C# keydown not working when I have a button

Question

5.00/5 (1 vote)

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I saw in the internet the problem, and the solution was setting the "KeyPreview" to "true". I have tried it, and it still didn't work. Why when I press one of the arrows (down, up, left or right) the lable still doesn't show off?

Updated:
Thank you for your answer Peter Vegter, but It still doesn't work.
To make this clear: regular letter does work and makes the label show off. The thing is that the arrows (down, up, left or right) don't work.
I think I know why - the "focus" is on the the button and not on the form.
I searched for this in the internet, and I found that I need to make the "KeyPreview" set as "true". I did it, and still it doesn't show the label when I press the arrows, only when I press letters.
If i remove the button, the arrows do work.

What I have tried:

C#

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            label1.Visible = false;
            this.KeyPreview = true;
            this.KeyDown += Form1_KeyDown;
        }

        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            label1.Visible = true;
        }

        private void button1_Click(object sender, EventArgs e)
        {

        }
    }

Posted 26-Feb-18 6:43am

Member 13697757

Updated 25-Oct-19 10:25am

v2

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Comments

#realJSOP 26-Feb-18 13:11pm

Set a breakpoint in the KeyDown event handler and see if the code is even handling the event.

[no name] 26-Feb-18 15:57pm

My mistake, I've updated my answer. That should work.

[no name] 26-Oct-19 14:59pm

I have tried "Solution 1" again with several buttons and labels on the Form and also with different .NET Frameworks and this solution still works well with me.
Maybe you made a mistake somewhere else in your code?

2 solutions

Solution 2

Place : this.Focus(); in your button after all the code the button does,

Problem is when button is clicked, it has the focus and your KeyDown and KeyUp events will not fire. Refocus on the form after your button is clicked and then your key events will once again fire.

Posted 25-Oct-19 10:26am

Member 14635180

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

User 7407470 · Accepted Answer · 2018-02-26T07:27:00

Solution 1

You have to use ProcessCmdKey to 'catch' the arrow (and some other) keys, like this:

C#

public Form1()
{
    InitializeComponent();
    label1.Visible = false;
}

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
    switch (keyData)
    {
        case Keys.Left: // left arrow key
            label1.Visible = true;
            return true;

        case Keys.Right: // right arrow key
            label1.Visible = true;
            return true;

        // etc.
    }
    return base.ProcessCmdKey(ref msg, keyData);
}

Posted 26-Feb-18 7:27am

User 7407470

Updated 26-Feb-18 10:06am

v3

Comments

den2k88 27-Feb-18 3:33am

I upvoted and bookmarked it: I will probably need it in the near future and I would have stumbled upon the same obstacle :D

[no name] 27-Feb-18 4:12am

That's very nice, thank you!

Nelek 26-Oct-19 14:34pm

OP has edited the question (yeah, it surprised me too, 1.5 years later) and he mentions you. You might have interest on checking up

[no name] 26-Oct-19 15:01pm

Thanks Nelek!
I've tested the solution again and it still works (see answer above). And yes, a nice result after 1.5 years! :)

Richard Deeming 29-Oct-19 13:27pm

Actually, the OP updated the question back in February 2018. The "updated" date on the question refers to the date when solution 2 was posted.

If you click on the "v2" link next to the date, you'll see the full revision history for the question[^]. :)

[no name] 29-Oct-19 14:13pm

Thank you, Richard. I just didn't check the message to me properly.

Nelek 29-Oct-19 15:29pm

I stand corrected. Thanks for the info.

Nelek 29-Oct-19 15:32pm

mmm... If I go to the revisions --> Show minor revisions --> Version 4 is from Oct. 25th 2019. Selecting Version 4 and Version 2 shows some changes...
But between 3 and 4, there are no changes

I didn't know that posting an answer gets a minor version to the question.
Confusing...

Richard Deeming 29-Oct-19 15:36pm

I suspect there's a bug lurking somewhere. v3 seems to be what's showing, which was from February 2018. But the revision list seems to suggest v2 is the current version, which matches the link on the question. There don't seem to be any changes between v3 and v4.

Nelek 29-Oct-19 15:37pm

Do you report it? Or should I?

Richard Deeming 29-Oct-19 15:41pm

I've just reported it. :)

Bugs and Suggestions[^]

Nelek 29-Oct-19 15:47pm

Thank you

C# keydown not working when I have a button

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C# keydown not working when I have a button

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