Is it possible to trigger Window_Loaded on the Timer.Tick event like this ?
DispatcherTimer timer = new DispatcherTimer
{
Interval = TimeSpan.FromSeconds(1)
};
timer.Tick += Window_Loaded;
timer.Start();
Or is there another way to do it ?
Your question probably confuses events and event handlers. In C#, events can only be raised from within the class they were declared in, unless they expose an internal or public method that can be called from outside. However, the Loaded event defined in FrameworkElement is not exposed that way, meaning you cannot raise it from your code.
What your code does is add your Window_Loaded event handler for the Loaded event, which is just a method. However, the sigatures of the corresponding Tick and the Loaded delegates do not match.
Tick - public delegate void EventHandler(object? sender, EventArgs e);
Loaded - public delegate void RoutedEventHandler(object sender, RoutedEventArgs e);
In order to add the window loaded event handler to the Tick event, you have to create a method or lambda that matches the Tick delegate and calls Window_Loaded with appropriate arguments, e.g.:
timer.Tick += OnTick;
private void OnTick(object sender, EventArgs e)
{
var routedEventArgs = new RoutedEventArgs();
// ...set the routed event args properties.
Window_Loaded(sender, routedEventArgs);
}
A word of caution. Although this might solve your problem it is most likely not the right approach for what you want to achieve. The Loaded event is called by the framework in the control's lifecycle.
Occurs when the element is laid out, rendered, and ready for interaction.
Whatever you are doing in your Window_loaded event handler should not be done periodically, because that does not comply with the sematics of this event. Maybe this is an XY problem.
public MainWindow()
{
InitializeComponent();
DispatcherTimer timer = new DispatcherTimer
{
Interval = TimeSpan.FromSeconds(1)
};
timer.Tick += Window_Loaded;
timer.Start();
}
private void Window_Loaded(object sender, EventArgs e)
{
}
Related
While debugging, can I look into textBox1.TextChanged to see the number of event subscriptions? If yes, then how do I drill to it? I need to know how many subscriptions there are at a given time for debugging because it looks like an event is triggered multiple times, but I suspect this bug is really because textBox1.TextChanged += handler is being mismanaged in the application, so there are too many subscribers.
Here is a simplified version of what I think is happening. If possible, I just want to set a breakpoint and count up the number of subscriptions to "textBox1.TextChanged":
private void textBox1_TextChanged(object sender, EventArgs e)
{
textBox1.TextChanged += textBox1_TextChanged;
MessageBox.Show("asdf");
textBox1.TextChanged -= textBox1_TextChanged;
textBox1.Text = DateTime.Now.ToString();
textBox1.TextChanged += textBox1_TextChanged;
}
Is that possible or is it more complicated?
If you're only concerned with doing it under the debugger, rather than programmatically, then this is perhaps a simpler, non-invasive way:
class _24003458
{
event EventHandler MyEvent;
public void Test()
{
MyEvent += Handler1;
MyEvent += Handler2;
MyEvent(this, EventArgs.Empty);
}
void Handler1(object sender, EventArgs e)
{
throw new NotImplementedException();
}
void Handler2(object sender, EventArgs e)
{
throw new NotImplementedException();
}
}
Put a breakpoint on either of the event handlers, and when it breaks, look at the Locals tab. The event, when expanded, will show the invocation count and event handlers:
You will have to use Reflection to get to the invocation list of the event delegate:
textBox1.TextChanged += textBox1_TextChanged;
MessageBox.Show("asdf");
textBox1.TextChanged -= textBox1_TextChanged;
textBox1.Text = DateTime.Now.ToString();
textBox1.TextChanged += textBox1_TextChanged;
var eventField = textBox1.GetType().GetField("TextChanged", BindingFlags.GetField
| BindingFlags.NonPublic
| BindingFlags.Instance);
var subscriberCount = ((EventHandler)eventField.GetValue(textBox1))
.GetInvocationList().Length;
It is not possible with an event like this (for good reason), however, it is possable via reflection as Selman22 says, above) if you are using an event directly you can do so:
private event EventHandler handler;
var delegates = handler.GetInvocationList();
You can create a member method which you add to the object which implements the INotifyPropertyChanged interface. It makes debugging very easy:
#if DEBUG
public System.Delegate[] GetInvocationList()
{
return PropertyChanged?.GetInvocationList();
}
#endif
I have Form with a Timer1.
