video: Always recreate the _window_, not just the GL context, like SD…

…L 1.2.

Fixes Dungeons of Dredmor (on Windows) positioning its game window weirdly
after the launcher dialog is done, since it was resizing the existing window
in-place instead of creating a new one and centering it.

src/SDL12_compat.c

@@ -5637,6 +5637,9 @@ EndVidModeCreate(void)
     OpenGLLogicalScalingFBO = 0;
     OpenGLLogicalScalingColor = 0;
     OpenGLLogicalScalingDepth = 0;
+    OpenGLLogicalScalingMultisampleFBO = 0;
+    OpenGLLogicalScalingMultisampleColor = 0;
+    OpenGLLogicalScalingMultisampleDepth = 0;
 
     MouseInputIsRelative = SDL_FALSE;
     MousePosition.x = 0;
@@ -6103,27 +6106,28 @@ SetVideoModeImpl(int width, int height, int bpp, Uint32 flags12)
         EndVidModeCreate();  /* rebuild the window if moving to/from a GL context */
     } else if (VideoSurface12->surface20 && (VideoSurface12->surface20->format->format != appfmt)) {
         EndVidModeCreate();  /* rebuild the window if changing pixel format */
-    } else if (VideoGLContext20) {
-        /* SDL 1.2 (infuriatingly!) destroys the GL context on each resize in some cases, on various platforms. Try to match that. */
+    } else {
+        SDL_assert(VideoSurface12 != NULL);
+        /* SDL 1.2 (infuriatingly!) destroys the window (and GL context!) on each resize in some cases, on various platforms. Try to match that. */
         #ifdef __WINDOWS__
-            /* The windx5 driver _always_ destroyed the GL context, unconditionally, but the default (windib) did not, so match windib.
+            /* The windx5 driver _always_ destroyed the window, unconditionally, but the default (windib) did not, so match windib.
              *  windib: keep if:
              *   - window already exists
              *   - BitsPerPixel hasn't changed
              *   - none of the window flags (except SDL_ANYFORMAT) have changed
              *   - window is already SDL_OPENGL.
              *   - window is not a fullscreen window.
              */
-            const SDL_bool destroy_gl_context = (
+            const SDL_bool recreate_window = (
                 ((VideoSurface12->flags & ~SDL12_ANYFORMAT) != (flags12 & ~SDL12_ANYFORMAT)) ||
-                (VideoSurface12->format->BitsPerPixel != bpp) ||
+                (!VideoSurface12->format || (VideoSurface12->format->BitsPerPixel != bpp)) ||
                 ((flags12 & SDL12_OPENGL) != SDL12_OPENGL) ||
                 ((flags12 & SDL12_FULLSCREEN) == SDL12_FULLSCREEN)
             ) ? SDL_TRUE : SDL_FALSE;
         #elif defined(__APPLE__)
-            const SDL_bool destroy_gl_context = SDL_TRUE; /* macOS ("quartz" backend) unconditionally destroys the GL context */
+            const SDL_bool recreate_window = SDL_TRUE; /* macOS ("quartz" backend) unconditionally destroys the GL context */
         #elif defined(__HAIKU__)
-            const SDL_bool destroy_gl_context = SDL_FALSE; /* BeOS and Haiku ("bwindow" backend) unconditionally keeps the GL context */
+            const SDL_bool recreate_window = SDL_FALSE; /* BeOS and Haiku ("bwindow" backend) unconditionally keeps the GL context */
         #elif defined(__LINUX__) || defined(unix) || defined(__unix__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(sun)
             /* The x11 backend does in _some_ cases, and since Linux software depends on that, even though Wayland and
              *   such wasn't a thing at the time, we treat everything that looks a little like Unix this way.
@@ -6134,31 +6138,18 @@ SetVideoModeImpl(int width, int height, int bpp, Uint32 flags12)
              *   - BitsPerPixel hasn't changed
              *   - SDL_NOFRAME hasn't changed
              */
-            const SDL_bool destroy_gl_context = (
+            const SDL_bool recreate_window = (
                 ((VideoSurface12->flags & SDL12_OPENGL) != (flags12 & SDL12_OPENGL)) ||
                 ((flags12 & SDL12_OPENGL) != SDL12_OPENGL) ||
-                (VideoSurface12->format->BitsPerPixel != bpp) ||
+                (!VideoSurface12->format || (VideoSurface12->format->BitsPerPixel != bpp)) ||
                 ((VideoSurface12->flags & SDL12_NOFRAME) != (flags12 & SDL12_NOFRAME))
             ) ? SDL_TRUE : SDL_FALSE;
         #else
-            const SDL_bool destroy_gl_context = SDL_TRUE;  /* everywhere else: nuke it from orbit. Oh well. */
+            const SDL_bool recreate_window = SDL_TRUE;  /* everywhere else: nuke it from orbit. Oh well. */
         #endif
 
-        if (destroy_gl_context) {
-            SDL20_GL_MakeCurrent(NULL, NULL);
-            SDL20_GL_DeleteContext(VideoGLContext20);
-            VideoGLContext20 = NULL;
-            SDL20_zero(OpenGLFuncs);
-            OpenGLBlitTexture = 0;
-            OpenGLBlitLockCount = 0;
-            OpenGLLogicalScalingWidth = 0;
-            OpenGLLogicalScalingHeight = 0;
-            OpenGLLogicalScalingFBO = 0;
-            OpenGLLogicalScalingColor = 0;
-            OpenGLLogicalScalingDepth = 0;
-            OpenGLLogicalScalingMultisampleFBO = 0;
-            OpenGLLogicalScalingMultisampleColor = 0;
-            OpenGLLogicalScalingMultisampleDepth = 0;
+        if (recreate_window) {
+            EndVidModeCreate();  /* rebuild the window if we can't resize it. */
         }
     }