So I have a form where I want to change the position of a trackbar and trigger the trackbar_scroll event after I click on a label. So far, clicking on the label changed the value of the trackbar, thats easy:
private void label4_Click(object sender, EventArgs e)
{
trackBar1.Value = 0;
}
private void trackBar1_Scroll(object sender, EventArgs e)
{
if (trackBar1.Value == 0)
{
try
{
//code...
}
catch
{
MessageBox.Show("Error occured");
}
}
}
How do I call the trackBar1_scroll(..) event from within the label click?
Try calling it directly. You just have to supply the parameters yourself:
trackBar1_Scroll(trackBar1, EventArgs.Empty);
or simply
trackBar1_Scroll(null, null);
if the parameters are not being utilized.
Another approach you could take, aside from #LarsTech answer (which is absolutely correct), would be to refactor your code to reduce the need to supply empty parameters. Since you're not actually using the EventArgs or referencing the sender directly, given your example above, you could do something like the following:
private void DoSomething(int value)
{
...
}
private void trackBar1_Scroll(object sender, EventArgs e)
{
DoSomething(trackBar1.Value);
}
private void label4_Click(object sender, EventArgs e)
{
DoSomething(...);
}
It always feels like code smell to me, when you call an event handler with empty parameters, simply to execute code which you could otherwise abstract out.
Related
This question already has answers here:
WinForms: How to programmatically fire an event handler?
(4 answers)
Closed 2 years ago.
I am using C# in WinForms to use a trackbar as follows. At the beginning of the code I define the event handler:
this.trackBar1.Scroll += new System.EventHandler(this.trackBar1_Scroll);
And here is the implementation when one scrolls the trackbar:
private void trackBar1_Scroll(object sender, EventArgs e)
{
//do something...
}
So this works, but I need to call the above function from inside another event handler such as:
public void numericUpDown1_TextChanged(object sender, EventArgs e)
{
//what to do here to call trackBar1_Scroll ?
}
What could be done to call trackBar1_Scroll from inside numericUpDown1_TextChanged?
Very often you do not need the sender and e parameters. Therefore just create a parameterless method
private void DoSomething() // Hopefully with a better name
{
// do things ...
}
and then call it inside your event handlers.
private void trackBar1_Scroll(object sender, EventArgs e)
{
DoSomething();
}
public void numericUpDown1_TextChanged(object sender, EventArgs e)
{
DoSomething();
}
If you give the method a descriptive name, your code becomes easier to read. But of course you could as well just call the other event handler. The event handler is just a method after all
public void numericUpDown1_TextChanged(object sender, EventArgs e)
{
trackBar1_ValueChanged(sender, e);
}
Since both of these event handlers have the same signature (the same parameter list and return type), you could declare a single one and attach the same to both controls:
void HandleUpdates(object sender, EventArgs e)
{
// do things...
}
And assign it with
trackBar1.Scroll += HandleUpdates;
numericUpDown1.TextChanged += HandleUpdates;
You can also assign it in the properties window on the events tab. new System.EventHandler(...) is not necessary. C# does it automatically for you.
I was wondering if there was a more efficient way to format the following code:
private void nmudc1_Enter(object sender, EventArgs e)
{
SelectAllNumericalUpDownText(nmudc1);
}
private void nmudc1_Click(object sender, EventArgs e)
{
SelectAllNumericalUpDownText(nmudc1);
}
private void nmudc2_Enter(object sender, EventArgs e)
{
SelectAllNumericalUpDownText(nmudc2);
}
private void nmudc2_Click(object sender, EventArgs e)
{
SelectAllNumericalUpDownText(nmudc2);
}
And so on.
I apologize if this has been asked before or elsewhere, and I assume the answer is relatively simple. Unfortunately, I have been unsuccessful in finding a suitable answer thus far.
I have thought about trying to put in in an array, or an object, but I really just have no idea how I would go about doing this to a function like this.
Thank you.
You can create only one event function, And send the sender as parameter to the SelectAllNumericalUpDownText function.
Register all events to this function:
nmudc1.Click += nmudc_Event;
nmudc1.Enter += nmudc_Event;
nmudc2.Click += nmudc_Event;
nmudc2.Enter += nmudc_Event;
Generic implementation to the function:
private void nmudc_Event(object sender, EventArgs e)
{
SelectAllNumericalUpDownText(sender as <TYPE>);
}
Since all event handlers in your code sample have the same method signature, you can simply use the same method to handle all the events:
private void NumericUpDown_event(object sender, EventArgs e)
{
SelectAllNumericalUpDownText(sender as NumericUpDown);
}
This is assuming, of course, that your sender object is actually a NumericUpDown.
