add child's form closing event

George Paroglou

I have already created in c# from a drawn image inside my tab control to close together the mdi form. I am trying to make the opposite (i.e. pressing the "x" of the form and close its tab as well)

I tried to add a code in my child's closing even but it doesn't recognize functions I used in my main form (Form1).

any suggestions?

Thanks in advanced.

51 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes15y ago
Accepted answer
Well, the names of the tabs should certainly be different though I'm not absolutely about the keys. When you create a tabpage separately and then add it to the tab control's TabPages collection, I'm not sure whether it automatically uses the name as the key or not.

Let's try changing the Form_Closed eventhandler to the following which should certainly not close more than one tab:

private void Spoudastes_Card_FormClosed(object sender, FormClosedEventArgs e)
{

   Form1 mainForm = (Form1)Application.OpenForms["Form1"];
   TabControl tc = (TabControl)mainForm.Controls["tabControl1"];
   for (int i = 0; i < tc.TabPages.Count; i++)
   {
   if (tc.TabPages[i].Name == this.Name) // or use Text properties
   {
   tc.TabPages.RemoveAt(i);
   break; // can't remove more than one tab
   }
   }
}

If it's still not working properly, then I'd put a breakpoint on the 'break' statement and single step from there to see if something else is getting unexpectedly called when the method returns.
Vulpes15y ago
The Name property is read/write so, in theory, you can change it as many times as you like.

However, are you sure that's a good idea here, when you have code which depends on being able to find the correct tabpage by name?
George Paroglou15y ago
vulpe, is it possible to change tabs name after clicked on a button? In other words assign to a button to change specific tab name from the initially asigned one to something else.
George Paroglou15y ago
still the same...from the very beginning I had the problem that as soon as the form closed worked fine the tabs' close didn't work and the opposite....perhaps I will propably leave from the x tabs' button to active the first tab and from tabpage's x button to active the one tab before....

cheers for you help vulpes.

If you have any new thought post it to try it.
Vulpes15y ago
Well, I don't know what else to suggest :(

The code in Spoudastes_Card_FormClosed is virtually the same as the code in TabControl1_MouseClick so, if the former works but the latter doesn't, it's very hard to see why that should be.

The only slight difference is that I used RemoveAt() in the FormClosed handler but RemoveByKey() in TabControl1_MouseClick. You can try changing that if you like and I'd also try calling Refresh() on the tabcontrol in case it's a redrawing problem:

foreach (Form f in this.MdiChildren)
{
if (f.Name == tabControl1.SelectedTab.Name)
{
int index = tabControl1.SelectedIndex; // get the index of the selected page before we remove it
tabControl1.TabPages.RemoveAt(index);
tabControl1.Refresh();

if (index >= 1)
{
tabControl1.SelectedTab = tabControl1.TabPages[index - 1];
}
else (if index == 0 && tabControl1.TabPages.Count > 0) // if removing first page and there's at least one other
{
tabControl1.SelectedTab = tabControl1.TabPages[0]; // set to new first page
}
tabControl1.Refresh();
f.Close();
break;
}
}
George Paroglou15y ago
I meant that the last bit of code change destroyed the the x tab button. It closes the tabs but it remains closed tabs' tabpages open... I hope this explanation is better than before :(
Vulpes15y ago
Sorry, George, I don't understand what you're saying.

