Rendering slideshows, WMF, EMF and EMF+

For rendering slideshow (HSLF/XSLF), WMF, EMF and EMF+ pictures, POI provides an utility class PPTX2PNG:

Usage: PPTX2PNG [options] <ppt or pptx file or 'stdin'

Options:

    -scale <float>    scale factor

    -fixSide <side>   specify side (long,short,width,height) to fix - use <scale> as amount of pixels

    -slide <integer>  1-based index of a slide to render

    -format <type>    png,gif,jpg (,null for testing)

    -outdir <dir>     output directory, defaults to origin of the ppt/pptx file

    -outfile <file>   output filename, defaults to "${basename}-${slideno}.${format}"

    -outpat <pattern> output filename pattern, defaults to "${basename}-${slideno}.${format}"

                      patterns: basename, slideno, format, ext

    -dump <file>      dump the annotated records to a file

    -quiet            do not write to console (for normal processing)

    -ignoreParse      ignore parsing error and continue with the records read until the error

    -extractEmbedded  extract embedded parts

Integrate rendering in your code

#1 - Use PPTX2PNG via file or stdin

For file system access, you need to save your slideshow/WMF/EMF/EMF+ first to disc and then call PPTX2PNG.main() with the corresponding parameters.

for stdin access, you need to redirect System.in before:

/* the file content */

InputStream is = ...;

/* Save and set System.in */

InputStream oldIn = System.in;

try {

    System.setIn(is);

    String[] args = {

        "-format", "png", // png,gif,jpg or null for test

        "-outdir", new File("out/").getCanonicalPath(),

        "-outfile", "export.png",

        "-fixside", "long",

        "-scale", "800",

        "-ignoreParse",

        "stdin"

    };

    PPTX2PNG.main(args);

} finally {

    System.setIn(oldIn);

}

#2 - Render WMF / EMF / EMF+ via the *Picture classes

File f = samples.getFile("santa.wmf");

try (FileInputStream fis = new FileInputStream(f)) {

    // for WMF

    HwmfPicture wmf = new HwmfPicture(fis);

    // for EMF / EMF+

    HemfPicture emf = new HemfPicture(fis);

    Dimension dim = wmf.getSize();

    int width = Units.pointsToPixel(dim.getWidth());

    // keep aspect ratio for height

    int height = Units.pointsToPixel(dim.getHeight());

    double max = Math.max(width, height);

    if (max > 1500) {

    width *= 1500/max;

    height *= 1500/max;

    }

    BufferedImage bufImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);

    Graphics2D g = bufImg.createGraphics();

    g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

    g.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);

    g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);

    g.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);

    wmf.draw(g, new Rectangle2D.Double(0,0,width,height));

    g.dispose();

    ImageIO.write(bufImg, "PNG", new File("bla.png"));

}

#3 - Render slideshows directly

File file = new File("example.pptx");

double scale = 1.5;

try (SlideShow<?, ?> ss = SlideShowFactory.create(file, null, true)) {

    Dimension pgsize = ss.getPageSize();

    int width = (int) (pgsize.width * scale);

    int height = (int) (pgsize.height * scale);

    for (Slide<?, ?> slide : ss.getSlides()) {

        BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);

        Graphics2D graphics = img.createGraphics();

        // default rendering options

        graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        graphics.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);

        graphics.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);

        graphics.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);

        graphics.setRenderingHint(Drawable.BUFFERED_IMAGE, new WeakReference<>(img));

        graphics.scale(scale, scale);

        // draw stuff

        slide.draw(graphics);

        ImageIO.write(img, "PNG", new File("output.png"));

        graphics.dispose();

        img.flush();

    }

}