If I create a simple Winforms app with a button and a textbox, and the following event handlers, I'd expect to see "False" when I hit the button. When I hit the button, it actually produces "True".
Why is the form valid? It doesn't appear that the validating event is executing at all, even though the docs say that passing false causes validation to be performed unconditionally.
private void button1_Click(object sender, EventArgs e)
{
MessageBox.Show(this.Validate(false).ToString());
}
private void textBox1_Validating(object sender, CancelEventArgs e)
{
e.Cancel = true;
}
It looks like you're trying to validate a child control of the Form. If that's the case, you should use one of the ValidateChildren methods instead of Validate.
Related
I have been developing a windows form application and ran into a problem.
After trying various things (Listed below) I have come to seek your knowledge to help point me in the right direction.
I have replicated a much simpler version of my program:
As you can see, I have two textboxes. I want to be able to click on the textbox on the bottom (textbox1) and call some form of an event, in this case, for simplicity, pop up a message box.
I have been through the events listed here:
https://msdn.microsoft.com/en-us/library/system.windows.forms.textbox_events(v=vs.110).aspx
And implemented them into my code as I expected one of them to work. However, this is not the case.
private void textBox1_TextChanged(object sender, EventArgs e)
{
MessageBox.Show("TextBox Entered");
}
//Above - Will pop message box when text entered.
private void textBox1_GotFocus(object sender, EventArgs e)
{
MessageBox.Show("TextBox Entered");
}
private void textBox1_Enter(object sender, EventArgs e)
{
MessageBox.Show("TextBox Entered");
}
private void textBox1_Click(object sender, EventArgs e)
{
MessageBox.Show("TextBox Entered");
}
Does anybody know what I am missing? I presume what I am trying to achieve is actually possible?
Kind Regards,
B.
Ensure the event is subscribed to the methods you have written. You can do this in the design view using the Events tab of the property window (looks like a lightning bolt). As mentioned by others, a double click in the events window will generate the event's method for you, and subscribe to it automatically.
Another way is to subscribe directly using code; you could write this in the form constructor for example:
textBox1.TextChanged += textBox1_TextChanged;
I am generating a number of buttons with similar or identical content and was hoping to use the names they are given to differentiate them. As the program is creating the buttons dynamically I can't create a separate event for them all and instead need to be able to grab the name to be able to know which button triggered the event.
Is there a way to pass through the name of a button to the click event it initiates? the sender object seems to contain the content but not the name.
It is for a event like this:
private void Button_Click(object sender, RoutedEventArgs e)
{
//getname of button
Canvas.Children.Remove(//name of button\\)
}
Far as I know, WPF does not even assign anything to the Name property automatically - that's just for developers to assign so we can reference the control.
However, you should be able to just pass in the sender to the remove method since it accepts a UIElement argument which Button is derived from.
Canvas.Children.Remove((Button)sender);
I'm not familiar with WPF. If this answer appears to be a junk, I'll delete it.
In ASP.Net, we can cast to a button to get the sender's information. Something like this -
private void Button_Click(object sender, RoutedEventArgs e)
{
var button = sender as Button;
button.Name
}
Perhaps getting at the control's name will work for you
private void button1_Click(object sender, RoutedEventArgs e)
{
Control control = (Control)sender;
Canvas.Children.Remove(control.Name);
}
I'm writing a Hangman program in C# and when I press a keyboard button I want the button on the form to be clicked. Where should I write this? In form1.load()?
No, you should select the Form on which you want the event to be triggered, then go to the properties pane, select the event tab and go down to KeyPress event, double click it and add some code.
Normaly something like this would do what you want, just google the KeyChar value to determine the keyPress you want to control, you can add more if statements:
private void Form1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == (char)13)
{
Button1.PerformClick();
}
//Other if statements if you want to keep an eye out for other keyPresses
}
[edit] I just remembered you might be also considering the shortcuts, in wich case the Button1.Text property should be marked &Button1, this way the "B" would be underlined and accept the alt+B shortcut to execute the button click event.
The & symbol is set before the letter you want for the shortcut, make sure you dont use the same letter for various buttons.