The only thing that's different is that we're inserting an if/else statement to set the selected tab. We're not closing anything other than what was closed before, namely the (previously) selected tab page and the corresponding child form. So what else should it be closing?
George Paroglou15y ago
it does go to the previous tab, it closes the correct tab but it remains their tabpages open...
Vulpes15y ago
OK, let's try changing this bit:

foreach (Form f in this.MdiChildren)
{
if (f.Name == tabControl1.SelectedTab.Name)
{
tabControl1.TabPages.RemoveByKey(f.Name);
f.Close();
break;
}
}

to this:

foreach (Form f in this.MdiChildren)
{
if (f.Name == tabControl1.SelectedTab.Name)
{
int index = tabControl1.SelectedIndex; // get the index of the selected page before we remove it
tabControl1.TabPages.RemoveByKey(f.Name);

if (index >= 1)
{
tabControl1.SelectedTab = tabControl1.TabPages[index - 1];
}
else (if index == 0 && tabControl1.TabPages.Count > 0) // if removing first page and there's at least one other
{
tabControl1.SelectedTab = tabControl1.TabPages[0]; // set to new first page
}

f.Close();
break;
}
}
George Paroglou15y ago
check the attatched file
Vulpes15y ago
George, can you just remind me what you've got in there at the moment?
George Paroglou15y ago
bingo for the close tabpage button and what do you suggest for the x tab button as well?
Vulpes15y ago
To set the active tabpage to the page before the one removed (or the page after if you're removing the first page), I'd suggest :

for(int i = 0; i < tc.TabPages.Count; i++)
{
if (tc.TabPages[i].Name == this.Name)
{
tc.TabPages.RemoveAt(i);
if (i >= 1)
{
tc.SelectedTab = tc.TabPages[i - 1];
}
else (if i == 0 && tc.TabPages.Count > 0) // if removing first page and there's at least one other
{
tc.SelectedTab = tc.TabPages[0]; // set to new first page
}
break;
}
}
George Paroglou15y ago
I activated again the

for(int i = 0; i < tc.TabPages.Count; i++)
{

if (tc.TabPages[i].Name == this.Name) // or use Text properties {
tc.TabPages.RemoveAt(i);

break; // can't remove more than one tab}
}

in Spoudastes_Card_FormClosed and both work fine...cheers for your help Vulpes ;)

If I want to make as an active tab with its tabpage exactly the previous tab of the one that I close how this can be done. I am asking cause it always activates the first tab.
George Paroglou15y ago
it seems to be ok with the closing X of each tab... the closing X of the tabpages doesn't close its assigned tab...:(
Vulpes15y ago
So, there's not necessarily any relation then between the selected tab and the active mdi child?

But, if that's the case, why are you closing the active mdi child when you close the selected tab?

Shouldn't you be closing the mdi child which corresponds to the selected tab?

The code for that would be:

if (r.Contains(p))
{
   mnuTab.DropDownItems.RemoveByKey(tabControl1.SelectedTab.Name);

   foreach(Form f in this.MdiChildren)
   {
   if (f.Name == tabControl1.SelectedTab.Name)
   {
   tabControl1.TabPages.RemoveByKey(f.Name);
   f.Close();
   break;
   }
   }
}

or am I still missing something here?
George Paroglou15y ago
nope it doesn't work...it closes the tab but it remains its tabpage open and this it changes the assignment of each tab with its tabpage
Vulpes15y ago
OK, just moving on a step, if you replace these two lines:

   this.ActiveMdiChild.Close();
   tabControl1.SelectedTab.Dispose();

with these (in this order), does it still seem to work OK?

   tabControl1.TabPages.RemoveByKey(this.ActiveMdiChild.Name);
   this.ActiveMdiChild.Close();
Sam Hobbs15y ago
Tab controls are complicated and I get the impression that you are using them in a manner different from their design. That might be no problem except I think you are not sure of the terminology to use to describe what you need to do. So the combination of those things make it frustrating to help.