I would like to set the Tick event of that timer1 to a timer2_Tick function that is already signed to another timer2.
How can I Set the 2 timers, to 1 event?
You do it the same way you assign any other event handler, you just happen to choose the same method for both timers.
System.Windows.Forms.Timer first = new System.Windows.Forms.Timer();
first.Tick += tick;
System.Windows.Forms.Timer second = new System.Windows.Forms.Timer();
second.Tick += tick;
private void tick(object sender, EventArgs e)
{
throw new NotImplementedException();
}
If you're using the designer, instead of attaching the events through code, then you can just go to the "Properties" tab, select events, and enter the same name for the Tick event for both timers.
Just assign same function to their Tick delegate.
myTimer1.Tick += new EventHandler(TimerEventProcessor);
myTimer2.Tick += new EventHandler(TimerEventProcessor); //THE SAME LIKE FIRST ONE
private static void TimerEventProcessor(Object myObject,
EventArgs myEventArgs) {
}
Assume that I have a WinFoms project. There is just one button (e.g. button1).
The question is: is it possible to trigger the ButtonClicked event via code without really clicking it?
Button controls have a PerformClick() method that you can call.
button1.PerformClick();
The .NET framework uses a pattern where for every event X there is a method protected void OnX(EventArgs e) {} that raises event X. See this Msdn article. To raise an event from outside the declaring class you will have to derive the class and add a public wrapper method. In the case of Button it would look like this:
class MyButton : System.Windows.Forms.Button
{
public void ProgrammaticClick(EventArgs e)
{
base.OnClick(e);
}
}
You can just call the event handler function directly and specify null for the sender and EventArgs.Empty for the arguments.
void ButtonClicked(object sender, EventArgs e)
{
// do stuff
}
// Somewhere else in your code:
button1.Click += new EventHandler(ButtonClicked);
// call the event handler directly:
ButtonClicked(button1, EventArgs.Empty);
Or, rather, you'd move the logic out of the ButtonClicked event into its own function, and then your event handler and the other code you have would in turn call the new function.
void StuffThatHappensOnButtonClick()
{
// do stuff
}
void ButtonClicked(object sender, EventArgs e)
{
StuffThatHappensOnButtonClick();
}
// Somewhere else in your code:
button1.Click += new EventHandler(ButtonClicked);
// Simulate the button click:
StuffThatHappensOnButtonClick();
The latter method has the advantage of letting you separate your business and UI logic. You really should never have any business logic in your control event handlers.
Yes, just call the method the way you would call any other. For example:
private void btnSayHello_Click(object sender, EventArgs e)
{
MessageBox.Show("Hello World!");
}
private void btnTriggerHello_Click(object sender, EventArgs e)
{
btnSayHello_Click(null, null);
}
button1.PerformClick();
But if you have to do something like this maybe it's better to move the code you have under the event on a new method ?
Why don't you just put your event code into a Method. Then have the Event execute the method. This way if you need to execute the same code that the Event rises, you can, but simply just calling the "Method".
void Event_Method()
{
//Put Event code here.
MessageBox.Show("Hello!");
}
void _btnSend_Click(object sender, EventArgs e)
{
Event_Method();
}
void AnotherMethod()
{
Event_Method();
}
Make sense? Now the "Click" event AND anywhere in code you can trigger the same code as the "Click" event.
Don't trigger the event, call the method that the event calls. ;)
In most cases you would not need to do that. Simply wrap your functionality in functions related to a specific purpose (task). You call this function inside your event and anywhere else it's needed.
Overthink your approach.
