sc-perf: possibly halve the iterations to find the most used XF index

Iterate only 513 equally attributed cells instead of 1024, per row.
This could be further enhanced if we remembered in advance in which
column the last attribution is located and use empty/default for the
rest, or use spans.

Change-Id: Id6172bd6c350a92fda4f1b637e70ff4f19d59c5a

1 files changed, 9 insertions, 0 deletions

diff --git a/sc/source/filter/excel/xetable.cxx b/sc/source/filter/excel/xetable.cxx
index d22eb46a9e57..37470f52bad0 100644
--- a/sc/source/filter/excel/xetable.cxx
+++ b/sc/source/filter/excel/xetable.cxx
@@ -1960,6 +1960,7 @@ void XclExpRow::Finalize( const ScfUInt16Vec& rColXFIndexes, bool bProgress )
     XclExpXFIndexMap aIndexMap;
     sal_uInt16 nRowXFIndex = EXC_XF_DEFAULTCELL;
     size_t nMaxXFCount = 0;
+    const size_t nHalfIndexes = aXFIndexes.size() / 2;
     for( aCellIt = aCellBeg; aCellIt != aCellEnd; ++aCellIt )
     {
         if( *aCellIt != EXC_XF_NOTFOUND )
@@ -1970,6 +1971,14 @@ void XclExpRow::Finalize( const ScfUInt16Vec& rColXFIndexes, bool bProgress )
             {
                 nRowXFIndex = *aCellIt;
                 nMaxXFCount = rnCount;
+                if (nMaxXFCount > nHalfIndexes)
+                {
+                    // No other XF index can have a greater usage count, we
+                    // don't need to loop through the remaining cells.
+                    // Specifically for the tail of unused default
+                    // cells/columns this makes a difference.
+                    break;  // for
+                }
             }
         }
     }