Partial stub of GdiAlphaBlend/AlphaBlend.

dlls/gdi/bitblt.c

diff --git a/dlls/gdi/bitblt.c b/dlls/gdi/bitblt.c
index 1d9e8bf..ef39099 100644
--- a/dlls/gdi/bitblt.c
+++ b/dlls/gdi/bitblt.c
@@ -395,6 +395,19 @@
     return ret;
 }
 
+/******************************************************************************
+ *           GdiAlphaBlend [GDI32.@]
+ */
+BOOL WINAPI GdiAlphaBlend(HDC hdcDest, int nXOriginDest, int nYOriginDest, int nWidthDest, int nHeightDest,
+                          HDC hdcSrc, int nXOriginSrc, int nYOriginSrc, int nWidthSrc, int nHeightSrc,
+                          BLENDFUNCTION blendFunction)
+{
+    FIXME("partial stub - using StretchBlt\n");
+    return StretchBlt(hdcDest, nXOriginDest, nYOriginDest, nWidthDest, nHeightDest,
+                      hdcSrc, nXOriginSrc, nYOriginSrc, nWidthSrc, nHeightSrc,
+                      SRCCOPY);
+}
+
 /*********************************************************************
  *      PlgBlt [GDI32.@]
  *

dlls/gdi/gdi32.spec

diff --git a/dlls/gdi/gdi32.spec b/dlls/gdi/gdi32.spec
index d3822cf..d58d467 100644
--- a/dlls/gdi/gdi32.spec
+++ b/dlls/gdi/gdi32.spec
@@ -118,6 +118,7 @@
 @ stdcall FloodFill(long long long long)
 @ stdcall FrameRgn(long long long long long)
 @ stub FreeImageColorMatcher
+@ stdcall GdiAlphaBlend(long long long long long long long long long long long)
 @ stub GdiAssociateObject
 @ stub GdiCleanCacheDC
 @ stdcall GdiComment(long long ptr)

dlls/msimg32/msimg32.spec

diff --git a/dlls/msimg32/msimg32.spec b/dlls/msimg32/msimg32.spec
index f1c75b2..a5e3be3 100644
--- a/dlls/msimg32/msimg32.spec
+++ b/dlls/msimg32/msimg32.spec
@@ -1,4 +1,4 @@
-@ stdcall AlphaBlend(long long long long long long long long long long long)
+@ stdcall AlphaBlend(long long long long long long long long long long long) gdi32.GdiAlphaBlend
 @ stub DllInitialize
 @ stdcall GradientFill(long ptr long ptr long long) gdi32.GdiGradientFill
 @ stdcall TransparentBlt(long long long long long long long long long long long) gdi32.GdiTransparentBlt

dlls/msimg32/msimg32_main.c

diff --git a/dlls/msimg32/msimg32_main.c b/dlls/msimg32/msimg32_main.c
index db9d9cc..43e7103 100644
--- a/dlls/msimg32/msimg32_main.c
+++ b/dlls/msimg32/msimg32_main.c
@@ -27,18 +27,6 @@
 WINE_DEFAULT_DEBUG_CHANNEL(msimg32);
 
 /******************************************************************************
- *           AlphaBlend   (MSIMG32.@)
- */
-BOOL WINAPI AlphaBlend( HDC hdcDest, int xDest, int yDest, int widthDest, int heightDst,
-                        HDC hdcSrc, int xSrc, int ySrc, int widthSrc, int heightSrc,
-                        BLENDFUNCTION func )
-{
-    FIXME("stub: AlphaBlend from %p to %p\n", hdcSrc, hdcDest );
-    SetLastError(ERROR_CALL_NOT_IMPLEMENTED);
-    return FALSE;
-}
-
-/******************************************************************************
  *           vSetDdrawflag   (MSIMG32.@)
  */
 void WINAPI vSetDdrawflag(void)

include/wingdi.h

diff --git a/include/wingdi.h b/include/wingdi.h
index b716864..ce66b8b 100644
--- a/include/wingdi.h
+++ b/include/wingdi.h
@@ -3133,6 +3133,9 @@
     ULONG LowerRight;
 } GRADIENT_RECT, *PGRADIENT_RECT, *LPGRADIENT_RECT;
 
+#define AC_SRC_OVER  0x00
+#define AC_SRC_ALPHA 0x01
+
 typedef struct _BLENDFUNCTION
 {
     BYTE BlendOp;