You could use the following alternative:
private void NumericUpDown_Event(object sender, EventArgs e)
{
if (!(sender is <controltype> nump))
return;
SelectAllNumericalUpDownText(nump);
}
By this you do not call the method if the sender is not of type < controltype >. Therefor you already used the generic EventArgs class you can subscript the Enter/Click event to this method.
I would like to call btnSubmit if certain conditions in axTws1_tickPrice are true. How do i do this?
private void btnSubmit_Click(object sender, EventArgs e)
{
//code here
}
private void axTws1_tickPrice(object sender, AxTWSLib._DTwsEvents_tickPriceEvent e)
{
if (Condition)
{
Call butSubmit (how do i do this)
}
}
You're better off having a common method that both of your control handlers call, rather than trying to call one handler from another. That way your code is more extensible and testable, and you don't have to worry about the event arguments or senders.
For example:
private void btnSubmit_Click(object sender, EventArgs e)
{
DoStuff();
}
private void axTws1_tickPrice(object sender, AxTWSLib._DTwsEvents_tickPriceEvent e)
{
if (Condition)
{
DoStuff();
}
}
private void DoStuff()
{
// code to do stuff common to both handlers
}
Multiple options.
Option 1 :
Preferred approach, move common logic to another method.
private void btnSubmit_Click(object sender, EventArgs e)
{
CommonLogic();
}
private void axTws1_tickPrice(object sender, AxTWSLib._DTwsEvents_tickPriceEvent e)
{
if (Condition)
{
CommonLogic();
}
}
private void CommonLogic()
{
// code for common logic
}
Option 2:
Executing PerformClick() method which generates a Click event for a button.
btnSubmit.PerformClick();
Option 3:
Invoke the event method like any other normal method.
btnSubmit_Click(sender, new EventArgs());
just call it with current parameters.
if (Condition)
{
butSubmit(sender, null)
}
Unbelievable, but
btnSubmit_Click(null,null);
Or other arguments if needed.
private void axTws1_tickPrice(object sender, AxTWSLib._DTwsEvents_tickPriceEvent e)
{
if (Condition)
{
button1_Click(sender, EventArgs.Empty);
}
}
button1_Click is similar to a normal method which accepts two inputs of type object and EventArgs So you can call them by giving the same parameters. if you are not going to use these arguments inside the method then you can call them by passing null,null don't use null if you want to use e or sender inside the method. in such situation call them as like i suggested above.
Thanks Steve and Hari - this worked well
private void btnSubmit_Click(object sender, EventArgs e)
{
DoStuff();
}
private void axTws1_tickPrice(object sender, AxTWSLib._DTwsEvents_tickPriceEvent e)
{
if (Condition)
{
DoStuff();
}
}
private void DoStuff()
{
// code to do stuff common to both handlers
}
I am having a problem in calling multiple buttons at the same time because each buttons works a different process there are more than 78 folders.
I want to call all the buttons at the same time in a single button called button4. Now it's calling button1 only and not working for button2.
Is there any way to call these buttons at the same time?
My code is:
private void button4_Click_1(object sender, EventArgs e)
{
button1.PerformClick();
button2.PerformClick();
}
Thanks in Advance.
You should in general not perform UI-style clicks on other buttons in order to invoke their behaviour.
Just call the respective event handling methods of the buttons you would like to "click".
example code:
private void button4_Click_1(object sender, EventArgs e)
{
button1_Click_1(null, EventArgs.Empty);
button2_Click_1(null, EventArgs.Empty);
// and so on
}
You should refactor the other events to call well-named methods.
Say button1 does some initialization; it should look like this:
private void button1_Click(object sender, EventArgs e)
{
Initialize();
}
Say button2 finalizes that intialization; it should look like this:
private void button2_Click(object sender, EventArgs e)
{
FinalizeInitialization();
}
Then if button4 does all of this; it should look like this:
private void button4_Click(object sender, EventArgs e)
{
Initialize();
FinalizeInitialization();
WhateverElseButton4ShouldDo();
}
Under most circumstances, you shouldn't call PerformClick() at all. Instead, you should call the same methods your event handlers call. So, if clicking button 3 should behave as click clicking button 1 and then button 2, you should have code like this:
private void button1_Click(object sender, EventArgs e)
{
SomeAction();
}
private void button2_Click(object sender, EventArgs e)
{
AnotherAction();
}
private void button3_Click(object sender, EventArgs e)
{
SomeAction();
AnotherAction();
}
(As a side note, your buttons should have descriptive names, not button1 and the like.)