Perhaps if you describe what you need to do from the point of view of a user that knows nothing about programming, then it will be easier to understand what you need. Don't tell us how you want to write the program and then ask for help with that; tell us what you need to do. Please don't talk about it in terms of a tab control; describe the UI. Then if there is something more appropriate than a tab control then we can suggest the alternative.
George Paroglou15y ago

Let's assume we use this code:

public void TabControl1_MouseClick(object sender, System.Windows.Forms.MouseEventArgs e)
{
TabControl tc = (TabControl)sender;
Point p = e.Location;
int _tabWidth = 0;
_tabWidth = this.tabControl1.GetTabRect(tc.SelectedIndex).Width - (_imgHitArea.X);
Rectangle r = this.tabControl1.GetTabRect(tc.SelectedIndex);
r.Offset(_tabWidth, _imgHitArea.Y);
r.Width = 13;
r.Height = 13;

if (r.Contains(p))
{
mnuTab.DropDownItems.RemoveByKey(tabControl1.SelectedTab.Name);
this.ActiveMdiChild.Close();
tabControl1.SelectedTab.Dispose();
}
}

this seems to work fine
Vulpes15y ago
Let's just go back to first principles which sometimes helps when you have something as convoluted as this.

Suppose we forget about the Form_Closed handler completely - just comment out the code for now.

What code do you need in TabControl1_MouseClick for that to work completely correctly?

If we can establish that then we might be able to synchronize the two.
George Paroglou15y ago
there is a problem of making both X button of tabpage to close its tab and as well the X button of the tab to close its tabpage.

By removing tabControl1.SelectedTab.Dispose(); from TabControl1_MouseClick it closes the tabpage and leaves open its tab...That's why I mentioned earlier that when one of these works ok the other acts incorrectly... There are not "synchronized".
Vulpes15y ago
I thought the purpose of the exercise was to close the tab associated with the form, which is apparently what's now happening.

What's all this about: "it closes the tabpage but all tabs are active and doesn't close at all" ?

All the remaining tabs will be active and I thought you didn't want any more to close?
George Paroglou15y ago
when I remove
tabControl1.SelectedTab.Dispose();
from TabControl1_MouseClick it closes the tabpage but all tabs are active and doesn't close at all....:(

When the tabs' x doesn't work tabpages' x works fine and just the opposite...:(
Vulpes15y ago
I've just noticed that the code you've removed is in the Form_Closed eventhandler, not in TabControl1_MouseClick, so there's no wonder the tab is not being removed!

That code needs to be restored. However, in TabControl1_MouseClick you need to remove this line:

tabControl1.SelectedTab.Dispose();
George Paroglou15y ago
public void TabControl1_MouseClick(object sender, System.Windows.Forms.MouseEventArgs e)
{
        TabControl tc = (TabControl)sender;
        Point p = e.Location;
        int _tabWidth = 0;
        _tabWidth = this.tabControl1.GetTabRect(tc.SelectedIndex).Width - (_imgHitArea.X);
        Rectangle r = this.tabControl1.GetTabRect(tc.SelectedIndex);
        r.Offset(_tabWidth, _imgHitArea.Y);
        r.Width = 13;
        r.Height = 13;

        if(r.Contains(p))
        {
                //if you want to close tab, you must close the corresponding form
                mnuTab.DropDownItems.RemoveByKey(tabControl1.SelectedTab.Name); //this is why you must make sure menu's and tab page's name are same
                this.ActiveMdiChild.Close(); //because of synchronize routine, you must close the form first before tab.
                tabControl1.SelectedTab.Dispose(); //if tab first, activated tab will change and so the child form, this will be the closed form.
//the wrong form will close....
        }
}
Vulpes15y ago
I don't understand that because if you're still closing the active MDI form, then the associated tab should close automatically:-/

Can you post the code of the TabControl1_MouseClick eventhandler, as you currently have it.
George Paroglou15y ago
while I removed the code of my previous post it destroyed the tabpages close button. While I press the X button of a tabpage it doesn't closes its tab.

any suggestion?
George Paroglou15y ago
bingo!

  for (int i = 0; i < tc.TabPages.Count; i++)
   {
   if (tc.TabPages[i].Name == this.Name) // or use Text properties
   {
   tc.TabPages.RemoveAt(i);
   break; // can't remove more than one tab
   }
   }

this shoud be removed.

cheers Vulpes
Vulpes15y ago
It's not this.ActiveMdiChild.Close() that you want to remove but the code which closes the tabpage. The Form_Closed event handler on the child form will take care of the latter.
George Paroglou15y ago
if I remove the this.ActiveMdiChild.Close(); from tabControl1_MouseClick eventhandler it closes the tabs correctly but it exchanges the tabpages without closing them at all.

any idea?
Vulpes15y ago
Looking at the code for the tabControl1_MouseClick eventhandler, one thing I can see is that you're closing the ActiveMdiChild.

