patch from Stefan Thurnherr: bug 57450: autosize columns in SXSSF using rows that have been flushed to disk

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1717146 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/ss/util/SheetUtil.java

@@ -36,6 +36,7 @@ import org.apache.poi.ss.usermodel.RichTextString;
 import org.apache.poi.ss.usermodel.Row;
 import org.apache.poi.ss.usermodel.Sheet;
 import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.util.Internal;
 
 
 /**
@@ -244,7 +245,8 @@ public class SheetUtil {
      * @param wb the workbook to get the default character width from
      * @return default character width in pixels
      */
-    private static int getDefaultCharWidth(final Workbook wb) {
+    @Internal
+    public static int getDefaultCharWidth(final Workbook wb) {
         Font defaultFont = wb.getFontAt((short) 0);
 
         AttributedString str = new AttributedString(String.valueOf(defaultChar));

src/ooxml/java/org/apache/poi/xssf/streaming/AutoSizeColumnTracker.java

@@ -0,0 +1,371 @@
+/* ====================================================================
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You under the Apache License, Version 2.0
+   (the "License"); you may not use this file except in compliance with
+   the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+==================================================================== */
+
+package org.apache.poi.xssf.streaming;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+import java.util.SortedSet;
+import java.util.TreeSet;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.DataFormatter;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.util.SheetUtil;
+import org.apache.poi.util.Internal;
+
+/**
+ * Tracks best fit column width for rows of an {@link SXSSFSheet},
+ * to be able to correctly calculate auto-sized column widths even
+ * if some rows are already flushed to disk.
+ * This is an auxiliary data structure that uses a TreeMap containing
+ * one entry per tracked column, where the key is the column index and
+ * the value is a pair of doubles. This data structure's memory footprint
+ * is linear with the number of *tracked* columns and invariant with
+ * the number of rows or columns in the sheet.
+ * @since 3.14beta1
+*/
+@Internal
+/*package*/ class AutoSizeColumnTracker {
+    private final int defaultCharWidth;
+    private final DataFormatter dataFormatter = new DataFormatter();
+
+    // map of tracked columns, with values containing the best-fit width for the column
+    // Using a HashMap instead of a TreeMap because insertion (trackColumn), removal (untrackColumn), and membership (everything)
+    // will be called more frequently than getTrackedColumns(). The O(1) cost of insertion, removal, and membership operations
+    // outweigh the infrequent O(n*log n) cost of sorting getTrackedColumns().
+    // Memory consumption for a HashMap and TreeMap is about the same
+    private final Map<Integer, ColumnWidthPair> maxColumnWidths = new HashMap<Integer, ColumnWidthPair>();
+    // untrackedColumns stores columns have been explicitly untracked so they aren't implicitly re-tracked by trackAllColumns
+    // Using a HashSet instead of a TreeSet because we don't care about order.
+    private final Set<Integer> untrackedColumns = new HashSet<Integer>();
+    private boolean trackAllColumns = false;
+
+    /**
+     * Tuple to store the column widths considering and not considering merged cells
+     * If more permutations are needed, it may be prudent to require the user to specify
+     * how they intend to auto-size a column when they track the column, so calculations
+     * are limited to the desired intentions. Unless this proves to be a performance problem,
+     * it's probably better to let the user defer how they want to auto-size to SXSSFSheet.autoSizeColumn,
+     * rather than twice (via SXSSFSheet.trackColumn(int column, boolean useMergedCells) and again at
+     * SXSFSheet.autoSizeColumn(int column, boolean useMergedCells))
+     * @since 3.14beta1
+     */
+    private static class ColumnWidthPair {
+        private double withSkipMergedCells;
+        private double withUseMergedCells;
+        
+        public ColumnWidthPair() {
+            this(-1.0, -1.0);
+        }
+        
+        public ColumnWidthPair(final double columnWidthSkipMergedCells, final double columnWidthUseMergedCells) {
+            withSkipMergedCells = columnWidthSkipMergedCells;
+            withUseMergedCells = columnWidthUseMergedCells;
+        }
+        
+        /**
+         * Gets the current best-fit column width for the provided settings
+         *
+         * @param useMergedCells true if merged cells are considered into the best-fit column width calculation
+         * @return best fit column width, measured in default character widths.
+         */
+        public double getMaxColumnWidth(final boolean useMergedCells) {
+            return useMergedCells ? withUseMergedCells : withSkipMergedCells;
+        }
+        
+        /**
+         * Sets the best-fit column width to the maximum of the current width and the provided width
+         *
+         * @param unmergedWidth the best-fit column width calculated with useMergedCells=False
+         * @param mergedWidth the best-fit column width calculated with useMergedCells=True
+         */
+        public void setMaxColumnWidths(double unmergedWidth, double mergedWidth) {
+            withUseMergedCells = Math.max(withUseMergedCells, mergedWidth);
+            withSkipMergedCells = Math.max(withUseMergedCells, unmergedWidth);
+        }
+    }
+    
+    /**
+     * AutoSizeColumnTracker constructor. Holds no reference to <code>sheet</code>
+     *
+     * @param sheet the sheet associated with this auto-size column tracker
+     * @since 3.14beta1
+     */
+    public AutoSizeColumnTracker(final Sheet sheet) {
+        // If sheet needs to be saved, use a java.lang.ref.WeakReference to avoid garbage collector gridlock.
+        defaultCharWidth = SheetUtil.getDefaultCharWidth(sheet.getWorkbook());
+    }
+    
+    /**
+     * Get the currently tracked columns, naturally ordered.
+     * Note if all columns are tracked, this will only return the columns that have been explicitly or implicitly tracked,
+     * which is probably only columns containing 1 or more non-blank values
+     *
+     * @return a set of the indices of all tracked columns
+     * @since 3.14beta1
+     */
+    public SortedSet<Integer> getTrackedColumns() {
+        SortedSet<Integer> sorted = new TreeSet<Integer>(maxColumnWidths.keySet());
+        return Collections.unmodifiableSortedSet(sorted);
+    }
+    
+    /**
+     * Returns true if column is currently tracked for auto-sizing.
+     *
+     * @param column the index of the column to check
+     * @return true if column is tracked
+     * @since 3.14beta1
+     */
+    public boolean isColumnTracked(int column) {
+        return trackAllColumns || maxColumnWidths.containsKey(column);
+    }
+    
+    /**
+     * Returns true if all columns are implicitly tracked.
+     *
+     * @return true if all columns are implicitly tracked
+     * @since 3.14beta1
+     */
+    public boolean isAllColumnsTracked() {
+        return trackAllColumns;
+    }
+    
+    /**
+     * Tracks all non-blank columns
+     * Allows columns that have been explicitly untracked to be tracked
+     * @since 3.14beta1
+     */
+    public void trackAllColumns() {
+        trackAllColumns = true;
+        untrackedColumns.clear();
+    }
+    
+    /**
+     * Untrack all columns that were previously tracked for auto-sizing.
+     * All best-fit column widths are forgotten.
+     * @since 3.14beta1
+     */
+    public void untrackAllColumns() {
+        trackAllColumns = false;
+        maxColumnWidths.clear();
+        untrackedColumns.clear();
+    }
+    
+    /**
+     * Marks multiple columns for inclusion in auto-size column tracking.
+     * Note this has undefined behavior if columns are tracked after one or more rows are written to the sheet.
+     * Any column in <code>columns</code> that are already tracked are ignored by this call. 
+     *
+     * @param columns the indices of the columns to track
+     * @since 3.14beta1
+     */
+    public void trackColumns(Collection<Integer> columns)
+    {
+        for (final int column : columns) {
+            trackColumn(column);
+        }
+    }
+
+    /**
+     * Marks a column for inclusion in auto-size column tracking.
