.NET, and "know" when a keyboard button is being pressed - c#

I'm making a program in C#, And I want to know when the user is pressing\pressed a keyboard button (for now: 1-9 buttons on keyboard).
How can I do it?

The Control.KeyPress event (and related KeyDown and KeyUp) should do what you need. Just define an event handler for the one you need in your form:
private void Form1_KeyPress(object sender, KeyPressEventArgs e)
{
MessageBox.Show("Key pressed: " + e.KeyChar);
}
The MSDN page under the link has a more extensive example that deals with "special" keys (you will need to use KeyPress or KeyDown for those).
If you want to capture keys while the focus is not on your form, that's a different matter entirely, but I don't think that's the case as you want to capture keys 1-9. Not the typical global hotkey :)

Don't forget to set the KeyPreview property to true, else other controls on your form (if you have other controls on your form) will receive the event (if they have focus) before the form gets it.

Hook an function to the OnKeyUp event of a form.
see here
private void form1_KeyUp(object sender, System.Windows.Forms.KeyEventArgs e)
{
if ((e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9) || (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9))
{
//Do something
}
}

What you search are the 2 Events KeyDown and KeyUp.
KeyUp is when a Key "was" pressed and the user lift his finger up.
KeyDown is the other event.
Just take a new Form. Go to the Events(Press F4) and you will find KeyDown and Up.
private void maskedTextBox1_KeyDown_1(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
and so on :D

Related

PerformClick + KeyDown doesn't work c# but works fine in vb net

I'm trying to convert VB.NET code to C#, from all the code I found this PerformClick issue and I don't know what happened.
My VB.Net code:
Private Sub FormLogin_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown
Select Case e.KeyCode
Case Keys.Enter
FlBtnLogin.PerformClick()
End Select
End Sub
The code worked, but when I tried to convert it to C#, it didn't work.
My C# code
private void FormLogin_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
FlBtnLogin.PerformClick();
}
}
Event Handler
this.KeyDown += new System.Windows.Forms.KeyEventHandler(this.FormLogin_KeyDown);
Any help and instruction would be appreciated, thanks
You would need to set the KeyPreview property of the form to true. If it is false, which it is by default, then the form will not raise keyboard events when a child control that can raise keyboard events has focus. Set it to true and the form will raise the events before the child control does. This is true in both C# and VB, so it's nothing specifically to do with the code you are converting.
As per #John which is the best option, this is another option if you want to have your events in a specific Control when the KeyPreview is OFF.
This code will only work if the form is on focus, but won't work if you put the focus/cursor on other controls.
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
MessageBox.Show("Enter!");
}
}
While this event will be called when the focus is on a TextBox.
private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
MessageBox.Show("Enter!");
}
}
So you must add the event on the control where you will likely press the Enter Key which is the TextBox for password.

Catching MAJ + TAB click on textbox

I have to catch the event when I pressed on Shift Tab in TextBox to write some code. It is possible to do that? I tried with that test on KeyUp event :
private void txtJustifTampon_KeyUp(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Tab && Control.ModifierKeys == Keys.ShiftKey)
{
//do stuff
}
}
One of the possible ways out is to use PreviewKeyDown instead of KeyUp since
Some key presses, such as the TAB, RETURN, ESC, and arrow keys, are
typically ignored by some controls because they are not considered
input key presses
private void txtJustifTampon_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e) {
// If Shift + Tab pressed (i.e. Tab with Shift modifier)
if (e.KeyCode == Keys.Tab && e.Modifiers == Keys.Shift) {
//TODO: put relevant code here (do stuff)
}
}
Please, notice that we should use Keys.Shift (not Keys.ShiftKey) as the modifier and we should apply modifier to the event argument (e.Modifiers)

Get keydown event without a textbox

Im trying to do like that: If I press the key "P" a messagebox will open in the screen.But I need to do it without a textbox or other tool, I want to do that direct in the form.
I tried:
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.P)
{ MessageBox.Show("Key P pressed"); }
}
Try with the KeyPress Event of the form. It just works fine.
Assuming this is Winforms, on the form you're trying to catch the event on, make sure to set
Form1.KeyPreview = true;
KeyPreview ensures that keyboard events anywhere on the particular form (such as to a textbox with focus) will still count as a keyboard event for the form itself.

