I am trying to have a permanent prefix input in the textbox. In my case, I want to have the following prefix:
DOMAIN\
So that users can only have to type their username after the domain prefix. It's not something I have to do, or pursue but my question is more out of curiosity.
I was trying to come up with some logic to do this on the TextChangedEvent however, this means I need to know which characters have been deleted where and then pre-append DOMAIN\ to whatever their input is - I can't work out the logic for this so I can't post what I have tried apart from where I got to.
public void TextBox1_TextChanged(object sender, EventArgs e)
{
if(!TextBox1.Text.Contains(#"DOMAIN\")
{
//Handle putting Domain in here along with the text that would be determined as the username
}
}
I've looked on the internet and can't find anything, How do I have text in a winforms textbox be prefixed with unchangable text? was trying to do a similar thing but the answers don't really help.
Any ideas on how I can keep the prefix DOMAIN\ in a TextBox?
Using the KISS principle is indicated here. Trying to catch key presses just won't do anything when the user uses Ctrl+V or the context menu's Cut and Paste commands. Simply restore the text when anything happened that fudged the prefix:
private const string textPrefix = #"DOMAIN\";
private void textBox1_TextChanged(object sender, EventArgs e) {
if (!textBox1.Text.StartsWith(textPrefix)) {
textBox1.Text = textPrefix;
textBox1.SelectionStart = textBox1.Text.Length;
}
}
And help the user avoid editing the prefix by accident:
private void textBox1_Enter(object sender, EventArgs e) {
textBox1.SelectionStart = textBox1.Text.Length;
}
Why not see in the event args of the textChanged what the value was before and the new value and if the Domain\ is not there in the new value, then keep the old one.
Or, why not just show the Domain\ as a label in front of the TextBox and just prepend it in code behind so that the final text is something like Domain\<username>.
Yeah I sort of solved this once I asked the question... I won't delete the question incase anybody else has the same question in the future, because I couldn't find a suitable answer. I set the Text to Domain\ and then used the KeyPress event.
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = (textBox1.GetCharIndexFromPosition(Cursor.Position) < 7);
}
I tend to keep working once I ask, instead of letting people do all the work for me :)
How about a reusable custom TextBox control. There are comments in the code
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
textBox1.Prefix = #"DOMAIN\";
}
}
class PrefixedTextBox : TextBox
{
private string _prefix = String.Empty;
public string Prefix
{
get { return _prefix; }
set
{
_prefix = value;
Text = value;
}
}
protected override void OnKeyDown(KeyEventArgs e)
{
// Don't allow Backspace and Delete if the only text is Prefix
if (Text == Prefix && (e.KeyCode == Keys.Back || e.KeyCode == Keys.Delete))
e.Handled = true;
// If home key is pressed set cursor just after the prefix
if (e.KeyCode == Keys.Home)
{
e.Handled = true;
SelectionStart = Prefix.Length;
}
// Don't allow cursor to be moved inside Prefix
if (SelectionStart <= Prefix.Length && (e.KeyCode == Keys.Left || e.KeyCode == Keys.Up))
e.Handled = true;
base.OnKeyDown(e);
}
protected override void OnClick(EventArgs e)
{
EnsureCursorPosition();
base.OnClick(e);
}
protected override void OnKeyPress(KeyPressEventArgs e)
{
EnsureCursorPosition();
// this was checked OnKeyDown. This prevents deleting and writing back behaviour
if (Text == Prefix && e.KeyChar == '\b')
e.Handled = true;
base.OnKeyPress(e);
}
protected override void OnKeyUp(KeyEventArgs e)
{
// Yet, some how an invalid text is entered fix it by just displaying the Prefix
if (!Text.StartsWith(Prefix))
Text = Prefix;
base.OnKeyUp(e);
}
private void EnsureCursorPosition()
{
// Never allow cursor position before Prefix
if (SelectionStart < Prefix.Length)
SelectionStart = Text.Length;
}
}
Related
I'm making a Notepad variant in Visual Studio (Winform, C#). It has a toolstrip, with options such as Undo, Cut, Copy, Paste, Delete, etc. The shortcut keys are enabled and connected with the menu options (CTRL + Z, CTRL + C, etc).
