Date: Sun, 6 Mar 2005 17:06:20 +0100

From: Per Inge Mathisen
Subject: [SDL] Fullscreen refresh on win32

Windows has a terrible default for fullscreen 3D apps of 60mhz refresh
rate. This can be fixed  by the user by going into his driver's
control panel and forcing the refresh rate higher. However, this not a
very user friendly way about it, and in any case SDL contains no code
that could figure out this that condition has afflicted the user.

So the question is, could SDL fix this for the user? It is possible
under Windows to request a higher refresh rate. The danger is of
course that if the user has an old monitor, and you request a too high
refresh rate, the monitor could be damaged. However, I believe there
might be a way around that: Check before switching what refresh rate
the user's desktop runs in, and if our fullscreen dimensions are equal
or less than those of the desktop, use the higher refresh rate of 60
and the desktop rate.

Since most users run their desktops in the same or higher resolution
something sane, this should fix this problem for most users.

Thoughts?

An alternative is to add an SDL_GL_GetAttribute(SDL_GL_REFRESH_RATE)
option so that programs can bitch at their users at their own
convenience.

  - Per

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%401298

src/video/wincommon/SDL_lowvideo.h

@@ -96,6 +96,7 @@ extern int mouse_relative;
 
 /* The GDI fullscreen mode currently active */
 #ifndef NO_CHANGEDISPLAYSETTINGS
+extern DEVMODE SDL_desktop_mode;
 extern DEVMODE SDL_fullscreen_mode;
 #endif
 

src/video/wincommon/SDL_sysevents.c

@@ -68,6 +68,7 @@ int SDL_resizing = 0;
 int mouse_relative = 0;
 int posted = 0;
 #ifndef NO_CHANGEDISPLAYSETTINGS
+DEVMODE SDL_desktop_mode;
 DEVMODE SDL_fullscreen_mode;
 #endif
 WORD *gamma_saved = NULL;

src/video/windib/SDL_dibvideo.c

@@ -335,6 +335,9 @@ int DIB_VideoInit(_THIS, SDL_PixelFormat *vformat)
 	DIB_CheckGamma(this);
 
 #ifndef NO_CHANGEDISPLAYSETTINGS
+	/* Query for the desktop resolution */
+	EnumDisplaySettings(NULL, ENUM_CURRENT_SETTINGS, &SDL_desktop_mode);
+
 	/* Query for the list of available video modes */
 	for ( i=0; EnumDisplaySettings(NULL, i, &settings); ++i ) {
 		DIB_AddMode(this, settings.dmBitsPerPel,
@@ -533,6 +536,7 @@ SDL_Surface *DIB_SetVideoMode(_THIS, SDL_Surface *current,
 	/* Set fullscreen mode if appropriate */
 	if ( (flags & SDL_FULLSCREEN) == SDL_FULLSCREEN ) {
 		DEVMODE settings;
+		BOOL changed;
 
 		memset(&settings, 0, sizeof(DEVMODE));
 		settings.dmSize = sizeof(DEVMODE);
@@ -540,7 +544,16 @@ SDL_Surface *DIB_SetVideoMode(_THIS, SDL_Surface *current,
 		settings.dmPelsWidth = width;
 		settings.dmPelsHeight = height;
 		settings.dmFields = DM_PELSWIDTH | DM_PELSHEIGHT | DM_BITSPERPEL;
-		if ( ChangeDisplaySettings(&settings, CDS_FULLSCREEN) == DISP_CHANGE_SUCCESSFUL ) {
+		if ( width <= SDL_desktop_mode.dmPelsWidth && height <= SDL_desktop_mode.dmPelsHeight ) {
+			settings.dmDisplayFrequency = SDL_desktop_mode.dmDisplayFrequency;
+			settings.dmFields |= DM_DISPLAYFREQUENCY;
+		}
+		changed = (ChangeDisplaySettings(&settings, CDS_FULLSCREEN) == DISP_CHANGE_SUCCESSFUL);
+		if ( ! changed && (settings.dmFields & DM_DISPLAYFREQUENCY) ) {
+			settings.dmFields &= ~DM_DISPLAYFREQUENCY;
+			changed = (ChangeDisplaySettings(&settings, CDS_FULLSCREEN) == DISP_CHANGE_SUCCESSFUL);
+		}
+		if ( changed ) {
 			video->flags |= SDL_FULLSCREEN;
 			SDL_fullscreen_mode = settings;
 		}

