I have a userControl and I've a button there, I'd like to call event when I'm clicking on the button in my main form from userControl. I do this:
UserControl
public UserControlerConstructor()
{
_button.Click += new EventHandler(OnButtonClicked);
}
public delegate void ButtonClickedEventHandler(object sender, EventArgs e);
public event ButtonClickedEventHandler OnUserControlButtonClicked;
private void OnButtonClicked(object sender, EventArgs e)
{
// Delegate the event to the caller
if (OnUserControlButtonClicked != null)
OnUserControlButtonClicked(this, e);
}
Form
public Form1()
{
userControlInstance.OnUserControlButtonClicked += new EventHandler(OnUCButtonClicked);
}
private void OnUCButtonClicked(object sender, EventArgs e)
{
throw new NotImplementedException();
}
It doesn't work because when I click in the form do nothing in the form code, but it does in userControl code. But I'd like to do in form code. I don't know how to call event from userControl to the form.
Well now I don't know if you're explicity want to use the delegate, no? If not, why don't you just do:
public Form1()
{
userControlInstance._button.Click += OnUCButtonClicked;
}
private void OnUCButtonClicked(object sender, EventArgs e)
{
throw new NotImplementedException();
}
up to now your code does not compile. You are using the wrong event handler type. It should show the following compiler error:
EventHandler cannot be converted to ButtonClickedEventHandler
Do the following steps:
1) put the declaration of the delegate outside of the class UserControlerConstructor:
public delegate void ButtonClickedEventHandler(object sender, EventArgs e);
public partial class UserControlerConstructor: UserControl
{
1) then change the type of the handler when registering the event in Form:
public Form1()
{
userControlInstance.OnUserControlButtonClicked += new ButtonClickedEventHandler(OnUCButtonClicked);
}
This way it should work
Related
I've tried to use event from an userControl to a form, but when I'm creating it in a form constructor I've an issue. I don't know where is a fail. There is my code.
UserControl
public GameField()
{
InitializeComponent();
button.Click += Button_Clicked;
}
public event EventHandler ButtonClicked;
private void Button_Clicked(object sender, EventArgs e)
{
if (this.ButtonClicked != null) this.ButtonClicked(sender, e);
}
Form
GameField gameField = new GameField(); //Instance of the derived class UserControl
public Form1()
{
InitializeComponent();
gameField.ButtonClicked += new EventHandler(this.btn_Click);
}
private void btn_Click(object sender, EventArgs e)
{
throw new NotImplementedException();
}
There is an issue
enter image description here
I think you wanted to subscribe to Button_Clicked instead of ButtonClicked in GameField.
button.Click += Button_Clicked;
Edit
I see, I have a hunch that you have two instances of GameField. The one that you added through the forms designer, probably named gameField1 and the one that you added in code to your form called gameField.
If you open Form1.Designer.cs can you see a gameField1 in there (or whatever name you gave when you added it through the designer)?
Can you try the following:
gameField1.ButtonClicked += new EventHandler(btn_Clicked); // name can be other than gameField1, gameField1 is just the automatically generated name by VS
I'd like to add a UserControl (UserControl2) to a panel on another form (MainForm) when the user clicks a button on the UserControl that is currently in the panel (UserControl1). UserControl2 should replace UserControl1 as the contents of the panel when this button is clicked.
I've tried figuring out how to use an event to communicate between UserControl1 and MainForm, but I just don't know where to start, as I can't find an example that is easily adaptable to my particular situation (Adding a control to a panel).
THIS question is similar, but doesn't quite fit what I'm trying to do (or at least I just don't know how to adapt it to what I'm trying to do)
I've tried this method, and get no errors, but my button doesn't do anything:
MainForm:
private void SubscribeToEvent(MyUserControl1 Button_Click)
{
MyUserControl1 CurrentClass = new MyUserControl1();
CurrentClass.Button.Click += new EventHandler(this.ButtonClickHandler);
}
private void ButtonClickHandler(object sender, EventArgs e)
{
MyUserControl2 MainPanelControls = new MyUserControl2();
MainPanel.SuspendLayout();
MainPanel.Controls.Clear();
MainPanel.Controls.Add(MainPanelControls);
MainPanel.ResumeLayout();
}
UserControl1:
public void Button_Click(object sender, EventArgs e)
{
//... Not sure what I'm missing here
}
I've also tried this method, this time trying to implement something similar to the method described in the link near the top of my question. I know these are obviously wrong (otherwise I wouldn't need to ask the question), but I don't have enough knowledge on the subject to figure it out on my own:
UserControl1:
public MyUserControl1()
{
InitializeComponent();
}
private MainForm mainForm = null;
public MyUserControl1(Form callingForm)
{
mainForm = callingForm as MainForm;
InitializeComponent();
}
//...
private void Button_Click(object sender, EventArgs e)
{
MyUserControl2 MainPanelControls = new MyUserControl2();
mainForm.MainPanel.SuspendLayout();
mainForm.MainPanel.Controls.Clear();
mainForm.MainPanel.Controls.Add(MainPanelControls);
mainForm.MainPanel.ResumeLayout();
}
Now when I click Button I get an "Object reference not set to an instance of an object" error at mainForm.MainPanel.SuspendLayout(); (Or anything past that point).
