I have tested ToggleFullScreen under Windows and indeed it does not
work. For me that’s a real pity because one of the reason I switched to
SDL instead of my own code was to implement fullscreen under linux.
(Mine was awful). If I gain fs under linux but lose it under win, I
don’t progress much 
I have some mostly-working code for toggling fullscreen/windowed in a
platform independent way with SDL. If anyone wants to
try/test/debug/comment upon, it’s at the bottom of this email.
SDL_WM_ToggleFullScreen() makes no promises to work, because the basic
assumption behind it is that your surface->pixels pointer won’t change.
Under X11, this assumption is valid, since the window itself isn’t
recreated; it’s just moved to the upper left corner, and the screen’s
resolution is changed to match the size of the window (that’s an
oversimplification, but that’s the gist of it).
Under Win32, you need to destroy the window, and recreate it with the
correct attributes, which means that the framebuffer might be/probably
will be somewhere else.
I am really talking about switching back and forth to fullscreen mode,
not initially creating a fullscreen window, which works well.
I wonder why this isn’t implemented. Is there a technical reason for
that, or just lack of time ? I would gladly contribute on this very
precise point if needed.
See above. If you can make SDL_WM_ToggleFullScreen() fit those assumptions
under Win32, go for it. Otherwise, look at this:
–ryan.
------------snip.-------------------
/*
- (This code may be considered public domain, and under no licensing
- restrictions. --rcg.)
*/
#define sdldebug printf
/**
- Attempt to flip the video surface to fullscreen or windowed mode.
- Attempts to maintain the surface’s state, but makes no guarantee
- that pointers (i.e., the surface’s pixels field) will be the same
- after this call.*
- Caveats: Your surface pointers will be changing; if you have any other
-
copies laying about, they are invalidated.
-
-
Do NOT call this from an SDL event filter on Windows. You can
-
call it based on the return values from SDL_PollEvent, etc, just
-
not during the function you passed to SDL_SetEventFilter().
-
-
Thread safe? Likely not.
-
-
This has been tested briefly under Linux/X11 and Win/DirectX. YMMV.
-
-
Palette setting is possibly/probably broken. Please fix.
-
-
@param surface pointer to surface ptr to toggle. May be different
-
pointer on return. MAY BE NULL ON RETURN IF FAILURE!
-
@param flags pointer to flags to set on surface. The value pointed
-
to will be XOR'd with SDL_FULLSCREEN before use. Actual
-
flags set will be filled into pointer. Contents are
-
undefined on failure. Can be NULL, in which case the
-
surface's current flags are used.
-
@return non-zero on success, zero on failure.
*/
static int attempt_fullscreen_toggle(SDL_Surface **surface, Uint32 *flags)
{
long framesize = 0;
void *pixels = NULL;
SDL_Rect clip;
Uint32 tmpflags = 0;
int w = 0;
int h = 0;
int bpp = 0;
int grabmouse = (SDL_WM_GrabInput(SDL_GRAB_QUERY) == SDL_GRAB_ON);
int showmouse = SDL_ShowCursor(-1);
#ifdef BROKEN
SDL_Color *palette = NULL;
int ncolors = 0;
#endif
sdldebug("attempting to toggle fullscreen flag...");
if ( (!surface) || (!(*surface)) ) /* don't try if there's no surface. */
{
sdldebug("Null surface (?!). Not toggling fullscreen flag.");
return(0);
} /* if */
if (SDL_WM_ToggleFullScreen(*surface))
{
sdldebug("SDL_WM_ToggleFullScreen() seems to work on this system.");
if (flags)
*flags ^= SDL_FULLSCREEN;
return(1);
} /* if */
if ( !(SDL_GetVideoInfo()->wm_available) )
{
sdldebug("No window manager. Not toggling fullscreen flag.");
return(0);
} /* if */
sdldebug("toggling fullscreen flag The Hard Way...");
tmpflags = (*surface)->flags;
w = (*surface)->w;
h = (*surface)->h;
bpp = (*surface)->format->BitsPerPixel;
if (flags == NULL) /* use the surface's flags. */
flags = &tmpflags;
SDL_GetClipRect(*surface, &clip);
/* save the contents of the screen. */
if ( (!(tmpflags & SDL_OPENGL)) && (!(tmpflags & SDL_OPENGLBLIT)) )
{
framesize = (w * h) * ((*surface)->format->BytesPerPixel);
pixels = malloc(framesize);
if (pixels == NULL)
return(0);
memcpy(pixels, (*surface)->pixels, framesize);
} /* if */
#ifdef BROKEN
if ((*surface)->format->palette != NULL)
{
ncolors = (surface)->format->palette->ncolors;
palette = malloc(ncolors * sizeof (SDL_Color));
if (palette == NULL)
{
free(pixels);
return(0);
} / if */
memcpy(palette, (surface)->format->palette->colors,
ncolors * sizeof (SDL_Color));
} / if */
#endif
if (grabmouse)
SDL_WM_GrabInput(SDL_GRAB_OFF);
SDL_ShowCursor(1);
*surface = SDL_SetVideoMode(w, h, bpp, (*flags) ^ SDL_FULLSCREEN);
if (*surface != NULL)
*flags ^= SDL_FULLSCREEN;
else /* yikes! Try to put it back as it was... */
{
*surface = SDL_SetVideoMode(w, h, bpp, tmpflags);
if (*surface == NULL) /* completely screwed. */
{
if (pixels != NULL)
free(pixels);
if (palette != NULL)
free(palette);
return(0);
} /* if */
} /* if */
/* Unfortunately, you lose your OpenGL image until the next frame... */
if (pixels != NULL)
{
memcpy((*surface)->pixels, pixels, framesize);
free(pixels);
} /* if */
#ifdef BROKEN
if (palette != NULL)
{
/* !!! FIXME : No idea if that flags param is right. */
SDL_SetPalette(surface, SDL_LOGPAL, palette, 0, ncolors);
free(palette);
} / if */
#endif
SDL_SetClipRect(*surface, &clip);
if (grabmouse)
SDL_WM_GrabInput(SDL_GRAB_ON);
SDL_ShowCursor(showmouse);
return(1);
} /* attempt_fullscreen_toggle */