Demo mode: Force resolution to that of the demo

Source/engine/demomode.cpp

@@ -390,6 +390,7 @@ void OverrideOptions()
 #endif
 		sgOptions.Graphics.limitFPS.SetValue(false);
 	}
+	forceResolution = Size(DemoGraphicsWidth, DemoGraphicsHeight);
 }
 
 bool IsRunning()

Source/utils/display.cpp

@@ -46,6 +46,8 @@ namespace devilution {
 extern SDLSurfaceUniquePtr RendererTextureSurface; /** defined in dx.cpp */
 SDL_Window *ghMainWnd;
 
+Size forceResolution;
+
 Uint16 gnScreenWidth;
 Uint16 gnScreenHeight;
 Uint16 gnViewportHeight;
@@ -155,7 +157,7 @@ void CalculateUIRectangle()
 
 Size GetPreferredWindowSize()
 {
-	Size windowSize = *sgOptions.Graphics.resolution;
+	Size windowSize = forceResolution.width != 0 ? forceResolution : *sgOptions.Graphics.resolution;
 
 #ifndef USE_SDL1
 	if (*sgOptions.Graphics.upscale && *sgOptions.Graphics.fitToScreen) {
@@ -243,7 +245,7 @@ bool SpawnWindow(const char *lpWindowName)
 #endif
 #ifdef NXDK
 	{
-		Size windowSize = *sgOptions.Graphics.resolution;
+		Size windowSize = forceResolution.width != 0 ? forceResolution : *sgOptions.Graphics.resolution;
 		VIDEO_MODE xmode;
 		void *p = nullptr;
 		while (XVideoListModes(&xmode, 0, 0, &p)) {

Source/utils/display.h

@@ -10,6 +10,7 @@
 #include "utils/sdl2_backports.h"
 #endif
 
+#include "utils/attributes.h"
 #include "utils/sdl_ptrs.h"
 #include "utils/ui_fwd.h"
 
@@ -26,6 +27,7 @@ extern SDLTextureUniquePtr texture;
 extern SDLPaletteUniquePtr Palette;
 extern SDL_Surface *PalSurface;
 extern unsigned int pal_surface_palette_version;
+extern DVL_API_FOR_TEST Size forceResolution;
 
 #ifdef USE_SDL1
 void SetVideoMode(int width, int height, int bpp, uint32_t flags);

test/timedemo_test.cpp

@@ -53,7 +53,7 @@ void RunTimedemo(std::string timedemoFolderName)
 
 	demo::OverrideOptions();
 
-	AdjustToScreenGeometry(*sgOptions.Graphics.resolution);
+	AdjustToScreenGeometry(forceResolution);
 
 	StartGame(false, true);