+     * Note this has undefined behavior if a column is tracked after one or more rows are written to the sheet.
+     * If <code>column</code> is already tracked, this call does nothing.
+     *
+     * @param column the index of the column to track for auto-sizing
+     * @return if column is already tracked, the call does nothing and returns false
+     * @since 3.14beta1
+     */
+    public boolean trackColumn(int column) {
+        untrackedColumns.remove(column);
+        if (!maxColumnWidths.containsKey(column)) {
+            maxColumnWidths.put(column, new ColumnWidthPair());
+            return true;
+        }
+        return false;
+    }
+    
+    /**
+     * Implicitly track a column if it has not been explicitly untracked
+     * If it has been explicitly untracked, this call does nothing and returns false.
+     * Otherwise return true
+     *
+     * @param column the column to implicitly track
+     * @return false if column has been explicitly untracked, otherwise return true
+     */
+    private boolean implicitlyTrackColumn(int column) {
+        if (!untrackedColumns.contains(column)) {
+            trackColumn(column);
+            return true;
+        }
+        return false;
+    }
+    
+    /**
+     * Removes columns that were previously marked for inclusion in auto-size column tracking.
+     * When a column is untracked, the best-fit width is forgotten.
+     * Any column in <code>columns</code> that is not tracked will be ignored by this call.
+     *
+     * @param columns the indices of the columns to track for auto-sizing
+     * @return true if one or more columns were untracked as a result of this call
+     * @since 3.14beta1
+     */
+    public boolean untrackColumns(Collection<Integer> columns)
+    {
+        untrackedColumns.addAll(columns);
+        return maxColumnWidths.keySet().removeAll(columns);
+    }
+    
+    /**
+     * Removes a column that was previously marked for inclusion in auto-size column tracking.
+     * When a column is untracked, the best-fit width is forgotten.
+     * If <code>column</code> is not tracked, it will be ignored by this call.
+     *
+     * @param column the index of the column to track for auto-sizing
+     * @return true if column was tracked prior this call, false if no action was taken
+     * @since 3.14beta1
+     */
+    public boolean untrackColumn(int column) {
+        untrackedColumns.add(column);
+        return maxColumnWidths.keySet().remove(column);
+    }
+
+    /**
+     * Get the best-fit width of a tracked column
+     *
+     * @param column the index of the column to get the current best-fit width of
+     * @param useMergedCells true if merged cells should be considered when computing the best-fit width
+     * @return best-fit column width, measured in units of 1/256th of a character width
+     * @throws IllegalStateException if column is not tracked and trackAllColumns is false
+     * @since 3.14beta1
+     */
+    public int getBestFitColumnWidth(int column, boolean useMergedCells) {
+        if (!maxColumnWidths.containsKey(column)) {
+            // if column is not tracked, implicitly track the column if trackAllColumns is True and column has not been explicitly untracked
+            if (trackAllColumns) {
+                if (!implicitlyTrackColumn(column)) {
+                    final Throwable reason = new IllegalStateException(
+                            "Column was explicitly untracked after trackAllColumns() was called.");
+                    throw new IllegalStateException(
+                            "Cannot get best fit column width on explicitly untracked column " + column + ". " +
+                            "Either explicitly track the column or track all columns.", reason);
+                }
+            }
+            else {
+                final Throwable reason = new IllegalStateException(
+                        "Column was never explicitly tracked and isAllColumnsTracked() is false " +
+                        "(trackAllColumns() was never called or untrackAllColumns() was called after trackAllColumns() was called).");
+                throw new IllegalStateException(
+                        "Cannot get best fit column width on untracked column " + column + ". " +
+                        "Either explicitly track the column or track all columns.", reason);
+            }
+        }
+        final double width = maxColumnWidths.get(column).getMaxColumnWidth(useMergedCells);
+        return (int) (256*width);
+    }
+    
+
+    
+    /**
+     * Calculate the best fit width for each tracked column in row
+     *
+     * @param row the row to get the cells
+     * @since 3.14beta1
+     */
+    public void updateColumnWidths(Row row) {
+        // track new columns
+        implicitlyTrackColumnsInRow(row);
+        
+        // update the widths
+        // for-loop over the shorter of the number of cells in the row and the number of tracked columns
+        // these two for-loops should do the same thing
+        if (maxColumnWidths.size() < row.getPhysicalNumberOfCells()) {
+            // loop over the tracked columns, because there are fewer tracked columns than cells in this row
+            for (final Entry<Integer, ColumnWidthPair> e : maxColumnWidths.entrySet()) {
+                final int column = e.getKey();
+                final Cell cell = row.getCell(column); //is MissingCellPolicy=Row.RETURN_NULL_AND_BLANK needed?
+
+                // FIXME: if cell belongs to a merged region, some of the merged region may have fallen outside of the random access window
+                // In this case, getting the column width may result in an error. Need to gracefully handle this.
+
+                // FIXME: Most cells are not merged, so calling getCellWidth twice re-computes the same value twice.
+                // Need to rewrite this to avoid unnecessary computation if this proves to be a performance bottleneck.
+
+                if (cell != null) {
+                    final ColumnWidthPair pair = e.getValue();
+                    updateColumnWidth(cell, pair);
+                }
+            }
+        }
+        else {
+            // loop over the cells in this row, because there are fewer cells in this row than tracked columns
+            for (final Cell cell : row) {
+                final int column = cell.getColumnIndex();
+
+                // FIXME: if cell belongs to a merged region, some of the merged region may have fallen outside of the random access window
+                // In this case, getting the column width may result in an error. Need to gracefully handle this.
+
+                // FIXME: Most cells are not merged, so calling getCellWidth twice re-computes the same value twice.
+                // Need to rewrite this to avoid unnecessary computation if this proves to be a performance bottleneck.
+
+                if (maxColumnWidths.containsKey(column)) {
+                    final ColumnWidthPair pair = maxColumnWidths.get(column);
+                    updateColumnWidth(cell, pair);
+                }
+            }
+        }
+    }
+    
+    /**
+     * Helper for {@link #updateColumnWidths(Row)}.
+     * Implicitly track the columns corresponding to the cells in row.
+     * If all columns in the row are already tracked, this call does nothing.
+     * Explicitly untracked columns will not be tracked.
+     *
+     * @param row the row containing cells to implicitly track the columns
+     * @since 3.14beta1
+     */
+    private void implicitlyTrackColumnsInRow(Row row) {
+        // track new columns
+        if (trackAllColumns) {
+            // if column is not tracked, implicitly track the column if trackAllColumns is True and column has not been explicitly untracked 
+            for (final Cell cell : row) {
+                final int column = cell.getColumnIndex();
+                implicitlyTrackColumn(column);
+            }
+        }
+    }
+    
+    /**
+     * Helper for {@link #updateColumnWidths(Row)}.
+     *
+     * @param cell the cell to compute the best fit width on
+     * @param pair the column width pair to update
+     * @since 3.14beta1
+     */
+    private void updateColumnWidth(final Cell cell, final ColumnWidthPair pair) {
+        final double unmergedWidth = SheetUtil.getCellWidth(cell, defaultCharWidth, dataFormatter, false);
+        final double mergedWidth = SheetUtil.getCellWidth(cell, defaultCharWidth, dataFormatter, true);
+        pair.setMaxColumnWidths(unmergedWidth, mergedWidth);
+    }
+}

