windib target can now control screensaver with SDL_VIDEO_ALLOW_SCREENSAVER.

  Fixes Bugzilla #415.

--HG--
branch : SDL-1.2
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/branches/SDL-1.2%402381

src/video/windib/SDL_dibevents.c

@@ -225,9 +225,14 @@ LRESULT DIB_HandleMessage(_THIS, HWND hwnd, UINT msg, WPARAM wParam, LPARAM lPar
 
 #if defined(SC_SCREENSAVE) && defined(SC_MONITORPOWER)
 		case WM_SYSCOMMAND: {
-			if ((wParam&0xFFF0)==SC_SCREENSAVE ||
-				(wParam&0xFFF0)==SC_MONITORPOWER)
+			const DWORD val = (DWORD) (wParam & 0xFFF0);
+			if ((val == SC_SCREENSAVE) || (val == SC_MONITORPOWER)) {
+				if (!this->hidden->allow_screensaver) {
+					/* Note that this doesn't stop anything on Vista
+					   if the screensaver has a password. */
 					return(0);
+				}
+			}
 		}
 		/* Fall through to default processing */
 #endif /* SC_SCREENSAVE && SC_MONITORPOWER */

src/video/windib/SDL_dibvideo.c

@@ -282,6 +282,7 @@ static HPALETTE DIB_CreatePalette(int bpp)
 
 int DIB_VideoInit(_THIS, SDL_PixelFormat *vformat)
 {
+	const char *env = NULL;
 #ifndef NO_CHANGEDISPLAYSETTINGS
 	int i;
 	DEVMODE settings;
@@ -380,6 +381,10 @@ int DIB_VideoInit(_THIS, SDL_PixelFormat *vformat)
 	this->hidden->origRotation = -1;
 #endif
 
+	/* Allow environment override of screensaver disable. */
+	env = SDL_getenv("SDL_VIDEO_ALLOW_SCREENSAVER");
+	this->hidden->allow_screensaver = ( (env && SDL_atoi(env)) ? 1 : 0 );
+
 	/* We're done! */
 	return(0);
 }

src/video/windib/SDL_dibvideo.h

@@ -41,6 +41,8 @@ struct SDL_PrivateVideoData {
     HBITMAP screen_bmp;
     HPALETTE screen_pal;
 
+    int allow_screensaver;
+
 #define NUM_MODELISTS	4		/* 8, 16, 24, and 32 bits-per-pixel */
     int SDL_nummodes[NUM_MODELISTS];
     SDL_Rect **SDL_modelist[NUM_MODELISTS];