If that child is handling the Form_Closed event then as soon as you call ActiveMdiChild.Close() that will trigger the Form_Closed event which will attempt to remove the tab associated with the form. However, you've then removing what then becomes the selected tab within the MouseClick eventhandler so you're potentially removing two tabs!

It would be better therefore not to remove any tabs in the MouseClick handler (unless they're not associated with the relevant form) and leave the Form_Closed event which gets triggered by the Close() method to remove the tab associated with the form.
George Paroglou15y ago
the Form_Closed evenhandler works fine but it destroyed the TabControl1 evenhandler which worked fine before we set the Form_Closed.

any idea what it is going wrong?
Vulpes15y ago
Yes, but the problem I've been trying to solve on this thread is how to close the relevant tab page when 'x' is pressed on the child form.

Before I can move on to anything else, I need to know whether the Form_Closed evenhandler works or not?

If it doesn't work, then there must be some unexpected side effect that we need to track down.
George Paroglou15y ago
During my testing I open three tabs with its tabpage. When I am trying to close the 1st tab it closes the other two as well leaving their tabpages open. If I do the test trying to close the second of the three tabs, it closes and the third tab and leaves the 1 tab active and its tabpage together with the third tabpage.
Vulpes15y ago
All that's telling us is the state of various variables when the breakpoint occurs. It's not telling us where the execution path leads after the Form_Closed eventhandler returns.

However, some of the things you've said recently are making me wonder now whether two tabs are removed when you close the child form (which is what I've been assuming) or only when you close a tabpage from the first form?
George Paroglou15y ago
I didn't understand a thing from the output....

I attached the screenshot if you can see anything strange....:(

I do believe that the problem is in TabControl1_MouseClick as when clicked in the X pic of first tab, it closes the last two tabs but it keeps open their tabpages. the error that prints is in tabControl1.SelectedTab.Dispose(); inside the TabControl1_MouseClick...
Vulpes15y ago
Place the cursor on the line where you'd like to set the breakpoint, select Toggle Breakpoint from the Debug menu (or press F9) and then Start Debugging. When execution reaches the breakpoint, you can then single step from there by pressing F11.
George Paroglou15y ago
indeed it is on a different form but we make active tabcontrol1 variable in spoudastes_card form.

what do you mean "to put a breakpoint"? how can be done?
Vulpes15y ago
I considered that when I was looking at the code but I couldn't see how pressing the X button on the Spoudastes_Card form could possibly trigger the tabControl1_MouseClick event as the tabcontrol is on a different form.

But, as I said in my previous post, the only way to find out is to put a breakpoint in the FormClosed eventhandler and single step from there to see what (if any) other handlers are getting called.
George Paroglou15y ago
perhaps the problem is not in this class but in Tabcontrol1_MouseClick cause this problem is happening while i am using the draw image of the tabs. X button of tabpages is working fine.
George Paroglou15y ago
please have a look in the code. I think it doesn't use the same key cause the closing button of the tabs works fine.
Vulpes15y ago
Well, you can change the accessibility of the tab control on Form1 from private (the default) to public or internal so that it can be accessed directly from Form2 without going through the Controls collection but I don't see what difference it will make - it's still the same tab control :)

If the code is closing two tab pages at once, then either there are two pages with the same key or the closure of the second one is being triggered by some other aspect of your program.
George Paroglou15y ago
I used the following code and the close draw image of the tabs doesn't work properly. It closes 2 tabs together and leaves the its tabpages open.