src/ooxml/java/org/apache/poi/xssf/streaming/SXSSFSheet.java

@@ -19,9 +19,11 @@ package org.apache.poi.xssf.streaming;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.TreeMap;
 
 import org.apache.poi.hssf.util.PaneInformation;
@@ -62,6 +64,7 @@ public class SXSSFSheet implements Sheet, Cloneable
     private final TreeMap<Integer,SXSSFRow> _rows=new TreeMap<Integer,SXSSFRow>();
     private final SheetDataWriter _writer;
     private int _randomAccessWindowSize = SXSSFWorkbook.DEFAULT_WINDOW_SIZE;
+    private final AutoSizeColumnTracker _autoSizeColumnTracker;
     private int outlineLevelRow = 0;
     private int lastFlushedRowNumber = -1;
     private boolean allFlushed = false;
@@ -71,6 +74,7 @@ public class SXSSFSheet implements Sheet, Cloneable
         _sh = xSheet;
         _writer = workbook.createSheetDataWriter();
         setRandomAccessWindowSize(_workbook.getRandomAccessWindowSize());
+        _autoSizeColumnTracker = new AutoSizeColumnTracker(this);
     }
 
     /**
@@ -1378,6 +1382,118 @@ public class SXSSFSheet implements Sheet, Cloneable
         _sh.setDefaultColumnStyle(column, style);
     }
     
+    
+    /**
+     * Track a column in the sheet for auto-sizing.
+     * Note this has undefined behavior if a column is tracked after one or more rows are written to the sheet.
+     * If <code>column</code> is already tracked, this call does nothing.
+     *
+     * @param column the column to track for autosizing
+     * @since 3.14beta1
+     * @see #trackColumnsForAutoSizing(Collection)
+     * @see #trackAllColumnsForAutoSizing()
+     */
+    public void trackColumnForAutoSizing(int column)
+    {
+        _autoSizeColumnTracker.trackColumn(column);
+    }
+    
+    /**
+     * Track several columns in the sheet for auto-sizing.
+     * Note this has undefined behavior if columns are tracked after one or more rows are written to the sheet.
+     * Any column in <code>columns</code> that are already tracked are ignored by this call.
+     *
+     * @param columns the columns to track for autosizing
+     * @since 3.14beta1
+     */
+    public void trackColumnsForAutoSizing(Collection<Integer> columns)
+    {
+        _autoSizeColumnTracker.trackColumns(columns);
+    }
+    
+    /**
+     * Tracks all columns in the sheet for auto-sizing. If this is called, individual columns do not need to be tracked.
+     * Because determining the best-fit width for a cell is expensive, this may affect the performance.
+     * @since 3.14beta1
+     */
+    public void trackAllColumnsForAutoSizing()
+    {
+        _autoSizeColumnTracker.trackAllColumns();
+    }
+    
+    /**
+     * Removes a column that was previously marked for inclusion in auto-size column tracking.
+     * When a column is untracked, the best-fit width is forgotten.
+     * If <code>column</code> is not tracked, it will be ignored by this call.
+     *
+     * @param column the index of the column to track for auto-sizing
+     * @return true if column was tracked prior to being untracked, false if no action was taken
+     */
+    /**
+     * 
+     *
+     * @param column the index of the column to track for auto-sizing
+     * @return true if column was tracked prior to this call, false if no action was taken
+     * @since 3.14beta1
+     * @see #untrackColumnsForAutoSizing(Collection)
+     * @see #untrackAllColumnsForAutoSizing(int)
+     */
+    public boolean untrackColumnForAutoSizing(int column)
+    {
+        return _autoSizeColumnTracker.untrackColumn(column);
+    }
+    
+    /**
+     * Untracks several columns in the sheet for auto-sizing.
+     * When a column is untracked, the best-fit width is forgotten.
+     * Any column in <code>columns</code> that is not tracked will be ignored by this call.
+     *
+     * @param columns the indices of the columns to track for auto-sizing
+     * @return true if one or more columns were untracked as a result of this call
+     *
+     * @param columns the columns to track for autosizing
+     * @since 3.14beta1
+     */
+    public boolean untrackColumnsForAutoSizing(Collection<Integer> columns)
+    {
+        return _autoSizeColumnTracker.untrackColumns(columns);
+    }
+    
+    /**
+     * Untracks all columns in the sheet for auto-sizing. Best-fit column widths are forgotten.
+     * If this is called, individual columns do not need to be untracked.
+     * @since 3.14beta1
+     */
+    public void untrackAllColumnsForAutoSizing()
+    {
+        _autoSizeColumnTracker.untrackAllColumns();
+    }
+    
+    /**
+     * Returns true if column is currently tracked for auto-sizing.
+     *
+     * @param column the index of the column to check
+     * @return true if column is tracked
+     * @since 3.14beta1
+     */
+    public boolean isColumnTrackedForAutoSizing(int column)
+    {
+        return _autoSizeColumnTracker.isColumnTracked(column);
+    }
+    
+    /**
+     * Get the currently tracked columns for auto-sizing.
+     * Note if all columns are tracked, this will only return the columns that have been explicitly or implicitly tracked,
+     * which is probably only columns containing 1 or more non-blank values
+     *
+     * @return a set of the indices of all tracked columns
+     * @since 3.14beta1
+     */
+    public Set<Integer> getTrackedColumnsForAutoSizing()
+    {
+        return _autoSizeColumnTracker.getTrackedColumns();
+    }
+
     /**
      * Adjusts the column width to fit the contents.
      *
@@ -1389,7 +1505,16 @@ public class SXSSFSheet implements Sheet, Cloneable
      * You can specify whether the content of merged cells should be considered or ignored.
      *  Default is to ignore merged cells.
      *  
-     * @param column the column index
+     *  <p>
+     *  Special note about SXSSF implementation: You must register the columns you wish to track with
+     *  the SXSSFSheet using {@link #trackColumnForAutoSizing(int)} or {@link #trackAllColumnsForAutoSizing()}.
+     *  This is needed because the rows needed to compute the column width may have fallen outside the
+     *  random access window and been flushed to disk.
+     *  Tracking columns is required even if all rows are in the random access window.
+     *  </p>
+     *  <p><i>New in POI 3.14 beta 1: auto-sizes columns using cells from current and flushed rows.</i></p>
+     *
+     * @param column the column index to auto-size
      */
     @Override
     public void autoSizeColumn(int column)
@@ -1407,21 +1532,53 @@ public class SXSSFSheet implements Sheet, Cloneable
      * You can specify whether the content of merged cells should be considered or ignored.
      *  Default is to ignore merged cells.
      *  
-     * @param column the column index
+     *  <p>
+     *  Special note about SXSSF implementation: You must register the columns you wish to track with
+     *  the SXSSFSheet using {@link #trackColumnForAutoSizing(int)} or {@link #trackAllColumnsForAutoSizing()}.
+     *  This is needed because the rows needed to compute the column width may have fallen outside the
+     *  random access window and been flushed to disk.
+     *  Tracking columns is required even if all rows are in the random access window.
+     *  </p>
+     *  <p><i>New in POI 3.14 beta 1: auto-sizes columns using cells from current and flushed rows.</i></p>
+     *
+     * @param column the column index to auto-size
      * @param useMergedCells whether to use the contents of merged cells when calculating the width of the column
      */
     @Override
     public void autoSizeColumn(int column, boolean useMergedCells)
     {
-        double width = SheetUtil.getColumnWidth(this, column, useMergedCells);
+        // Multiple calls to autoSizeColumn need to look up the best-fit width
+        // of rows already flushed to disk plus re-calculate the best-fit width
+        // of rows in the current window. It isn't safe to update the column
+        // widths before flushing to disk because columns in the random access
+        // window rows may change in best-fit width. The best-fit width of a cell
+        // is only fixed when it becomes inaccessible for modification.
+        // Changes to the shared strings table, styles table, or formulas might
+        // be able to invalidate the auto-size width without the opportunity
+        // to recalculate the best-fit width for the flushed rows. This is an
+        // inherent limitation of SXSSF. If having correct auto-sizing is
+        // critical, the flushed rows would need to be re-read by the read-only
+        // XSSF eventmodel (SAX) or the memory-heavy XSSF usermodel (DOM). 
+        final int flushedWidth;
+        try {
+            // get the best fit width of rows already flushed to disk
+            flushedWidth = _autoSizeColumnTracker.getBestFitColumnWidth(column, useMergedCells);
+        }
+        catch (final IllegalStateException e) {
+            throw new IllegalStateException("Could not auto-size column. Make sure the column was tracked prior to auto-sizing the column.", e);
+        }
         
