Fixed display mode calculations for applications which are not DPI aware.

If your application wants to have access to the full resolution even when the system has DPI scaling enabled, call SetProcessDPIAware() before calling SDL_Init()

e.g.
	typedef BOOL (WINAPI *SetProcessDPIAware_t)(void);
	HMODULE hMod = LoadLibrary("user32.dll");
	if ( hMod ) {
		SetProcessDPIAware_t pSetProcessDPIAware = GetProcAddress( hMod, "SetProcessDPIAware" );
		if ( pSetProcessDPIAware ) {
			pSetProcessDPIAware();
		}
		FreeLibrary( hMod );
	}

src/video/windows/SDL_windowsmodes.c

@@ -50,6 +50,8 @@ WIN_GetDisplayMode(LPCTSTR deviceName, DWORD index, SDL_DisplayMode * mode)
     data->DeviceMode.dmFields =
         (DM_BITSPERPEL | DM_PELSWIDTH | DM_PELSHEIGHT | DM_DISPLAYFREQUENCY |
          DM_DISPLAYFLAGS);
+	data->ScaleX = 1.0f;
+	data->ScaleY = 1.0f;
 
     /* Fill in the mode information */
     mode->format = SDL_PIXELFORMAT_UNKNOWN;
@@ -63,6 +65,13 @@ WIN_GetDisplayMode(LPCTSTR deviceName, DWORD index, SDL_DisplayMode * mode)
         char bmi_data[sizeof(BITMAPINFOHEADER) + 256 * sizeof(RGBQUAD)];
         LPBITMAPINFO bmi;
         HBITMAP hbm;
+		int logical_width = GetDeviceCaps( hdc, HORZRES );
+		int logical_height = GetDeviceCaps( hdc, VERTRES );
+
+		data->ScaleX = (float)logical_width / devmode.dmPelsWidth;
+		data->ScaleY = (float)logical_height / devmode.dmPelsHeight;
+		mode->w = logical_width;
+		mode->h = logical_height;
 
         SDL_zero(bmi_data);
         bmi = (LPBITMAPINFO) bmi_data;
@@ -93,7 +102,7 @@ WIN_GetDisplayMode(LPCTSTR deviceName, DWORD index, SDL_DisplayMode * mode)
         } else if (bmi->bmiHeader.biBitCount == 4) {
             mode->format = SDL_PIXELFORMAT_INDEX4LSB;
         }
-    } else {
+	} else {
         /* FIXME: Can we tell what this will be? */
         if ((devmode.dmFields & DM_BITSPERPEL) == DM_BITSPERPEL) {
             switch (devmode.dmBitsPerPel) {
@@ -224,10 +233,10 @@ WIN_GetDisplayBounds(_THIS, SDL_VideoDisplay * display, SDL_Rect * rect)
 {
     SDL_DisplayModeData *data = (SDL_DisplayModeData *) display->current_mode.driverdata;
 
-    rect->x = (int)data->DeviceMode.dmPosition.x;
-    rect->y = (int)data->DeviceMode.dmPosition.y;
-    rect->w = data->DeviceMode.dmPelsWidth;
-    rect->h = data->DeviceMode.dmPelsHeight;
+    rect->x = (int)SDL_ceil(data->DeviceMode.dmPosition.x * data->ScaleX);
+    rect->y = (int)SDL_ceil(data->DeviceMode.dmPosition.y * data->ScaleY);
+    rect->w = (int)SDL_ceil(data->DeviceMode.dmPelsWidth * data->ScaleX);
+    rect->h = (int)SDL_ceil(data->DeviceMode.dmPelsHeight * data->ScaleY);
 
     return 0;
 }
@@ -252,8 +261,7 @@ WIN_GetDisplayModes(_THIS, SDL_VideoDisplay * display)
             if (!SDL_AddDisplayMode(display, &mode)) {
                 SDL_free(mode.driverdata);
             }
-        }
-        else {
+        } else {
             SDL_free(mode.driverdata);
         }
     }

src/video/windows/SDL_windowsmodes.h

@@ -31,6 +31,8 @@ typedef struct
 typedef struct
 {
     DEVMODE DeviceMode;
+	float ScaleX;
+	float ScaleY;
 } SDL_DisplayModeData;
 
 extern int WIN_InitModes(_THIS);