how to handle the Windows Form got focus event in C#? - c#

I have Windows Form.Now i want to perform some function when the form get focused(that was already opened).For example,form has already opened, and user minimized that window and perform some other function.Finally, he will maximize that form to doing function.So, on that time, i want to perform function(while getting focused to the user). how i do it?

You can try the Form's Activated event.
EDIT:
This is the code I tried
public Form1()
{
this.Activated += new EventHandler(Form1_Activated);
}
void Form1_Activated(object sender, EventArgs e)
{
Console.WriteLine("Activated");
}

Related

How to launch method when window got focus again in WPF?

My app is multi-window, here is quickly how it works:
In main window I have a list of items, when I click on one, it opens another window where I can modify it. When I close that window, I want main window to refresh its content. I've tried many event handlers including GotFocus() but it doesn't want to launch my method to refresh the list. Any advise?
If you want something to happen when the other window is closed, you can subscribe to its closed event. This will fire when the windows is closed.
private void Button_Click(object sender, RoutedEventArgs e)
{
var wnd = new Window1();
wnd.Closed += wnd_Closed;
wnd.Show();
}
void wnd_Closed(object sender, EventArgs e)
{
MessageBox.Show("Closed");
}

Show MessageBox immediately in Windows Forms?

Is there any way to have a messagebox immediately pop up when a form opens? I just want to display a short message about how to use the form when it opens. I tried
private void myForm_Load(object sender, EventArgs e)
{
DialogResult dialogOpen = MessageBox.Show("Use the navigation menu to get started.", "Welcome!", MessageBoxButtons.OK);
}
but it doesn't work.
Showing a MessageBox during Form_Load works just fine for me. I literally copy/pasted the code from your original post, and it worked. I'm on .NET Framework 4.5 on Windows 8.1.
Are you sure your Load event handler is getting called? Perhaps the it's not hooked up to the Load event properly.
I don't see why it wouldn't work in Form_Load. Definitely try doing as others have pointed out by putting it beneath form initialization.
Though, given that you're just showing a message box, I don't think there is any reason to store the result, so a simple MessageBox.Show(message); Should do the trick.
As #s.m. said, from a UX point of view, having a notification thrown in your face as soon as the app starts would be very obnoxious, at least if you have it EVERY time. Personally, I would create a boolean Settings variable, set it to true the first time the message is displayed, and only display it when the setting is false, i.e. the first time the message is displayed.
private boolean splashShown = Properties.Settings.Default.splashShown;
private void Form_Load(object sender, EventArgs e)
{
if (!splashShown)
{
MessageBox.Show("message");
myForm.Properties.Settings.Default.splashShown = true;
myForm.Properties.Settings.Default.Save();
}
}
And set up the splashShown Setting in your form properties.
If the problem is that your Form_Load() method isn't actually attached to your Form.Load() event, you can double click the form window in the designer and it will automatically created the Form_Load() base method for you and attach it to the Form.Load() event
Is there a reason to use the Load method of the form? If not you could to it in the constructor of form. If you want it to show up immediately after your form loads, you should do it in the constructor after the form is initialized. It should look something like this:
public partial class myForm : Form
{
public myForm()
{
InitializeComponent();
DialogResult dialogOpen = MessageBox.Show("Use the navigation menu to get started.", "Welcome!", MessageBoxButtons.OK);
}
}
The constructor (public myForm()) and the InitializeComponent(); should be automatically added to the form by Visual Studio after creating it.
Form_Load event occurs before the form is really visible.
I use:
static private bool splashShown = false;
private void Form1_Activated(object sender, System.EventArgs e)
{
if (!splashShown)
{
MessageBox.Show("message");
splashShown = true;
}
}
I have used this and it works fine. App start brings up messagebox first before all else.
InitializeComponent();
MessageBox.Show("put your message here");

