Unable to see Apache POI updated data value in BarChart in pptx without editing

Question

I have a pptx template, it has just 1 slide for testing purpose. The slide has a simple bar chart. I am able to edit the bar chart by double clicking it on pptx file and I could change the values in Sheet1 (Data sheet for Barchart), and, I able to see the changes immediately in BarChart.

Now, I am trying to do the same using POI API. I am doing the below steps here

1. Read the template file = "MyTemplate.pptx" - https://docs.google.com/file/d/0B-q0lBy0lKLic3dCSUVsZUdGQzA/edit?usp=sharing
2. Have all shapes in Map
3. Read the BarChart shape by referring it's name - "MyBarChart"
4. Read the excel file of the BarChart
5. Update a cell Value in Sheet1
6. Save everything and write into another file - "MyPresentation.pptx"

When I open the file - "MyPresentation.pptx", it does not show up the updated cell value upfront in the Bar. I need to double click the chart to change it to EDIT mode to get the latest value reflected. Why does BarChart is not getting refreshed when it's underlying Data Sheet is updated using POI?

Any suggestion to solve the issue?

Here is the completed code, attached pptx template file as well.

package com.ppt;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;

import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.openxml4j.opc.PackagePart;
import org.apache.poi.xslf.usermodel.XMLSlideShow;
import org.apache.poi.xslf.usermodel.XSLFGraphicFrame;
import org.apache.poi.xslf.usermodel.XSLFShape;
import org.apache.poi.xslf.usermodel.XSLFSheet;
import org.apache.poi.xslf.usermodel.XSLFSlide;

public class PPTChart {

    public static void main(String args[]) throws InvalidFormatException, IOException{ 

        XMLSlideShow ppt;

        // Read pptx template
        ppt = new XMLSlideShow(new FileInputStream("MyTemplate.pptx"));

        // Get all slides
        XSLFSlide[] slide = ppt.getSlides();

        // Get working slide that is slide=0
        XSLFSlide slide0 = slide[0];
        XSLFShape[] shapes = slide0.getShapes();

        // Add all shapes into a Map
        Map <String, XSLFShape> shapesMap = new HashMap<String, XSLFShape>();
        for(XSLFShape shape : shapes)
        {
            shapesMap.put(shape.getShapeName(), shape);
            System.out.println(shape.getShapeName() + "  " + shape.getShapeId() + "   " + shape);

        }

        // Read the bar chart
        XSLFGraphicFrame chart = (XSLFGraphicFrame) shapesMap.get("MyBarChart");

        // Get the chart sheet
        XSLFSheet sheet =  chart.getSheet();

        for(int i=0; i<sheet.getRelations().size(); i++)
        {
            System.out.println("Partname =" + sheet.getRelations().get(i).getPackagePart().getPartName());



            if(sheet.getRelations().get(i).getPackagePart().getPartName().toString().contains(".xls"))
            {

                System.out.println("Found the bar chart excel");

                // BarChart Excel package part
                PackagePart barChartExcel  = sheet.getRelations().get(i).getPackagePart();

                // Reference the excel in workbook
                HSSFWorkbook wb = new HSSFWorkbook(barChartExcel.getInputStream());

                // Read sheet where Barchart data is available
                HSSFSheet mysheet =  wb.getSheetAt(1);

                // Read first
                HSSFRow row = mysheet.getRow(1);


                //Print first cell value for debugging
                System.out.println("Updating cell value from - " + row.getCell(1));

                // New value
                double insertValue = 7777777.0;


                wb.getSheetAt(1).getRow(1).getCell(1).setCellValue(insertValue);

                // Set first BarChart as active sheet
                HSSFSheet mysheet0 =  wb.getSheetAt(0);
                mysheet0.setActive(true);

                // Write the updated excel back to workbook
                OutputStream excelOut = barChartExcel.getOutputStream();
                excelOut.flush();
                wb.write(excelOut);
                excelOut.close();

                // Write workbook to file
                FileOutputStream o = new FileOutputStream("MyPresentation.pptx");
                ppt.write(o);
                o.close();
                System.out.println("new ppt is created....");

                break; // Exit
            }

        }
    }
}

Answer 1

I'm working on something similar right now. Check out the thread link below for actually updating the chart visuals. You have to modify the plot area portion of the underlying XML.

How can one programmatically read the graph values from a Powerpoint presentation using Apache's POI?

Answer 2

Here is the code you'd use to do it with pptx4j.

You ought to be able to convert that to equivalent POI code.

Note that the pptx4j code is updating an OpenXML spreadsheet, whereas your code is targeting the legacy binary format.