fix emf transparency handling (bnc#820385)

46e53913 fixed some transparency emf problems
on X11, it however did it by implementing alpha support in X11SalBitmap only
and made generic code rely on it. Now it doesn't work at least on Windows,
after reverting it works on Windows but not on X11. As I have no idea what
the real problem is, at least keep both code paths.

Change-Id: I2f2cf247becfcd777b4f3d129efe4d6a5d641f7b

vcl/inc/salbmp.hxx

@@ -48,7 +48,6 @@ public:
                                     Size& rSize,
                                     bool bMask = false ) = 0;
     virtual bool            HasAlpha() const { return false; }
-    virtual void            SetHasAlpha( bool ) { }
     virtual void            Destroy() = 0;
     virtual Size            GetSize() const = 0;
     virtual sal_uInt16      GetBitCount() const = 0;

vcl/source/gdi/gdimtf.cxx

@@ -47,6 +47,10 @@
 #include <com/sun/star/graphic/XGraphic.hpp>
 #include <com/sun/star/graphic/XGraphicRenderer.hpp>
 
+#ifdef UNX
+#include <unx/salbmp.h>
+#endif
+
 using namespace com::sun::star;
 
 #define GAMMA( _def_cVal, _def_InvGamma )   ((sal_uInt8)MinMax(FRound(pow( _def_cVal/255.0,_def_InvGamma)*255.0),0L,255L))
@@ -442,18 +446,39 @@ bool GDIMetaFile::ImplPlayWithRenderer( OutputDevice* pOut, const Point& rPos, S
                 }
 
                 SalBitmap* pSalBmp = ImplGetSVData()->mpDefInst->CreateSalBitmap();
-                pSalBmp->SetHasAlpha( true );
-
-                if( pSalBmp->Create( xBitmapCanvas, aSize ) )
+                // I don't quite understand this, but the old code didn't work properly on X11 when alpha was used,
+                // and the commit that changed to the new code relied on alpha support in bitmap
+                // (which that commit implemented only in X11SalBitmap) and so it didn't work on Windows.
+                // So keep both.
+#ifdef UNX
+                X11SalBitmap* X11Bmp = static_cast< X11SalBitmap* >( pSalBmp );
+                X11Bmp->SetHasAlpha( true );
+                if( X11Bmp->Create( xBitmapCanvas, aSize ) )
                 {
-                    Bitmap aBitmap( pSalBmp );
+                    Bitmap aBitmap( X11Bmp );
                     if ( pOut->GetMapMode() == MAP_PIXEL )
                         pOut->DrawBitmap( rPos, aBitmap );
                     else
                         pOut->DrawBitmap( rPos, rLogicDestSize, aBitmap );
                     return true;
                 }
+#else
+                SalBitmap* pSalMask = ImplGetSVData()->mpDefInst->CreateSalBitmap();
 
+                if( pSalBmp->Create( xBitmapCanvas, aSize ) && pSalMask->Create( xBitmapCanvas, aSize, true ) )
+                {
+                    Bitmap aBitmap( pSalBmp );
+                    Bitmap aMask( pSalMask );
+                    AlphaMask aAlphaMask( aMask );
+                    BitmapEx aBitmapEx( aBitmap, aAlphaMask );
+                    if ( pOut->GetMapMode() == MAP_PIXEL )
+                        pOut->DrawBitmapEx( rPos, aBitmapEx );
+                    else
+                        pOut->DrawBitmapEx( rPos, rLogicDestSize, aBitmapEx );
+                    return true;
+                }
+                delete pSalMask;
+#endif
                 delete pSalBmp;
             }
         }