I have a question. Examples that i find is on a "KeyPress" and they are not longer working on WPF
Can you tell me, how to allow only specified keys from keybord to be write on WPF textbox? I know about keyUp and Down functions, but how to define letters that i want to by type into it?
I think it will be easier, if i will post my code and i tell u what i want to do. What to change here?
private void textBox_KeyDown(object sender, KeyEventArgs e)
{
//something here to only allow "A" key to be pressed and displeyed into textbox
if (e.Key == Key.A)
{
stoper.Start();
}
}
private void textBox_KeyUp(object sender, KeyEventArgs e)
{
if (e.Key == Key.A)
{
//here i stop the stopwatch to count time of pressing the key
stoper.Stop();
string aS = stoper.ElapsedMilliseconds.ToString();
int aI = Convert.ToInt32(aS);
stoper.Reset();
}
}
You can use PreviewKeyDown and use e.Key to filter out what you need.
Or, in any place of your code you can use Keyboard class:
if (Keyboard.IsKeyDown(Key.E)) { /* your code */ }
UPDATE:
To forbid a key, you need to set event as handled:
if (e.Key == Key.E)
{
e.Handled = true;
MessageBox.Show($"{e.Key.ToString()} is forbidden");
}
That thing works pretty fine to me (thanks for #JohnyL):
private void textBox_KeyDown(object sender, KeyEventArgs e)
{
//something here to only allow "A" key to be pressed and displeyed into textbox
if (e.Key == Key.A)
{
stoper.Start();
}
else
e.Handled = true;
}
private void textBox_KeyUp(object sender, KeyEventArgs e)
{
if (e.Key == Key.A)
{
//here i stop the stopwatch to count time of pressing the key
stoper.Stop();
string aS = stoper.ElapsedMilliseconds.ToString();
int aI = Convert.ToInt32(aS);
stoper.Reset();
}
}
Related
Instead of copying and pasting for each number is there a method that could reference to all buttons?
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
if(e.KeyCode == Keys.D5)
{
Five.PerformClick();
}
}
private void Form1_KeyUp(object sender, KeyEventArgs e)
{
if(e.KeyCode == Keys.D5)
{
Five.PerformClick();
}
}
Firstly, the enum values Keys.D0 to Keys.D9 have sequential integer values. You can abuse this knowledge to turn the KeyCode directly into an array index.
var buttons = new Button[] {Zero, One, ... etc ...};
if(e.KeyCode >= Keys.D0 && e.KeyCode <= Keys.D9){
var index = (int)e.KeyCode - (int)Keys.D0;
var button = buttons[index];
button.PerformClick();
}
if(e.KeyCode >= Keys.NumPad0 && e.KeyCode <= Keys.NumPad9){
// similar to the above
}
Or you could rearrange your code. Create a separate method for doing the work of "user entered a digit". Then call that method from both the button click event and form key event.
private void HandleDigit(int value){
// todo
}
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
if(e.KeyCode >= Keys.D0 && e.KeyCode <= Keys.D9){
var value = (int)e.KeyCode - (int)Keys.D0;
HandleDigit(value);
}
}
Maybe this can give you an idea -- instead of the code you show something like
Button.PerformClick('5');
would do what you want. Or even
Button.PerformNumberClick(5);
and if + is preseed
Button.PerformOperatorClick('+');
You can create and event for the first button and then tie all the calculator buttons to that event, inside the event you know what key (number) is pressed.
Here is a code that could be useful, i only added two buttons to test it and notice when i live the form im releasing handles unsubscribing the events:
using System;
using System.Windows.Forms;
namespace Calculator
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
CmdButton1.KeyDown += CmdButtonKeyDown;
CmdButton2.KeyDown += CmdButtonKeyDown;
}
private void CmdButtonKeyDown(object sender, KeyEventArgs e)
{
if(e.KeyCode==Keys.NumPad1 || e.KeyCode == Keys.NumPad2 )
MessageBox.Show("KeyPressed is " + e.KeyCode.ToString());
}
private void Form1_Leave(object sender, EventArgs e)
{
CmdButton1.KeyDown -= CmdButtonKeyDown;
CmdButton2.KeyDown -= CmdButtonKeyDown;
}
}
}
I have registed ctrl+` as a hotkey,and I want to display a window when I press the hotkey and not release the leftctrl key and toggle ` key to do something else just like alt+tab switch the application.Here is the code.
private void ListOnKeyDown(object sender, KeyEventArgs e)
{
if (e.SystemKey==Key.LeftCtrl && e.Key == Key.Oem3)
{
m_host.SelectNext();
}
}
But I found this way only fired one key.So what's the right way to fire the key event?
And here is the debug information.
debug information
Just change your keydown event to detect the modifier this way
private void ListOnKeyDown(object sender, KeyEventArgs e)
{
if (Keyboard.Modifiers == ModifierKeys.Control && e.Key == Key.Oem3)
{
m_host.SelectNext();
e.Handled = true;
}
}
Because onKeyDown event works for ONE key only, in order to use two keys at same time you need little improvise:
bool firstkeyisOn = false;
private void ListOnKeyDown(object sender, KeyEventArgs e)
{
if (e.SystemKey==Key.LeftCtrl/*Or other key by choice*/)
{
firstkeyisOn = true;
e.Handled = true;
return;
}
if(firstkeyisOn && (e.Key == Key.Oem3/*Or other key by choice*/))
{
m_host.SelectNext();
}
}
private void ListOnKeyUp(object sender, KeyEventArgs e)
{
if (e.SystemKey==Key.LeftCtrl/*Key must be same as holding one*/)
{
firstkeyisOn = false;
}
//or
//firstkeyisOn = false;
}
To cancel hotkey mode you just add firstkeyisOn = false under OnKeyUp event and you good to go.
