Export jfreechart to pptx as EMF image - line rendering improper

Question

I am trying to export a timeseries XY linechart into a pptx document using JFreechart-FreeHEP vector graphics-apache poi XSLF. The logic i follow is as below

use jfreechart to create the chart
export chart as emf image using the freehep api
add this image to the pptx slide using apache poi XSLF lib.

The problem is with the way in which lines are rendered in the EMF image. please see the image below. The lines rendered are not exactly straight, they are kind of zig-zagged. The horizontal lines are rendered straight, but the vertical lines are not rendered as straight lines, they are like -> /\/\/\/\/\/\/\/\/\ . Appreciate any suggestions towards getting the lines to be rendered as straight lines.

This issue is only with EMF format, I tried the same with PNG,JPG format and the lines are rendered as straight lines. The reason why i am using EMF is because , after exporting to pptx, other picture formats (JPEG/PNG/TIF/BMP) seem to lose their quality - clarity and brightness.

Screen shot of EMF image

code i am using is as below

    chart = createChart(createDataset());
    ChartPanel panel = new ChartPanel(chart);

    EMFGraphics2D emffile = new EMFGraphics2D(new File(
            "C:\\Users\\out\\chart.emf"),
            new Dimension(1500, 600));
    emffile.setDeviceIndependent(true);

    emffile.setRenderingHint(RenderingHints.KEY_RENDERING,
            RenderingHints.VALUE_RENDER_QUALITY);
    emffile.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL,
            RenderingHints.VALUE_STROKE_NORMALIZE);
    emffile.startExport();
    chart.draw((Graphics2D) emffile.create(), new Rectangle(1500, 600));
    emffile.endExport();
    emffile.closeStream();
    XMLSlideShow pptx = new XMLSlideShow();
    XSLFSlide slide = pptx.createSlide();

    byte[] pptxpic = IOUtils.toByteArray(new FileInputStream(
            "C:\\Users\\out\\chart.emf"));

    int idx = pptx.addPicture(pptxpic, XSLFPictureData.PICTURE_TYPE_EMF);
    XSLFPictureShape pic = slide.createPicture(idx);
    pic.setAnchor(new java.awt.Rectangle(0, 25, 720, 500));

    pptx.write(new FileOutputStream(
            "C:\\Users\\out\\poitest002.pptx"));

I didn't like the blury images when exporting jfreechart images within jasperreports too, so I've adapted a graphics2d context from apache poi to export to powerpoint shapes directly. I played around with FreeHep in the beginning, but also didn't like the results. Maybe this helps someone with the same issue: https://code.google.com/p/pptx-shape-exporter/ — kiwiwings, Jan 29 '15 at 17:33

score 1 · Accepted Answer · answered Jul 16 '14 at 00:34

Fixed this issue by saving the file in higher resolution and then crop to a lower one when inserting in the slide. The chart was saved as a png file before inserting that in the slide.

byte[] pptxpic = null;

ChartUtilities.saveChartAsPNG(pngfile, chart, 1000, 800);

pptxpic = IOUtils.toByteArray(new FileInputStream(pngfile));

int idx = pptxTemplate.addPicture(pptxpic,
                XSLFPictureData.PICTURE_TYPE_PNG);
XSLFPictureShape pic = slidedips.createPicture(idx);

pic.setAnchor(new java.awt.Rectangle(0, 60, 960, 630));

Export jfreechart to pptx as EMF image - line rendering improper

1 Answers1