How to resize a chart using XSSF (Apache POI 3.8)?

Question

I am wondering whether there is a way to resize a chart using Apache POI (XSSF). Currently I am using an Excel template, which has a chart that changes when more data is inserted using namedRanges.

Everything works fine, the only troubles I'm facing are:

• The chart always stays the same size, so if there are more entries, it gets cluttered making the chart kind of useless.
• I am using dates, but I am not able to represent the date as day/month(17/10) on the chart. Basically instead of 04/01/2001, it writes 36982.

The purpose of the workbook is to list several jobs and check whether they took longer on a given date, the graph is for helping to identify the ocurrences of longer elapsed times. The jobs runtime might range from seconds to hours.

This is the code I am using:

 package le_package.poi_tests.xssflibrary; import java.io.*; import java.text.SimpleDateFormat; import java.util.Date; import org.apache.poi.openxml4j.opc.OPCPackage; import org.apache.poi.ss.usermodel.Cell; import org.apache.poi.ss.usermodel.Name; import org.apache.poi.ss.usermodel.Row; import org.apache.poi.ss.usermodel.Sheet; import org.apache.poi.xssf.usermodel.XSSFWorkbook; public class POIReadFile { public static void main(String[] args) { try { String jobName = "I am a job"; String jobParent = "I am your father, Job."; int rowNum = 40; int deface = 4; //Open Excel as OOXML XSSFWorkbook currentWorkbook = new XSSFWorkbook( OPCPackage.open("include/excelTemplate.xlsx")); //Get sheet in position 0 Sheet currentSheet = currentWorkbook.getSheetAt(0); //Get sheet name for processing String sheetName = currentSheet.getSheetName(); //Set values for headers currentSheet.getRow(1).getCell(0).setCellValue(jobName); currentSheet.getRow(1).getCell(1).setCellValue(jobParent); for (int i=0; i<rowNum; i++) { //Create row in a given position Row newRow = currentSheet.createRow(i+deface); //Create cell within row Cell newCell0 = newRow.createCell(0); Cell newCell1 = newRow.createCell(1); Cell newCell2 = newRow.createCell(2); String cellDate = ""; /* Set CellType * 0 - Numeric | 1 - String | 2 - Formula | 3 - Blank | 4 - Boolean | 5 - Error */ newCell0.setCellType(0); cellDate = "3/"+(i+1)+"/2001 00:00:00"; //Convert text into date Date currentCellDate = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss").parse(cellDate); //System.out.println(currentCellDate.toString()+"--"+cellDate); //Set CellValue newCell0.setCellValue(currentCellDate); cellDate = "4/"+(i+1)+"/2001 00:00:00"; currentCellDate = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss").parse(cellDate); //System.out.println(currentCellDate.toString()+"--"+cellDate); newCell1.setCellType(0); newCell1.setCellValue(currentCellDate); //setCellFormula sets the formula to be evaluated by excel, it doesn't need to start with '=' newCell2.setCellFormula("A" + (i+deface+1) + "-B" + (i+deface+1)); } //Search for named range Name rangeCell = currentWorkbook.getName("startRange"); //Set new range for named range String reference = sheetName + "!$A$" + ( deface+1 ) + ":$A$" + ( rowNum+deface ); //Assigns range value to named range rangeCell.setRefersToFormula(reference); rangeCell = currentWorkbook.getName("endRange"); reference = sheetName + "!$B$"+(deface+1) + ":$B$" + (rowNum+deface); rangeCell.setRefersToFormula(reference); rangeCell = currentWorkbook.getName("elapsedTime"); reference = sheetName + "!$C$"+(deface+1) + ":$C$" + (rowNum+deface); rangeCell.setRefersToFormula(reference); //Create a fileStream to write into a file FileOutputStream newExcelFile = new FileOutputStream(jobName+".xlsx"); //Write Stream currentWorkbook.write(newExcelFile); //Close New Excel File newExcelFile.close(); } catch (Exception e) { System.out.println("AAAAARGH, I was wounded by the following exception!:"); e.printStackTrace(); System.out.println("Sorry, your program is dead :("); } } } 

Is it possible to do what I need?

Thanks.

*Note: I am not asking to create a chart from the scratch, I only need to resize the one the template has, and change some cells to date instead of the number that is written.

Answer 1

After researching how xlsx works, I was able to find how to get it done.

//Call the partiarch to start drawing
XSSFDrawing drawing = ((XSSFSheet)currentSheet).createDrawingPatriarch();
//Create CTMarket for anchor
CTMarker chartEndCoords = CTMarker.Factory.newInstance();
//The coordinates are set in columns and rows, not pixels.
chartEndCoords.setCol(column);
//Set Column offset
chartEndCoords.setColOff(0);
chartEndCoords.setRow(row);
chartEndCoords.setRowOff(0);
//drawing.getCTDrawing().getTwoCellAnchorArray(0).setFrom(chartStartCoords);
drawing.getCTDrawing().getTwoCellAnchorArray(0).setTo(chartEndCoords);

/*
    This line of code allows to resize the chart:
        The Patriarch is what allows to get control over the drawings, since
        a chart is considered a graph in xlsx you can access it with getCTDrawing.
        Each graph is stored in the tag getTwoCellAnchorArray, where the array position
        is the chart you have; for example getTwoCellAnchorArray(3) would refer to the
        forth graph within the sheet.

        Each getTwoCellAnchorArray has several properties as FROM and TO, which define
        where the existing graph starts and ends.   
*/

If you have any comments, let me know.

Answer 2

1. Give your date cells, date format. Apache poi date format

2. POI cannot modify graphics AFAIK.