C# How To Subscribe To An Event For Each Control In A Form?

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Hello Everyone!
I have yet another question,
How to i subscribe to an event for every control that exist in my form?
Here is what i have so far:

C#

foreach (Control ctrl in this.Controls)
{
    ctrl.MouseEnter += new System.EventHandler(this.Form1_MouseEnter);
    ctrl.MouseLeave += new System.EventHandler(this.Form1_MouseLeave);
}

Marcin Kozub gave me a this solution C# How To Tell If A WinForm Has Focus Or Not?[^]
where he subscribed to the events "MouseEnter" and "MouseLeave" for the main form only
now what i want to do is to use a for each loop to suscribe to those 2 events for every control that i have in my form.
sorry Marcin and or everyone if i am being picky.
thanks for everyone's help again!
who knows i just might do an article about this app i am developing (it mimics what a star trek computer, but just not the firing phasers or torpedoes part)

--UPDATE--
Marcin Kozub solved part of the reason i had this problem and now i have encountered the same problem just in a different form.
i was trying to loop through all the controls in the form and set there visibility to either true or false based on a variable that i set but then i encountered the problem where i it would set ALL the controls to either visible or not nut just the keyboard buttons i wanted(i made a onscreen keyboard out of button controls).
here is what i am using currently to do this:

C#

foreach (Button ctrl in this.Controls)
{
    ctrl.Visible = true;
}

but when i do this VS gives me an InvalidCastException error saying:
Unable to cast object of type 'System.Windows.Forms.ListBox' to type 'System.Windows.Forms.Button'.
this is because i have a ListBox and i should have seen this comming but the types won't work with each other(duh! i said to my self!)
so how do i solve this?

Posted 16-Dec-14 8:41am

MasterCodeon

Updated 16-Dec-14 10:49am

v3

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Comments

Kornfeld Eliyahu Peter 16-Dec-14 15:19pm

Your question is not clear...

MasterCodeon 16-Dec-14 15:31pm

i want to know how to iterate through all controls of a form, and for each control in the form, subscribe to an event linked to the (whatever the name control is that i am currently accessing in a foreach loop) on the form.

Kornfeld Eliyahu Peter 16-Dec-14 15:35pm

So? You already have a loop for the first level of controls, if you want to go deeper than create some kind of recursion...That's what you are looking for?
(Also consider that not all control necessarily have all the events you want)

MasterCodeon 16-Dec-14 15:41pm

no not really i don't have any child control(unless you count buttons on a context menu strip) but the only events i want to subscribe to are the "MouseEnter" and the "MouseLeave" events, so i am pretty sure all of my buttons, list boxes, text boxes and labels will have those events.
And my foreach loop that i have does not work.

Kornfeld Eliyahu Peter 16-Dec-14 15:42pm

Doesn't work in what way?

MasterCodeon 16-Dec-14 15:50pm

ok so what happens with this loop is that for each control in the "Controls" property of the form the local variable "ctrl" is always the text of the control. So if i had a control that had the text "Test Button" the value of ctrl would be "Test Button" but the button that says "Test Button" has a name of "button1" not "Test Button" so the loop is trying to get the button in the form named "Test Button" when there is no button named that.
sorry if this sounds complicated or if you can't understand this (i have come to learn not by you but by my own experience that i tend to over complicate things)

Kornfeld Eliyahu Peter 16-Dec-14 16:10pm

What are you saying is that the foreach loop enumerates the Text property of the controls instead the controls themselves?
Now that is strange...
Maybe you mean that in the debugger window you see something like this:

Name Value Type
ctrl {Text = "button2"} System.Windows.Forms.Control {System.Windows.Forms.Button}

That's the way the debugger displays objects! The value of an object is the value of its default property. Text is the default property for most controls...

MasterCodeon 16-Dec-14 16:15pm

ah yes that clears things up.
yes i do see ctrl {Text = "button2"}
but for the first button i have its:
ctrl {Text = "Test Button"}
thanks for the explanation.