I've also tried modifying Joh's answer, but end up with the same Null Reference Exception, this time on my Button_Click event at ButtonClickedToMainForm(this, e); I'm not sure if I need to create an instance of ButtonClickedToMainForm, or how to do that properly (if it's not something else, that is).
I have a feeling I've likely just placed some of this code in the wrong place, so I'm hoping someone more experienced may be able to help me sort that out.
UPDATE
This is my attempt at implementing Joh's answer, being so new to this, I'm not quite sure where I've messed up:
MainForm:
namespace MyProject
{
public delegate void ButtonClickToMainForm(object sender, EventArgs e);
public partial class MainForm : Form
{
public MainForm()
{
InitializeComponent();
UserControl1 userControl1 = new UserControl1();
userControl1.Button1Clicked += userControl1_Button1Clicked;
}
private void userControl1_Button1Clicked(object sender, EventArgs e)
{
try
{
UserControl2 MainPanelControls = new UserControl2();
MainPanel.SuspendLayout();
MainPanel.Controls.Clear();
MainPanel.Controls.Add(MainPanelControls);
MainPanel.ResumeLayout();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
}
}
UserControl1:
public partial class UserControl1: UserControl
{
public event ButtonClickToMainForm Button1Clicked;
public UserControl1()
{
InitializeComponent();
}
private void OnButton1Clicked(object sender, EventArgs e)
{
Button1Clicked?.Invoke(this, e);
}
private void Button1_Click(object sender, EventArgs e)
{
Button1Clicked(this, e); //"Object reference not set to an instance of an object."
}
}
I'm sure it's something simple I'm missing on UserControl1, I'm just not sure what.
Here is an easy example for a delegate event.When you implement it in all your usercontrols it should work for your problem.
UserControl:
//Create a delegate
public delegate void ButtonClickToMainForm(object sender, EventArgs e);
public partial class UserControl1 : UserControl
{
//Your own event based on created delegate
public event ButtonClickToMainForm ButtonClickedToMainForm;
public UserControl1()
{
InitializeComponent();
}
//This method will invoke your event
private void OnButtonClickedToMainForm(object sender, EventArgs e)
{
ButtonClickedToMainForm?.Invoke(this, e);
}
private void button1_Click(object sender, EventArgs e)
{
//On button1_Click this will fire the event on mainform
OnButtonClickedToMainForm(this, e);
}
and the mainForm :
public Form1()
{
InitializeComponent();
//Subscribe to event from your usercontrol
userControl11.ButtonClickedToMainForm += UserControl11_ButtonClickedToMainForm;
}
//Button on userControl1 has been clicked
private void UserControl11_ButtonClickedToMainForm(object sender, EventArgs e)
{
//do your things here...
}
Hope this helps.
I've got a problem with subscribing from a form to an event in an user control.
MainForm-Code:
public partial class mainForm : Form
{
public mainForm()
{
InitializeComponent();
UserControl menuView = new mnlib.mnlibControl();
newWindow(menuView);
}
public void newWindow(UserControl control)
{
this.mainPanel.Controls.Clear();
this.mainPanel.Controls.Add(control);
}
mnlibControl.OnLearnClick += new EventHandler(ButtonClick); //Error in this line
protected void ButtonClick(object sender, EventArgs e)
{
//handling..
}
}
UserControl-Code:
public partial class mnlibControl : UserControl
{
public mnlibControl()
{
InitializeComponent();
}
private void btn_beenden_Click(object sender, EventArgs e)
{
Application.Exit();
}
public event EventHandler LearnClick;
private void btn_lernen_Click(object sender, EventArgs e)
{
if (this.LearnClick != null)
this.LearnClick(this, e);
}
}
Now, visual studio marks the "mnlibControl.OnLearnClick ..." line as wrong. "mnlibControl" would not be found, maybe a missing using directive etc. .
All this code and both forms are located in the same project file.
I tried around and googled like hell but just can't find a solution for my problem.
In the UserControl form there is a button - when it's clicket it shall trigger the newWindow method in the mainForm and open up another window.
My source for this solution of my problem is: How do I make an Event in the Usercontrol and Have it Handeled in the Main Form?
