I know that in C# the Form.Load event occurs only before the form is displayed for the first time.
Is there any similar event handler (in C#) which occurs every time that the form is displayed?
Assuming that you're showing and hiding the form instead of destroying it.. then you can hook into the VisibleChanged event and perform some code when its Visible property is true.
It can be
Shown event - fired when the form is first shown
Load event - fired whenever the user loads the form
Activate event - fired each time the form is activated or receives the focus
VisibleChanged event - fired whenever the visibility changes
Related
I have searched for the question that when is the validating event fired but the answer I found so far is that when the validation starts.
What I want to know is the actual firing time of the validating event.
For example, the click event is fired when a control is clicked by either mouse or keyboard and similarly leave is fired when a control is no more the current focused control.
So what is the explanation of validating event being fired?
The Validating event is fired only when the control that receives the focus has the CausesValidation property set to true. For example, if you have written code in TextBox's Validating event, and you click the OK button (CausesValidation = true) then the Validating event is raised, but if you click the Cancel button (CausesValidation = false) then the Validating event would not be able to fire.
I've got a winform application. In the application I have a Panel with multiple Buttons.
Now when the Buttons don't have the Focus I can capture the keypressed Events in the form itself. But when the Buttons have the Focus the form (even if the Buttons don't catch the Event explecitely) only they get the keypressed Event and not the form.
Now my question is: Is there any way to centralize the keypressed behaviour (without creating a keypressed Event for each and every button and call a central method with that Event)?
In essence only 1 method needs to be defined with the appropriate Parameters:
Example:
private void Event_Key_Press_Check(object sender, KeyPressEventArgs e)
This method then only Needs to be put in as the Name of the method used in the Event (form designer), or added as the Event.
That way only 1 method is used.
Thus there is no shorter way and the Event Needs to be defined for every single button (instead of 1 central Event that is always triggered).
Set form property KeyPreview to true and set KeyPress handler. Then form will handle this event before buttons.
See KeyPreview MSDN documentation.
I've had the same issue, and it was pretty easy to resolve :)
Check here : KeyPress at form level with controls
Just set the KeyPreview property (of your form) to True. This way your form will handle KeyPress event before any other control, even if one of them has the focus
I am working with an existing WinForm application and it uses the following code to re-activate a child form that has previously been loaded:
private void Activate(Form frm)
{
frm.WindowState = FormWindowState.Maximized;
this.ActivateMdiChild(frm);
}
The trouble I'm having is that when the form is re-activated, I can not seem to find any event on the form that gets raised naturally by the code above. I'm also having difficulty adding code to manually raise the event on the child form, and I think it's because I'm working with a generic Form object.
I've tried Load, MdiChildActivate, MaximumSizeChanged, Activated and a few other events, and none of them fire upon running the code above. I basically need to update some of the form elements after that code is called above and figured an event would work well.
Does anyone know an event that will be raised on the child form after it has been reactivated?
Have you tried the Enter event of the child form? I don't think it fires if the form is already active though.
Another option would be to cast it as your own type and add your own event, then fire it directly.
Simple question. I have a MainForm and a settingsForm. The settings form is initialized once and then shown every time the user clicks a button. I need it to do something when this button is clicked.
m_inputSettings.ShowDialog(this); //edit settings selected, so show that form
This is the MainForm calling the settings form, which it does fine. But I need the SettingsForm to do something every time this happens. Presently, I cant figure out if this call actually triggers any events I can set handlers for. Does it trigger an event? If not, is there another way I can tell my SettingsForm to do something every time this call happens?
Note: Any code in the mainform after that line doesn't get executed until the SettingsForm returns, but that is intentional.
Thanks.
Edit: One of the things I want my form to do it select a specific control when this happens, but it seems that that is impossible until after the form is done loading everything.
You can override the OnVisibleChanged method in your settings form. Make sure to call base.OnVisibleChanged though as to not screw up any potential observers of the event (and anything else the base class may do inside of that method.)
FormShown event - raised only once when form is displayed first time.
OnPaint / OnActivate - every time form is activated, but these events raised even when you switch with other application, which probably you don't want to do.
If you are changing form visbility, then you can use OnVisibleChanged
If you are minimizing the form, you can use OnSizeChanged / OnLocationChanged event.
If none suits you, make a public property and set false when form is closed / hidded, and set true before showing it. OnActivate, use this property to do your task.
Maybe use VisibleChanged event.
Override OnShown() event in your form this will raise only once after the form is opened
The disadvantage of OnVisibleChanged is it will also get raised when the form is closed.
On Paint , On Activate and OnEnter will raise before form is shown to the user.
I have created a custom control that inherit the TextBox, in that control i have override validating event and in validating event i have put validation that checks for the empty field.
Now when i use that control on my winform and when i click on save button it immediate fires save event.. the validation event of custom control fires and it displays the error message but still it does not stop the save event to fire....
the save button CauseValidation Property is set to true..
i have also put (this.ValidateChildren())
i have also put CancelEventArgs ce.Cancel = true; in Custom Textbox control
but neither working to stop the save event to fires..
i only want to fire Save event if Textbox is not empty.
validating event fires, shows message for empty field and immediate fires save event..
now if you got an idea then if you have solution then please provide solution..
Validating event of the textbox is fired only when cusor leaves that textbox. If you directly click on the save button, Validating event of the textbox will not be fired.
I think, on Save button you need to provide some validation to check if textbox is empty or not.
Hope this helps..