Develop Reference

How to block space in passwordbox in wpf

I’m using a PasswordBox control in wpf.
I want to block space in the control, but i can’t find the way.
I tried to use a KeyDown event but the event isn’t working.
What is the best way to block space in the PasswordBox?

For WPF you should using PreviewKeyDown Based on docs occurs before the KeyDown event When a key is pressed while focus is on this control.
XAML:
<PasswordBox x:name="txtPasscode" PreviewKeyDown="txtPasscode_PreviewKeyDown"/>
and in behind :
private void txtPasscode_PreviewKeyDown(object sender, KeyEventArgs e)
{
if (e.Key == Key.Space && txtPasscode.IsFocused == true)
{
e.Handled = true;
}
}
Also in C# native try this :
private void txtPasscode_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == ' ') e.Handled = true;
}

The KeyDown event you're handling actually fires after the character added to the passwordbox. You can block it by handling PreviewKeyDown this way(KeyDown won't fire anymore if user pressed space):
private void passwordbox_PreviewKeyDown(object sender, KeyEventArgs e)
{
if (e.Key == Key.Space)
{
e.Handled = true;
}
}
If you need to block an event you're going to use the event beginning with "Preview"(read more here).

Button KeyPress Not Working for Enter Key

I have a button for which I set the KeyPress event.
this.myButton.KeyPress += new KeyPressEventHandler(this.myButtonEvent_keypress);
private void myButtonEvent_keypress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == (char)Keys.Return || e.KeyChar == (char)Keys.Space)
{
// do something
}
}
Now whenever the Space key is pressed, I get the event triggered. This part works fine.
But for some reason, the Enter key press is not triggering the KeyPress
event. Also Alt, Ctrl, Shift are not working.
How can I make the button receive Enter key press?
UPDATE:
I tried below too without any luck
this.myButton.MouseClick += new MouseEventHandler(myButton_Click);

When a Button has focus and you press Enter or Space the Click event raises.
So to handle Enter or Space it's enough to handle Click event and put the logic you need there.
So you just need to use button1.Click += button1_Click;
private void button1_Click(object sender, EventArgs e)
{
MessageBox.Show("Clicked!");
}
If you really want to know if Enter or Space was pressed, you can hanlde PreviewKeyDown event:
private void button1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
{
if(e.KeyCode== Keys.Enter)
{
MessageBox.Show("Enter");
}
if (e.KeyCode == Keys.Space)
{
MessageBox.Show("Space");
}
}

Enter and space can be handled using click event.
this.myButton.Click += new EventHandler(myButton_Click);

The Button control in WinForms will eat Enter, Space, Tab, ESC, and a few other special key's press events. One method to intercept these events is to override Control.ProcessDialogKey. Or you can override IsDialogKey to say if a key should be handled as a special case.
A another option is to set KeyPreview = true on you parent Form. Then you can handle all KeyPress events at the Form level and use Form.ActiveControl if you need to see what control has Focus

How can I override the default button on a form when focus is in a TextBox

I have a winform form which has typical OK and Cancel buttons.
The OK button is set as the default button. When the user presses the ENTER key, the form is closed.
The form also has a text box which has a Search button beside it. The text box allows the user to enter search text and the Search button initiates the search function.
I would like the user to be able to press the ENTER key when the text box has the input focus and have the search function activate.
The problem is that the form is grabbing the ENTER key event before the text box's handler gets it.
EDIT: I've tried using the following event handlers, but they never get hit, and the form closes when the Enter key is hit:
private void txtFilter_KeyUp(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
Search();
e.Handled = true;
}
}
private void txtFilter_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
Search();
e.Handled = true;
}
}
I've also tried enabling the KeyPreview property on the form and implementing a KeyDown event handler for the form, but the Enter key never seems to cause any of these to be hit.
What is the best way to accomplish this?

