I'm developing a simple WPF application where I want to use the text changed method for a specific text field. the thing is I implemented the method but, the method gets fired in very short period, like even after i enter one character. I want to check whether the text change is completed in order to go with the methods written in the text changed method.
private void searchBox_TextChanged(object sender, TextChangedEventArgs e)
{
if (...) // how to check whether the typing is finished?
{
// code goes here
}
}
I think you'll need the LostFocus event for this. As #SLaks comment says, you can't predict whether the user will press another key. Alternatively, you could databind the control - depending on what you're actually trying to do that may make more sense.
Instead of TextChanged, try monitoring the LostFocus event, which will fire when the user has left the textbox, either through pressing Enter/Tab or clicking somewhere else on the form.
Agree with LostFocus
UIElement.LostFocus Event
Question does not ask about binding but something to consider.
In binding the equivalent is UpdateSourceTrigger="LostFocus"
Binding.UpdateSourceTrigger Property
With binding you can get into more advanced validation UI effects.
How to: Implement Binding Validation
Related
I would like to validate my textbox when the textbox is deselected.
It should validate the textbox value in the same way as Google's Create Account page.
If the textbox value passes validation it should proceed further otherwise it should show message like: This value is not valid.
Events of Validation And LostFocus can be you here.
Here is some code for validate textbox value
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.lostfocus.aspx
if its a desktop app/WinForms u can use what Suspitsyn Kirill said, and for a web app it would be quite close.
The textbox has event handlers for on focus etc. using the code behind you can assign what the events will do.
Dont remember the C# ones exactly but it should be
private void textBox1_LostFocus(object sender, System.EventArgs e)
{
textBox1_Validating()
}
add the lostfocus on the element to direct to this method.
You could also do it with javascript same concept.
I want to bring the cursor to a textbox when i clicked a button. How can i do that? I tried Focus() method but it didn't not work. The code is shown below.
CsNIPAddrTextBox.Focus();
CsNIPAddrTextBox.TabIndex = 1;
Try textbox1.select(). It's the best approach to bring your cursor to your textbox. It also selects content of the texbox which makes it easier for the user to edit what's inside the textbox.
If that's a 'proper' TextBox (i.e. not custom) then simply calling Focus() should work. It might not, however, if it's read-only (I'm not sure - I've not tried. I know you can get a caret in a read-only box, which implies it can get focus). Certainly if it's not Enabled then you won't be able to set focus.
Check the CanFocus property is true - if it's not, then there might be some other reason preventing the control from receiving focus.
If that's true, however, and the caret still doesn't make it to the control - you need to verify that it is receiving it. Add an event handler for the text box's GotFocus event and breakpoint it to clarify that it gets hit. My guess is that it your breakpoint will be hit. If so - then the answer is that another process is setting focus to another control immediately after your button click occurs. For example, if you do this kind of thing in a validation event handler you'll get a similar result, because the Windows Forms pipeline is already in the process of changing controls when the handler is fired.
Also - why are you setting TabIndex=1? Generally TabIndex is set at design time and left alone (unless of course these are dynamically created). Unless you have a particular reason for doing this I'd get rid of that line. It doesn't have a bearing on why this would/wouldn't work - just an observation.
Edit again:
If you try to select a TextBox in the Click event of a TreeView, it usually fails, because after the Click event the TreeNode will be selected, making your previous Focus() or Select() useless. The workable way is, perhaps, calling them in a Timer.
Timer t = new Timer();
t.Interval = 10;
t.Tick += new EventHandler((s,ev)=>textBox2.Focus());
t.Start();
This is more like a hack though...
Set theActiveControl property of the form
ActiveControl = yourtextbox
You have to use TextBox.Select Method
For example
textbox1.Select(textbox1.Text.Length,0);
Sets the cursor to the end of the text in yout textbox.
If i read right you are talking about moving mouse cursor to the textbox? - Then you can use code like this:
System.Windows.Forms.Cursor.Position =
PointToScreen(
new Point( textBox1.Location.X + 5, textBox1.Location.Y + 5)
);
I know many of you had provided answers, but this may be useful to some who weren't able to get from previous responses.
