Resolves: #i124966# keep picture format information

- <GfxLink> instance - also for the reading of preview picture data

in order to avoid trouble on save in case that the preview data equals the
picture data

(cherry picked from commit d6af1b60)

Conflicts:
	svx/source/svdraw/svdograf.cxx

Change-Id: Ifecb07b4d5d33d593502fccd6f21644893027d2d

svx/source/svdraw/svdograf.cxx

@@ -1352,9 +1352,11 @@ IMPL_LINK( SdrGrafObj, ImpSwapHdl, GraphicObject*, pO )
                     {
                         pFilterData = new com::sun::star::uno::Sequence< com::sun::star::beans::PropertyValue >( 3 );
 
-                        com::sun::star::awt::Size aPreviewSizeHint( 64, 64 );
-                        bool bAllowPartialStreamRead = true;
-                        bool bCreateNativeLink = false;
+                        const com::sun::star::awt::Size aPreviewSizeHint( 64, 64 );
+                        const bool bAllowPartialStreamRead = true;
+                        // create <GfxLink> instance also for previews in order to avoid that its corresponding
+                        // data is cleared in the graphic cache entry in case that the preview data equals the complete graphic data
+                        const bool bCreateNativeLink = true;
                         (*pFilterData)[ 0 ].Name = "PreviewSizeHint";
                         (*pFilterData)[ 0 ].Value <<= aPreviewSizeHint;
                         (*pFilterData)[ 1 ].Name = "AllowPartialStreamRead";