src/video/windx5/SDL_dx5video.c

@@ -656,6 +656,14 @@ static HRESULT WINAPI EnumModes2(DDSURFACEDESC *desc, VOID *udata)
 	int bpp = desc->ddpfPixelFormat.dwRGBBitCount;
 	int refreshRate = desc->dwRefreshRate;
 #endif
+	int maxRefreshRate;
+
+	if ( desc->dwWidth <= SDL_desktop_mode.dmPelsWidth &&
+	     desc->dwHeight <= SDL_desktop_mode.dmPelsHeight ) {
+		maxRefreshRate = SDL_desktop_mode.dmDisplayFrequency;
+	} else {
+		maxRefreshRate = 85;	/* safe value? */
+	}
 
 	switch (bpp)  {
 		case 8:
@@ -667,7 +675,7 @@ static HRESULT WINAPI EnumModes2(DDSURFACEDESC *desc, VOID *udata)
 			     enumlists[bpp]->r.w == (Uint16)desc->dwWidth &&
 			     enumlists[bpp]->r.h == (Uint16)desc->dwHeight ) {
 				if ( refreshRate > enumlists[bpp]->refreshRate &&
-				     refreshRate <= 85 /* safe value? */ ) {
+				     refreshRate <= maxRefreshRate ) {
 					enumlists[bpp]->refreshRate = refreshRate;
 #ifdef DDRAW_DEBUG
  fprintf(stderr, "New refresh rate for %d bpp: %dx%d at %d Hz\n", (bpp+1)*8, (int)desc->dwWidth, (int)desc->dwHeight, refreshRate);
@@ -926,6 +934,11 @@ int DX5_VideoInit(_THIS, SDL_PixelFormat *vformat)
 					GetDeviceCaps(hdc,BITSPIXEL);
 	ReleaseDC(SDL_Window, hdc);
 
+#ifndef NO_CHANGEDISPLAYSETTINGS
+	/* Query for the desktop resolution */
+	EnumDisplaySettings(NULL, ENUM_CURRENT_SETTINGS, &SDL_desktop_mode);
+#endif
+
 	/* Enumerate the available fullscreen modes */
 	for ( i=0; i<NUM_MODELISTS; ++i )
 		enumlists[i] = NULL;
@@ -1093,6 +1106,7 @@ SDL_Surface *DX5_SetVideoMode(_THIS, SDL_Surface *current,
 		 */
 		if ( (flags & SDL_FULLSCREEN) == SDL_FULLSCREEN ) {
 			DEVMODE settings;
+			BOOL changed;
 
 			memset(&settings, 0, sizeof(DEVMODE));
 			settings.dmSize = sizeof(DEVMODE);
@@ -1100,7 +1114,16 @@ SDL_Surface *DX5_SetVideoMode(_THIS, SDL_Surface *current,
 			settings.dmPelsWidth = width;
 			settings.dmPelsHeight = height;
 			settings.dmFields = DM_PELSWIDTH | DM_PELSHEIGHT | DM_BITSPERPEL;
-			if ( ChangeDisplaySettings(&settings, CDS_FULLSCREEN) == DISP_CHANGE_SUCCESSFUL ) {
+			if ( width <= SDL_desktop_mode.dmPelsWidth && height <= SDL_desktop_mode.dmPelsHeight ) {
+				settings.dmDisplayFrequency = SDL_desktop_mode.dmDisplayFrequency;
+				settings.dmFields |= DM_DISPLAYFREQUENCY;
+			}
+			changed = (ChangeDisplaySettings(&settings, CDS_FULLSCREEN) == DISP_CHANGE_SUCCESSFUL);
+			if ( ! changed && (settings.dmFields & DM_DISPLAYFREQUENCY) ) {
+				settings.dmFields &= ~DM_DISPLAYFREQUENCY;
+				changed = (ChangeDisplaySettings(&settings, CDS_FULLSCREEN) == DISP_CHANGE_SUCCESSFUL);
+			}
+			if ( changed ) {
 				video->flags |= SDL_FULLSCREEN;
 				SDL_fullscreen_mode = settings;
 			}