CODEWITHSUNDEEP
c#winformsevents
Shaho
Shaho

Reputation: 182

How to prevent call several KeyDown events by pressing a single key on the keyboard?

I have set KeyPreview property of the form to true in order to call keyboard events of the form before control events. Both the form and the control in the form have KeyDown event like:

form:

private void Form1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.Control && (e.KeyCode == Keys.Enter || e.KeyCode == Keys.Return)) {
         MessageBox.Show("Control + Enter (Form)");
    }
}

control:

private void TextBox1_KeyDown(object sender, KeyEventArgs e)
{
    if (!e.Control && (e.KeyCode == Keys.Enter || e.KeyCode == Keys.Return)) {
         MessageBox.Show("Control + Enter (TextBox)");
    }
}

As you see the difference between these two parts of code is that in the form event code I need to call the KeyDown event when the user presses CTRL and Enter keys at the same time, In the TextBox event code, I need to call the event when the user presses Enter key without holding CTRL-key.

The problem is that when I press Ctrl and Enter keys at the same time both of the above events will call. How to prevent call both events?

Upvotes: 1

Views: 640

Answers (2)

dear_vv
dear_vv

Reputation: 2358

I suggest you use the textBox1_KeyUp event. You can refer to the following code. My test was successful.

   public Form1()
    {
        InitializeComponent();
        this.KeyPreview = true;
    }       
    private void Form1_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.Control && (e.KeyCode == Keys.Enter || e.KeyCode == Keys.Return))
        {
            MessageBox.Show("Control + Enter (Form)");
        }
    }
    private void textBox1_KeyUp(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Control)
        {
            e.Handled = true;
        }
        else if (e.KeyCode == Keys.Enter)
        {
            MessageBox.Show("Control + Enter (TextBox)");
        }
    }

Upvotes: 4

Mr.MK
Mr.MK

Reputation: 202

Use the ProcessCmdKey and like this.

protected override bool ProcessCmdKey(ref Message msg, System.Windows.Forms.Keys keyData)
        {
            int WM_ALRT_DOWN = 0x0104;
            int WM_KEYDOWN = 0x0100;

            if (msg.Msg == WM_ALRT_DOWN && (int)msg.WParam == (int)Keys.F4) //Alt + F4
            {
                return true;  // The key is manually processed
            }
            if (msg.Msg == WM_KEYDOWN && (int)msg.WParam == (int)Keys.Escape) //Esc 
            {
                return true;  // The key is manually processed
            }
            if (msg.Msg == WM_KEYDOWN && (int)msg.WParam == (int)Keys.Space) //Space
            {
                return true;  // The key is manually processed
            }
}

Upvotes: 0

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