Resolves: #i125187# more precision where the BLIP graphic is located

(cherry picked from commit 2be700ef)

Conflicts:
	filter/source/msfilter/msdffimp.cxx

Change-Id: I3926d5f47469049662a292063f9810826c575154

filter/source/msfilter/msdffimp.cxx

@@ -5821,25 +5821,46 @@ void SvxMSDffManager::GetDrawingGroupContainerData( SvStream& rSt, sal_uLong nLe
             nLenFBSE = nLength;
             // is FBSE big enough for our data
             bool bOk = ( nSkipBLIPLen + 4 + nSkipBLIPPos + 4 <= nLenFBSE );
+            bool bBLIPIsDirectlyEmbedded(false);
 
-            if( bOk )
+            if(bOk)
             {
-                rSt.SeekRel( nSkipBLIPLen );
+                rSt.SeekRel(nSkipBLIPLen);
                 rSt.ReadUInt32( nBLIPLen );
-                rSt.SeekRel( nSkipBLIPPos );
+
+                // #i125187# do not simply skip these four bytes, but read them. This value
+                // is zero when the BLIP is embedded to the FBSE directly following in the
+                // stream, else 1. Use this as hint to be more reliable (see below)
+                rSt.ReadUInt32( nBLIPPos );
+
+                if (0 == nBLIPPos)
+                {
+                    bBLIPIsDirectlyEmbedded = true;
+                }
+
                 rSt.ReadUInt32( nBLIPPos );
                 bOk = rSt.GetError() == 0;
 
-                nLength -= nSkipBLIPLen+ 4 + nSkipBLIPPos + 4;
+                nLength -= nSkipBLIPLen + 4 + nSkipBLIPPos + 4;
             }
 
             if( bOk )
             {
-                // specialty:
-                // If nBLIPLen is less than nLenFBSE AND nBLIPPos is NULL,
-                // then we assume, that the image is in FBSE!
-                if( (!nBLIPPos) && (nBLIPLen < nLenFBSE) )
+                // #i125187# the original check to test if the BLIP is following embeded in the FBSE was
+                // was (!nBLIPPos && nBLIPLen < nLenFBSE), but there are ppt documents
+                // where this is not sufficient (what means that for BLIPs in the picture
+                // stream the same conditions can be true sometimes). I experimented with various
+                // ppt files and detected that the four bytes before reading the nBLIPPos
+                // contain a flag which describes that embedding more reliable, thus I will
+                // use it here now in the form of the bBLIPIsDirectlyEmbedded variable (see above).
+                // This modification works with all ppt files I found which use directly embedded
+                // BLIPs and with the file which showed the error. More work may be needed when
+                // exceptions to this more strict schema may show up, though.
+                if (0 == nBLIPPos && nBLIPLen < nLenFBSE && bBLIPIsDirectlyEmbedded)
+                {
+                    // get BLIP file position as directly following embedded
                     nBLIPPos = rSt.Tell() + 4;
+                }
 
                 // That worked great!
                 // We store, that we do have one FBSE more in the pointer array.