There is no OnLearnClick in your component. You need to subscribe to LearnClick. You also need to subscribe in function block. You also should use concrete type (mnlib.mnlibControl), not UserControl:
public mainForm()
{
InitializeComponent();
mnlib.mnlibControl menuView = new mnlib.mnlibControl();
menuView.LearnClick += new EventHandler(ButtonClick);
newWindow(menuView);
}
Your code mnlibControl.OnLearnClick += new EventHandler(ButtonClick); must be within any of functional block (i.e. method, property, ...).
You have to place this line inside an actual method:
mnlibControl.LearnClick += new EventHandler(ButtonClick);
Like this:
public mainForm()
{
InitializeComponent();
UserControl menuView = new mnlib.mnlibControl();
newWindow(menuView);
mnlibControl.OnLearnClick += new EventHandler(ButtonClick);
}
I create a custom user control and use that in my form.
but it does not capture any mouse event!
what is the problem?
thanks
Define the event in your custom control
private delegate void MyClickEvent(object sender, EventArgs e);
public event MyClickEvent MyClick;
public void OnMyClickEvent(object sender, EventArgs e)
{
if (MyClick != null)
MyClick(sender, e);//execute event
}
Now in MainForm
public partial class Form1
{
public Form1()
{
myCustomButton.MyClick += FireThisOnClick;
}
private void FireThisOnClick(object sender, EventArgs e)
{
//this will be executed on click
}
}
hi
call event from form2 in form1?
for example :
The following code into form2 :
private void Form2_Load(object sender, EventArgs e)
{
MessageBox.Show("http://stackoverflow.com");
}
What to write in a form1?
Why are you wanting to call the event? Will you know the sender and the Event Args?
Why don't you just create a public method in Form2 that Form1 is able to see?
how about form2.Form2_Load(this, null)
You can't call private members of a class from outside it.
You can change the accessibility to internal, which will make it visible within the assembly - if your form1 is in the same assembly.
Alternatively you can make it a public method, which would make it globally accessible.
However, you shouldn't call event handlers in such a manner - they are supposed to handle events that the declaring class raises.
For the sample code you gave, a better solution would be to create a public or internal method that can be called from this event handler:
private void Form2_Load(object sender, EventArgs e)
{
MyMethod();
}
public MyMethod()
{
MessageBox.Show("http://stackoverflow.com");
}
In order to call this method from form1, it needs to know about form2:
// in form1
Form frm2 = new Form2();
frm2.MyMethod();
You can't raise an Event from outside a class.
The convention is that you call a OnEventname method in the class. Usually this method is protected (can't only accessed from the class itself or others that inherit from it)
// in form1
private void Method1()
{
using (var form2 = new Form2())
{
form2.Show();
form2.RaiseLoadEvent(EventArgs.Empty);
}
}
// Create this method in form2
public void RaiseLoadEvent(EventArgs e)
{
OnLoad(this, e);
}
// The OnLoad method already exists in form 2
// But it usually looks like this
protected void OnLoad(EventArgs e)
{
var eh = LoadEventHandler;
if (eh != null)
{
eh(this, e);
}
}
But I don't suggest to raise the LoadEvent, because It is raised only once after the creation of the form. More usual is to react to the Load event to modify the form.
privat void Method1()
{
using (var form2 = new Form2())
{
// Add Event Handler
form2.Load += new EventHandler(form2_Load);
form2.ShowDialog();
}
// Allways remove Event Handler to avoid memory leaks
form2.Load -= new EventHandler(form2_Load);
}
private void form2_Load(object sender, EventArgs e)
{
form2.Text = "Hello from form1";
}
Form1 (the event publisher) should expose a separate, public event property for Form2 (the subscriber) to subscribe to.
For example: the form publishing the event will look like this:
public partial class Publisher : Form
{
public event PostUpdateHandler OnPostUpdate;
public Publisher()
{
InitializeComponent();
new Subscriber(this).Show();
}
private void button1_Click(object sender, EventArgs e)
{
if (OnPostUpdate != null)
{
OnPostUpdate(new PostUpdateArgs(textBox1.Text));
}
}
}
public delegate void PostUpdateHandler(PostUpdateArgs args);
public class PostUpdateArgs : EventArgs
{
public string UpdateText;
public PostUpdateArgs(string s)
{
UpdateText = s;
}
}
The subscribing form looks like this:
public partial class Subscriber : Form
{
public Subscriber()
{
InitializeComponent();
}
public Subscriber(Publisher publisher) : this()
{
publisher.OnPostUpdate += new PostUpdateHandler(publisher_OnPostUpdate);
}
private void publisher_OnPostUpdate(PostUpdateArgs args)
{
this.Form2_Load(null, null);
}
private void Subscriber_FormClosed(object sender, FormClosedEventArgs e)
{
this.Dispose();
}
private void Form2_Load(object sender, EventArgs e)
{
MessageBox.Show("http://stackoverflow.com");
}
}
When the user presses button1 on the publishing form, the subscribing form will execute the code associated with the delegate, resulting in a message box popping up with the message http://stackoverflow.com.