Despite me working with C# (Windows Forms) for years, I'm having a brain fail moment, and can't for the life of me figure out how to catch a user typing Ctrl + C into a textbox.
My application is basically a terminal application, and I want Ctrl + C to send a (byte)3 to a serial port, rather than be the shortcut for Copy to Clipboard.
I've set the shortcuts enabled property to false on the textbox. Yet when the user hits Ctrl + C, the keypress event doesn't fire.
If I catch keydown, the event fires when the user presses Ctrl (that is, before they hit the C key).
It's probably something stupidly simple that I'm missing.
Go ahead and use the KeyDown event, but in that event check for both Ctrl and C, like so:
if (e.Control && e.KeyCode == Keys.C) {
//...
e.SuppressKeyPress = true;
}
Also, to prevent processing the keystroke by the underlying TextBox, set the SuppressKeyPress property to true as shown.
Key events occur in the following order:
KeyDown
KeyPress
KeyUp
The KeyPress event is not raised by noncharacter keys; however, the noncharacter keys do raise the KeyDown and KeyUp events.
Control is a noncharacter key.
You can check with this line of code:
if (e.KeyData == (Keys.Control | Keys.C))
I had a problem catching Ctrl + C on a TextBox by KeyDown. I only got Control key when both Control and C were pressed. The solution was using PreviewKeyDown:
private void OnLoad()
{
textBox.PreviewKeyDown += OnPreviewKeyDown;
textBox.KeyDown += OnKeyDown;
}
private void OnPreviewKeyDown( object sender, PreviewKeyDownEventArgs e)
{
if (e.Control)
{
e.IsInputKey = true;
}
}
private void OnKeyDown( object sender, KeyEventArgs e)
{
if (e.Control && e.KeyCode == Keys.C) {
textBox.Copy();
}
}
D'oh! Just figured it out. Out of the three possible events, the one I haven't tried is the one I needed! The KeyUp event is the important one:
private void txtConsole_KeyUp(object sender, KeyEventArgs e)
{
if (e.KeyData == (Keys.C | Keys.Control))
{
_consolePort.Write(new byte[] { 3 }, 0, 1);
e.Handled = true;
}
}
If you want to catch such combinations of keys in KeyPress Event look at this table here:
http://www.physics.udel.edu/~watson/scen103/ascii.html
in Non-Printing Characters section you can see the Dec numbers for each combination.
For example, Dec number for Ctrl + C is 3. So you can catch it in KeyPress Event like this:
private void btnTarget_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar != 3) // if it is not Ctrl + C
{
// do something
}
}
Try the following: capture the up arrow and down arrow events. When you detect down arrow for CTRL, set a flag; when you detect up arrow, reset the flag. If you detect the C key while the flag is set, you have Ctrl+C.
Edit. Ouch... Jay's answer is definitely better. :-)
I don't know if it's because some change in newer version or because I am trying to use this on ListBox, but there is no e.Control in KeyEventArgs e that I get from KeyDown.
I had to work around solution, I came up with this (it's not the prettiest one, but it works fine):
private List<Key> KeyBuff = new List<Key>();
private void ListBox_KeyDown(object sender, KeyEventArgs e)
{
if (!KeyBuff.Exists(k => k == e.Key))
KeyBuff.Add(e.Key);
if (KeyBuff.Exists(k => k == Key.LeftCtrl || k == Key.RightCtrl) &&
KeyBuff.Exists(k => k == Key.C))
{
// Desired detection
Clipboard.SetText(SelectedText);
}
}
private void ListBox_KeyUp(object sender, KeyEventArgs e)
{
KeyBuff.Clear();
}
For me, it's not working with KeyDown event so I tried with PreviewKeyDown and it's worked.
private void txt_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
{
if (e.Control == true && e.KeyCode == Keys.C)
{
Clipboard.SetText(txt.SelectedText);
}
}
Related
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)
I would like to perform some actions when the user presses Ctrl + K on a textbox.
private void subject_TextBox_KeyDown(object sender, KeyEventArgs e)
{
if (e.Control && e.KeyCode == Keys.K)
MessageBox.Show("!");
}
Nothing happens when I run it.
When I debug I can see that e.Control is true (this means I pressed Ctrl) but the e.KeyCode is not equivalent to K.
Any ideas?
protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
if (keyData == (Keys.Control | Keys.K) && focusedTextbox == subject_TextBox)
{
//Some Code
}
}
private TextBox focusedTextbox = null;
private void subject_TextBox_KeyDown(object sender, KeyEventArgs e)
{
MethodName(e.KeyCode)
}
private void MethodName(Keys keys)
{
focusedTextbox = (TextBox)sender;
}
Use this code, this should work i have tested it myself and it will work, you will want to run the 'MethodName' method in each textbox, or if you can find a better way to change the 'focusedTextBox' field then do that hope this helped.
In the KeyDown event, you just ask for the 'state' of the keyboard.
You might want to check out this topic:
Capture multiple key downs in C#
Really don't know what is the problem reason.
