How to tell if wxArtProvider::GetIcon() was successful?

[gbuergisser]

This may be a dumb question... My application is calling wxArtProvider::GetIcon() and adds the returned wxIcon to an imag list with wxImageList::Add(). The documentation of GetIcon() says it returns a wxNullIcon upon failure.
Now how can I tell if GetIcon() really found the icon I wanted? How can I check the returned value against wxNullIcon or check if it is a valid (not empty) icon? IsOk() also returns true for a wxNullIcon...

[doublemax]

You could try this:

Code: Select all

if( your_icon.IsSameAs( wxNullIcon ) ) 

I haven't tested it though.

[gbuergisser]

Thanks for the hint but unfortunately it doesn't work.

[doublemax]

With platform and wx version?

I just tested it and wxNullIcon::Ok() returns false. Also its width and height are 0.

[gbuergisser]

Hmm, I think it needs some clarification: I originally tried IsOK() and not Ok(). But I now have tried both. And for a wxNullIcon they really return false. So far so good. But the real problem seems to be that wxArtProvider::GetIcon() doesn not return a wxNullIcon if it is called with a name it cannot find.

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wxIcon icon = wxArtPrivoder::GetIcon("foobar", wxART_MENU);
if (!icon.IsOk()) {
   /* This block is never being executed */
}

Platform Fedora 17, 3.5.4-2.fc17.x86_64 / wxWidgets 2.9.3

[doublemax]

Code: Select all

wxIcon icon = wxArtProvider::GetIcon("foobar", wxART_MENU);
wxLogMessage(wxT("icon: ok=%d width=%d height=%d"), icon.Ok(), icon.GetWidth(), icon.GetHeight() );
if (!icon.IsOk()) {
  wxLogMessage("icon not found");
}

This works fine for me under MSW (2.9.4). Maybe it's a platform specific problem.
What kind of icon does it return? Maybe the implementation is different and returns some kind of default icon in any case.

[gbuergisser]

I copied/pasted your snippet into my application and it reports "ok=1 width=16 height=16". But then no icon is visible in the list ctrl that uses it. May be a platform dependent behaviour...