Lost surfaces

SDL Development
1

Hello all,

 I was trying to deal with those "lost surfaces" that I get after

switching to another application. Here is what I would like to
know:

   - what surfaces can be lost?
   - where must I check that?
   - how should I resore them? Just reload?

 My OS: WinXP Pro
 My compiler: MS VS 2003--

Thanks for attention,
Flashback

2

My understanding is that hardware surfaces get lost under windows when
you switch applications (from a full screen SDL hardware surface
enabled app)…

I’m afraid I never quite resolved how to reload surfaces correctly
myself. I believe the SDL core guys (Sam, etc) may well add a single
event we can check under Windows in the future, although I’m not sure
at all …On Fri, 17 Dec 2004 17:18:03 +0200, Flashback wrote:

Hello all,

 I was trying to deal with those "lost surfaces" that I get after

switching to another application. Here is what I would like to
know:

   - what surfaces can be lost?
   - where must I check that?
   - how should I resore them? Just reload?

 My OS: WinXP Pro
 My compiler: MS VS 2003

–
Thanks for attention,
Flashback

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–
Rob Sadedin
No Substance Software (www.nosubstancesoftware.com)

3

Flashback wrote:

Hello all,

I was trying to deal with those "lost surfaces" that I get after

switching to another application. Here is what I would like to
know:

  - what surfaces can be lost?

Surfaces that are in video memory, this only happens under windows.

  - where must I check that?

You must check the return value of SDL_BlitSurface. If it returns -2,
the surface is lost.

  - how should I resore them? Just reload?

Yes.

My OS: WinXP Pro
My compiler: MS VS 2003

For more information, see the SDL_BlitSurface man page :
http://www.libsdl.org/cgi/docwiki.cgi/SDL_5fBlitSurface

Stephane

4

Hello All,

  - where must I check that?

You must check the return value of SDL_BlitSurface. If it returns -2,
the surface is lost.
So, I must check that only for surfaces that were created using
SDL_CreateRGBSurface(SDL_HWSURFACE, …)? What about those which
passed through SDL_DisplayFormat[Alpha] ?

For more information, see the SDL_BlitSurface man page :
http://www.libsdl.org/cgi/docwiki.cgi/SDL_5fBlitSurface
I think this is described in Doc project too, I use it offline.
Though that description confused me a bit. They say there that I
must lock surface, then write stuff to image->pixels… The result
is equal to reloading, I suppose. (?)–
Best regards,
Flashback

5

Flashback wrote:

Hello All,

 - where must I check that?

You must check the return value of SDL_BlitSurface. If it returns -2,
the surface is lost.

 So, I must check that only for surfaces that were created using

SDL_CreateRGBSurface(SDL_HWSURFACE, …)? What about those which
passed through SDL_DisplayFormat[Alpha] ?

Keep in mind that SDL_CreateRGBSurface(SDL_HWSURFACE…) doesn’t always
give a hw surface.
You can’t tell what SDL_DisplayFormat returns either.

Just testing the return value from SDL_BlitSurface after each call is ok.

For more information, see the SDL_BlitSurface man page :
http://www.libsdl.org/cgi/docwiki.cgi/SDL_5fBlitSurface

 I think this is described in Doc project too, I use it offline.

Though that description confused me a bit. They say there that I
must lock surface, then write stuff to image->pixels… The result
is equal to reloading, I suppose. (?)

Well, you have to fill in the ->pixels member of the surface.
Or delete/recreate the surface

Stephane

6

Hello Stephane Marchesin,

Keep in mind that SDL_CreateRGBSurface(SDL_HWSURFACE…) doesn’t always
give a hw surface.
You can’t tell what SDL_DisplayFormat returns either.

Just testing the return value from SDL_BlitSurface after each call is ok.
Sure, thanks. Testing the return value is a lot of code,
though. Especially in rather big projects as mine.

Well, you have to fill in the ->pixels member of the surface.
Or delete/recreate the surface
OK, thanks. You have cleared several things to me.–
Best regards,
Flashback