How to catch Esc key from all forms in project ?

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Hallo,

I wonder how I can partial Form and add class that handle in specific event.
For example, on Esc Key the form will close, but for all kind of forms in my project.
So, I thought to add partial class on Form and capture the keys event and if is ESC do Close action on current form.

Any idea ?
I know that i can create a new Form of mine and inherit, but I look for somthing more elegant.

Thanks

Posted 24-Jan-15 21:41pm

Matrix2324

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Sergey Alexandrovich Kryukov 25-Jan-15 4:01am

Which Form? Is it System.Windows.Forms.Form?
Do you run it as a modal form?
—SA

Matrix2324 25-Jan-15 4:20am

There is a main form(System.Windows.Forms.Form) that from him calld to sub forms.
I wont that when the key Esc happen the current sub form closed.
But I wont to write the code only in the main form.
I tried to use Wm_Message but unsuccessfully.

Sergey Alexandrovich Kryukov 25-Jan-15 5:21am

Of course. Now, modal or not? What is "sub-form"? Are you using MDI (better don't)?
If you implement something you need in one form, put it to base form class and inherit it.
—SA

Matrix2324 25-Jan-15 7:04am

this model, I mean there is main model and from him open a new model form.
I want to mange from the main model on specific event thats happen in another model, like "Esc" key or catch and handle when the enable button change.

Sergey Alexandrovich Kryukov 25-Jan-15 12:13pm

Model or modal?!
—SA

Matrix2324 27-Jan-15 0:30am

modal... :)

Sergey Alexandrovich Kryukov 27-Jan-15 1:05am

All right, I answered the question already. Are you getting it?
—SA

Matrix2324 28-Jan-15 2:48am

I see your answer and already know this(see in my question), but I like to know if there is another way.
Like to use partial class to System.Windows.Forms and there capture the event ? - i can catch the windows messages with user32.dll, but i search for something else.

Sergey Alexandrovich Kryukov 28-Jan-15 11:28am

Why another way? Well, of course, use the partial class, but it's nothing but syntax, it only to organize your code files better, not related to any functionality.

Don't use user32.dll (P/Invoke). Don't you see that everything is available in .NET FCL?

That tells me that your "already know this" is far from truth :-(
I explained you what to do, just learn it properly. Your follow-up questions will be welcome.

—SA

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InbarBarkai · Answer 1 · 2015-01-24T21:57:00

Solution 2

I can think of 2 ways.

Bind every form to a common event handler.
Catch the key down event with an external event using windows api such as SetWindowsHookEx.
This will catch every key down in the application.
To my experience, this method is buggy and unreliable.

Posted 24-Jan-15 21:57pm

InbarBarkai

Comments

Matrix2324 25-Jan-15 4:21am

I think use Wm_Message but unsuccessfully.

Sergey Alexandrovich Kryukov 25-Jan-15 5:34am

Don't take this advice seriously. :-)
—SA

Sergey Alexandrovich Kryukov · Answer 2 · 2015-01-24T23:31:00

If the form is modal, it's much better to have "Cancel" and/or "OK" ("Apply", "Accept", "Done") buttons used to finish modal state. Then you can handle Cancel (and/or Enter) by setting the properties CancelButton and/or AcceptButton of these buttons:
https://msdn.microsoft.com/en-us/library/system.windows.forms.form.cancelbutton(v=vs.110).aspx[^],
https://msdn.microsoft.com/en-us/library/system.windows.forms.form.acceptbutton(v=vs.110).aspx[^].

If the form is not modal, closing it by Escape would be a really, really bad idea. But of course you should be able to handle form keyboard event. The trick here is: the focus is usually taken by some other control on the form, so you should do something about it. This is done by setting the form property KeyPreview. Then you can handle the form event PreviewKeyDown or override the method OnPreviewKeyDown:
https://msdn.microsoft.com/en-us/library/system.windows.forms.form.keypreview(v=vs.110).aspx[^],
https://msdn.microsoft.com/en-us/library/system.windows.forms.control.previewkeydown(v=vs.110).aspx[^],
https://msdn.microsoft.com/en-us/library/system.windows.forms.control.onpreviewkeydown(v=vs.110).aspx[^].

You mentioned that you don't want to do something for all forms. Of course. You should not repeat any code in different form classes; instead, always inherit some base form class with common functionality.

—SA