opening a window form from another form programmatically

I am making a Windows Forms application. I have a form. I want to open a new form at run time from the original form on a button click. And then close this new form (after 2,3 sec) programatically but from a thread other than gui main thread.
Can anybody guide me how to do it ?
Will the new form affect or hinder the things going on in the original main form ? (if yes than how to stop it ?)
To open from with button click please add the following code in the button event handler
var m = new Form1();
m.Show();
Here Form1 is the name of the form which you want to open.
Also to close the current form, you may use
this.close();
I would do it like this:
var form2 = new Form2();
form2.Show();
and to close current form I would use
this.Hide(); instead of
this.close();
check out this Youtube channel link for easy start-up tutorials you might find it helpful if u are a beginner
This is an old question, but answering for gathering knowledge.
We have an original form with a button to show the new form.
The code for the button click is below
private void button1_Click(object sender, EventArgs e)
{
New_Form new_Form = new New_Form();
new_Form.Show();
}
Now when click is made, New Form is shown. Since, you want to hide after 2 seconds we are adding a onload event to the new form designer
this.Load += new System.EventHandler(this.OnPageLoad);
This OnPageLoad function runs when that form is loaded
In NewForm.cs ,
public partial class New_Form : Form
{
private Timer formClosingTimer;
private void OnPageLoad(object sender, EventArgs e)
{
formClosingTimer = new Timer(); // Creating a new timer
formClosingTimer.Tick += new EventHandler(CloseForm); // Defining tick event to invoke after a time period
formClosingTimer.Interval = 2000; // Time Interval in miliseconds
formClosingTimer.Start(); // Starting a timer
}
private void CloseForm(object sender, EventArgs e)
{
formClosingTimer.Stop(); // Stoping timer. If we dont stop, function will be triggered in regular intervals
this.Close(); // Closing the current form
}
}
In this new form , a timer is used to invoke a method which closes that form.
Here is the new form which automatically closes after 2 seconds, we will be able operate on both the forms where no interference between those two forms.
For your knowledge,
form.close() will free the memory and we can never interact with that form again
form.hide() will just hide the form, where the code part can still run
For more details about timer refer this link, https://learn.microsoft.com/en-us/dotnet/api/system.timers.timer?view=netframework-4.7.2
You just need to use Dispatcher to perform graphical operation from a thread other then UI thread. I don't think that this will affect behavior of the main form. This may help you :
Accessing UI Control from BackgroundWorker Thread
This might also help:
void ButtQuitClick(object sender, EventArgs e)
{
QuitWin form = new QuitWin();
form.Show();
}
Change ButtQuit to your button name and also change QuitWin to the name of the form that you made.
When the button is clicked it will open another window, you will need to make another form and a button on your main form for it to work.
private void btnchangerate_Click(object sender, EventArgs e)
{
this.Hide(); //current form will hide
Form1 fm = new Form1(); //another form will open
fm.Show();
}
on click btn current form will hide and new form will open

