Fix ShiftMergedRegions

RT

main/SS/UserModel/Helpers/RowShifter.cs

@@ -49,39 +49,50 @@ namespace NPOI.SS.UserModel.Helpers
         {
             var ShiftedRegions = new List<CellRangeAddress>();
             ISet<int> removedIndices = new HashSet<int>();
-            //move merged regions completely if they fall within the new region boundaries when they are Shifted
             var size = sheet.NumMergedRegions;
-            var lastCol = sheet.Any() ? sheet.Max(r => r.LastCellNum) : 0;
 
             for (var i = 0; i < size; i++)
             {
                 var merged = sheet.GetMergedRegion(i);
 
-                // remove merged region that overlaps Shifting
-                if (RemovalNeeded(merged, startRow, endRow, n, lastCol))
+                //Shift if the merged region inside the Shifting rows
+                if (merged.FirstRow >= startRow && merged.LastRow <= endRow)
                 {
+                    merged.FirstRow += n;
+                    merged.LastRow += n;
+                    //have to Remove/add it back
+                    ShiftedRegions.Add(merged);
                     removedIndices.Add(i);
+
                     continue;
                 }
 
-                var inStart = merged.FirstRow >= startRow || merged.LastRow >= startRow;
-                var inEnd = merged.FirstRow <= endRow || merged.LastRow <= endRow;
-
                 //don't check if it's not within the Shifted area
-                if (!inStart || !inEnd)
+                if (n > 0)
                 {
-                    continue;
+                    // area is moved down
+                    if (merged.LastRow < startRow
+                     || merged.FirstRow > endRow + n
+                     || merged.FirstRow > endRow && merged.LastRow < startRow + n
+                    )
+                    {
+                        continue;
+                    }
                 }
-
-                //only shift if the region outside the Shifted rows is not merged too
-                if (!merged.ContainsRow(startRow - 1) && !merged.ContainsRow(endRow + 1))
+                else
                 {
-                    merged.FirstRow += n;
-                    merged.LastRow += n;
-                    //have to Remove/add it back
-                    ShiftedRegions.Add(merged);
-                    removedIndices.Add(i);
+                    // area is moved up
+                    if (merged.LastRow < startRow + n
+                     || merged.FirstRow > endRow
+                     || merged.FirstRow > endRow + n && merged.LastRow < startRow
+                    )
+                    {
+                        continue;
+                    }
                 }
+
+                //remove merged region that overlaps Shifting
+                removedIndices.Add(i);
             }
 
             if (removedIndices.Count != 0)
@@ -89,7 +100,7 @@ namespace NPOI.SS.UserModel.Helpers
                 sheet.RemoveMergedRegions(removedIndices.ToList());
             }
 
-            //read so it doesn't Get Shifted again
+            //add it which is within the shifted area back
             foreach (var region in ShiftedRegions)
             {
                 sheet.AddMergedRegion(region);
@@ -97,19 +108,6 @@ namespace NPOI.SS.UserModel.Helpers
 
             return ShiftedRegions;
         }
-
-        // Keep in sync with {@link ColumnShifter#removalNeeded}
-        private bool RemovalNeeded(CellRangeAddress merged, int startRow, int endRow, int n, int lastCol)
-        {
-            // build a range of the rows that are overwritten, i.e. the target-area, but without
-            // rows that are moved along
-            var firstRow = startRow + n;
-            var lastRow = endRow + n;
-            CellRangeAddress overwrite = new CellRangeAddress(firstRow, lastRow, 0, lastCol);
-
-            // if the merged-region and the overwritten area intersect, we need to remove it
-            return merged.Intersects(overwrite);
-        }
         
         /// <summary>
         /// Verify that the given column indices and step denote a valid range of columns to shift