Port fullscreen handling to SDL 3.

SDL 3 has a new approach to fullscreen handling, which is way better
than the old fiddling with several window flags. In SDL 3:

* The SDL_FULLSCREEN_FLAG puts the window in fullscreen window mode.
* For exclusive fullscreen a fullscreen mode must be requested and set.
* Applying the mode to the window is asynchronous, the mode change may
  occure at any later time. The window can be synchronized to force the
  mode change.

This is - of course - totaly untested, since the client doesn't build
yet with SDL 3. There will likely be bugs and shortcomings.

And the code is still ugly, it can be refactored somewhat more.

src/client/vid/glimp_sdl3.c

@@ -27,6 +27,13 @@
  * =======================================================================
  */
 
+/* TODO SDL3:
+ *  * Bump copyright.
+ *  * Do we need to request High DPI modes when vid_highdpiaware > 0?
+ *  * `fullscreen` should be an enum to make the code more readable.
+ *  * Debug fullscreen handling, maybe refactor it further.
+ */
+
 #include "../../common/header/common.h"
 #include "header/ref.h"
 
@@ -87,7 +94,7 @@ ClearDisplayIndices(void)
 }
 
 static qboolean
-CreateSDLWindow(int flags, int w, int h)
+CreateSDLWindow(int flags, int fullscreen, int w, int h)
 {
 	if (SDL_WINDOWPOS_ISUNDEFINED(last_position_x) || SDL_WINDOWPOS_ISUNDEFINED(last_position_y) || last_position_x < 0 ||last_position_y < 24)
 	{
@@ -111,66 +118,83 @@ CreateSDLWindow(int flags, int w, int h)
 	SDL_SetNumberProperty(props, SDL_PROP_WINDOW_CREATE_HEIGHT_NUMBER, h);
 	SDL_SetNumberProperty(props, "flags", flags);
 
-	window = SDL_CreateWindowWithProperties (props);
+	window = SDL_CreateWindowWithProperties(props);
 	SDL_DestroyProperties(props);
 
 	if (window)
 	{
-
 		/* save current display as default */
 		last_display = SDL_GetDisplayForWindow(window);
 		SDL_GetWindowPosition(window, &last_position_x, &last_position_y);
 
-		SDL_DisplayMode real_mode;
+		/* Set requested fullscreen mode. */
-
+		if (flags & SDL_WINDOW_FULLSCREEN)
-		if ((flags & (SDL_WINDOW_FULLSCREEN | SDL_WINDOW_FULLSCREEN_DESKTOP)) == SDL_WINDOW_FULLSCREEN)
 		{
-			if (SDL_GetWindowFullscreenMode(window, &real_mode) != 0)
+            /* SDLs behavior changed between SDL 2 and SDL 3: In SDL 2
+			   the fullscreen window could be set with whatever mode
+			   was requested. In SDL 3 the fullscreen window is always
+			   created at desktop resolution. If a fullscreen window
+			   is requested, we can't do anything else are done here. */
+			if (fullscreen == 2)
 			{
-				SDL_DestroyWindow(window);
+				return true;
-				window = NULL;
-
-				Com_Printf("Can't get display mode: %s\n", SDL_GetError());
-
-				return false;
 			}
-		}
 
-		/* Normally SDL stays at desktop refresh rate or chooses something
+			/* Otherwise try to find a mode near the requested one and
-		   sane. Some player may want to override that.
+			   switch to it in exclusive fullscreen mode. */
+			/* TODO SDL3: Leak? */
+		    const SDL_DisplayMode *closestMode = SDL_GetClosestFullscreenDisplayMode(last_display, w, h, vid_rate->value, false);
 
-		   Reminder: SDL_WINDOW_FULLSCREEN_DESKTOP implies SDL_WINDOW_FULLSCREEN! */
+			if (closestMode == NULL)
-		if ((flags & (SDL_WINDOW_FULLSCREEN | SDL_WINDOW_FULLSCREEN_DESKTOP)) == SDL_WINDOW_FULLSCREEN)
-		{
-			if (vid_rate->value > 0)
 			{
-				SDL_DisplayMode closest_mode;
+				Com_Printf("SDL was unable to find a mode close to %ix%i@%f\n", w, h, vid_rate->value);
-				SDL_DisplayMode requested_mode = real_mode;
 
-				requested_mode.refresh_rate = (int)vid_rate->value;
+				if (vid_rate->value != 0)
-
-				if (SDL_GetClosestFullscreenDisplayMode(last_display, &requested_mode, &closest_mode) == NULL)
 				{
-					Com_Printf("SDL was unable to find a mode close to %ix%i@%i\n", w, h, requested_mode.refresh_rate);
+					Com_Printf("Retrying with desktop refresh rate\n");
-					Cvar_SetValue("vid_rate", -1);
+					closestMode = SDL_GetClosestFullscreenDisplayMode(last_display, w, h, 0, false);
-				}
-				else
-				{
-					Com_Printf("User requested %ix%i@%i, setting closest mode %ix%i@%i\n",
-							w, h, requested_mode.refresh_rate, w, h, closest_mode.refresh_rate);
 
-					if (SDL_SetWindowFullscreenMode(window, &closest_mode) != 0)
+					if (closestMode != NULL)
 					{
-						Com_Printf("Couldn't switch to mode %ix%i@%i, staying at current mode\n",
+						Cvar_SetValue("vid_rate", 0);
-								w, h, closest_mode.refresh_rate);
-						Cvar_SetValue("vid_rate", -1);
 					}
 					else
 					{
-						Cvar_SetValue("vid_rate", closest_mode.refresh_rate);
+						Com_Printf("SDL was unable to find a mode close to %ix%i@0\n", w, h);
+						return false;
 					}
 				}
+			}
 
