Direct Draw weird stuff

I'm working on a Direct Draw program. I'm having a weird problem though. Whenever I alt-tab out of it and then return everything goes black. It's still working, but the graphics disappear.
Is this caused by so called "lost surfaces"? How do I restore them?

I have no idea what you are talking about with diectdraw, because i am new to C++ or maybe some completely different reason, but i have been programming java for a long time, and it has been a problem that when a window is covered, certain things on it will not come back. THere is a handle in java called Iconized() and DeIconized() that deal with a minimize and unminimize, and another one, unfocused or something to that extent, i havent used these often so i don't know the details, but conventially they are used to call repaint() on certain objects. May this be in order? i have no idea hw to do this in C++ though. I may also be way off the mark too. If i am, just ignore me.

~Inquirer

P.S. What is DirectDraw?

Magos, what you need to do is:

1 - declare a global bool variable to represent a paused state.
2 - Check for a WM_ACTIVATEAPP message, if the wParam = 0
then your app is being deactivated, set paused to true. If the
wParam is non-zero then your app is being activated, set paused
to false, restore all surfaces (don't forget to re-blit your *.bmps
back into your surfs after restoring them).
3 - In your main loop if paused == true then don't do any blitting.

Quote:

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Originally posted by Inquirer
P.S. What is DirectDraw?

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Inquirer,
Microsoft's DirectX 2d graphic library.

*****

Losing your surfaces in DirectDraw can't be fixed like that. The
LPDIRECTDRAW7 object has a function to restore surfaces.

HRESULT IDirectDraw7::RestoreAllSurfaces();

This won't reload your graphics into the surfs (as I mentioned
above, so you have to reblit your *.bmp's onto the surfs after a
call to it).

Not the same as getting a WM_PAINT message.

Thanks

Quote:

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Originally posted by jdinger
Magos, what you need to do is:

1 - declare a global bool variable to represent a paused state.
2 - Check for a WM_ACTIVATEAPP message, if the wParam = 0
then your app is being deactivated, set paused to true. If the
wParam is non-zero then your app is being activated, set paused
to false, restore all surfaces (don't forget to re-blit your *.bmps
back into your surfs after restoring them).
3 - In your main loop if paused == true then don't do any blitting.

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How do I restore them? In a D3D tutorial I read you used something like this:

if(Surface->IsLost()==DDR_SURFACELOST) Surface->Restore();

However, that constant is undeclared in DirectDraw...

[EDIT]
Oh, never mind. I didn't read your last post... :).
[/EDIT]

YES! It works now, when I do:

if(Surface->IsLost()) Surface->Restore();

No need for that constant :)