I have a working method
something_Click(object sender, EventArgs e)
{
code
}
...
It of course executes after someone clicks the element. What I need to do is, to execute this method immediately after the element appears on the screen (it is StripStatusLabel). I have tried just to add a call of the method to beginning of the code, but it did nothing.
You can call Button.PerformClick on your button in a Form.Load event handler.
You might also want to consider moving that logic into its own method, and call that method from both the button handler and the Load event, as this will be more clear. (It's obviously code you want triggered on more than just a "button click").
Depending on what framework you are targeting (WPF vs Winforms) you might be able to handle the Load event instead. It triggers when the element appears on screen.
It's not best practice to fire a form event which would normally be originated from teh user. In the sense, you are trying to "fake" the click. Think of the future debugging, or of the colleague who might inherit your project. When inspecting code you would expect something_Click to only be fired when there is a click on "something".
A better solution is to put the "code" part in your snip into a method whose name reflects what it really does.
They you may fire this method in different areas. Fire it at the click, at the load, anywhere.
something_Click(object sender, EventArgs e)
{
DoStuff();
}
OnAppearToScreen()
{
DoStuff();
}
DoStuff()
{
//code that actually does stuff
}
Later on, when you want to check when "the stuff" was done to your object, you can easily tell by code inspection.
Related
I am creating a simple Windows Form with a DataGridView that contains a total of 6 columns. Only one of these columns (the very first) is a button column. I am having trouble with the handler for when the button, or rather, cell is clicked.
For reference (if it matters), the name of my DataGridView is infoGrid.
The only operation that I have the handler perform is a simple popup window, just so I can know the handler is being correctly called. I also have not added conditions yet to ensure it was the first column that was clicked, but I do plan on implementing conditions when I can get the handler to properly work. This is what I have:
private void infoGrid_CellClick(object sender, DataGridViewCellEventArgs e)
{
MessageBox.Show("It's working.", "Test", MessageBoxButtons.OK);
}
After spending a couple of hours scouring the internet for an answer, I noticed that just about all examples on this website and others use dataGridView1_CellClick for their method name. I wasn't sure if that was just a generic answer, but I tried it myself, and still got nothing.
I added breakpoints at the beginning of this method as well, and found that no matter how many times I click ANY cell, the handler is never even called.
Does anybody know what I may be doing wrong? All help is appreciated!
CDove actually answered this for me in his comment to the original question, but I just wanted to make it more visible for anyone else who may have the same problem.
After creating the handler method, you have to go to the designer and click the lightning bolt "Events" button under the "Properties" side bar. Then find the event you want to handle, and add the handling method that you created to it.
Once again, credit for this answer goes to CDove.
I have a question when programing in c#. I want to call an event from another event like this.
private void button1_Click(object sender, EventArgs e)
{
Form2 formulario = new Form2();
formulario.ShowDialog();
// here i call an event from the second form. that event is radiobutton_checkedchange
formulario.radioButton1_CheckedChanged(sender, e);
The problem is that i look everyware how to solve this problem... They said me that an event is like a method but i think is not the same, because when i call that event like a method it looks like i call it just once. The event dont recognize the checked change.
am I wrong ? is this posible in c#. Thanks to all, i'm new in programing with events. And sorry for my bad english
First, radioButton1_CheckedChanged is not an event, it is probably an event handler. In the end, it is still a method like all others.
You shouldn't directly call the event handler of an event, just create another method and what the call there. Put this in your Form2:
private void radioButton1_CheckedChanged(object sender, EventArgs e)
{ // private, only accessible from the class itself
this.SetState();
}
public void SetState()
{ // public, accessible from anywhere
// put your original code from radioButton1_CheckedChanged here
}
In that way, you don't have to call event specific code, but you can write that away in a separate method, which is easier to use and clearer in its purpose.
If both forms share the same data object / view model, you can set the value from there. That would be better from a OOP perspective. Look into MVVM or MVC for good design patterns to do so.
It sounds like you have logic in radioButton1_CheckedChanged that you also want to call when the button is clicked. If that's the case, then move the common logic to a new method and call it from both places.
If you want to change the checked status of radioButton1 then just change its status. Event hnadlers respond to UI changes, they do not generate them.
Understanding that I can use the Forms.Shown event to be notified when a form fully is shown for the very first time, I found no way yet to get something similar later in the form's lifetime.