This piece of code detect most keys and puts it in a messageBox, but one of the keys it doesn't is the enter key. *Note it is a key_down method
MessageBox.Show(e.KeyData.ToString());
so far I have tried so many methods to fix and searched a lot for an answer
I have tried this
private void button1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
MessageBox.Show("this is it");
e.IsInputKey = true;
}
}
it says 0 references which I know I'm not calling the method but where do I call it?
where ever I do call it, it gives an error.
you delete this line
e.IsInputKey = true;
private void button1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
MessageBox.Show("this is it");
//e.IsInputKey = true;
}
}
or
private void button1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
MessageBox.Show("this is it");
//e.IsInputKey = true;
}
}
In your Form1 Design Properties:
AcceptButton Property set dropdown to button1 or the name of your Button
KeyUp Event of your Button
private void button1_KeyUp(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
MessageBox.Show("Enter key has been pressed");
}
}
or
private void button1_KeyUp(object sender, KeyEventArgs e)
{
button1_KeyDown(sender, e);
}
private void button1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
MessageBox.Show("Enter key has been pressed");
}
}
Put this line soon after: InitializeComponents(); -->
button1.PreviewKeyDown +=new PreviewKeyDownEventHandler(button1_PreviewKeyDown);
.
The event you're trying to use will only fire when you focus on that button. The focus is passed in 2 different ways ( via user interaction ) one of which is an actual mouse click on that element and another is "tabbing" on to the control, and make sure you read about "Events" and "EventsHandlers"
I have a code like below
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == 13)
{
if (!textBox1.AcceptsReturn)
{
button1.PerformClick();
}
}
}
After I hit Enter, it'll send a message to another textbox and begin a new line. Can anyone help me to bring the cursor back to its first line?
I tried textBox1.SelectionStart, SelectionLength and Focus but it doesn't work, is there any another way?
You can prevent that the keypress is passed on to the control by setting the KeyPressEventArgs.Handled property to true:
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == 13)
{
if (!textBox1.AcceptsReturn)
{
button1.PerformClick();
e.Handled = true;
}
}
}
As you mentioned in a comment that you are implementing a chat app, you also might want to implement the typical behavior of Shift+Return inserting a new line:
private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyValue == 13 && !e.Shift)
{
if (!textBox1.AcceptsReturn && !string.IsNullOrEmpty(textBox1.Text))
{
button1.PerformClick();
textBox1.Text = "";
e.Handled = true;
}
}
}
To set cursor position to the beginning of a textbox, use the following...
I will hazard a guess that you didn't use these in combination with each other...
textBox1.SelectionStart = 0;
textBox1.SelectionLength = 0;
I have magnetic card reader, It emulates Keyboard typing when user swipes card. I need to handle this keyboard typing to one string, when my WPF window is Focused. I can get this typed Key list, but I don't know how to convert them to one string.
private void Window_KeyDown(object sender, KeyEventArgs e)
{
list.Add(e.Key);
}
EDIT: Simple .ToString() method not helps. I've tried this already.
Rather than adding to a list why not build up the string:
private string input;
private bool shiftPressed;
private void Window_KeyDown(object sender, KeyEventArgs e)
{
if (e.Key == Key.LeftShift || e.Key == Key.RightShift)
{
shiftPressed = true;
}
else
{
if (e.Key >= Key.D0 && e.Key <= Key.D9)
{
// Number keys pressed so need to so special processing
// also check if shift pressed
}
else
{
input += e.Key.ToString();
}
}
}
private void Window_KeyUp(object sender, KeyEventArgs e)
{
if (e.Key == Key.LeftShift || e.Key == Key.RightShift)
{
shiftPressed = false;
}
}
Obviously you need to reset input to string.Empty when you start the next transaction.
...or you can try this:
string stringResult = "";
list.ForEach(x=>stringResult+=x.ToString());
EDIT:
After good Timur comment I decided to suggest this:
you can use keyPress event to everything like this:
string stringResult = "";
private void Window_KeyPress(object sender, KeyPressEventArgs e)
{
stringResult += e.KeyChar;
}
Listen To PreviewTextInput Event Instead ...
the TextCompositionEventArgs has a property called "Text" which give you the text representation for key
for example Key.D2 will be just "2" ...i think it will
do the purpose
private void MainWindow_OnPreviewTextInput(object sender, TextCompositionEventArgs e)
{
list.Add(e.Text);
}
You could have a member variable which is a StringBuilder.
something like
class A
{
StringBuilder _contents = new StringBuilder();
private void Window_KeyDown(object sender, KeyEventArgs e)
{
_contents.Append(e.Key.ToString());
}
}
You would have to create a new StringBuilder each time a new card was swiped and then to get the string you would use _contents.ToString();
String combined = String.Empty;
private void Window_KeyDown(object sender, KeyEventArgs e)
{
combined = combined + e.Key.ToString();
}