Try handling the Enter and Leave events of the TextBox to clear out your form's AcceptButton property:
private void txtFilter_Enter(object sender, EventArgs e) {
this.AcceptButton = null;
}
private void txtFilter_Leave(object sender, EventArgs e) {
this.AcceptButton = closeButton;
}
Then you can just process your KeyUp event as your want:
private void txtFilter_KeyUp(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
Search();
}
}

Add a KeyDown event handler to the textBox and then add this to it
if (e.KeyCode == Keys.Enter)
{
btnSearch.PerformClick();
}

C# keypress doesn't capture 'delete' key

I have added a keyPress event on a ListView. With a breakpoint on my event, I can see that most of the keys trigger the event. However, a few among which, the one I'm interested in (delete), just won't trigger my event.
Is that weird ? And no, there's no broken keys on my keyboard :D
private void listView1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == (char)Keys.Delete)
{
ListView target = (ListView)sender;
if (target.SelectedIndices != null && target.SelectedIndices.Count > 0)
{
string ric = target.SelectedItems[0].SubItems[0].Text;
//target.Items.RemoveAt(target.SelectedIndices[0]);
ListModels.getInstance().getModel("Vols").removeRic(ric);
}
}
}

The reason for this is that the KeyPress event sends a character to the control based upon the character-key you press. However, as you'd expect, the delete key does not represent a character and is thus a non-character key.
Therefore using the KeyPress event will do nothing as you have noticed. You should use the KeyDown or KeyUp Events, either of which will work absolutely fine. The nuance being whether you want your event to fire upon pressing, or letting go of a key.

You'll want to use the KeyDown event for this.

In KeyDown use the condition as follows,
if (e.KeyCode == Keys.Delete)
{
// Your Logic....
}

Use keyDown instead; keyPress is something like a full keyDown + keyUp

The problem is that if you set EditMode property to EditOnEnter it won't fire. If you use EditOnKeyStrokeOfF2 it will fire the event

If you are looking for a solution where the user should only be able to choose from the defined items, then I believe you can do it with this:
private void DropDownRank_KeyDown(object sender, KeyEventArgs e)
{
e.SuppressKeyPress = true;
}

See this code:
private void Form1_Load(object sender, EventArgs e)
{
listView1.KeyUp += new KeyEventHandler(ListView_KeyUp);
}
/// <summary>鍵盤觸發 ListView 清單</summary>
private void ListView_KeyUp(object sender, KeyEventArgs e)
{
ListView ListViewControl = sender as ListView;
if (e.KeyCode == Keys.Delete)
{
foreach (ListViewItem eachItem in ListViewControl.SelectedItems)
{
ListViewControl.Items.Remove(eachItem);
}
}
}

I tried all the stuff mentioned above but nothing worked for me, so im posting what i actually did and worked, in the hopes of helping others with the same problem as me:
Add an event handler in the constructor:
public partial class Test
{
public Test()
{
this.RemoveHandler(KeyDownEvent, new KeyEventHandler(Test_KeyDown));
// im not sure if the above line is needed (or if the GC takes care of it
// anyway) , im adding it just to be safe
this.AddHandler(KeyDownEvent, new KeyEventHandler(Test_KeyDown), true);
InitializeComponent();
}
//....
private void Test_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Delete)
{
//your logic
}
}
}

Alternative to set focus from within the Enter event

I have a textbox and in some cases in Enter event I need to set the focus to a different textbox.
I tried that code:
private void TextBox1_Enter(object sender, EventArgs e)
{
if(_skipTextBox1) TextBox2.Focus();
}
But this code doesn't work. After that I found on MSDN:
Do not attempt to set focus from within the Enter, GotFocus, Leave, LostFocus, Validating, or Validated event handlers.
So how can I do it other way?

Postpone executing the Focus() method until after the event is finished executing. Elegantly done by using the Control.BeginInvoke() method. Like this:
private void textBox2_Enter(object sender, EventArgs e) {
this.BeginInvoke((MethodInvoker)delegate { textBox3.Focus(); });
}

You could handle the KeyPress event instead:
private void TextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == (char)Keys.Return)
{
e.Handled = true;
TextBox2.Focus();
}
}

textBox.Select();
or
textBox.Focus();
or
set TabIndex = 0 from properties of that textBox.
both methods are use to set focus on textBox in C#, .NET