I.e. consider adding/removing controls or resizing the form.
I thought about registering for the Application.Idle event and somehow connect this to my form but I'm unsure whether this is the right way to go.
In addition I thought about subclassing the LayoutEngine class to gain access to some events/overrides. Again this doesn't look the right way to go for me.
So my question is:
When programmatically adding/removing/resizing a control when a form is already visible, how can I detect when the form is fully finished layouting and drawing again?
I.e. consider adding/removing controls or resizing the form
No, you never want to do this when the user can see the window. There are two basic places where you want to write code like this before the user can see you monkeying with the window, actually seeing it changing size, moving around and generally flickering madly because of multiple Paint events.
First and foremost is your class constructor. That's where you initialize the object in .NET, adding or removing controls belongs there.
Secondary is the Load event. An event that's generally very poorly understood and gets used way to often in Winforms. Induced by it being the default event for the Form class, an historical accident that goes back to early versions of Visual Basic where it was the event to use to initialize the form. That is no longer appropriate, .NET class objects should be initialized in their constructor.
Load, or rather OnLoad(), is appropriate when your code needs to know the Location or Size of the window. Everything that needs to happen to the native window is done by then. It has a valid Handle property, Windows picked a Location, it got rescaled if necessary to accommodate the machine's DPI setting, its Size property is now valid, reflecting scaling and any user preferences, layout was performed so every control is in its expected place. The only thing that didn't happen yet is that the Paint event wasn't fired yet. So the window is not yet visible to the user. That happens very soon after Load completes.
So sizing or moving the window is typically appropriate in OnLoad, given that you now know the real size and location. Do beware DPI rescaling, never hard-code a size.
If you need code run some fixed time after the window is displayed then a Timer is appropriate.
I'm taking a guess here, but the form's OnPaint event might do the trick. You can just override the base OnPaint handler, call the parent function, and put any logic you have after that.
You could use separate events call for each of the events that call a common function
I.E. ResizeEnd for resizing, ControlAdded and ControlRemoved for the controls.
private void Form1_ResizeEnd(object sender, EventArgs e)
{
DoWork()
}
private void Form1_ControlAdded(object sender, ControlEventArgs e)
{
DoWork()
}
private void Form1_ControlRemoved(object sender, ControlEventArgs e)
{
DoWork()
}
private void DoWork()
{
//What needs to be done for each of them
}
Im not sure about the timing of these calls though.
I'm using User Controls in C# winforms, and I would like some code to be executed after the load event, and after the control has been shown. If no such event exists, is it possible to make one?
You could use one of events from this list. OnPaint would be most likely candidate.
Form Events:
Construtor
Load
Layout
Activated
PaintÂ
Closing
Closed
Deactivate
Dispose
and for Controls:
Enter
GotFocus
Leave
Validating
Validated
LostFocus
If you can't find one that fits you needs, this article explains how to construct and fire event.
Create a public method in user control
Call the method on Parent win-form Shown Event
This will call the code you want to run once.
You can also use user-control paint event, but this will Expensive call. Because your code will execute every time the control is redrawn.
So it is better to use a flag which you can determine whether to run the code or not
i.e.
private bool _run =true;
private void Control_Paint(object sender, PaintEventArgs e)
{
if(!_run) return;
//call the code you need to run
_run = false;
}
I'm developing a simple WPF application where I want to use the text changed method for a specific text field. the thing is I implemented the method but, the method gets fired in very short period, like even after i enter one character. I want to check whether the text change is completed in order to go with the methods written in the text changed method.
private void searchBox_TextChanged(object sender, TextChangedEventArgs e)
{
if (...) // how to check whether the typing is finished?
{
// code goes here
}
}
I think you'll need the LostFocus event for this. As #SLaks comment says, you can't predict whether the user will press another key. Alternatively, you could databind the control - depending on what you're actually trying to do that may make more sense.
Instead of TextChanged, try monitoring the LostFocus event, which will fire when the user has left the textbox, either through pressing Enter/Tab or clicking somewhere else on the form.
Agree with LostFocus
UIElement.LostFocus Event
Question does not ask about binding but something to consider.
In binding the equivalent is UpdateSourceTrigger="LostFocus"
Binding.UpdateSourceTrigger Property
With binding you can get into more advanced validation UI effects.
How to: Implement Binding Validation