-        if (width != -1) {
+        // get the best-fit width of rows currently in the random access window
-            width *= 256;
+        final int activeWidth = (int) (256 * SheetUtil.getColumnWidth(this, column, useMergedCells));
-            int maxColumnWidth = 255*256; // The maximum column width for an individual cell is 255 characters
+
-            if (width > maxColumnWidth) {
+        // the best-fit width for both flushed rows and random access window rows
-                width = maxColumnWidth;
+        // flushedWidth or activeWidth may be negative if column contains only blank cells
-            }
+        final int bestFitWidth = Math.max(flushedWidth,  activeWidth);
-            setColumnWidth(column, (int)(width));
+        
+        if (bestFitWidth > 0) {
+            final int maxColumnWidth = 255*256; // The maximum column width for an individual cell is 255 characters
+            final int width = Math.min(bestFitWidth,  maxColumnWidth);
+            setColumnWidth(column, width);
         }
     }
 
@@ -1681,6 +1838,8 @@ public class SXSSFSheet implements Sheet, Cloneable
         if (firstRowNum!=null) {
             int rowIndex = firstRowNum.intValue();
             SXSSFRow row = _rows.get(firstRowNum);
+            // Update the best fit column widths for auto-sizing just before the rows are flushed
+            _autoSizeColumnTracker.updateColumnWidths(row);
             _writer.writeRow(rowIndex, row);
             _rows.remove(firstRowNum);
             lastFlushedRowNumber = rowIndex;

