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

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   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
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       http://www.apache.org/licenses/LICENSE-2.0

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   distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.poi.ss.util;

import java.awt.font.FontRenderContext;
import java.awt.font.TextAttribute;
import java.awt.font.TextLayout;
import java.awt.geom.AffineTransform;
import java.awt.geom.Rectangle2D;
import java.text.AttributedString;
import java.util.List;
import java.util.Locale;
import java.util.Map;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.CellType;
import org.apache.poi.ss.usermodel.CellValue;
import org.apache.poi.ss.usermodel.DataFormatter;
import org.apache.poi.ss.usermodel.Font;
import org.apache.poi.ss.usermodel.FormulaEvaluator;
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;


/**
 * Helper methods for when working with Usermodel sheets
 *
 * @author Yegor Kozlov
 */
public class SheetUtil {

    /**
     * Excel measures columns in units of 1/256th of a character width
     * but the docs say nothing about what particular character is used.
     * '0' looks to be a good choice.
     */
    private static final char defaultChar = '0';

    /**
     * This is the multiple that the font height is scaled by when determining the
     * boundary of rotated text.
     */
    private static final double fontHeightMultiple = 2.0;

    /**
     *  Dummy formula evaluator that does nothing.
     *  YK: The only reason of having this class is that
     *  {@link org.apache.poi.ss.usermodel.DataFormatter#formatCellValue(org.apache.poi.ss.usermodel.Cell)}
     *  returns formula string for formula cells. Dummy evaluator makes it to format the cached formula result.
     *
     *  See Bugzilla #50021
     */
    private static final FormulaEvaluator dummyEvaluator = new FormulaEvaluator() {
        @Override
        public void clearAllCachedResultValues(){}
        @Override
        public void notifySetFormula(Cell cell) {}
        @Override
        public void notifyDeleteCell(Cell cell) {}
        @Override
        public void notifyUpdateCell(Cell cell) {}
        @Override
        public CellValue evaluate(Cell cell) {return null;  }
        @Override
        public Cell evaluateInCell(Cell cell) { return null; }
        @Override
        public void setupReferencedWorkbooks(Map<String, FormulaEvaluator> workbooks) {}
        @Override
        public void setDebugEvaluationOutputForNextEval(boolean value) {}
        @Override
        public void setIgnoreMissingWorkbooks(boolean ignore) {}
        @Override
        public void evaluateAll() {}
        @Override
        public CellType evaluateFormulaCell(Cell cell) { return cell.getCachedFormulaResultType(); }
    };

    /**
     * drawing context to measure text
     */
    private static final FontRenderContext fontRenderContext = new FontRenderContext(null, true, true);

    /**
     * Compute width of a single cell
     *
     * @param cell 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
     */
    public static double getCellWidth(Cell cell, int defaultCharWidth, DataFormatter formatter, boolean useMergedCells) {
        List<CellRangeAddress> mergedRegions = cell.getSheet().getMergedRegions();
        return getCellWidth(cell, defaultCharWidth, formatter, useMergedCells, mergedRegions);
    }

    /**
     * Compute width of a single cell
     *
     * This method receives the list of merged regions as querying it from the cell/sheet
     * is time-consuming and thus caching the list across cells speeds up certain operations
     * considerably.
     *
     * @param cell 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
     * @param mergedRegions The list of merged regions as received via cell.getSheet().getMergedRegions()
     * @return  the width in pixels or -1 if cell is empty
     */
    public static double getCellWidth(Cell cell, int defaultCharWidth, DataFormatter formatter, boolean useMergedCells,
                                      List<CellRangeAddress> mergedRegions) {
        Sheet sheet = cell.getSheet();
        Workbook wb = sheet.getWorkbook();
        Row row = cell.getRow();
        int column = cell.getColumnIndex();

        // FIXME: this looks very similar to getCellWithMerges below. Consider consolidating.
        // We should only be checking merged regions if useMergedCells is true. Why are we doing this for-loop?
        int colspan = 1;
        for (CellRangeAddress region : mergedRegions) {
            if (region.isInRange(row.getRowNum(), column)) {
                if (!useMergedCells) {
                    // If we're not using merged cells, skip this one and move on to the next.
                    return -1;
                }
                cell = row.getCell(region.getFirstColumn());
                colspan = 1 + region.getLastColumn() - region.getFirstColumn();
            }
        }

        CellStyle style = cell.getCellStyle();
        CellType cellType = cell.getCellType();

        // for formula cells we compute the cell width for the cached formula result
        if (cellType == CellType.FORMULA)
            cellType = cell.getCachedFormulaResultType();