We can't say what those button click handlers do. So it's hard to say what's wrong. But try moving the code away from button click handlers. Create some class that contains code that should run after button click. Then call this class' methods from button click handlers. It will be easier to debug and test that code.
public class ButtonActions
{
public void DoSomething() {...}
public void DoSomething2() {...}
public void DoSomething3() {...}
public void DoAll()
{
DoSomething();
DoSomething2();
DoSomething3();
}
}
// here instead of clicking all buttons call method that does it all
protected void button_Click(object sender, EventArgs e)
{
var buttonActions = new ButtonActions();
buttonActions.DoAll();
}
I want to call btnDisconnect_Click within btnExit_Click.
private void btnDisconnect_Click(object sender, EventArgs e)
{
//does something
}
private void btnExit_Click(object sender, EventArgs e)
{
//I want to call btnDisconnect_Click. What line of code should I use here?
}
Usually in cases like these I make my click handlers only call another function and pass in appropriate arguments:
private void btnDisconnect_Click(object sender, EventArgs e)
{
DoDisconnect();
}
private void DoDisconnect()
{
...
}
Then I can call that same function from wherever:
private void btnExit_Click(object sender, EventArgs e)
{
DoDisconnect();
}
This way your "disconnect" logic is gummed up by taking dummy arguments that don't actually affect the disconnect behavior in any way.
It also means you can start factoring out view logic from forms.
That depends on if you are using the arguments passed to the event handlers
You could yust call it using nulls
Something like
private void btnDisconnect_Click(object sender, EventArgs e)
{
//does something
}
private void btnExit_Click(object sender, EventArgs e)
{
//I want to call btnDisconnect_Click. What line of code should I use here?
btnDisconnect_Click(null,null);
}
They're just methods. Just call it. You'll need to provide whatever event arguments btnDisconnect_Click is expecting (which is probably nothing). So the simplest thing is:
private void btnExit_Click(object sender, EventArgs e)
{
btnDisconnect_Click(this, EventArgs.Empty);
}
This will pass the current form/window/whatever it is as the sender, and an EventArgs object with no data.
You can call it just as you have it listed. The this below isn't necessary but it puts context on the code:
private void btnExit_Click(object sender, EventArgs e)
{
//I want to call btnDisconnect_Click. What line of code should I use here?
this.btnDisconnect_Click(null, null);
// If you need to have sender as something you can always put
// this in directly
this.btnDisconnect_Click(this.btnDisconnect, new System.EventArgs());
}
I'm going to make an assumption here and say that what you're trying to do is call a Disconnect (perhaps a network resource) for both the disconnect and exit buttons. Instead of calling one event handler method from the other you may want to refactor the disconnect event handler's code into a separate method. Then call that method from both handlers. For example:
private void Disconnect()
{
//Disconnect here
}
private void btnDisconnect_Click(object sender, EventArgs e)
{
//do some other stuff here
Disconnect();
}
private void btnExit_Click(object sender, EventArgs e)
{
//do some other exit stuff here
Disconnect();
}
This makes your code much cleaner and saves you from having to call one event handler from another. This begins to separate your view logic from the rest of your program's logic, which is much more desirable and much easier to maintain in the long run. For instance you may want a separate controller for handling the network resource, instead of embedding it into the view's logic.
In the simplest case you can just call the btnDiconnect_Click directly as follows:
private void btnDisconnct_Click(Object sender, EventArgs e)
{
//Does Something
}
private void btnExit_Click(Object sender, EventArgs e)
{
//Call btnDisconnect_Click()
btnDisconnect_Click(sender, e);
}
You could just call the method passing in valid parameters.
btnDisconnect_Click(btnDisconnect,new EventArgs());
However you might want to consider refactoring out the code in btnDisconnect into a new method and calling that instead:
private void doSomething()
{
//....
}
private void btnDisconnect_Click(object sender, EventArgs e)
{
doSomething();
}
private void btnExit_Click(object sender, EventArgs e)
{
doSomething();
}
{// this is probably your constructor
.
public delegate void MyCustomHandler(object sender, EventArgs e);
.
MyCustomHandler myCustomHandler = new MyCustomHandler(); //you can do more in your delegates constructor, members etc
myCustomHandler += btnExit_Click;
myCustomHandler += btnDisconnect_Click;
}
private void btnDisconnect_Click(object sender, EventArgs e)
{
// do Something
}
private void btnExit_Click(object sender, EventArgs e)
{
// do Something
}
//And wherever you need to invoke these, you do
myCustomHandler(object sender, EventArgs e);