src/ooxml/testcases/org/apache/poi/xssf/streaming/TestAutoSizeColumnTracker.java

@@ -0,0 +1,203 @@
+package org.apache.poi.xssf.streaming;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.junit.Assume.assumeFalse;
+import static org.junit.Assume.assumeTrue;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.SortedSet;
+import java.util.TreeSet;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.Font;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.ss.util.CellRangeAddress;
+import org.apache.poi.ss.util.SheetUtil;
+import org.junit.After;
+import org.junit.Assume;
+import org.junit.Before;
+import org.junit.Test;
+
+
+/**
+ * Tests the auto-sizing behaviour of {@link SXSSFSheet} when not all
+ * rows fit into the memory window size etc.
+ * 
+ * @see Bug #57450 which reported the original mis-behaviour
+ */
+public class TestAutoSizeColumnTracker {
+    
+    private SXSSFSheet sheet;
+    private SXSSFWorkbook workbook;
+    private AutoSizeColumnTracker tracker;
+    private static final SortedSet<Integer> columns;
+    static {
+        SortedSet<Integer>_columns = new TreeSet<Integer>();
+        _columns.add(0);
+        _columns.add(1);
+        _columns.add(3);
+        columns = Collections.unmodifiableSortedSet(_columns);
+    }
+    private final static String SHORT_MESSAGE = "short";
+    private final static String LONG_MESSAGE = "This is a test of a long message! This is a test of a long message!";
+    
+    @Before
+    public void setUpSheetAndWorkbook() {
+        workbook = new SXSSFWorkbook();
+        sheet = workbook.createSheet();
+        tracker = new AutoSizeColumnTracker(sheet);
+    }
+    
+    @After
+    public void tearDownSheetAndWorkbook() throws IOException {
+        if (sheet != null) {
+            sheet.dispose();
+        }
+        if (workbook != null) {
+            workbook.close();
+        }
+    }
+    
+    @Test
+    public void trackAndUntrackColumn() {
+        assumeTrue(tracker.getTrackedColumns().isEmpty());
+        tracker.trackColumn(0);
+        Set<Integer> expected = new HashSet<Integer>();
+        expected.add(0);
+        assertEquals(expected, tracker.getTrackedColumns());
+        tracker.untrackColumn(0);
+        assertTrue(tracker.getTrackedColumns().isEmpty());
+    }
+    
+    @Test
+    public void trackAndUntrackColumns() {
+        assumeTrue(tracker.getTrackedColumns().isEmpty());
+        tracker.trackColumns(columns);
+        assertEquals(columns, tracker.getTrackedColumns());
+        tracker.untrackColumn(3);
+        tracker.untrackColumn(0);
+        tracker.untrackColumn(1);
+        assertTrue(tracker.getTrackedColumns().isEmpty());
+        tracker.trackColumn(0);
+        tracker.trackColumns(columns);
+        tracker.untrackColumn(4);
+        assertEquals(columns, tracker.getTrackedColumns());
+        tracker.untrackColumns(columns);
+        assertTrue(tracker.getTrackedColumns().isEmpty());
+    }
+    
+    @Test
+    public void trackAndUntrackAllColumns() {
+        assumeTrue(tracker.getTrackedColumns().isEmpty());
+        tracker.trackAllColumns();
+        assertTrue(tracker.getTrackedColumns().isEmpty());
+        
+        Row row = sheet.createRow(0);
+        for (int column : columns) {
+            row.createCell(column);
+        }
+        // implicitly track the columns
+        tracker.updateColumnWidths(row);
+        assertEquals(columns, tracker.getTrackedColumns());
+        
+        tracker.untrackAllColumns();
+        assertTrue(tracker.getTrackedColumns().isEmpty());
+    }
+    
+    @Test
+    public void isColumnTracked() {
+        assumeFalse(tracker.isColumnTracked(0));
+        tracker.trackColumn(0);
+        assertTrue(tracker.isColumnTracked(0));
+        tracker.untrackColumn(0);
+        assertFalse(tracker.isColumnTracked(0));
+    }
+    
+    @Test
+    public void getTrackedColumns() {
+        assumeTrue(tracker.getTrackedColumns().isEmpty());
+        
+        for (int column : columns) {
+            tracker.trackColumn(column);
+        }
+
+        assertEquals(3, tracker.getTrackedColumns().size());
+        assertEquals(columns, tracker.getTrackedColumns());
+    }
+    
+    @Test
+    public void isAllColumnsTracked() {
+        assertFalse(tracker.isAllColumnsTracked());
+        tracker.trackAllColumns();
+        assertTrue(tracker.isAllColumnsTracked());
+        tracker.untrackAllColumns();
+        assertFalse(tracker.isAllColumnsTracked());
+    }
+    
+    @Test
+    public void updateColumnWidths_and_getBestFitColumnWidth() {
+        tracker.trackAllColumns();
+        Row row1 = sheet.createRow(0);
+        Row row2 = sheet.createRow(1);
+        // A1, B1, D1
+        for (int column : columns) {
+            row1.createCell(column).setCellValue(LONG_MESSAGE);
+            row2.createCell(column+1).setCellValue(SHORT_MESSAGE);
+        }
+        tracker.updateColumnWidths(row1);
+        tracker.updateColumnWidths(row2);
+        sheet.addMergedRegion(CellRangeAddress.valueOf("D1:E1"));
+        
+        assumeRequiredFontsAreInstalled(workbook, row1.getCell(columns.iterator().next()));
+        
+        // Excel 2013 and LibreOffice 4.2.8.2 both treat columns with merged regions as blank
+        /**    A     B    C      D   E
+         * 1 LONG  LONG        LONGMERGE
+         * 2       SHORT SHORT     SHORT
+         */
+        
+        // measured in Excel 2013. Sizes may vary.
+        final int longMsgWidth = (int) (57.43*256);
+        final int shortMsgWidth = (int) (4.86*256);
+        
+        checkColumnWidth(longMsgWidth, 0, true);
+        checkColumnWidth(longMsgWidth, 0, false);
+        checkColumnWidth(longMsgWidth, 1, true);
+        checkColumnWidth(longMsgWidth, 1, false);
+        checkColumnWidth(shortMsgWidth, 2, true);
+        checkColumnWidth(shortMsgWidth, 2, false);
+        checkColumnWidth(-1, 3, true);
+        checkColumnWidth(longMsgWidth, 3, false);
+        checkColumnWidth(shortMsgWidth, 4, true); //but is it really? shouldn't autosizing column E use "" from E1 and SHORT from E2?
+        checkColumnWidth(shortMsgWidth, 4, false);
+    }
+    
+    private void checkColumnWidth(int expectedWidth, int column, boolean useMergedCells) {
+        final int bestFitWidth = tracker.getBestFitColumnWidth(column, useMergedCells);
+        if (bestFitWidth < 0 && expectedWidth < 0) return;
+        final double abs_error = Math.abs(bestFitWidth-expectedWidth);
+        final double rel_error = abs_error / expectedWidth;
+        if (rel_error > 0.25) {
+            fail("check column width: " +
+                    rel_error + ", " + abs_error + ", " +
+                    expectedWidth + ", " + bestFitWidth);
+        }
+        
+    }
+    
+    private static void assumeRequiredFontsAreInstalled(final Workbook workbook, final Cell cell) {
+        // autoSize will fail if required fonts are not installed, skip this test then
+        Font font = workbook.getFontAt(cell.getCellStyle().getFontIndex());
+        System.out.println(font.getFontHeightInPoints());
+        System.out.println(font.getFontName());
+        Assume.assumeTrue("Cannot verify autoSizeColumn() because the necessary Fonts are not installed on this machine: " + font,
+                          SheetUtil.canComputeColumnWidth(font));
+    }
+}

src/ooxml/testcases/org/apache/poi/xssf/streaming/TestSXSSFSheet.java

@@ -23,6 +23,8 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 
 import java.io.IOException;
+import java.util.SortedSet;
+import java.util.TreeSet;
 
 import org.apache.poi.ss.SpreadsheetVersion;
 import org.apache.poi.ss.usermodel.BaseTestSheet;
@@ -46,6 +48,12 @@ public class TestSXSSFSheet extends BaseTestSheet {
         SXSSFITestDataProvider.instance.cleanup();
     }
     
+    @Override
+    protected void trackColumnsForAutoSizingIfSXSSF(Sheet sheet) {
+        SXSSFSheet sxSheet = (SXSSFSheet) sheet;
+        sxSheet.trackAllColumnsForAutoSizing();
+    }
+
 
     /**
      * cloning of sheets is not supported in SXSSF

src/ooxml/testcases/org/apache/poi/xssf/streaming/TestSXSSFSheetAutoSizeColumn.java