        Font font = wb.getFontAt(style.getFontIndex());

        double width = -1;
        if (cellType == CellType.STRING) {
            RichTextString rt = cell.getRichStringCellValue();
            if (rt != null && rt.getString() != null) {
                String[] lines = rt.getString().split("\\n");
                for (String line : lines) {
                    String txt = line + defaultChar;

                    AttributedString str = new AttributedString(txt);
                    copyAttributes(font, str, 0, txt.length());

                    /*if (rt.numFormattingRuns() > 0) {
                        // TODO: support rich text fragments
                    }*/

                    width = getCellWidth(defaultCharWidth, colspan, style, width, str);
                }
            }
        } else {
            String sval = null;
            if (cellType == CellType.NUMERIC) {
                // Try to get it formatted to look the same as excel
                try {
                    sval = formatter.formatCellValue(cell, dummyEvaluator);
                } catch (Exception e) {
                    sval = String.valueOf(cell.getNumericCellValue());
                }
            } else if (cellType == CellType.BOOLEAN) {
                sval = String.valueOf(cell.getBooleanCellValue()).toUpperCase(Locale.ROOT);
            }
            if(sval != null) {
                String txt = sval + defaultChar;
                AttributedString str = new AttributedString(txt);
                copyAttributes(font, str, 0, txt.length());

                width = getCellWidth(defaultCharWidth, colspan, style, width, str);
            }
        }
        return width;
    }

    /**
     * Calculate the best-fit width for a cell
     * If a merged cell spans multiple columns, evenly distribute the column width among those columns
     *
     * @param defaultCharWidth the width of a character using the default font in a workbook
     * @param colspan the number of columns that is spanned by the cell (1 if the cell is not part of a merged region)
     * @param style the cell style, which contains text rotation and indention information needed to compute the cell width
     * @param minWidth the minimum best-fit width. This algorithm will only return values greater than or equal to the minimum width.
     * @param str the text contained in the cell
     * @return the best fit cell width
     */
    private static double getCellWidth(int defaultCharWidth, int colspan,
            CellStyle style, double minWidth, AttributedString str) {
        TextLayout layout = new TextLayout(str.getIterator(), fontRenderContext);
        final Rectangle2D bounds;
        if(style.getRotation() != 0){
            /*
             * Transform the text using a scale so that it's height is increased by a multiple of the leading,
             * and then rotate the text before computing the bounds. The scale results in some whitespace around
             * the unrotated top and bottom of the text that normally wouldn't be present if unscaled, but
             * is added by the standard Excel autosize.
             */
            AffineTransform trans = new AffineTransform();
            trans.concatenate(AffineTransform.getRotateInstance(style.getRotation()*2.0*Math.PI/360.0));
            trans.concatenate(
            AffineTransform.getScaleInstance(1, fontHeightMultiple)
            );
            bounds = layout.getOutline(trans).getBounds();
        } else {
            bounds = layout.getBounds();
        }
        // frameWidth accounts for leading spaces which is excluded from bounds.getWidth()
        final double frameWidth = bounds.getX() + bounds.getWidth();
        return Math.max(minWidth, ((frameWidth / colspan) / defaultCharWidth) + style.getIndention());
    }

    /**
     * Compute width of a column and return the result
     *
     * @param sheet the sheet to calculate
     * @param column    0-based index of the column
     * @param useMergedCells    whether to use merged cells
     * @return  the width in pixels or -1 if all cells are empty
     */
    public static double getColumnWidth(Sheet sheet, int column, boolean useMergedCells) {
        return getColumnWidth(sheet, column, useMergedCells, sheet.getFirstRowNum(), sheet.getLastRowNum());
    }

    /**
     * Compute width of a column based on a subset of the rows and return the result
     *
     * @param sheet the sheet to calculate
     * @param column    0-based index of the column
     * @param useMergedCells    whether to use merged cells
     * @param firstRow  0-based index of the first row to consider (inclusive)
     * @param lastRow   0-based index of the last row to consider (inclusive)
     * @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){
        DataFormatter formatter = new DataFormatter();
        int defaultCharWidth = getDefaultCharWidth(sheet.getWorkbook());

        List<CellRangeAddress> mergedRegions = sheet.getMergedRegions();
        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, mergedRegions);
                width = Math.max(width, cellWidth);
            }
        }
        return width;
    }

    /**
     * Get default character width using the Workbook's default font
     *
     * @param wb the workbook to get the default character width from
     * @return default character width in pixels
     */
    @Internal
    public static int getDefaultCharWidth(final Workbook wb) {
        Font defaultFont = wb.getFontAt( 0);