private void Spoudastes_Card_FormClosed(object sender, FormClosedEventArgs e)
{

Form1 mainForm = (Form1)Application.OpenForms["Form1"];
TabControl tc = (TabControl)mainForm.Controls["tabControl1"];
tc.TabPages.RemoveByKey((string)this.Name);
}

Can I, in any way, make tabControl1 variable active in my second form?
Vulpes15y ago
If you're opening and closing TabPages as you're opening and closing forms, then I don't think you can rely on the index of the TabPage to stay the same for a given form.

A better idea would be associate a TabPage object with the form when you open it. You could use the form's Tag property and the TabPage's key for this. For example, suppose you're opening Form2 from Form1 with code like this:

   Form2 form2 = new Form2();
   form2.MdiParent = this;
   tabControl1.TabPages.Add("Form2", "Form2");
   form2.Tag = "Form2"; // use TabPage key here
   form2.Show();

In Form2's Form_Closed handler you could then use the following code to close the TabPage at the same time as the form:

   private void Form2_FormClosed(object sender, FormClosedEventArgs e)
   {
   Form1 mainForm = (Form1)this.MdiParent;
   TabControl tc = (TabControl)mainForm.Controls["tabControl1"];
   tc.TabPages.RemoveByKey((string)this.Tag);
   }
George Paroglou15y ago
its the second situation vulpes.

It seems to work for just for more than one tabpages already opened. At the last tabpage prints an error in the number of index that doesn't exist.

also noticed that this depends on the closing order of the tabpages( i.e. if I close the 1 out of 2 tabpages and open a brand new tabpage it stucks every tab to the same tabpage....:(
Vulpes15y ago
I don't understand what the relationship is between Form2 and the TabControl.

If the TabControl is on Form2 then it would close automatically when Form2 was closed.

If it's on Form1 but Form2 isn't inside a TabPage, then what do you mean about Form2 having a specific tab?

If you mean that Form2 relates to the second TabPage, then this code should work:

   private void Form2_FormClosed(object sender, FormClosedEventArgs e)
   {
   Form1 mainForm = (Form1)Application.OpenForms["Form1"];
   TabControl tc = (TabControl)mainForm.Controls["tabControl1"];
   tc.TabPages.RemoveAt(1); // close tabpage at index 1 i.e. the second page
   }
George Paroglou15y ago
Form2 is mdi child and Form1 is my parent. I open my main form (Form1) and inside I open Form2 and a tabcontrol. I want to make the X of Form2 to close also its specific tab.

I used the code you gave me but it gives an error in 3rd line.
Vulpes15y ago
You'll need to clarify the situation first, George.

Are you saying that there's a TabControl on Form1 and one of its TabPages contains an instance of Form2?

If so, then I don't see how Form2 can be an MDI child of Form1 because Form1 is not its container - the TabPage is.

If this is the situation and you wanted to close the TabPage on Form1 when Form2 was closed, then you'd need to handle Form2's FormClosed event as follows:

   private void Form2_FormClosed(object sender, FormClosedEventArgs e)
   {
   Form1 mainForm = (Form1)Application.OpenForms["Form1"];
   TabControl tc = (TabControl)mainForm.Controls["tabControl1"];
   tc.TabPages.Remove((TabPage)this.Parent);
   }
George Paroglou15y ago
cheers for your reply vulpes. Form1 is MDI parent of the child. could you please specify me the syntax of public or internal instance methods? Where to put the reference of the main form?
Vulpes15y ago
If Form1 is the MDI parent of the child, then you can get a reference to the main form as follows:

Form1 mainForm = (Form1)this.MdiParent;

You can then call public or internal instance methods of Form1 from the child using the mainForm reference.

If Form1 isn't the MDI parent, then you can get a reference instead using:

Form1 mainForm = (Form1)Application.OpenForms["Form1"];