@@ -0,0 +1,363 @@
+package org.apache.poi.xssf.streaming;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.junit.Assume.assumeFalse;
+import static org.junit.Assume.assumeTrue;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.SortedSet;
+import java.util.TreeSet;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.Font;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.ss.util.CellRangeAddress;
+import org.apache.poi.ss.util.SheetUtil;
+import org.junit.After;
+import org.junit.Assume;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameter;
+import org.junit.runners.Parameterized.Parameters;
+
+
+/**
+ * Tests the auto-sizing behaviour of {@link SXSSFSheet} when not all
+ * rows fit into the memory window size etc.
+ * 
+ * @see Bug #57450 which reported the original mis-behaviour
+ */
+@RunWith(Parameterized.class)
+public class TestSXSSFSheetAutoSizeColumn {
+    
+    private static final String SHORT_CELL_VALUE = "Ben";
+    private static final String LONG_CELL_VALUE = "B Be Ben Beni Benif Benify Benif Beni Ben Be B";
+    
+    // Approximative threshold to decide whether test is PASS or FAIL:
+    //  shortCellValue ends up with approx column width 1_000 (on my machine),
+    //  longCellValue ends up with approx. column width 10_000 (on my machine)
+    //  so shortCellValue can be expected to be < 5000 for all fonts
+    //  and longCellValue can be expected to be > 5000 for all fonts
+    private static final int COLUMN_WIDTH_THRESHOLD_BETWEEN_SHORT_AND_LONG = 5000;
+    private static final int MAX_COLUMN_WIDTH = 255*256;
+    
+    private static final SortedSet<Integer> columns;
+    static {
+        SortedSet<Integer>_columns = new TreeSet<Integer>();
+        _columns.add(0);
+        _columns.add(1);
+        _columns.add(3);
+        columns = Collections.unmodifiableSortedSet(_columns);
+    }
+    
+    
+    private SXSSFSheet sheet;
+    private SXSSFWorkbook workbook;
+    
+    @Parameter(0)
+    public boolean useMergedCells;
+    
+    @Parameters(name="{index}: useMergedCells={0}")
+    public static Collection<Object[]> data() {
+        return Arrays.asList(new Object[][] {     
+                 {false},
+                 {true}, 
+           });
+    }
+    
+    @After
+    public void tearDownSheetAndWorkbook() throws IOException {
+        if (sheet != null) {
+            sheet.dispose();
+        }
+        if (workbook != null) {
+            workbook.close();
+        }
+    }
+    
+    @Test
+    public void test_EmptySheet_NoException() {
+        workbook = new SXSSFWorkbook();
+        sheet = workbook.createSheet();
+        sheet.trackAllColumnsForAutoSizing();
+        
+        for (int i = 0; i < 10; i++) {
+            sheet.autoSizeColumn(i, useMergedCells);
+        }
+    }
+    
+    @Test
+    public void test_WindowSizeDefault_AllRowsFitIntoWindowSize() {
+        workbook = new SXSSFWorkbook();
+        sheet = workbook.createSheet();
+        sheet.trackAllColumnsForAutoSizing();
+        
+        final Cell cellRow0 = createRowWithCellValues(sheet, 0, LONG_CELL_VALUE);
+        
+        assumeRequiredFontsAreInstalled(workbook, cellRow0);
+
+        createRowWithCellValues(sheet, 1, SHORT_CELL_VALUE);
+
+        sheet.autoSizeColumn(0, useMergedCells);
+
+        assertColumnWidthStrictlyWithinRange(sheet.getColumnWidth(0), COLUMN_WIDTH_THRESHOLD_BETWEEN_SHORT_AND_LONG, MAX_COLUMN_WIDTH);
+    }
+    
+    @Test
+    public void test_WindowSizeEqualsOne_ConsiderFlushedRows() {
+        workbook = new SXSSFWorkbook(null, 1); // Window size 1 so only last row will be in memory
+        sheet = workbook.createSheet();
+        sheet.trackAllColumnsForAutoSizing();
+        
+        final Cell cellRow0 = createRowWithCellValues(sheet, 0, LONG_CELL_VALUE);
+        
+        assumeRequiredFontsAreInstalled(workbook, cellRow0);
+
+        createRowWithCellValues(sheet, 1, SHORT_CELL_VALUE);
+
+        sheet.autoSizeColumn(0, useMergedCells);
+
+        assertColumnWidthStrictlyWithinRange(sheet.getColumnWidth(0), COLUMN_WIDTH_THRESHOLD_BETWEEN_SHORT_AND_LONG, MAX_COLUMN_WIDTH);
+    }
+
+    @Test
+    public void test_WindowSizeEqualsOne_lastRowIsNotWidest() {
+        workbook = new SXSSFWorkbook(null, 1); // Window size 1 so only last row will be in memory
+        sheet = workbook.createSheet();
+        sheet.trackAllColumnsForAutoSizing();
+        
+        final Cell cellRow0 = createRowWithCellValues(sheet, 0, LONG_CELL_VALUE);
+        
+        assumeRequiredFontsAreInstalled(workbook, cellRow0);
+
+        createRowWithCellValues(sheet, 1, SHORT_CELL_VALUE);
+
+        sheet.autoSizeColumn(0, useMergedCells);
+
+        assertColumnWidthStrictlyWithinRange(sheet.getColumnWidth(0), COLUMN_WIDTH_THRESHOLD_BETWEEN_SHORT_AND_LONG, MAX_COLUMN_WIDTH);
+    }
+    
+    @Test
+    public void test_WindowSizeEqualsOne_lastRowIsWidest() {
+        workbook = new SXSSFWorkbook(null, 1); // Window size 1 so only last row will be in memory
+        sheet = workbook.createSheet();
+        sheet.trackAllColumnsForAutoSizing();
+        
+        final Cell cellRow0 = createRowWithCellValues(sheet, 0, SHORT_CELL_VALUE);
+
+        assumeRequiredFontsAreInstalled(workbook, cellRow0);
+        
+        createRowWithCellValues(sheet, 1, LONG_CELL_VALUE);
+
+        sheet.autoSizeColumn(0, useMergedCells);
+
+        assertColumnWidthStrictlyWithinRange(sheet.getColumnWidth(0), COLUMN_WIDTH_THRESHOLD_BETWEEN_SHORT_AND_LONG, MAX_COLUMN_WIDTH);
+    }
+    
+    // fails only for useMergedCell=true
+    @Test
+    public void test_WindowSizeEqualsOne_flushedRowHasMergedCell() {
+        workbook = new SXSSFWorkbook(null, 1); // Window size 1 so only last row will be in memory
+        sheet = workbook.createSheet();
+        sheet.trackAllColumnsForAutoSizing();
+        
+        Cell a1 = createRowWithCellValues(sheet, 0, LONG_CELL_VALUE);
+
+        assumeRequiredFontsAreInstalled(workbook, a1);
+        sheet.addMergedRegion(CellRangeAddress.valueOf("A1:B1"));
+        
+        createRowWithCellValues(sheet, 1, SHORT_CELL_VALUE, SHORT_CELL_VALUE);
+        
+        /**
+         *    A      B
+         * 1 LONGMERGED
+         * 2 SHORT SHORT
+         */
+        
+        sheet.autoSizeColumn(0, useMergedCells);
+        sheet.autoSizeColumn(1, useMergedCells);
+
+        if (useMergedCells) {
+            // Excel and LibreOffice behavior: ignore merged cells for auto-sizing.
+            // POI behavior: evenly distribute the column width among the merged columns.
+            //               each column must be auto-sized in order for the column widths
+            //               to add up to the best fit width.
+            final int colspan = 2;
