Develop Reference

How to call an event handler from another method

Given the following event handler code:
private void image1_MouseDown(object sender, MouseButtonEventArgs e)
{
///////////
}
How can I call it from another method:
private void timerTick(object sender, EventArgs e)
{
image1_MouseDown(object, e); // error
}

Event handlers are regular methods like any others.
The reason you can't call it like you're trying to do, is because the MouseDown event takes a MouseButtonEventArgs instance, while the Tick event of timers take the base class EventArgs.
You'll need to create a new instance of MouseButtonEventArgs, but then you'll need to initialize it with a device, and other event data.
A better option would be to refactor the body of the MouseDown event handler to a method taking individual parameters, which you can then call without having to create a MouseButtonEventArgs instance.
private void image1_MouseDown(object sender, MouseButtonEventArgs e)
{
this.ProcessImageMouseDown(e.ChangedButton, e.ButtonState, e.GetPosition(sender as FrameworkElement));
}
private void timerTick(object sender, EventArgs e)
{
this.ProcessImageMouseDown(MouseButton.Left, MouseButtonState.Pressed, new Point(10d, 20d));
}
private void ProcessImageMouseDown(MouseButton button, MouseButtonState state, System.Windows.Point position)
{
// Do actual processing here.
}

How to call a Control's event handler? Get EventArgs value C#

I am trying to call a OnCellEditEnding event from another event,
private void BillsTableRecords_OnCellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
{
// do stuff here
}
My issue is I don't know how to pass the DataGridCellEditEndingEventArgs into the method, i.e. the e in the below method obviously gives an error as it is referencing RoutedEventArgs not DataGridCellEditEndingEventArgs.
private void BillsRecordsCheckBox_OnChecked(object sender, RoutedEventArgs e)
{
BillsTableRecords_OnCellEditEnding(sender, e);
}
So how do obtain the value from DataGridCellEditEndingEventArgs so that I can pass the value in the method? Please note that the DataGrid cell with be selected at this point so it will contain a value.

I wouldn't recommend this approach. Event handlers are to be called by events; their signature does not really fit for a standalone call. In case you execute business code in your event handler, it is also not good design, because your event handlers are UI code, which should be separated from business code.
The best way to go here is to create a dedicated method that does what you want and call it from both event handlers:
private void DoStuff(/* add the parameters you need*/) {
//do stuff
}
private void BillsTableRecords_OnCellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
{
DoStuff();
}
private void BillsRecordsCheckBox_OnChecked(object sender, RoutedEventArgs e)
{
DoStuff();
}

try that
private void BillsRecordsCheckBox_OnChecked(object sender, RoutedEventArgs e)
{
BillsTableRecords_OnCellEditEnding(sender, new DataGridCellEditEndingEventArg());
}
If you want to keep the arguments from the RoutedEventArgs, add them to the constructor of DataGridCellEditEndingEventArg

Binding Form Closing event in class

Hello I'm trying to make a class that can handle the form closing event for my winForm
I have figured out how to work the event handlers, like this for a ContextMenuStrip items click event:
mnuItemShow.Click += new EventHandler(mnuItemShow_Click);
private void mnuItemShow_Click(object sender, EventArgs e)
{
}
But I can't figure out how to bind the Form Closing event..
I have tried it like this:
this.form.FormClosing += new EventHandler(closing);
private override void closing(EventArgs e)
{
}
But I get this error message:
No overload for 'closing' matches delegate 'System.EventHandler'

This works:
this.FormClosing += new System.Windows.Forms.FormClosingEventHandler(this.Main_FormClosing);
private void Main_FormClosing(object sender, FormClosingEventArgs e)
{
}

it should be like this:
private void closing(object sender, FormClosingEventArgs e)
{
}
and you have to add handler like below
frm.FormClosing += new FormClosingEventHandler();

c# trigger/call events from another control

In VFP9, if i have two buttons (butt1 & butt2) If i want to trigger butt2 click event from butt1 i just do this from butt1 click event butt2.click() and it will call whatever code i have in the procedure/event in butt2. How do i do that in c#?
How do I call event of a certain control from another control like
below
.
private void button2_Click(object sender, EventArgs e)
{
button1.click()
}

You can call the handler directly like this button1_Click(button1, null);
Example Usage:
Button button1;
Button button2;
public Form1()
{
button1.Click += new EventHandler(button1_Click);
button2.Click += new EventHandler(button2_Click);
}
void button2_Click(object sender, EventArgs e)
{
button1_Click(button1, null);
}
public void button1_Click(object sender, EventArgs e)
{
//Action when click occurs
}

Why are you trying to simulate button click, if you just want to execute some logic?
Wrap this logic into separate method, an call it from click handlers you choose:
private Foo1() {}
private Foo2() {}
private button1_Click(object sender, EventArgs e)
{
Foo1();
Foo2();
}
private button2_Click(object sender, EventArgs e)
{
Foo2();
}

just bind the button1 click event to button2 click event in form_load or designer.csbutton2.Click+=new EventHandler(button1_Click);

calling a event handler within another event handler?

Here is the short sample code:
private void txtbox1_DoubleClick(object sender, EventArgs e)
{
button1_Click(object sender, EventArgs e); //can I call button1 event handler?
}
private void button1_Click(object sender, EventArgs e)
{
MessageBox.Show(txtbox1.Text);
}
I wonder if it would be okay to code in the above way?

You can do that - although the code you provide can't be compiled. It should look like this:
private void txtbox1_DoubleClick(object sender, EventArgs e)
{
button1_Click(sender, e);
}
private void button1_Click(object sender, EventArgs e)
{
MessageBox.Show(txtbox1.Text);
}
But for best practice and code readability, you're probably better off doing this, especially as you are not making use of sender and e:
private void txtbox1_DoubleClick(object sender, EventArgs e)
{
ShowMessageBox();
}
private void button1_Click(object sender, EventArgs e)
{
ShowMessageBox();
}
private void ShowMessageBox()
{
MessageBox.Show(txtbox1.Text);
}

Yes you can do that; an event handler is just another method.
However it might be worth creating a new method that shows the message box, and having both Click event handlers call that:
private void txtbox1_DoubleClick(object sender, EventArgs e)
{
ShowTextboxMessage();
}
private void button1_Click(object sender, EventArgs e)
{
ShowTextboxMessage();
}
private void ShowTextboxMessage()
{
MessageBox.Show(txtbox1.Text);
}

An event handler is nothing more than a method, so you can call it like any other.