use bitmap mask if any in splash screen (closes #10470)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@58746 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -130,6 +130,7 @@ All (GUI):
 - Implemented wxWindow::DragAcceptFiles() on all platforms.
 - Added wxAUI_MGR_LIVE_RESIZE flag to wxAuiManager and made it the default on
   wxMac with CoreGraphics where sash drawing isn't implemented.
+- Use bitmap mask in wxSplashScreen.
 
 All (Unix):
 

src/generic/splash.cpp

@@ -150,7 +150,8 @@ static void wxDrawSplashBitmap(wxDC& dc, const wxBitmap& bitmap, int WXUNUSED(x)
 #endif // USE_PALETTE_IN_SPLASH
 
     dcMem.SelectObjectAsSource(bitmap);
-    dc.Blit(0, 0, bitmap.GetWidth(), bitmap.GetHeight(), & dcMem, 0, 0);
+    dc.Blit(0, 0, bitmap.GetWidth(), bitmap.GetHeight(), &dcMem, 0, 0, wxCOPY,
+            true /* use mask */);
     dcMem.SelectObject(wxNullBitmap);
 
 #ifdef USE_PALETTE_IN_SPLASH