May the event is fired as soon as the Ctrl is pressed, without waiting to the K to be pressed as well.
However, when I use the same code in the TextBox_KeyUp event, it works fine.
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.
I have a textbox and below it i have a listbox.
While the user is typing in the textbox if he presses the up or down arrow he should make a selection in the listbox. The textbox detects all the characters (except space) but it seems that it can't detect the arrow presses.
Any solution for this? This is a WPF project btw.
EDIT, Here's the working code thanks to T.Kiley:
private void searchBox_PreviewKeyDown(object sender, KeyEventArgs e)
{
if (e.IsDown && e.Key == Key.Down)
{
e.Handled = true;
//do your action here
}
if (e.IsDown && e.Key == Key.Up)
{
e.Handled = true;
//do another action here
}
}
I just tried this and it works. Add a preview key down event to the textbox
private void TextBox_PreviewKeyDown(object sender, System.Windows.Input.KeyEventArgs e)
{
if (e.IsDown && e.Key == Key.Down)
MessageBox.Show("It works");
}
You can listen to they KeyDown event of the TextBox. In the handler, check whether the arrow key was pressed (you might need to listen to key up to avoid triggering your code multiple times if the user holds down the button for too long).
private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Down)
{
// Do some code...
}
}
I am checking the keycode for a textbox, and I want a certain task to be performed when the user presses Enter.
It has been working perfectly, but the task that I am trying to perform now, usually is done using a mouse click. So on the OK on that task (a FolderBrowserDialog), it keeps calling the dialog control.
Oddly enough, even though the debugger shows me into the if branch, for e it shows {KeyData = LButton|MButton|Back}, but KeyValue is still 13...
I think it may be that the textbox remembers its last entry... True ?
In my troubleshooting, I have added a boolean variable so I only go into FolderBrowser when it is true, I have tried to add and delete a space from the textbox after the Browse, and even clear the textbox... Each attempt seemed to make things worse.
It seemed that I was in a quasi-infinite loop - yet it would go away after lots of "ok"'s, and stepping through, I found that for every letter I type in the textbox, I spend 4 to 5 rounds in the CheckKeys. I don't understand why... Or how to fix it.
I added a "e.Handled" which did me no good.
Here's the code:
private void txtDir_TextChanged(object sender, EventArgs e)
{
this.txtDir.KeyUp += new System.Windows.Forms.KeyEventHandler(CheckKeys);
}
private void CheckKeys(object sender, System.Windows.Forms.KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
if (sender == txtDir && txtDir.Text != "" && System.IO.Directory.Exists(txtDir.Text))
{
btnBrowse_Click(this, e);
}
}
}
Why am I going through this check so many times ? Can I add a different test ? Am I doing something wrong ? (nothing is set as default action, for form or textbox...)
Thank you.
In your code you added handler for KeyUp at TextChanged Event. so, When TextChanged new handler will be added for KeyUp Event. Thats why multiple time each letter is checked. put Handler at Form load event.
e.g. If I have entered five letter in TextBox so, 5 Handler will be added for KeyUp. means Number of KeyUp Event Handler equals to number of time TextChanged Event called.
this.txtDir.KeyUp += new System.Windows.Forms.KeyEventHandler(CheckKeys);
this add new handler for KeyUp event. So, when this line execute new handler will be added.
By putting Handler at Form Load event, you can solve multiple letter checked problem.
Try with,
private void FormLoad(object sender, EventArgs e)
{
this.txtDir.KeyUp += new System.Windows.Forms.KeyEventHandler(CheckKeys);
}
private void CheckKeys(object sender, System.Windows.Forms.KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
if (sender == txtDir && txtDir.Text != "" && System.IO.Directory.Exists(txtDir.Text))
{
btnBrowse_Click(this, e);
}
}
}
And one more thing As I understand your code, you want to execute btnBrowse_Click if Enter pressed in TextBox control. But Enter key not handled with KeyUp event you need KeyDown Event handler to handle Enter key.
Code:
private void FormLoad(object sender, EventArgs e)
{
this.txtDir.KeyDown += new System.Windows.Forms.KeyEventHandler(CheckKeys);
}
private void CheckKeys(object sender, System.Windows.Forms.KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
if (sender == txtDir && txtDir.Text != "" && System.IO.Directory.Exists(txtDir.Text))
{
btnBrowse_Click(this, e);
}
}
}
Use KeyDown event instead of TextChanged and write down e.Handle = True in it.
write down following code in your textBox.KeyDown event:
if (e.KeyCode == Keys.Enter)
{
if (sender == txtDir && txtDir.Text != "" && System.IO.Directory.Exists(txtDir.Text))
{
e.Hanlde = true; //it will be close enter keydown handling at this time
btnBrowse_Click(this, e);
}
}
Replaced TextChanged with KeyDown directly and it works again !
(on a side note, I still don't understand why each letter is tested several times...)
Edit: Now after reading the accepted answer, I do understand...