I recently had this problem where I wanted to programatically click a button that had multiple event handlers assigned to it (think UserControl or derived classes).
For example:
myButton.Click += ButtonClicked1
myButton.Click += ButtonClicked2;
void ButtonClicked1(object sender, EventArgs e)
{
Console.WriteLine("ButtonClicked1");
}
void ButtonClicked2(object sender, EventArgs e)
{
Console.WriteLine("ButtonClicked1");
}
When you click the button, both functions will get called. In the instances where you want to programmatically fire an event handler for a function from a form (for example, when a user presses enter in a Text field then call the InvokeOnClick method passing through the control you. For example
this.InvokeOnClick(myButton, EventArgs.Empty);
Where this is the Form instance you are in.
use a for loop to call the button_click event
private void btnadd_Click(object sender, RoutedEventArgs e)
{
for (int i = 0; i <= 2; i++)
StuffThatHappensOnButtonClick();
}
void StuffThatHappensOnButtonClick()
{
........do stuff
}
we assume at least one time you need click the button
In this following function, that gets executed whenever I do
timer1.Enabled = true
private void timer1_Tick(object sender, EventArgs e)
{
//code here
}
How can I control what gets send to the (object sender, EventArgs e) ?
I want to use its parameters
The method signature is fixed, so you can't pass extra parameters to it. However, the this reference is valid within the event handler, so you can access instance members of the class (variables declared inside class but outside of any method).
1) You can use Tag property of your timer as userState
void timer1_Tick(object sender, EventArgs e)
{
Timer timer = (Timer)sender;
MyState state = timer.Tag as MyState;
int x = state.Value;
}
2) You can use field of reference type to read it in Timer's thread
void timer1_Tick(object sender, EventArgs e)
{
int x = _myState.Value;
}
3) You can use System.Threading.Timer to pass state to timer event handler
Timer timer = new Timer(Callback, state, 0, 1000);
If you want to access Timer's property in the timer1_tick method, you could do via
this.timer1 ex: this.timer1.Enabled =false;
or
Timer timer = (Timer) sender;
timer.Enabled = false;
Maybe you could make an inheritance from timer class, and there, cast the tick event (from Timer) into a tick_user event or something like this that modify de params and put into EventArgs (this is the right place to do, not in sender) other parameters you want. Also you can make a method with more or less parameters, it's up to you.
Hope this helps.
I want to detach the custom event but could not detach. Below I am using -= to detach the event. I assume after this, the TextChanged2 method should not be invoked as I have unregistered the event. Is my understanding wrong?
public delegate void TextChangedEventHandler1(object sender, TextBoxargs ta);
public event TextChangedEventHandler1 TextChanged1;
private void textBox1_TextChanged(object sender, EventArgs e)
{
this.TextChanged1 -= new TextChangedEventHandler1(TextChanged2);
TextChanged2(sender, e);
}
public void TextChanged2(object sender, EventArgs e)
{
textBox1.Text = textBox1.Text.ToUpper();
}
What you are doing is right. But using the following line of the code you can detach the event handler.
this.TextChanged1 -= new TextChangedEventHandler1(TextChanged2);
But on the second line you called the function directly so that it called the textchange2 function:
TextChanged2(sender, e);
I want to detach the custom event but
could not detach.
You do. You detach very well your event.
TextChanged2 method should not be
invoked as I have unregistered the
event.
It should not be invoked when this.textChanged1, but you invoke it yourself by calling TextChanged2(sender, e);
I suggest you give some more reasonable names to your methods, controls, and events. I could imagine half the confusion here stems from confusing names.
For example, in one comment to an answer, you mention that if you don't call the TextChanged2 event handler (for the TextChanged1 event...) explicitly, it will never get called. This would lead to the question when, and where, you raise the TextChanged1 event. If you have indeed subscribed the TextChanged2 handler to the TextChanged1 event with the += operator, then the handler will be invoked as soon as the event is raised.
Use
this.TextChanged1 -= TextChanged2;