Converting short colorVal = CellStyle.getBottomBorderColor () to RGB value while using Apache POI Java library - itext

Question

I am reading Excel sheet using Apache POI and writing it to a PDF using iText library.This has been achieved successfully but I am getting default black border for every cell that I write to PDF. So I need to get the cell border color using Apache POI which can be achieved using CellStyle class method getBottomBorderColor() which returns a short value.However I need a way to convert this value to RGB value so that while writing cell to PDF I can apply that RGB color value to the cell border.

Answer 1

The short value from CellStyle.getBottomBorderColor is an index of the color in the color palette of the workbook. This is an olld approach for storing colors from the old binary *.xls Excel format. So in apache poi there is only HSSFPalette which only should be used in HSSF and not more be used in XSSF.
In newer *.xlsx Excel formats, the color will either be stored directly as hex value or as reference to a theme color. So for XSSF there is XSSFCellStyle.getBottomBorderXSSFColor to get that color directly and not via index.
So unfortunately we have to differ both aproaches dependent on the kind of Excel workbook.
Example:
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.*;
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.hssf.util.HSSFColor;
import java.io.FileInputStream;
class ExcelCellBorderColor{
public static void main(String[] args) throws Exception {
Workbook wb = WorkbookFactory.create(new FileInputStream("ExcelCellBorderColor.xlsx"));
//Workbook wb = WorkbookFactory.create(new FileInputStream("ExcelCellBorderColor.xls"));
String strrgb;
Sheet sheet = wb.getSheetAt(0);
for (Row row : sheet) {
for (Cell cell : row) {
CellStyle style = cell.getCellStyle();
if (style instanceof XSSFCellStyle) {
XSSFColor xssfcolor = ((XSSFCellStyle)style).getBottomBorderXSSFColor();
if (xssfcolor != null) {
byte[] brgb = xssfcolor .getRGB();
strrgb = "R:"+String.format("%02X", brgb[0])+",G:"+String.format("%02X", brgb[1])+",B:"+String.format("%02X", brgb[2]);
System.out.println("Cell " + cell.getAddress() + " has border bottom color: " + strrgb);
}
} else if (style instanceof HSSFCellStyle) {
short colorindex = ((HSSFCellStyle)style).getBottomBorderColor();
HSSFPalette palette = ((HSSFWorkbook)wb).getCustomPalette();
HSSFColor hssfcolor = palette.getColor(colorindex);
if (hssfcolor != null) {
short[] srgb = hssfcolor.getTriplet();
strrgb = "R:"+String.format("%02X", srgb[0])+",G:"+String.format("%02X", srgb[1])+",B:"+String.format("%02X", srgb[2]);
System.out.println("Cell " + cell.getAddress() + " has border bottom color index: " + colorindex + ". This is " + strrgb);
}
}
}
}
wb.close();
}
}

Answer 2

you can archive this by using this color class
CTScRgbColor scrgb = (CTScRgbColor)ch;
int r = scrgb.getR();
int g = scrgb.getG();
int b = scrgb.getB();
color = new Color(255 * r / 100000, 255 * g / 100000, 255 * b / 100000);