+			Com_Printf("User requested %ix%i@%f, setting closest mode %ix%i@%f\n",
+					w, h, vid_rate->value, closestMode->w, closestMode->h , closestMode->refresh_rate);
+
+
+			/* TODO SDL3: Same code is in InitGraphics(), refactor into
+			 * a function? */
+			if (SDL_SetWindowFullscreenMode(window, closestMode) < 0)
+			{
+				Com_Printf("Couldn't set closest mode: %s\n", SDL_GetError());
+				return false;
+			}
+
+			if (SDL_SetWindowFullscreen(window, true) < 0)
+			{
+				Com_Printf("Couldn't switch to exclusive fullscreen: %s\n", SDL_GetError());
+				return false;
+			}
+
+			int ret = SDL_SyncWindow(window);
+
+			if (ret > 0)
+			{
+				Com_Printf("Synchronizing window state timed out\n");
+				return false;
+			}
+			else if (ret < 0)
+			{
+				Com_Printf("Couldn't synchronize window state: %s\n", SDL_GetError());
+				return false;
 			}
 		}
 	}
@@ -186,18 +210,22 @@ CreateSDLWindow(int flags, int w, int h)
 static int
 GetFullscreenType()
 {
-	if (SDL_GetWindowFlags(window) & SDL_WINDOW_FULLSCREEN_DESKTOP)
+	if (SDL_GetWindowFlags(window) & SDL_WINDOW_FULLSCREEN)
 	{
-		return 2;
+		/* TODO SDL3: Leak? */
-	}
+		const SDL_DisplayMode *fsmode = SDL_GetWindowFullscreenMode(window);
-	else if (SDL_GetWindowFlags(window) & SDL_WINDOW_FULLSCREEN)
+
-	{
+		if (fsmode != NULL)
-		return 1;
+		{
-	}
+			return 1;
-	else
+		}
-	{
+		else
-		return 0;
+		{
+			return 2;
+		}
 	}
+
+	return 0;
 }
 
 static qboolean
@@ -454,14 +482,10 @@ GLimp_InitGraphics(int fullscreen, int *pwidth, int *pheight)
 	int height = *pheight;
 	unsigned int fs_flag = 0;
 
-	if (fullscreen == 1)
+	if (fullscreen == 1 || fullscreen == 2)
 	{
 		fs_flag = SDL_WINDOW_FULLSCREEN;
 	}
-	else if (fullscreen == 2)
-	{
-		fs_flag = SDL_WINDOW_FULLSCREEN_DESKTOP;
-	}
 
 	/* Only do this if we already have a working window and a fully
 	initialized rendering backend GLimp_InitGraphics() is also
@@ -473,7 +497,69 @@ GLimp_InitGraphics(int fullscreen, int *pwidth, int *pheight)
 		/* If we want fullscreen, but aren't */
 		if (GetFullscreenType())
 		{
-			SDL_SetWindowFullscreen(window, fs_flag);
+			/* TODO SDL3: Leak? */
+			const SDL_DisplayMode *closestMode;
+
+			if (fullscreen == 1)
+			{
+				closestMode = SDL_GetClosestFullscreenDisplayMode(last_display, width, height, vid_rate->value, false);
+
+				if (closestMode == NULL)
+				{
+					Com_Printf("SDL was unable to find a mode close to %ix%i@%f\n", width, height, vid_rate->value);
+
+					if (vid_rate->value != 0)
+					{
+						Com_Printf("Retrying with desktop refresh rate\n");
+						closestMode = SDL_GetClosestFullscreenDisplayMode(last_display, width, height, 0, false);
+
+						if (closestMode != NULL)
+						{
+							Cvar_SetValue("vid_rate", 0);
+						}
+						else
+						{
+							Com_Printf("SDL was unable to find a mode close to %ix%i@0\n", width, height);
+							return false;
+						}
+					}
+				}
+			}
+			else if (fullscreen == 2)
+			{
+				/* Fullscreen window */
+				closestMode = NULL;
+			}
+
+			if (SDL_SetWindowFullscreenMode(window, closestMode) < 0)
+			{
+				Com_Printf("Couldn't set fullscreen modmode: %s\n", SDL_GetError());
+				Cvar_SetValue("vid_fullscreen", 0);
+			}
+			else
+			{
+				if (SDL_SetWindowFullscreen(window, true) < 0)
+				{
+					Com_Printf("Couldn't switch to exclusive fullscreen: %s\n", SDL_GetError());
+					Cvar_SetValue("vid_fullscreen", 0);
+				}
+				else
+				{
+					int ret = SDL_SyncWindow(window);
+
+					if (ret > 0)
+					{
+						Com_Printf("Synchronizing window state timed out\n");
+						Cvar_SetValue("vid_fullscreen", 0);
+					}
+					else if (ret < 0)
+					{
+						Com_Printf("Couldn't synchronize window state: %s\n", SDL_GetError());
+						Cvar_SetValue("vid_fullscreen", 0);
+					}
+				}
+			}
+
 			Cvar_SetValue("vid_fullscreen", fullscreen);
 		}
 
@@ -524,7 +610,7 @@ GLimp_InitGraphics(int fullscreen, int *pwidth, int *pheight)
 
 	while (1)
 	{
-		if (!CreateSDLWindow(flags, width, height))
+		if (!CreateSDLWindow(flags, fullscreen, width, height))
 		{
 			if((flags & SDL_WINDOW_OPENGL) && gl_msaa_samples->value)
 			{