This worked for me, setting Select() on input text had set the cursor to the textbox.
Have this in form constructor:
this.Activated += OnActivated;
Handler Code:
private void OnActivated(object sender, EventArgs eventArgs)
{
txtUser.Select();
}
if textbox.Multiline=true and/or textbox.WordWrap = true, the cursor might be hiding at the bottom of the field.
I am pasting text in textbox1.text and I need textbox1 should fire its leave event by itself.
For now I am using this following code. but i will appreciate if anyone can suggest me an elegant or better way:-
private void event()
{
textbox1.Text = SearchedText;
textbox1.Focus();
textbox2.Focus();
}
First I am pasting text, then setting up Focus on the control, then set up focus again on second control. It is firing leave event of textbox1, but any thing better?
Just call the code directly, no need to wait for an event:
private void textBox1_Leave(object sender, EventArgs e) {
mumble();
}
private void someEvent() {
textBox1.Text = SearchedText;
mumble();
}
void mumble() {
// etc...
}
Just calling textBox1_Leave(this, EventArgs.Empty) works fine too.
You should handle the TextChanged or Validated events instead of the Leave event.
To FORCE Leave, Validating and so on Events, no matter what, I've found ONE working solution.
First i tried:
ProcessTabStop(true);
ProcessTabStop(false);
instead of:
textbox1.Focus();
textbox2.Focus();
Problem with the TextBox 1 and 2 Focus() is that its only Active Component that needs Leave, Validating and so on fired, not other Controls, and besides, what if the form is dynamic, you as a programmer not necessarily have any idea what Control you are trying to Leave, that's why i changed Control.Focus() method to ProcessTabStop method above. The problem is then, if only ONE Control has TabStop true, there is no control to go to and back from. So Events are NOT Fired.
Next problem is that i not necessarily Close the Form with the mouse so Focus doesn't change, I use a Key (Ctrl+Enter) to Accept the Form, and then Leave, validating and so on are NOT fired, when i Send Form Close, as Form Close registers weather there are changes or not. But Values are set in Leave on TextBoxes, so I had to find a solution that worked no matter what i did to it. I almost gave up, actually i had a problem report all filled out, when I thought, what if i set ActiveControl to Null and then to the Control it came from. It worked, but had som "Flicker" due to color change on Parent Panel depending on Active or Inactive.
The "Workaround" that works in all cases is:
Control Old = ActiveControl;
// ActiveControl.SuspendLayout();
// ActiveControl.FindForm().SuspendLayout();
ActiveControl = null;
ActiveControl = Old;
// ActiveControl.FindForm().ResumeLayout();
// ActiveControl.ResumeLayout();
That seems to fire Leave, Validating and so on Events, no matter number of Form Controls and TabStopped Controls. You MAY need to SuspendLayout on either ActiveControl, or Form. My Control (Parent Panel) changes color when Active/Inactive, if I do not Suspend Layout on Form, parent panel gets an unwanted "flicker" effect.
Looking at the solution, it is very obvious, now I've found it, but took me half a day to try different things that solved one or another problem, but not all.
I know this a VERY old thread, but one of very few articles I've found on the subject of Forcing Leave Event to be Fired.
Is there any event that fire when the value of the textbox change from a peace of code and when the textbox is validated or lost the focus and the event don't fire on the key press,because I have a lot of calculation and It's not possible to do it on every key press
Use TextChanged for text changed.
Use LostFocus for when textbox looses focus.
Use Validating or Validated for validation.
Here is the order in which events are called for TextBox:
// Reference : http://msdn.microsoft.com/en-us/library/system.windows.forms.control.validated.aspx
1) Enter
2) GotFocus
3) Leave
4) Validating
5) Validated
6) LostFocus
This should help you decide where you want to put your code.
There's no event that will fulfill your requirement of being raised when the textbox's value is changed programmatically through code, but not when text is typed into it by the user. The TextChanged event is going to be raised either way (this is fairly intuitive—the text value is changing, and the computer doesn't know or care what is responsible for changing it). As the documentation for this event indicates:
User input or setting the Text property to a new value raises the TextChanged event.
