winex11: Fix alpha blending in X11DRV_UpdateLayeredWindow.

[Sebastian Lackner]

Based on a patch by Dmitry Timoshkov.

Signed-off-by: Sebastian Lackner <sebastian at fds-team.de>
---

Fixes https://bugs.winehq.org/show_bug.cgi?id=33943.

Battle.Net initially creates completely transparent popup windows and
afterwards uses UpdateLayeredWindow without hdcSrc to let them fade in.
Testing confirms that this works fine on Windows - on Wine however the
original content is lost and no longer available. To avoid that, this
patch stores the original content in the surface and uses
_NET_WM_WINDOW_OPACITY to create a transparency effect. The same method
is already used by SetLayeredWindowAttributes. If compositing is disabled,
the window content will be visible immediately.

Dmitrys original patch used a different approach, and manually implemented
the alpha blending in x11drv_surface_flush using additional buffers,
however this shouldn't really be necessary (yet). We can still use it
later if there is any benefit compared to using _NET_WM_WINDOW_OPACITY.

 dlls/winex11.drv/window.c |   36 +++++++++++++++++-------------------
 1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/dlls/winex11.drv/window.c b/dlls/winex11.drv/window.c
index 7408a0eb480..3f169ea296f 100644
--- a/dlls/winex11.drv/window.c
+++ b/dlls/winex11.drv/window.c
@@ -410,14 +410,11 @@ static void sync_window_region( struct x11drv_win_data *data, HRGN win_region )
 
 
 /***********************************************************************
- *              sync_window_opacity
+ *              set_window_opacity
  */
-static void sync_window_opacity( Display *display, Window win,
-                                 COLORREF key, BYTE alpha, DWORD flags )
+static void set_window_opacity( Display *display, Window win, BYTE alpha )
 {
-    unsigned long opacity = 0xffffffff;
-
-    if (flags & LWA_ALPHA) opacity = (0xffffffff / 0xff) * alpha;
+    unsigned long opacity = (0xffffffff / 0xff) * alpha;
 
     if (opacity == 0xffffffff)
         XDeleteProperty( display, win, x11drv_atom(_NET_WM_WINDOW_OPACITY) );
@@ -1527,7 +1524,7 @@ static void create_whole_window( struct x11drv_win_data *data )
 
     /* set the window opacity */
     if (!GetLayeredWindowAttributes( data->hwnd, &key, &alpha, &layered_flags )) layered_flags = 0;
-    sync_window_opacity( data->display, data->whole_window, key, alpha, layered_flags );
+    set_window_opacity( data->display, data->whole_window, (layered_flags & LWA_ALPHA) ? alpha : 0xff );
 
     XFlush( data->display );  /* make sure the window exists before we start painting to it */
 
@@ -1647,7 +1644,7 @@ void CDECL X11DRV_SetWindowStyle( HWND hwnd, INT offset, STYLESTRUCT *style )
     {
         data->layered = FALSE;
         set_window_visual( data, &default_visual );
-        sync_window_opacity( data->display, data->whole_window, 0, 0, 0 );
+        set_window_opacity( data->display, data->whole_window, 0xff );
         if (data->surface) set_surface_color_key( data->surface, CLR_INVALID );
     }
 done:
@@ -2536,7 +2533,7 @@ void CDECL X11DRV_SetLayeredWindowAttributes( HWND hwnd, COLORREF key, BYTE alph
     if (data)
     {
         if (data->whole_window)
-            sync_window_opacity( data->display, data->whole_window, key, alpha, flags );
+            set_window_opacity( data->display, data->whole_window, (flags & LWA_ALPHA) ? alpha : 0xff );
         if (data->surface)
             set_surface_color_key( data->surface, (flags & LWA_COLORKEY) ? key : CLR_INVALID );
 
@@ -2560,7 +2557,7 @@ void CDECL X11DRV_SetLayeredWindowAttributes( HWND hwnd, COLORREF key, BYTE alph
         Window win = X11DRV_get_whole_window( hwnd );
         if (win)
         {
-            sync_window_opacity( gdi_display, win, key, alpha, flags );
+            set_window_opacity( gdi_display, win, (flags & LWA_ALPHA) ? alpha : 0xff );
             if (flags & LWA_COLORKEY)
                 FIXME( "LWA_COLORKEY not supported on foreign process window %p\n", hwnd );
         }
@@ -2576,7 +2573,6 @@ BOOL CDECL X11DRV_UpdateLayeredWindow( HWND hwnd, const UPDATELAYEREDWINDOWINFO
 {
     struct window_surface *surface;
     struct x11drv_win_data *data;
-    BLENDFUNCTION blend = { AC_SRC_OVER, 0, 255, 0 };
     COLORREF color_key = (info->dwFlags & ULW_COLORKEY) ? info->crKey : CLR_INVALID;
     char buffer[FIELD_OFFSET( BITMAPINFO, bmiColors[256] )];
     BITMAPINFO *bmi = (BITMAPINFO *)buffer;
@@ -2604,6 +2600,10 @@ BOOL CDECL X11DRV_UpdateLayeredWindow( HWND hwnd, const UPDATELAYEREDWINDOWINFO
     }
     else set_surface_color_key( surface, color_key );
 
+    if (data->whole_window)
+        set_window_opacity( data->display, data->whole_window,
+                            (info->dwFlags & ULW_ALPHA) ? info->pblend->SourceConstantAlpha : 0xff );
+
     if (surface) window_surface_add_ref( surface );
     release_win_data( data );
 
@@ -2627,14 +2627,12 @@ BOOL CDECL X11DRV_UpdateLayeredWindow( HWND hwnd, const UPDATELAYEREDWINDOWINFO
     {
         IntersectRect( &rect, &rect, info->prcDirty );
         memcpy( src_bits, dst_bits, bmi->bmiHeader.biSizeImage );
-        PatBlt( hdc, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, BLACKNESS );
-    }
-    ret = GdiAlphaBlend( hdc, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top,
-                         info->hdcSrc,
-                         rect.left + (info->pptSrc ? info->pptSrc->x : 0),
-                         rect.top + (info->pptSrc ? info->pptSrc->y : 0),
-                         rect.right - rect.left, rect.bottom - rect.top,
-                         (info->dwFlags & ULW_ALPHA) ? *info->pblend : blend );
+    }
+    ret = BitBlt( hdc, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top,
+                  info->hdcSrc,
+                  rect.left + (info->pptSrc ? info->pptSrc->x : 0),
+                  rect.top + (info->pptSrc ? info->pptSrc->y : 0),
+                  SRCCOPY );
     if (ret)
     {
         memcpy( dst_bits, src_bits, bmi->bmiHeader.biSizeImage );
-- 
2.11.0