I am trying to call a click event from within another a method from the same Window Form file. It just won't work form me.
For instance:
theClass = partial class(System.Windows.Forms.Form)
method AlarmListBox_Click(sender: System.Object; e: System.EventArgs);
private
protected
public
method DoSomething;
end;
method theClass.DoSomething;
begin
self.AlarmListBox_Click; <<<this is where i want to call the click event
end;
No matter what I do, it keeps raising compiler errors. I tried AlarmListBox.Click, AlarmListBox.performClick, etc.
Some of the errors I got:
There is no overloaded method "AlarmListBox_Click" with 0
parameters.
Cannot access underlying event field
So, how do you fire an event within the same window Form?
It's best to call the Event handler with the default parameters:
AlarmListBox_Click(self, EventArgs.Empty);
By passing self into the method you define that the source of the call was not the AlarmListBox but your form. You could also can pass in custom EventArgs that state that the Event was not raised because of a click on the AlarmListBox but from your code.
You are not passing the parameters of the method AlarmListBox_Click
Try this
AlarmListBox_Click(nil, nil);
Related
Using c++ builder borland (bcb6).
I wish to invoke manually button click event. I did:
FMap->bbDoneInClick(NULL);
While Done button located on the FMap form, but something went wrong with that.
Do I need to call bbDoneInClick with different parameters and not with NULL ?
Instead of NULL use the Form1 or the bbDone itself ...
it depends on the event code itself how it uses the Sender parameter
Also you can call the event handler safely only if the form is already created
if it does not access Canvas you can use it even in TForm1::TForm1 constructor
if it does you need to take care of not using it prior to OnShow or OnActivate
to avoid VCL problems or App crashes
for common handlers it is sufficient to use main window ... (I use this instead of NULL)
if you have single even handler for multiple components then the even is usually deciding the operation or target from the Sender parameter so in that case you need to pass the pointer to component itself
I am a noob to Windows Forms so this is likely a remedial question. I have a child component with a button and a text field. I want to use multiple instances of these in a parent component or form. At runtime, when the user clicks one of the buttons, I want the parent to get the event to decide what to do with the associated text.
Coming from the long lost world of Borland C++ Builder, during design time, I would simply double-click on the buttons and handlers in the parent would be created which I could just elaborate the code. With Windows Forms, the component controls are not clickable (at design time) from the parent and are "frozen". It is not obvious to me how to pass any child button clicks to a parent. I've tried things like changing the button modifier from private to public but that doesn't help. How is this best accomplished.
Note I am using C++ as I am sharing header file definitions with an associated C++ embedded app.
-Bob
UPDATE:
My apologies, I thought I was still in my C# search :(
This is slightly complicated if you actually want to bubble up an event, or very easy if you use methods.
Methods:
In your child container, add a constructor or property that takes in and stores the parent. Then in the button handler, call this.Parent.ButtonClicked(this); and of course in the parent, add a ButtonClicked(ChildType child) method. That should get you there that way.
Custom Event:
To use events, you need to add a few things. Firstly, add a custom EventArgs class as such:
class ChildClickedEventArgs : EventArgs
{
// include a ctor and property to store and retrieve the child instance.
}
Then add a public delegate for it:
public delegate void ChildClickedEventHandler(object sender, ChildClickedEventArgs e);
Then to your child class, add a ButtonClicked event:
public event ChildClickedEventHandler ChildClicked;
And finally, a helper method to raise it:
private OnButtonClicked()
{
if (this.ChildClicked != null)
{
this.ChildClicked(this, new ChildClickedEventArgs(this));
}
}
Then when you add the child class to the parent, add an event handler for each, and you can handle your custom event for your custom control.
Alternatively:
If you can expose the Button in your child class, simply do the above but register it to this.child.Button.Clicked, saving adding the event handler yourself.
I want to call a click in event from a button in VB6, I can't seem to figure it out. I have tried this code here but it doesn't work.
Call cmdLoads_Click(Sender, e)
I have also set the sub to public as well, still no luck.
The button sub has to have an index:
Private Sub cmdLoads_Click(index As Integer)
The name of the command button is cmdLoads, it is really cmdLoads(0). So all I had to do is change the code to this to make it work.
Call cmdLoads_Click(0)
A command button (or any other object raising events) can have multiple sinks (event subscribers) so calling "xxx_Click" sub will not notify any of the other listeners.
In short: use cmdLoads(0).Value = True as it's more portable.
How to raise a click event manually for a button in windows phone ?
Is it possible technically ? And is that a good suggestion to raise such event manually ?
You can raise events manually just like with any other function, since per-se, an event handler is nothing but a function that is associated with data passed to it in case of an event.
So, let's say you have a mock event handler:
private void Button_Click_1(object sender, RoutedEventArgs e)
{
Debug.WriteLine("TEST");
}
You can easily invoke it manually with:
Button_Click_1(btnTest, new RoutedEventArgs());
In this case, you can supply your own sender. If you want to raise an event specifically, without having to explicitly bind to your own event handler, take a look at this answer - you can use Reflection, although I am not sure why you'd need it like that.
I have following requirements:
Obtain action associated with NSButton using : - (SEL)action
Call the obtained action.
Can we perform 2nd pt. Generally we invoke an action like this- [self abc:nil] just thinking if we can invoke the method obtained from 2nd pt. in same way!
Try:
SEL actionSelector = [button action];
[self performSelector: actionSelector withObject:nil];
The action is just a selector—the name of a method. Any number of objects may have a method by that name, and even if only one class implements the method, you may have any number of instances of that class. So, you can't just call the name of a method, because that doesn't express what object will respond to it. You need an object that implements that method, and you need to send that message by that name to that object.
The most likely object you want to send the action message to is the button's target, so get that, the same way you got its action, and send the message to that object. Or, better yet, send the button a performClick: message; if you want to simulate the user clicking the button, that's the way to do that.