Alistair Leslie-Hughes : windowscodecs: Avoid implicit cast changing value.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 013f54af1f721dce651c85f87a5339ba3cb9d4a1
URL:    https://gitlab.winehq.org/wine/wine/-/commit/013f54af1f721dce651c85f87a5339b...

Author: Alistair Leslie-Hughes <leslie_alistair(a)hotmail.com>
Date:   Thu May  2 09:55:01 2024 +1000

windowscodecs: Avoid implicit cast changing value.

This appear to be introduced with commit 12f73ed9d851.

When This->stride is negative (bottom up image) it converts the multiplication to an UINT.
Thus causing the pointer to be incorrect when y > 0.

---

 dlls/windowscodecs/bmpdecode.c        | 2 +-
 dlls/windowscodecs/wincodecs_common.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/dlls/windowscodecs/bmpdecode.c b/dlls/windowscodecs/bmpdecode.c
index 9d4867447f0..ae6feda5b50 100644
--- a/dlls/windowscodecs/bmpdecode.c
+++ b/dlls/windowscodecs/bmpdecode.c
@@ -432,7 +432,7 @@ static HRESULT BmpFrameDecode_ReadABGRasBGR(BmpDecoder* This)
     {
         for (y = 0; y < height; y++)
         {
-            pixel = This->imagedatastart + This->stride * y;
+            pixel = This->imagedatastart + This->stride * (INT)y;
 
             for (x = 0; x < width; x++)
             {
diff --git a/dlls/windowscodecs/wincodecs_common.h b/dlls/windowscodecs/wincodecs_common.h
index f56e91e1f54..dcccdc2e5f1 100644
--- a/dlls/windowscodecs/wincodecs_common.h
+++ b/dlls/windowscodecs/wincodecs_common.h
@@ -201,7 +201,7 @@ void reverse_bgr8(UINT bytesperpixel, LPBYTE bits, UINT width, UINT height, INT
 
     for (y=0; y<height; y++)
     {
-        pixel = bits + stride * y;
+        pixel = bits + stride * (INT)y;
 
         for (x=0; x<width; x++)
         {