The rest of the Notepad variant is filled with a multiline textbox.
The problem arises when I want to delete the text from the textbox via the Delete key, or the menu option - while that works (i.e. the characters to the right of the current caret position are deleted, selected characters are deleted, etc), I am unable to undo that specific action.
This is the relevant part of my code:
private void mnuCut_Click(object sender, EventArgs e)
{
if(txtbox.SelectedText != "")
{
txtbox.Cut();
}
}
private void mnuCopy_Click(object sender, EventArgs e)
{
if (txtbox.SelectedText != "")
{
txtbox.Copy();
}
}
private void mnuPaste_Click(object sender, EventArgs e)
{
if(Clipboard.GetDataObject().GetDataPresent(DataFormats.Text) == true)
{
if(txtbox.SelectionLength > 0)
{
txtbox.SelectionStart = txtbox.SelectionStart + txtbox.SelectionLength;
}
txtbox.Paste();
}
}
private void mnuUndo_Click(object sender, EventArgs e)
{
if(txtbox.CanUndo == true)
{
txtbox.Undo();
txtbox.ClearUndo();
}
}
private void txtbox_KeyUp(object sender, KeyEventArgs e)
{
// Delete
if(e.KeyCode == Keys.Delete)
{
if(txtbox.SelectionLength < 1)
{
txtbox.SelectionLength = 1;
}
txtbox.SelectedText = "";
}
// Select all
if(e.Modifiers == Keys.ControlKey && e.KeyCode == Keys.A)
{
txtbox.SelectAll();
}
}
private void mnuDelete_Click(object sender, EventArgs e)
{
if (txtbox.SelectionLength < 1)
{
txtbox.SelectionLength = 1;
}
txtbox.SelectedText = "";
}
private void selectAllToolStripMenuItem_Click(object sender, EventArgs e)
{
txtbox.SelectAll();
}
I think the problem may be in the way I'm deleting characters with the mnuDelete_Click and KeyUp event handlers. The same thing happens if I replace txtbox.SelectedText = "" with txtbox.SelectedText = String.Empty.
I know that I might be better off by using, say, txtbox.Cut(), like this:
private void txtbox_KeyUp(object sender, KeyEventArgs e)
{
// Delete
if(e.KeyCode == Keys.Delete)
{
if(txtbox.SelectionLength < 1)
{
txtbox.SelectionLength = 1;
}
//txtbox.SelectedText = "";
txtbox.Cut();
}
// Select all
if(e.Modifiers == Keys.ControlKey && e.KeyCode == Keys.A)
{
txtbox.SelectAll();
}
}
private void mnuDelete_Click(object sender, EventArgs e)
{
if (txtbox.SelectionLength < 1)
{
txtbox.SelectionLength = 1;
}
//txtbox.SelectedText = "";
txtbox.Cut();
}
But, even though this works, it'll replace the current contents of the clipboard with whatever was deleted / cut, which is something I don't want.
Finally, I ended up using SendKeys.Send("{BACKSPACE}"), and that gave the desired functionality. But the solution doesn't feel right - the original action was pressing the Delete key, not the Backspace key.
So, my question is this - how can delete characters via the Delete key, and obtain the ability to undo it, without resorting to hacky solutions? Or does it make no difference in the end, because it works as it is?
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 a read only rich text box and an editable text box. The text from the read only is from the editable. They can't be viewed at the same time. When the user presses a key it hides the read only and then selects that position in the editable.