C# form Activated and Deactivate events

I have two forms, mainForm and subForm. When mainForm loses focus I want subForm to disappear and then reappear as mainForm regains focus. I'm using the Activated and Deactivate events on the mainForm to keep track of whether mainForm has focus or not. When the Activated is fired I do subForm.Show() and the opposite for Deactivate. The problem I have is that when subForm gains focus mainForm disappear because I don't know how to say programmatically "make subForm disappear when the mainForm's Deactivate event fires except if it's because the subForm gained focus. The whole point of what I'm doing is to make both windows disappear when the mainForm loses focus because the user clicked on another application or use ALT+TAB to switch. I don't want to leave the subForm behind. Is there any way of checking as the Deactive fires whether it was because another form belonging to the application gained focus as opposed to some other application?
class MainForm : Form
{
SubForm subForm = new SubForm();
private void mainForm_Activated(object sender, EventArgs e)
{
this.subForm.Show();
}
private void mainForm_Deactivate(object sender, EventArgs e)
{
this.subForm.Hide()
// I need some logic to make sure that it is only hidden
// when the mainForm loses focus because the user clicked
// some other application in the taskbar and not when the
// subForm itself gains the focus.
}
}
This works on my machine.
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
}
private Form2 _form2;
private void Form1_Load(object sender, EventArgs e) {
_form2 = new Form2();
_form2.Show();
HandleFocusEvents();
}
private void HandleFocusEvents() {
this.LostFocus += Form_LostFocus;
_form2.LostFocus += Form_LostFocus;
this.GotFocus += Form_GotFocus;
}
private void Form_LostFocus(object sender, EventArgs e) {
if (!_form2.ContainsFocus && !this.ContainsFocus) {
_form2.Hide();
}
}
private void Form_GotFocus(object sender, EventArgs e) {
if (!_form2.Visible) {
_form2.Show();
}
}
}
In your main forms code, where you create an new instance of the sub form, add an event that is fired whenever the instance of the sub form form is activated. In the event handler for it set a bool variable to true. Now, do the same, for the deactivate event of the sub forms instance, except set the bool variable to false.
Now in the event for the main form loosing focus, before hiding it check that bool variable and make sure it is false "the sub form doesn't have focus" and only then would you hide the main form.
I could provide code if I could see what you have so far. There are a lot of different ways you could to this.
Hope this helps you!
If I understand it correctly, this sounds like just a normal MDI application. Can you make your main form the MDI Parent and set the sub form MDI parent to the main form? Most of these activation stuff that you are talking about should then be look after automatically? Or at most just trap the minimize event in the subform to then also minimize mdi parent form

Detect when a form has been closed c#

I have a WinForm that I create that shows a prompt with a button. This is a custom WinForm view, as a message box dialog was not sufficient.
I have a background worker started and running. I also want to exit the while(aBackgroundWorker.IsBusy) loop if the button on myForm was clicked.
//MyProgram.cs
using(CustomForm myForm = new CustomForm())
{
myForm.Show(theFormOwner);
myForm.Refresh();
while(aBackgroundWorker.IsBusy)
{
Thread.Sleep(1);
Application.DoEvents();
}
}
Right now, in the CustomForm the Button_clicked event, I have
//CustomForm.cs
private void theButton_Click(object sender, EventArgs e)
{
this.Close();
}
Do I need to add more code to the CustomForm class, or the location where I declare and initialize the form in order to be able to detect a closure?
To detect when the form is actually closed, you need to hook the FormClosed event:
this.FormClosed += new FormClosedEventHandler(Form1_FormClosed);
void Form1_FormClosed(object sender, FormClosedEventArgs e)
{
// Do something
}
Alternatively:
using(CustomForm myForm = new CustomForm())
{
myForm.FormClosed += new FormClosedEventHandler(MyForm_FormClosed);
...
}
void MyForm_FormClosed(object sender, FormClosedEventArgs e)
{
// Do something
}
You might be going overkill. To show a form like a dialog window and wait for it to exit before returning control back to the calling form, just use:
mySubForm.ShowDialog();
This will "block" the main form until the child is closed.
Make sure your background worker supports cancellation and as others have pointed out use the form closed event handler. This code should point you in the right direction:
using(CustomForm myForm = new CustomForm())
{
myForm.FormClosed += new FormClosedEventHandler(ChildFormClosed);
myForm.Show(theFormOwner);
myForm.Refresh();
while(aBackgroundWorker.IsBusy)
{
Thread.Sleep(1);
Application.DoEvents();
}
}
void ChildFormClosed(object sender, FormClosedEventArgs e)
{
aBackgroundWorker.CancelAsync();
}
Handle the FormClosing event of the form to be notified when the form is closing, so you can perform any cleanup.
You should be able to hook into the FormClosing and FormClosed events.
http://msdn.microsoft.com/en-us/library/system.windows.forms.form.formclosing.aspx
http://msdn.microsoft.com/en-us/library/system.windows.forms.form.formclosed.aspx
Closing is before it's closed.
Closed is after it's closed.
A couple things...
First, it appears that loop is there in order to prevent execution form proceeding while the dialog is open. If that is the case, change you .Show(parent) to .ShowDialog(parent). That will also take care of the rest of your question.
Note that this.Hide(); is not the same as this.Close(); in the actual dialog your overriding the closed event

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