supporting change for bug 57450 from Stefan Thurnherr

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1712217 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -207,31 +207,60 @@ public class SheetUtil {
      * @return  the width in pixels or -1 if cell is empty
      */
     public static double getColumnWidth(Sheet sheet, int column, boolean useMergedCells, int firstRow, int lastRow){
-        Workbook wb = sheet.getWorkbook();
         DataFormatter formatter = new DataFormatter();
+        int defaultCharWidth = getDefaultCharWidth(sheet.getWorkbook());
+
+        double width = -1;
+        for (int rowIdx = firstRow; rowIdx <= lastRow; ++rowIdx) {
+            Row row = sheet.getRow(rowIdx);
+            if( row != null ) {
+                double cellWidth = getColumnWidthForRow(row, column, defaultCharWidth, formatter, useMergedCells);
+                width = Math.max(width, cellWidth);
+            }
+        }
+        return width;
+    }
+
+    /**
+     * Get default character width
+     *
+     * @param wb the workbook to get the default character width from
+     * @return default character width
+     */
+    private static int getDefaultCharWidth(final Workbook wb) {
         Font defaultFont = wb.getFontAt((short) 0);
 
         AttributedString str = new AttributedString(String.valueOf(defaultChar));
         copyAttributes(defaultFont, str, 0, 1);
         TextLayout layout = new TextLayout(str.getIterator(), fontRenderContext);
         int defaultCharWidth = (int) layout.getAdvance();
+        return defaultCharWidth;
+    }
 
-        double width = -1;
+    /**
-        for (int rowIdx = firstRow; rowIdx <= lastRow; ++rowIdx) {
+     * Compute width of a single cell in a row
-            Row row = sheet.getRow(rowIdx);
+     * Convenience method for {@link getCellWidth}
-            if( row != null ) {
+     *
+     * @param row the row that contains the cell of interest
+     * @param column the column number of the cell whose width is to be calculated
+     * @param defaultCharWidth the width of a single character
+     * @param formatter formatter used to prepare the text to be measured
+     * @param useMergedCells    whether to use merged cells
+     * @return  the width in pixels or -1 if cell is empty
+     */
+    private static double getColumnWidthForRow(
+            Row row, int column, int defaultCharWidth, DataFormatter formatter, boolean useMergedCells) {
+        if( row == null ) {
+            return -1;
+        }
 
         Cell cell = row.getCell(column);
 
         if (cell == null) {
-                    continue;
+            return -1;
         }
 
-                double cellWidth = getCellWidth(cell, defaultCharWidth, formatter, useMergedCells);
+        return getCellWidth(cell, defaultCharWidth, formatter, useMergedCells);
-                width = Math.max(width, cellWidth);
-            }
-        }
-        return width;
     }
 
     /**