I would like it to enter the key that was pressed into the editable without playing the error "ding"
I'm thinking that an override of the read only error function would be ideal but i'm not sure what that is.
private void EditCode(object sender, KeyPressEventArgs e)
{
int cursor = txtReadOnly.SelectionStart;
tabText.SelectedIndex = 0;
ToggleView(new object(), new EventArgs());
txtEdit.SelectionStart = cursor;
txtEdit.Text.Insert(cursor, e.KeyChar.ToString());
}
Answer:
private void EditCode(object sender, KeyPressEventArgs e)
{
e.Handled = true;
int cursor = txtCleanCode.SelectionStart;
tabText.SelectedIndex = 0;
ToggleView(new object(), new EventArgs());
txtCode.Text = txtCode.Text.Insert(cursor, e.KeyChar.ToString());
txtCode.SelectionStart = cursor + 1;
}
I'll have to make it check if it's a non-control char but that's another deal. Thanks everyone!
One idea is to make the rich text box editable but canceling out all keys:
private void richtextBox1_KeyDown(object sender, KeyEventArgs e)
{
// Stop the character from being entered into the control
e.Handled = true;
// add any other code here
}
Here is one way: Check for <Enter> so the user can still use the navigation keys:
private void txtReadOnly_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
e.Handled = true; // no ding for normal keys in the read-only!
txtEdit.SelectionStart = txtReadOnly.SelectionStart;
txtEdit.SelectionLength = txtReadOnly.SelectionLength;
}
}
No need to fiddle with a cursor. Make sure to have:
txtEdit.HideSelection = false;
and maybe also
txtReadOnly.HideSelection = false;
Obviously to keep the two synchronized :
private void txtEdit_TextChanged(object sender, EventArgs e)
{
txtReadOnly.Text = txtEdit.Text;
}
You will need o decide on some way fo r the user to return from editing to viewing. Escape should be reserved for aborting the edit! Maybe Control-Enter?
This is the code I currently have:
private void textBox_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = !char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar) && e.KeyChar != '.';
if (e.KeyChar == '.' && (sender as TextBox).Text.IndexOf('.') > -1) e.Handled = true;
}
KeyPress isn't good enough to do this kind of validation. A simple way to bypass it is to paste text into the text box with Ctrl+V. Or the context menu, no key event at all.
In this specific case, the TextChanged event will get the job done:
private void textBox_TextChanged(object sender, EventArgs e) {
var box = (TextBox)sender;
if (box.Text.StartsWith(".")) box.Text = "";
}
But there's a lot more to validating numeric values. You also need to reject stuff like 1.1.1 or 1.-2 etcetera. Use the Validating event instead. Drop an ErrorProvider on the form and implement the event like this:
private void textBox_Validating(object sender, CancelEventArgs e) {
var box = (TextBox)sender;
decimal value;
if (decimal.TryParse(box.Text, out value)) errorProvider1.SetError(box, "");
else {
e.Cancel = true;
box.SelectAll();
errorProvider1.SetError(box, "Invalid number");
}
}
You probably want to use the TextChanged event, since the user could paste in values. For the best experience given the requirements, I'd suggest simply removing any leading . characters.
void textBox1_TextChanged(object sender, EventArgs e)
{
if (textBox1.Text.StartsWith("."))
{
textBox1.Text = new string(textBox1.Text.SkipWhile(c => c == '.').ToArray());
}
}
This does not address a requirement to use only digits -- wasn't clear in the question if that is the case.
This works for copy and pasting too.
private void textBox1_KeyUp(object sender, KeyEventArgs e)
{
int decimalCount=0;
string rebuildText="";
for(int i=0; i<textBox1.Text.Length; i++)
{
if (textBox1.Text[i] == '.')
{
if (i == 0) break;
if (decimalCount == 0)
rebuildText += textBox1.Text[i];
decimalCount++;
}
else if ("0123456789".Contains(textBox1.Text[i]))
rebuildText += textBox1.Text[i];
}
textBox1.Text = rebuildText;
textBox1.SelectionStart = textBox1.Text.Length;
}
You can try this:
private void TextBox_TextChanged(object sender, EventArgs e)
{
TextBox.Text = TextBox.Text.TrimStart('.');
}
How can I allow the users of my program to type in a value and have it auto-complete, however, I also what to prevent them from entering new data because it would cause the data to be unfindable (unless you had direct access to the database).
