tdf#92296: Fix off-by-one formatting of text runs on OOXML export

This essentially reverts commit 8865ed2e
and implements a different fix for tdf#90812:
If the formatting of entire cell is uniform, remove formatting of the
leading text run and create corresponding cell style. In all other cases,
write out formattings for each individual run.

Change-Id: I7724b7a474f773f2cdc39e9150d843642fb05bbe
Reviewed-on: https://gerrit.libreoffice.org/19811Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>

sc/source/filter/excel/xestring.cxx

@@ -428,10 +428,9 @@ void XclExpString::WriteXml( XclExpXmlStream& rStrm ) const
         const XclExpFont* pFont = NULL;
         for ( ; aIt != aEnd; ++aIt )
         {
-            // pFont getting first then pass it to run otherwise pFont is NULL.
-            pFont = rFonts.GetFont( aIt->mnFontIdx );
             nStart = lcl_WriteRun( rStrm, GetUnicodeBuffer(),
                     nStart, aIt->mnChar-nStart, pFont );
+            pFont = rFonts.GetFont( aIt->mnFontIdx );
         }
         lcl_WriteRun( rStrm, GetUnicodeBuffer(),
                 nStart, GetUnicodeBuffer().size() - nStart, pFont );

sc/source/filter/excel/xetable.cxx

@@ -723,13 +723,18 @@ void XclExpLabelCell::Init( const XclExpRoot& rRoot,
     mxText = xText;
     mnSstIndex = 0;
 
-    // create the cell format
-    sal_uInt16 nXclFont = mxText->RemoveLeadingFont();
-    if( GetXFId() == EXC_XFID_NOTFOUND )
+    const XclFormatRunVec& rFormats = mxText->GetFormats();
+    // Create the cell format and remove formatting of the leading run
+    // if the entire string is equally formatted
+    if( rFormats.size() == 1 )
     {
-        OSL_ENSURE( nXclFont != EXC_FONT_NOTFOUND, "XclExpLabelCell::Init - leading font not found" );
-        bool bForceLineBreak = mxText->IsWrapped();
-        SetXFId( rRoot.GetXFBuffer().InsertWithFont( pPattern, ApiScriptType::WEAK, nXclFont, bForceLineBreak ) );
+        sal_uInt16 nXclFont = mxText->RemoveLeadingFont();
+        if( GetXFId() == EXC_XFID_NOTFOUND )
+        {
+            OSL_ENSURE( nXclFont != EXC_FONT_NOTFOUND, "XclExpLabelCell::Init - leading font not found" );
+            bool bForceLineBreak = mxText->IsWrapped();
+            SetXFId( rRoot.GetXFBuffer().InsertWithFont( pPattern, ApiScriptType::WEAK, nXclFont, bForceLineBreak ) );
+        }
     }
 
     // get auto-wrap attribute from cell format