add guard lines on both on top and bottom of the buffer

Author: FunkyFr3sh

src/ddsurface.c

@@ -1553,17 +1553,17 @@ HRESULT dd_CreateSurface(
             if (dst_surface->hdc)
                 InterlockedIncrement(&g_dds_gdi_handles);
 
+            DWORD map_offset = dst_surface->pitch * g_config.guard_lines;
+
             dst_surface->mapping =
                 CreateFileMappingA(
                     INVALID_HANDLE_VALUE,
                     NULL,
                     PAGE_READWRITE | SEC_COMMIT,
                     0,
-                    bmp_size + 256,
+                    bmp_size + 256 + map_offset,
                     NULL);
 
-            DWORD map_offset = 0;
-
             if (dst_surface->mapping)
             {
                 LPVOID data = MapViewOfFile(dst_surface->mapping, FILE_MAP_ALL_ACCESS, 0, 0, 0);