+            final int expectedWidth = (10000 + 1000)/colspan; //average of 1_000 and 10_000
+            final int minExpectedWidth = expectedWidth / 2;
+            final int maxExpectedWidth = expectedWidth * 3 / 2;
+            assertColumnWidthStrictlyWithinRange(sheet.getColumnWidth(0), minExpectedWidth, maxExpectedWidth); //short
+        } else {
+            assertColumnWidthStrictlyWithinRange(sheet.getColumnWidth(0), COLUMN_WIDTH_THRESHOLD_BETWEEN_SHORT_AND_LONG, MAX_COLUMN_WIDTH); //long
+        }
+        assertColumnWidthStrictlyWithinRange(sheet.getColumnWidth(1), 0, COLUMN_WIDTH_THRESHOLD_BETWEEN_SHORT_AND_LONG); //short
+    }
+    
+    @Test
+    public void autoSizeColumn_trackColumnForAutoSizing() {
+        workbook = new SXSSFWorkbook();
+        sheet = workbook.createSheet();
+        sheet.trackColumnForAutoSizing(0);
+        
+        SortedSet<Integer> expected = new TreeSet<Integer>();
+        expected.add(0);
+        assertEquals(expected, sheet.getTrackedColumnsForAutoSizing());
+        
+        sheet.autoSizeColumn(0, useMergedCells);
+        try {
+            sheet.autoSizeColumn(1, useMergedCells);
+            fail("Should not be able to auto-size an untracked column");
+        }
+        catch (final IllegalStateException e) {
+            // expected
+        }
+    }
+    
+    @Test
+    public void autoSizeColumn_trackColumnsForAutoSizing() {
+        workbook = new SXSSFWorkbook();
+        sheet = workbook.createSheet();
+        
+        sheet.trackColumnsForAutoSizing(columns);
+        SortedSet<Integer> sorted = new TreeSet<Integer>(columns);
+        assertEquals(sorted, sheet.getTrackedColumnsForAutoSizing());
+        
+        sheet.autoSizeColumn(sorted.first(), useMergedCells);
+        try {
+            assumeFalse(columns.contains(5));
+            sheet.autoSizeColumn(5, useMergedCells);
+            fail("Should not be able to auto-size an untracked column");
+        }
+        catch (final IllegalStateException e) {
+            // expected
+        }
+    }
+    
+    @Test
+    public void autoSizeColumn_untrackColumnForAutoSizing() {
+        workbook = new SXSSFWorkbook();
+        sheet = workbook.createSheet();
+        
+        sheet.trackColumnsForAutoSizing(columns);
+        sheet.untrackColumnForAutoSizing(columns.first());
+        
+        assumeTrue(sheet.getTrackedColumnsForAutoSizing().contains(columns.last()));
+        sheet.autoSizeColumn(columns.last(), useMergedCells);
+        try {
+            assumeFalse(sheet.getTrackedColumnsForAutoSizing().contains(columns.first()));
+            sheet.autoSizeColumn(columns.first(), useMergedCells);
+            fail("Should not be able to auto-size an untracked column");
+        }
+        catch (final IllegalStateException e) {
+            // expected
+        }
+    }
+    
+    @Test
+    public void autoSizeColumn_untrackColumnsForAutoSizing() {
+        workbook = new SXSSFWorkbook();
+        sheet = workbook.createSheet();
+        
+        sheet.trackColumnForAutoSizing(15);
+        sheet.trackColumnsForAutoSizing(columns);
+        sheet.untrackColumnsForAutoSizing(columns);
+        
+        assumeTrue(sheet.getTrackedColumnsForAutoSizing().contains(15));
+        sheet.autoSizeColumn(15, useMergedCells);
+        try {
+            assumeFalse(sheet.getTrackedColumnsForAutoSizing().contains(columns.first()));
+            sheet.autoSizeColumn(columns.first(), useMergedCells);
+            fail("Should not be able to auto-size an untracked column");
+        }
+        catch (final IllegalStateException e) {
+            // expected
+        }
+    }
+    
+    @Test
+    public void autoSizeColumn_isColumnTrackedForAutoSizing() {
+        workbook = new SXSSFWorkbook();
+        sheet = workbook.createSheet();
+        
+        sheet.trackColumnsForAutoSizing(columns);
+        for (int column : columns) {
+            assertTrue(sheet.isColumnTrackedForAutoSizing(column));
+            
+            assumeFalse(columns.contains(column+10));
+            assertFalse(sheet.isColumnTrackedForAutoSizing(column+10));
+        }
+    }
+    
+    @Test
+    public void autoSizeColumn_trackAllColumns() {
+        workbook = new SXSSFWorkbook();
+        sheet = workbook.createSheet();
+        
+        sheet.trackAllColumnsForAutoSizing();
+        sheet.autoSizeColumn(0, useMergedCells);
+        
+        sheet.untrackAllColumnsForAutoSizing();
+        try {
+            sheet.autoSizeColumn(0, useMergedCells);
+            fail("Should not be able to auto-size an implicitly untracked column");
+        } catch (final IllegalStateException e) {
+            // expected
+        }
+    }
+    
+    @Test
+    public void autoSizeColumn_trackAllColumns_explicitUntrackColumn() {
+        workbook = new SXSSFWorkbook();
+        sheet = workbook.createSheet();
+        
+        sheet.trackColumnsForAutoSizing(columns);
+        sheet.trackAllColumnsForAutoSizing();
+        
+        sheet.untrackColumnForAutoSizing(0);
+        try {
+            sheet.autoSizeColumn(0, useMergedCells);
+            fail("Should not be able to auto-size an explicitly untracked column");
+        } catch (final IllegalStateException e) {
+            // expected
+        }
+    }
+    
+    
+    private static void assumeRequiredFontsAreInstalled(final Workbook workbook, final Cell cell) {
+        // autoSize will fail if required fonts are not installed, skip this test then
+        Font font = workbook.getFontAt(cell.getCellStyle().getFontIndex());
+        Assume.assumeTrue("Cannot verify autoSizeColumn() because the necessary Fonts are not installed on this machine: " + font,
+                          SheetUtil.canComputeColumnWidth(font));
+    }
+    
+    private static Cell createRowWithCellValues(final Sheet sheet, final int rowNumber, final String... cellValues) {
+        Row row = sheet.createRow(rowNumber);
+        int cellIndex = 0;
+        Cell firstCell = null;
+        for (final String cellValue : cellValues) {
+            Cell cell = row.createCell(cellIndex++);
+            if (firstCell == null) {
+                firstCell = cell;
+            }
+            cell.setCellValue(cellValue);
+        }
+        return firstCell;
+    }
+    
+    private static void assertColumnWidthStrictlyWithinRange(final int actualColumnWidth, final int lowerBoundExclusive, final int upperBoundExclusive) {
+        assertTrue("Expected a column width greater than " + lowerBoundExclusive + " but found " + actualColumnWidth,
+                actualColumnWidth > lowerBoundExclusive);
+        assertTrue("Expected column width less than " + upperBoundExclusive + " but found " + actualColumnWidth, actualColumnWidth < upperBoundExclusive);
+       
+    }
+    
+}

