From b7f485d935479f6d47d1ef203a7758c9fc177a2b Mon Sep 17 00:00:00 2001
From: FunkyFr3sh <cc.red.alert.1@googlemail.com>
Date: Sat, 24 Apr 2021 08:14:48 +0200
Subject: [PATCH] #83 fix surface lock with rect

---
 src/ddsurface.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/ddsurface.c b/src/ddsurface.c
index aef009e..17aa4a4 100644
--- a/src/ddsurface.c
+++ b/src/ddsurface.c
@@ -690,7 +690,15 @@ HRESULT dds_Lock(IDirectDrawSurfaceImpl *This, LPRECT lpDestRect, LPDDSURFACEDES
 {
     dbg_dump_dds_lock_flags(dwFlags);
 
-    return dds_GetSurfaceDesc(This, lpDDSurfaceDesc);
+    HRESULT ret = dds_GetSurfaceDesc(This, lpDDSurfaceDesc);
+
+    if (lpDestRect && lpDDSurfaceDesc && lpDestRect->left >= 0 && lpDestRect->top >= 0)
+    {
+        lpDDSurfaceDesc->lpSurface = 
+            (char*)This->surface + (lpDestRect->left * This->lx_pitch) + (lpDestRect->top * This->l_pitch);
+    }
+
+    return ret;
 }
 
 HRESULT dds_SetColorKey(IDirectDrawSurfaceImpl *This, DWORD flags, LPDDCOLORKEY colorKey)