I must admit I had a "What is he talking about" moment when I read your first comment, but I got over it as I read on and saw that you had placed a MessageBox in the handler (the beeping little bugger). :))

However, during my testing to write this response, I came to realize that your method is probably the better one to use as it will trap key-strokes from those of us who were taught programming and computer usage back in the stone-age. :))

The TextBox.AcceptsReturn property only comes into play when MultiLine = true and Form.AcceptButton != null.

I don't know if this is useful, but the following is synopsis of results of pressing "Enter" key with the various setups.

1. Form.AcceptButton = null, TextBox.MultiLine = false, AcceptsReturn = true or false

KeyDown & KeyPress & KeyUp fire.

2. Form.AcceptButton = null, TextBox.MultiLine = true, AcceptsReturn = true or false

KeyDown & KeyPress & KeyUp fire.

3. Form has AcceptButton, TextBox.MultiLine = false

AcceptButton.Click fires
KeyDown & KeyPress are not fired when you press Enter.
KeyUp does fire.

4. Form has AcceptButton, TextBox.MultiLine = true, AcceptsReturn = false (need to use ctrl-Enter for new line)

AcceptButton.Click fires
KeyDown & KeyPress are not fired when you press Enter.
KeyUp does fire.

5. Form has AcceptButton, TextBox.MultiLine = true, AcceptsReturn = true

AcceptButton.Click does not fire
KeyDown & KeyPress & KeyUp fire.

And now for my admittance that your method is probably the .

The key event handlers process sequentially: KeyDown, KeyPress, KeyUp (http://msdn.microsoft.com/en-us/library/vstudio/system.windows.forms.control.keydown%28v=vs.100%29.aspx).

If you set "e.SuppressKeyPress = true;" in the KeyDown handler, the KeyPress event does not fire and the KeyUp event fires. In common keyboard usage, using this method will work, however for the most robust method would be to handle the KeyPress event for "e.KeyChar == 13" and set "e.Handled = true;". This is because the KeyPress event is raised in response to WM_CHAR or WM_IME_CHAR messages.

To demonstate the failure of the "e.SuppressKeyPress = true" method, try entering Ctrl-M or Alt-(on NumPad)013 (hold Alt Key then press/release NumPad keys 0, 1, 3) ; these will both generate as KeyPress event with "e.KeyChar = 13", but will not generate a KeyPress event with "e.KeyCode = Keys.Enter".

So in my final analysis, the method you showed is the best to catch the various ways that a carriage return can be inputted on a PC.

BillWoodruff · Accepted Answer · 2014-01-30T17:41:00

Note: this reply is revised based on testing information provided by Mit62. However the code example given is a completely usable alternative to using 'SuppressKeyPress in a KeyDown EventHandler as shown by TnTinMan above.

TnTinMn is on the right track: the cause of the "beep" is an artifact of the way that .NET WinForms handles an Enter KeyPress in a TextBox when certain combinations of the 'AcceptsReturn and 'MultiLine properties are set.

Here's an example of using the KeyPress EventHandler to stop the "beep:"

C#

private void SearchFeild_KeyPress(object sender, KeyPressEventArgs e)
{
    if (e.KeyChar == EnterChar)
    {
        if (btnBack.Visible)
        {
            btnBack.PerformClick();
        }
        else
        {
            btnSearcch.PerformClick();
        }

        e.Handled = true;
    }
}

Note that if you do something like call 'MessageBox.Show("some text"); in code called from the above code: you are going to get a "beep" !

System beep on keyDown

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