KeyUp event firing from next control

I've 5 buttons in my windows application. When I click arrow keys the focus changing between buttons, then only
KeyUp
event firing. How to stop this?
Subscribe to the PreviewKeyDown event instead.
Occurs before the KeyDown event when a key is pressed while focus is on this control.
As you move through the buttons, the sender parameter will contain the previously selected button.
I found a solution that should work for you, adapted from here. Apparently, MS made the decision that the arrow keys wouldn't trigger the KeyDown event, so you can't cancel them.
One workaround is to specify that your arrow keys are normal input keys, like any other key. Then the KeyDown event will fire and you can cancel the button press if you want.
private void button1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
{
if (e.KeyCode == Keys.Left || e.KeyCode == Keys.Right || e.KeyCode == Keys.Up || e.KeyCode == Keys.Down)
e.IsInputKey = true;
}
private void button1_KeyDown(object sender, KeyEventArgs e)
{
e.Handled = true;
}
You may want to read the other answers and comments in that post to see what would work best in your situation.
Answer for your question in comment
void button1_LostFocus(object sender, EventArgs e)
{
button1.Focus();
}
To prevent Up from moving focus from a Button you have to utilize at least 3 methods:
bool _focus;
private void button1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
{
if (e.KeyCode == Keys.Up)
_focus = true;
}
private void button1_KeyUp(object sender, KeyEventArgs e)
{
_focus = false;
}
private void button1_Leave(object sender, EventArgs e)
{
if(_focus)
button1.Focus(); // or (sender as Control)
}
Trick is to use flag when user press Up and to return focus in Leave. You have to unflag in KeyUp, otherwise it would be impossible to change focus (by pressing Tab to example).
You could possible unflag in Leave, I didn't test it.

