Is it possible to duplicate a GDI handle?

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+1 Q:

Is it possible to duplicate a GDI handle?

Or in my particular case a windows region (HRGN)?

Updated: The problems is the following:

I've a collection of objects, each of these objects can hold a HRGN. These region once acquired is released when the object is destroyed. Since some of those objects are stored in a std::vector I've to define an assignement operator.

Until now I've just assigned those HRGN, but that is a bug. If I duplicate such objects each one of those will try to delete the same region, and one of those wil be using a non existent region.

+3 A:

No, it is not possible. GDI objects support only a single handle per object.

Fyodor Soikin 2010-05-06 21:16:48

I hoped I was missing some api call, seem that the correction solution is to keep a reference counting myself. Thank you.

Ismael 2010-05-07 14:31:39

+3 A:

You cannot make a duplicate of HRGN handle, but you could get a copy using CombineRgn function.

Kirill V. Lyadvinsky 2010-05-06 21:24:11

I though of that using RGN_COPY, but I didn't know how to create an empty region.

Ismael 2010-05-07 14:18:13

Bad idea, GDI heap is very limited at least on older OSes.

Anton Tykhyy 2010-05-07 14:32:17

Yes, you are right, I didn't consider that.

Ismael 2010-05-07 15:22:38

It is limited ( [more about it](http://blogs.technet.com/markrussinovich/archive/2010/03/31/3322423.aspx) ) but the one region requires a very small amount of that memory.

Kirill V. Lyadvinsky 2010-05-08 07:43:18

+1 A:

Wrap each HRGN in a reference-counting object modeled after any smart pointer e.g. shared_ptr.

Anton Tykhyy 2010-05-07 14:31:38

ansaurus

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Is it possible to duplicate a GDI handle?

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