If you need to run custom validation logic when you add text to your textbox in code, you will need to invoke whatever method contains the validation logic yourself. Extract it into a separate method, which you call from the Validating/Validated event handler and from all of the places in your code where you set the textbox's Text property.
As a supplement to the other answers that have already been posted, I strongly recommend using either the Validating (if you want to be able to cancel the validation) or Validated events to handle the textbox losing focus, rather than the somewhat more obviously named LostFocus event.
You can use the LostFocus or Validated events.
Use a member variable.
private bool _changeByCode;
public void DoSomeChanges()
{
_changeByCode = true;
textbox1.Text = "Hello";
_changeByCode = false;
}
public void Textbox1_Change(object source, EventArgs e)
{
if (_changeByCode)
return;
//do your validation here.
}
I have a check box and I have subscribed for the CheckedChanged event. The handler does some operations in there. I check and uncheck the checkbox programmatically (ex: chkbx_Name.Checked = true), and the CheckedChanged event gets fired.
I want this event to be fired only when I manually check or uncheck it. Is there any way to avoid firing of this event when i check/uncheck it programmatically?
unsubscribe the event before you set:
check1.CheckChanged -= check1_CheckChanged;
then you can programmatically set the value without the checkbox firing its CheckChanged event:
check1.Checked = true;
then re-subscribe:
check1.CheckChanged += check1_CheckChanged;
[EDIT: March 29, 2012]
The problem with Tanvi's approach is you need to catch all source of manual check or uncheck. Not that there's too many(it's only from mouse click and from user pressing spacebar), but you have to consider invoking a refactored event from MouseClick and KeyUp(detecting the spacebar)
It's more neat for a CheckBox(any control for that matter) to be agnostic of the source of user input(keyboard, mouse, etc), so for this I will just make the programmatic setting of CheckBox really programmatic. For example, you can wrap the programmatic setting of the property to an extension method:
static class Helper
{
public static void SetCheckProgrammatically(
this CheckBox c,
EventHandler subscribedEvent, bool b)
{
c.CheckedChanged -= subscribedEvent; // unsubscribe
c.Checked = b;
c.CheckedChanged += subscribedEvent; // subscribe
}
}
Using this approach, your code can respond neatly to both user's mouse input and keyboard input via one event only, i.e. via CheckChanged. No duplication of code, no need to subscribe to multiple events (e.g. keyboard, checking/unchecking the CheckBox by pressing spacebar)
No. Those property change events fire whenever the property value changes, regardless of whether this was done by your code, by the control's own code or databinding. It's all the same code path, usually.
What you can do, however, if your event handler resides in the same class as the code that changes the property value, is to introduce a private boolean field in the class which you use as an indicator of whether the current property change is triggered by your code or by the user. After your change you simply reset it. The event handler would then look at the field and decide of whether it should do anything or not:
class Foo : Form {
private bool checkedProgrammatically = false;
void someMethod() {
// ...
checkedProgrammatically = true;
checkBox1.Checked = true;
checkedProgrammatically = false;
// ...
}
private void checkBox1_CheckChanged(object sender, EventArgs e) {
if (checkedProgrammatically) return;
// ...
}
}
I'm sorry I can't just comment on Michael Buen's answer due to my being new here (no reputation), but for what it's worth I strongly prefer his solution to Johannes Rössel's for a couple of reasons.
1) the checkedProgrammatically variable is a little too close to global for me. There's nothing to stop another method accidentally setting it to true, causing all your events to stop.
2) you could end up with a lot of variables depending on the number of events you're dealing with. It would be easy to change the wrong one and the results can be difficult to debug.
3) it's more obvious what you're doing when you unsubscribe then resubscribe. All the logic is right there, and you don't need to change your event handlers to exit early depending on certain conditions.
I've used both methods extensively and I find Michael's a lot easier in the long run.
You can use the MouseClick event and in that check for the checked state of the checkbox.
This way it wont be triggered programatically, it would only be called when the user manually checks or unchecks the checkbox.
You can set boolean variable before changing value programiticaly, and check than reset that variable in checkedchanged event