You wouldn't write the code in Form.Load() if you want it to happen in response to a keyboard event. That event occurs (and the code inside of it is executed) when your form first loads (appears on screen).
How about handling the KeyPress event and writing the code in that method, instead? Your form has one of those events, too.
Sample code:
private void Form1_KeyPress(object sender, KeyPressEventArgs e)
{
Button1.PerformClick();
}
The PerformClick method will generate a Click event for a Button control. You can handle that Click event in a similar way:
private void Button1_Click(object sender, EventArgs e)
{
// do something in response to the button being clicked
// ...
MessageBox.Show("Button clicked!");
}
If this event-handling stuff is confusing to you, make sure that you pick up a good book on programming in C# and/or the .NET Framework so that you learn it well. It's very important and not something to skip!
You have to enable KeyPreview property on the form, then you have to implements the KeyPress event directly on the form :
Form1.KeyPress +=new KeyPressEventHandler(Form1_KeyPress);
private void Form1_KeyPress(object sender, KeyPressEventArgs e) {
if(e.KeyCode == someKey) {
button1.performclick();
}
}
private void Form_KeyDown(object sender, KeyEventArgs e)
{
if(e.KeyCode == Keys.Left)
{
// Do your hang job
Button_Click(sender, EventArgs.Empty);
}
}
You need to subscribe to the events of interest and process them after. But before you need to read and study how to do that. It's a not a difficult issue in C#.
http://msdn.microsoft.com/en-us/library/ms171534.aspx
One time subscribed to the events create a function that you can call from button click and from keydown.
In Visual C# Form Application, When I Click on the button I want to add to the other controls(like listboxes,labels,textboxes) in same form.
How do I do this?
I have no idea what "to come to the other controls" might mean. But the event handlers in your Form derived class is the switchboard. Implement the button's Click event and have it do whatever you want done with any other controls. A trivial example:
private void button1_Click(object sender, EventArgs e) {
label1.Text = "You clicked the button!";
}
In the form designer, add an event handler to the button's Click event.
The form designer will give you a new method like this; add your code into this method:
private void button_Click(object sender, EventArgs e)
{
// Write some code that uses list boxes, labels, text boxes etc.
}
You question is somewhat unclear, but if you simply want to access other controls on the form, just go ahead and do so:
private void YourButton_Click(object sender, EventArgs e)
{
string someValue = yourTextBox.Text;
// do something with the value
}
If you want to add one event handler to many controls, you can do it.
Just go to properties of control you wish to subscribe, find appropriate event from list (ex: onClick) and choise your existed handler.
But this method will be sutable if events compotable.
Describe your task more detail.
I have made a WinForms application with a custom richtextbox control.
I am referring it as a Windows control (a dll file) in my project. In my program for the richtextbox I have written functionality inside it's textchanged event.
I want to do additional work only after the textchanged event is fired or in other ways once the text is added to the textbox. Something like I want to call a function foo() in the text_changedevent. It only calls foo and fails to process the underlying textchanged event.
Any way in C# I can make it process the internal textchanged event first, and then look into my text changed event?
think of the scenario I have written the code for mytextbox_textchanged
private void txt_code_TextChanged(object sender, EventArgs e)
{
//some code which will always be called whenever textchanged event occurs.
}
Now I inherit this control in my project say MyApp1. Here I have a label where I want to display the number of lines contained inside my textbox. So I would write
private void my_inherited_txt_code_TextChanged(object sender, EventArgs e)
{
//code to update the label with my_inherited_txt_code.lines.length
}
so my problem was, I first wanted the txt_code_TextChanged event to be called and then do the code written inside my_inherited_txt_code_TextChanged. Which was solved by writing
private void my_inherited_txt_code_TextChanged(object sender, EventArgs e)
{
base.OnTextChanged(e);
MessageBox.Show("foo");
}
Do you mean:
protected override void OnTextChanged(EventArgs e)
{
base.OnTextChanged(e);
// your code here...
}
I cant see why you shouldnt be able to call a method from the text_changed event?
Do you get any errors or what happens exactly?