How to check if a window is valid? Topic is solved

[Frank]

Hi,

I have a function that gets a wxWindow*. I need to test if the pointee is sill a valid window. Because it can happen that the window is closed by the user between saving the window pointer and calling AddPendingEvent() for this window.

Or in Short: I need a wx equavilent for the WinAPI IsWindow()

Or, as alternative: Is there a way to install some sort of global "Hook" with wich I can automatically add EventHandlers for Creation/Destruction for every created Window, so I can manage a global std::set<> of valid windows to check against.

[JimFairway]

Hi,

I suspect you have to catch the close event for the window (EVT_CLOSE) and notify the object that recorded the pointer to the window that it's being destroyed. Otherwise, the pointer will most likely point to random data.

See http://docs.wxwidgets.org/2.6/wx_window ... rview.html for the sequence regarding which deletion.

Hope that helps,


Jim

[doublemax]

Another option could be to store the window id instead of the pointer and then use wxWindow::FindWindowById()

http://docs.wxwidgets.org/stable/wx_wxw ... windowbyid

[Frank]

Unluckily, most of my windows are created with wxID_ANY, so I can't use the ID.

And since half of the pointee's are wxPanels in a notebook (sort of), I can't use the name either.

The other half are TopLevel windows, but sadly there is no wxWindow wich holds HWND_DESKTOP, so I also can't use wxWindow::GetChilds() to check against those.

But wait: If wx can find a window by it's ID, that means it must have a list of all windows somewhere. Maybee I can just patch in a function to check against this list.

[JimFairway]

Hi

Unluckily, most of my windows are created with wxID_ANY, so I can't use the ID.

If you go with doublemax's idea (which looks fairly straightforward), it doesn't matter if you use wxID_ANY, just call GetId() after you create the window and store that.

Jim

[doublemax]

But wait: If wx can find a window by it's ID, that means it must have a list of all windows somewhere. Maybee I can just patch in a function to check against this list.

wx keeps a list of toplevel windows, from there it searches recursively.

Check wxFindWindowHelper() in /src/common/wincmn.cpp

[computerquip]

Can't you make a reference and then check the reference to see whether or not the data still exists?

EDIT: Might be valid but not very convenient >.>

[Frank]

Thanks, I take a closer look into these. The ID-Thingy seems to be the esiest way to do this. I look into it tommorow.

[Frank]

I've written my own dialog class, from wich I derive the Non-Modal Dialogs.

This class connects a wxEVT_DESTROY to the to-be-notified window, so it can set the pointer to 0, when it gets destroyed.

Also, I just can make a member PostData (const boost::any&), without any need for the derived class to check if the window still exists or not.