Stop the 'Ding' when pressing Enter

I have a very simple Windows Forms Application. And, in Windows (or, atleast Windows Forms Applications), when you press Enter while inside a Single-line TextBox Control, you hear a Ding. It's an unpleasent sound, that indicated you cannot enter a newline, because it is a single-line TextBox.
This is all fine. However, in my Form, I have 1 TextBox, and a Search Button. And I am allowing the user to Perform a search by pressing Enter after they've finished typing, so they don't have to use the mouse to click the Search Button.
But this Ding sound occurs. It's very annoying.
How can we make it so just that sound doesn't play at all in my Form?
#David H - Here's how I'm detecting the enter pressing:
private void textBox1_KeyUp(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
// Perform search now.
}
}
It works for me:
private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
//Se apertou o enter
if (e.KeyCode == Keys.Enter)
{
//enter key is down
this.doSomething();
e.Handled = true;
e.SuppressKeyPress = true;
}
}
The SuppressKeyPress is the really trick. I hope that help you.
Check out the Form.AcceptButton property. You can use it to specify a default button for a form, in this case for pressing enter.
From the docs:
This property enables you to designate
a default action to occur when the
user presses the ENTER key in your
application. The button assigned to
this property must be an
IButtonControl that is on the current
form or located within a container on
the current form.
There is also a CancelButton property for when the user presses escape.
Try
textBox.KeyPress += new KeyPressEventHandler(keypressed);
private void keypressed(Object o, KeyPressEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
e.Handled = true; //this line will do the trick
}
}
Just add e.SuppressKeyPress = true; in your "if" statement.
private void textBox1_KeyUp(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
//If true, do not pass the key event to the underlying control.
e.SuppressKeyPress = true; //This will suppress the "ding" sound.*/
// Perform search now.
}
}
You can Use KeyPress instead of KeyUp or KeyDown its more efficient
and here's how to handle
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == (char)Keys.Enter)
{
e.Handled = true;
button1.PerformClick();
}
}
and say peace to the 'Ding'
Use SuppressKeyPress to stop continued processing of the keystroke after handling it.
public class EntryForm: Form
{
public EntryForm()
{
}
private void EntryTextBox_KeyDown(object sender, KeyEventArgs e)
{
if(e.KeyCode == Keys.Enter)
{
e.Handled = true;
e.SuppressKeyPress = true;
// do some stuff
}
else if(e.KeyCode == Keys.Escape)
{
e.Handled = true;
e.SuppressKeyPress = true;
// do some stuff
}
}
private void EntryTextBox_KeyUp(object sender, KeyEventArgs e)
{
if(e.KeyCode == Keys.Enter)
{
// do some stuff
}
else if(e.KeyCode == Keys.Escape)
{
// do some stuff
}
}
}
On WinForms the Enter key causes a Ding sound because the form property AcceptButton is not specified.
If you don't need an AcceptButton the ding sound can be suppressed by setting the form KeyPreview to true and enter the following KeyPress event:
private void Form_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == '\r')
e.Handled = true;
}
No matter what control is active, there will be no more ding sound when pressing the Enter key. Since the key event proccessing order is KeyDown, KeyPress and KeyUp the Enter key will still work for the KeyDown events for the controls.
I stumbled on this post while trying to handle a KeyDown this worked for me.
If e.KeyCode = Keys.Enter Then
e.SuppressKeyPress = True
btnLogIn.PerformClick()
End If
Supressing the Key Press stops the event from being sent to the underlying control. This should work if you're manually handling everything that the enter key will be doing within that textbox. Sorry about the Visual Basic.
$("#txtSomething").keypress(function (e) {
if (e.which == 13) {
e.Handled = true; //This will prevent the "ding" sound
//Write the rest of your code
}
});
There is a very little chance anyone gets to this answer but some other answers are truly scary. Suppressing event on KeyDown kills 2 additional events in one strike. Setting e.Handled property to true is useless in this context.
The best way is to set Form.AcceptButton property to the actual Search Button.
There is also another way of utilizing Enter key - some people may want it to act as TAB button. To do that, add a new Button, set its Location property outside of the Form area (i.e. (-100, -100)) - setting Visible property to false may disable Button handlers in some cases. Set Form.AcceptButton property to your new button. In Click event handler add following code
this.SelectNextControl(ActiveControl, true, true, true, true)
Now, you may want to transfer focus only when focus it on TextBox you may want to either test ActiveControl type or use e.Supress property in event handlers of controls not meant to use Enter as TAB
That's it. You don't even need to capture e.KeyCode
Set your Search button's IsDefault property to true. This will make it a default button and it will be auto-clicked when Enter is pressed.
Well I lived with this problem long enough and looked it up here.
After thinking about this for quite some time and wanting the simplest way to fix it I came up with the easiest but not so elegant way to fix it.
Here is what I did.
Put 2 invisible buttons "Ok" and "Cancel" on the form.
Set the AcceptButton and CancelButton Property on the form to the invisible buttons.
Added no code to the buttons!
This solved all the secondary problems listed in this thread including the ToolStripMenu. My biggest complaint was the BindingNavigator, when I would enter a record number into the Current position to navigate to and pressed enter.
As per the original question in which the programmer wanted a search function when the enter button was pressed I simply put the search code in the invisible OK Button!
So far this seems to solve all problems but as we all know with Visual Studio, something will probably crop up.
The only other possible elegant way I could think of would be to write a new keystroke handling class which is way to much work for most of my projects.
You can set your textbox multi-line to true then handle the Enter key press.
private void yourForm_Load(object sender, EventArgs e)
{
textBox1.Multiline = true;
}
//then write your TextBox codes
private void textBox1_KeyUp(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
// doSomething();
}
}
i changed the textbox properties for an multiline textbox and it works for me.
Concerning the e.SuppressKeyPress = true; solution, it works fine by itself. Setting SuppressKeyPress to true also sets Handled to true, so there's no need to use e.Handled= true;
void RTextBox_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyData == Keys.Enter)
{
//do ...
bool temp = Multiline;
Multiline = true;
e.Handled = true;
Multiline = temp;
}
}

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