Sergey Alexandrovich Kryukov 16-Dec-14 15:57pm

It's a tiny bit more complex than that. I answered, please see...
-SA

Marcin Kozub 16-Dec-14 16:21pm

I've updated my answer to original post: http://www.codeproject.com/Answers/852547/Csharp-How-To-Tell-If-A-WinForm-Has-Focus-Or-Not

MasterCodeon 16-Dec-14 16:35pm

yes i say thats great.
it works like a charm thanks!

MasterCodeon 16-Dec-14 16:36pm

oops i meant to say "i saw"

3 solutions

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sergey Alexandrovich Kryukov · Accepted Answer · 2014-12-16T09:56:00

Solution 1

You would need to create a recursive method traversing all controls of some parent control; for example:

C#

using System;
using System.Windows.Forms;

//...

static void SubcribeToMouseEnterLeaveEvents(Control parent, EventHandler enterHandler, EventHandler leaveHandler) {
    foreach (Control child in parent.Controls)
        SubcribeToMouseEnterLeaveEvents(child, enterHandler, leaveHandler);
    parent.MouseEnter += enterHandler;
    parent.MouseLeave += leaveHandler;
}

Then, if you really need to subscribe for all controls on the form, call it starting from your form instance (remember that Form is Control); for example:

C#

SubcribeToMouseEnterLeaveEvents(myFormInstance, // could be "this",
                                                // if called in you form class
    (sender, eventArgs) => {
        // something you want to do on enter
    }, (sender, eventArgs) => {
        // something you want to do on leave
    });

That's it. For the events using other EventArgs types (derived from System.EventArgs), you would need to use generic System.EventHandler<>.

—SA

Posted 16-Dec-14 9:56am

Sergey Alexandrovich Kryukov

Updated 16-Dec-14 18:06pm

v2

Comments

MasterCodeon 16-Dec-14 16:05pm

I get the first part but when i try to use the second code snippet VS gives me 12 errors
could you explain a little more i don't get it
sorry i am kind of a newbie

Sergey Alexandrovich Kryukov 16-Dec-14 16:21pm

Of course I tested everything before posting. Compilation errors? What is your C# version? If it's too low, I'll tell you the other way on the second fragment.
But what could be a problem for you? If you know how to subscribe to one event on one control instance, everything else should not be a problem.
—SA

MasterCodeon 16-Dec-14 16:27pm

uh i don't know how to find what version of C# i am using but i know i am using Visual Studio 2010 and the .NET Framework 4.5(but i know the .NET version has nothing to do with C# version)
and is the second snippet supposed to be a void, is it supposed to be public private what?
sorry for being such a newbie when it comes to this
i have worked with python for 2 years and a couple of years before that my dad started to teach me C# and just recently i picked up C# again(but i am doing pretty good at it so far, or at least i know the basics.)

BillWoodruff 16-Dec-14 22:11pm

Sergey, the code will not work for the simple reason that the recursive call is incorrect:

SubcribeToEvent(child, enterHandler, leaveHandler);

should read:

SubcribeToMouseEnterLeaveEvents(child, enterHandler, leaveHandler);

I suspect the same demon that messes with my code messed with yours :)

Sergey Alexandrovich Kryukov 17-Dec-14 0:05am

Ah, thank you very much, I just renamed the method at the last moment. Fixing...
—SA

MasterCodeon 16-Dec-14 16:08pm

Oh and you wouldn't by any chance be a user on BlenderArtist forms would you?
because if so i have funnily enough asked you questions related to bge programming(my user name is SGA)

Sergey Alexandrovich Kryukov 16-Dec-14 16:23pm

This is something unrelated to this question... No, I don't know BlenderArtist and not very interested to know. At least, you could give us a link...
—SA

MasterCodeon 16-Dec-14 16:29pm

ok sorry i say a user who has a simalr user name and avatar picture
here is the site i was talking about http://blenderartists.org/

Sergey Alexandrovich Kryukov 17-Dec-14 0:09am

All right, thank you. I don't know what name do you mean by probably this artist is not me.
—SA

MasterCodeon 16-Dec-14 16:09pm

and yes i can see that this is a very complex question that i asked

Sergey Alexandrovich Kryukov 16-Dec-14 16:23pm

Complex? Are you kidding? This is one of the very basic "problems"...
—SA

MasterCodeon 16-Dec-14 16:30pm

oh yikes, its complicated to me at least i would hate to see what a complicated problem would look like

Philippe Mori 16-Dec-14 21:07pm

Effectively, in real life application problems are more complex then than. For example, if controls are added or remove dynamically, then you might need to unhook event handlers that are not used anymore.
On the other hand, you might be able to simplify the problem if you put buttons in a panel as you can then hide the whole panel at once.