Does anyone know how to do this?
The reasoning behind not using just a dropdown style combobox is because entering data by typing it is and then refusing characters that are not part of an option in the list is because it's easier on the user.
If you have used Quickbook's Timer, that is the style of comboboxes I am going for.
Kudos to BFree for the help, but this is the solution I was looking for. The ComboBox is using a DataSet as it's source so it's not a custom source.
protected virtual void comboBoxAutoComplete_KeyPress(object sender, KeyPressEventArgs e) {
if (Char.IsControl(e.KeyChar)) {
//let it go if it's a control char such as escape, tab, backspace, enter...
return;
}
ComboBox box = ((ComboBox)sender);
//must get the selected portion only. Otherwise, we append the e.KeyChar to the AutoSuggested value (i.e. we'd never get anywhere)
string nonSelected = box.Text.Substring(0, box.Text.Length - box.SelectionLength);
string text = nonSelected + e.KeyChar;
bool matched = false;
for (int i = 0; i < box.Items.Count; i++) {
if (((DataRowView)box.Items[i])[box.DisplayMember].ToString().StartsWith(text, true, null)) {
matched = true;
break;
}
}
//toggle the matched bool because if we set handled to true, it precent's input, and we don't want to prevent
//input if it's matched.
e.Handled = !matched;
}
This is my solution, I was having the same problem and modify your code to suit my solution using textbox instead of combobox, also to avoid a negative response after comparing the first string had to deselect the text before comparing again against autocomplet list, in this code is an AutoCompleteStringCollection shiper, I hope this solution will help
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
String text = ((TextBox)sender).Text.Substring(
0, ((TextBox)sender).SelectionStart) + e.KeyChar;
foreach(String s in this.shippers)
if (s.ToUpperInvariant().StartsWith(text.ToUpperInvariant()) ||
e.KeyChar == (char)Keys.Back || e.KeyChar == (char)Keys.Delete)
return;
e.Handled = true;
}
OK, here's what I came up with. Hack? Maybe, but hey, it works. I just filled the combobox with the days of the week (hey, I needed something), and then handle the keypress event. On every key press, I check if that word matches the begining of any word in the AutoCompleteSourceCollection. If it doesn't, I set e.Handled to true, so the key doesn't get registered.
public Form5()
{
InitializeComponent();
foreach (var e in Enum.GetValues(typeof(DayOfWeek)))
{
this.comboBox1.AutoCompleteCustomSource.Add(e.ToString());
}
this.comboBox1.KeyPress += new KeyPressEventHandler(comboBox1_KeyPress);
}
private void comboBox1_KeyPress(object sender, KeyPressEventArgs e)
{
string text = this.comboBox1.Text + e.KeyChar;
e.Handled = !(this.comboBox1.AutoCompleteCustomSource.Cast<string>()
.Any(s => s.ToUpperInvariant().StartsWith(text.ToUpperInvariant()))) && !char.IsControl(e.KeyChar);
}
EDIT: If you're on .Net 3.5 you'll need to reference System.Linq. If you're on .NET 2.0 then use this instead:
private void comboBox1_KeyPress(object sender, KeyPressEventArgs e)
{
string text = this.comboBox1.Text + e.KeyChar;
foreach (string s in this.comboBox1.AutoCompleteCustomSource)
{
if (s.ToUpperInvariant().StartsWith(text.ToUpperInvariant()))
{
return;
}
}
e.Handled = true;
}
I know I'm about six years late but maybe this can help somebody.
private void comboBox1_Leave(object sender, EventArgs e)
{
if (comboBox1.Items.Contains(comboBox1.Text)) { MessageBox.Show("YE"); }
else { MessageBox.Show("NE"); }
OR
if (comboBox1.FindStringExact(comboBox1.Text) > -1) { MessageBox.Show("YE"); }
else { MessageBox.Show("NE"); }
}