src/ooxml/testcases/org/apache/poi/xssf/usermodel/TestSXSSFBugs.java

@@ -24,6 +24,7 @@ import org.apache.poi.ss.usermodel.PrintSetup;
 import org.apache.poi.ss.usermodel.Sheet;
 import org.apache.poi.ss.usermodel.Workbook;
 import org.apache.poi.xssf.SXSSFITestDataProvider;
+import org.apache.poi.xssf.streaming.SXSSFSheet;
 import org.apache.poi.xssf.streaming.SXSSFWorkbook;
 import org.junit.Ignore;
 import org.junit.Test;
@@ -33,6 +34,12 @@ public final class TestSXSSFBugs extends BaseTestBugzillaIssues {
         super(SXSSFITestDataProvider.instance);
     }
     
+    @Override
+    protected void trackColumnsForAutoSizingIfSXSSF(Sheet sheet) {
+        SXSSFSheet sxSheet = (SXSSFSheet) sheet;
+        sxSheet.trackAllColumnsForAutoSizing();
+    }
+
     // override some tests which do not work for SXSSF
     @Override @Ignore("cloneSheet() not implemented") @Test public void bug18800() { /* cloneSheet() not implemented */ }
     @Override @Ignore("cloneSheet() not implemented") @Test public void bug22720() { /* cloneSheet() not implemented */ }

src/testcases/org/apache/poi/ss/usermodel/BaseTestBugzillaIssues.java

@@ -56,6 +56,10 @@ public abstract class BaseTestBugzillaIssues {
         _testDataProvider = testDataProvider;
     }
     
+    protected void trackColumnsForAutoSizingIfSXSSF(Sheet sheet) {
+        // do nothing for Sheet base class. This will be overridden for SXSSFSheets.
+    }
+
     /**
      * Unlike org.junit.Assert.assertEquals(double expected, double actual, double delta),
      * where delta is an absolute error value, this function's factor is a relative error,
@@ -373,6 +377,7 @@ public abstract class BaseTestBugzillaIssues {
         Workbook wb = _testDataProvider.createWorkbook();
         BaseTestSheetAutosizeColumn.fixFonts(wb);
         Sheet sheet = wb.createSheet("Sheet1");
+        trackColumnsForAutoSizingIfSXSSF(sheet);
         Row row = sheet.createRow(0);
         Cell cell0 = row.createCell(0);
 
@@ -429,6 +434,7 @@ public abstract class BaseTestBugzillaIssues {
         Workbook wb = _testDataProvider.createWorkbook();
         BaseTestSheetAutosizeColumn.fixFonts(wb);
         Sheet sheet = wb.createSheet();
+        trackColumnsForAutoSizingIfSXSSF(sheet);
         Row row = sheet.createRow(0);
         Cell cell0 = row.createCell(0);
         Cell cell1 = row.createCell(1);
@@ -664,6 +670,7 @@ public abstract class BaseTestBugzillaIssues {
         d2Percent.setDataFormat(format.getFormat("0.00%"));
 
         Sheet s = wb.createSheet();
+        trackColumnsForAutoSizingIfSXSSF(s);
         Row r1 = s.createRow(0);
 
         for (int i=0; i<3; i++) {

src/testcases/org/apache/poi/ss/usermodel/BaseTestSheet.java

@@ -51,6 +51,10 @@ public abstract class BaseTestSheet {
     	_testDataProvider = testDataProvider;
     }
     
+    protected void trackColumnsForAutoSizingIfSXSSF(Sheet sheet) {
+        // do nothing for Sheet base class. This will be overridden for SXSSFSheets.
+    }
+
     @Test
     public void createRow() throws IOException {
         Workbook workbook = _testDataProvider.createWorkbook();
@@ -994,6 +998,7 @@ public abstract class BaseTestSheet {
     public void bug48325() throws IOException {
         Workbook wb = _testDataProvider.createWorkbook();
         Sheet sheet = wb.createSheet("Test");
+        trackColumnsForAutoSizingIfSXSSF(sheet);
         CreationHelper factory = wb.getCreationHelper();
 
         Row row = sheet.createRow(0);

src/testcases/org/apache/poi/ss/usermodel/BaseTestSheetAutosizeColumn.java

@@ -57,12 +57,17 @@ public abstract class BaseTestSheetAutosizeColumn {
         _testDataProvider = testDataProvider;
     }
     
+    protected void trackColumnsForAutoSizingIfSXSSF(Sheet sheet) {
+        // do nothing for Sheet base class. This will be overridden for SXSSFSheets.
+    }
+
     @Test
     public void numericCells() throws Exception {
         Workbook workbook = _testDataProvider.createWorkbook();
         fixFonts(workbook);
         DataFormat df = workbook.getCreationHelper().createDataFormat();
         Sheet sheet = workbook.createSheet();
+        trackColumnsForAutoSizingIfSXSSF(sheet);
 
         Row row = sheet.createRow(0);
         row.createCell(0).setCellValue(0); // getCachedFormulaResult() returns 0 for not evaluated formula cells
@@ -104,6 +109,7 @@ public abstract class BaseTestSheetAutosizeColumn {
         Workbook workbook = _testDataProvider.createWorkbook();
         fixFonts(workbook);
         Sheet sheet = workbook.createSheet();
+        trackColumnsForAutoSizingIfSXSSF(sheet);
 
         Row row = sheet.createRow(0);
         row.createCell(0).setCellValue(0); // getCachedFormulaResult() returns 0 for not evaluated formula cells
@@ -135,6 +141,7 @@ public abstract class BaseTestSheetAutosizeColumn {
         Workbook workbook = _testDataProvider.createWorkbook();
         fixFonts(workbook);
         Sheet sheet = workbook.createSheet();
+        trackColumnsForAutoSizingIfSXSSF(sheet);
         DataFormat df = workbook.getCreationHelper().createDataFormat();
 
         CellStyle style1 = workbook.createCellStyle();
@@ -202,6 +209,7 @@ public abstract class BaseTestSheetAutosizeColumn {
         Workbook workbook = _testDataProvider.createWorkbook();
         fixFonts(workbook);
         Sheet sheet = workbook.createSheet();
+        trackColumnsForAutoSizingIfSXSSF(sheet);
         Row row = sheet.createRow(0);
         
         Font defaultFont = workbook.getFontAt((short)0);
@@ -237,6 +245,7 @@ public abstract class BaseTestSheetAutosizeColumn {
         Workbook workbook = _testDataProvider.createWorkbook();
         fixFonts(workbook);
         Sheet sheet = workbook.createSheet();
+        trackColumnsForAutoSizingIfSXSSF(sheet);
         Row row = sheet.createRow(0);
 
         CellStyle style1 = workbook.createCellStyle();
@@ -264,6 +273,7 @@ public abstract class BaseTestSheetAutosizeColumn {
         Workbook workbook = _testDataProvider.createWorkbook();
         fixFonts(workbook);
         Sheet sheet = workbook.createSheet();
+        trackColumnsForAutoSizingIfSXSSF(sheet);
 
         Row row = sheet.createRow(0);
         sheet.addMergedRegion(CellRangeAddress.valueOf("A1:B1"));
@@ -292,6 +302,7 @@ public abstract class BaseTestSheetAutosizeColumn {
        Workbook workbook = _testDataProvider.createWorkbook();
        fixFonts(workbook);
        Sheet sheet = workbook.createSheet();
+       trackColumnsForAutoSizingIfSXSSF(sheet);
        
        Row r0 = sheet.createRow(0);
        r0.createCell(0).setCellValue("I am ROW 0");