Maciej Los 16-Dec-14 16:37pm

5ed!

Sergey Alexandrovich Kryukov 17-Dec-14 0:10am

Thank you, Maciej.
—SA

MasterCodeon 16-Dec-14 16:52pm

i have updated/modified my question take a look

Sergey Alexandrovich Kryukov 17-Dec-14 0:14am

Quite apparently, the cast works only if the types are assignment compatible: the runtime type should be of the type you cast to or derived. Dynamic cast solves this problem (you should understand that this would be certain violation of OOP). Solution 3 gives you the idea how to discriminate control by some type.
—SA

BillWoodruff · Accepted Answer · 2014-12-16T16:26:00

If you use the stack-based recursive technique I demonstrate here [^], you can easily get all the Buttons

C#

foreach(Control theControl in (SpecialMethods.GetAllControls(this)).OfType<Button>().ToList())
{
    // do something with/to/using each Button
}

There's another QA answer I posted yesterday (Dec. 16, 2014), demonstrating using stack based recursion: [^].

It's important to know when you do, or do not, want recursion ! If all your Buttons you want to add EventHandlers to are in the ControlCollection of one container (Form, Panel, etc.), then you do not want recursion: you can build your List<Button> by simply:

C#

List<Button> ButtonList = ButtonContainer.Controls.OfType<Button>().ToList();

MasterCodeon · Accepted Answer · 2014-12-16T13:52:00

I solved my updated problem my self!
here is the code i sued to solve the UPDATED problem NOT the first problem:

first i declare a public List like this:

C#

public List<string> ButtonList = new List<string>();
</string></string>

next i add all the buttons i want to manipulate:

C#

ButtonList.Add(V.Name);
ButtonList.Add(W.Name);
ButtonList.Add(X.Name);
ButtonList.Add(Y.Name);
ButtonList.Add(Z.Name);
ButtonList.Add(Sqig.Name);
ButtonList.Add(Btn1.Name);
ButtonList.Add(Btn2.Name);
ButtonList.Add(Btn3.Name);
//ect.. ect..

and now when i want to make the buttons disappear or reappear i just illiterate through the list like this:

C#

foreach (string ctrl in ButtonList)
{
    this.Controls[ctrl].Visible = false;
}

--UPDATE--
this update is thanks to BillWoodruff and his solution.
so instead of adding all the controls manualy i just get all the controls of the type "Button and add those to the list like this:

C#

ButtonList = this.Controls.OfType<Button>().ToList();

i had to change the ButtonList declaration line from:

C#

public List<string> ButtonList = new List<string>();

to:

C#

public List<Button> ButtonList = new List<Button>();

i just changed the List type from string to Button
but i didn't want 5 of the function buttons i just wanted the Onscreen keyboard buttons to be added to the list so i just removed them like this:

C#

ButtonList.Remove(LockThisComputer);
//ect.. ect..

and then when i want to change something with the buttons i just illiterate through the list like this:

C#

foreach (Button ctrl in ButtonList)
{
    //Do whatever you want to the current button by using the variable "ctrl" and           whatever the operation you wanted to do with the button
    //here is an example:
    ctrl.Visible = Boolean.Parse(OskEnabled);
    //OskEnabled is a global string variable that i load and set at runtime but here it is Parsed by the Boolean.Parse method.

}

in conclusion both of the solutions work its just that the updated one is sooo much easier.
thank you all very much for helping me with my coding problems,
MasterCodeon

C# How To Subscribe To An Event For Each Control In A Form?

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C# How To Subscribe To An Event For Each Control In A Form?

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