        AttributedString str = new AttributedString(String.valueOf(defaultChar));
        copyAttributes(defaultFont, str, 0, 1);
        TextLayout layout = new TextLayout(str.getIterator(), fontRenderContext);
        return (int) layout.getAdvance();
    }

    /**
     * Compute width of a single cell in a row
     * Convenience method for {@link #getCellWidth}
     *
     * @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,
            List<CellRangeAddress> mergedRegions) {
        if( row == null ) {
            return -1;
        }

        Cell cell = row.getCell(column);

        if (cell == null) {
            return -1;
        }

        return getCellWidth(cell, defaultCharWidth, formatter, useMergedCells, mergedRegions);
    }

    /**
     * Check if the Fonts are installed correctly so that Java can compute the size of
     * columns.
     *
     * If a Cell uses a Font which is not available on the operating system then Java may
     * fail to return useful Font metrics and thus lead to an auto-computed size of 0.
     *
     *  This method allows to check if computing the sizes for a given Font will succeed or not.
     *
     * @param font The Font that is used in the Cell
     * @return true if computing the size for this Font will succeed, false otherwise
     */
    public static boolean canComputeColumnWidth(Font font) {
        // not sure what is the best value sample-here, only "1" did not work on some platforms...
        AttributedString str = new AttributedString("1w");
        copyAttributes(font, str, 0, "1w".length());

        TextLayout layout = new TextLayout(str.getIterator(), fontRenderContext);
        return (layout.getBounds().getWidth() > 0);
    }

    /**
     * Copy text attributes from the supplied Font to Java2D AttributedString
     */
    private static void copyAttributes(Font font, AttributedString str, @SuppressWarnings("SameParameterValue") int startIdx, int endIdx) {
        str.addAttribute(TextAttribute.FAMILY, font.getFontName(), startIdx, endIdx);
        str.addAttribute(TextAttribute.SIZE, (float)font.getFontHeightInPoints());
        if (font.getBold()) str.addAttribute(TextAttribute.WEIGHT, TextAttribute.WEIGHT_BOLD, startIdx, endIdx);
        if (font.getItalic() ) str.addAttribute(TextAttribute.POSTURE, TextAttribute.POSTURE_OBLIQUE, startIdx, endIdx);
        if (font.getUnderline() == Font.U_SINGLE ) str.addAttribute(TextAttribute.UNDERLINE, TextAttribute.UNDERLINE_ON, startIdx, endIdx);
    }

    /**
     * Return the cell, without taking account of merged regions.
     * <p>
     * Use {@link #getCellWithMerges(Sheet, int, int)} if you want the top left
     * cell from merged regions instead when the reference is a merged cell.
     * <p>
     * Use this where you want to know if the given cell is explicitly defined
     * or not.
     *
     * @param sheet The workbook sheet to look at.
     * @param rowIx The 0-based index of the row.
     * @param colIx The 0-based index of the cell.
     * @return cell at the given location, or null if not defined
     * @throws NullPointerException if sheet is null
     */
    public static Cell getCell(Sheet sheet, int rowIx, int colIx) {
        Row r = sheet.getRow(rowIx);
        if (r != null) {
            return r.getCell(colIx);
        }
        return null;
    }

    /**
     * Return the cell, taking account of merged regions. Allows you to find the
     *  cell who's contents are shown in a given position in the sheet.
     *
     * <p>If the cell at the given co-ordinates is a merged cell, this will
     *  return the primary (top-left) most cell of the merged region.
     * <p>If the cell at the given co-ordinates is not in a merged region,
     *  then will return the cell itself.
     * <p>If there is no cell defined at the given co-ordinates, will return
     *  null.
     *
     * @param sheet The workbook sheet to look at.
     * @param rowIx The 0-based index of the row.
     * @param colIx The 0-based index of the cell.
     * @return cell at the given location, its base merged cell, or null if not defined
     * @throws NullPointerException if sheet is null
     */
    public static Cell getCellWithMerges(Sheet sheet, int rowIx, int colIx) {
        final Cell c = getCell(sheet, rowIx, colIx);
        if (c != null) return c;

        for (CellRangeAddress mergedRegion : sheet.getMergedRegions()) {
            if (mergedRegion.isInRange(rowIx, colIx)) {
                // The cell wanted is in this merged range
                // Return the primary (top-left) cell for the range
                Row r = sheet.getRow(mergedRegion.getFirstRow());
                if (r != null) {
                    return r.getCell(mergedRegion.getFirstColumn());
                }
            }
        }

        // If we get here, then the cell isn't defined, and doesn't
        //  live within any merged regions
        return null;
    }
}