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Rendering slideshows, WMF, EMF and EMF+

Note
Please be aware, that the documentation on this page reflects the current development, which might not have been released. If you rely on a unreleased feature, either use a nightly development build or feel free to ask on the mailing list for the release schedule.

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/.pptx/.emf/.wmf 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,svg,pdf (,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
-inputType <type> default input file type (OLE2,WMF,EMF), default is OLE2 = Powerpoint
some files (usually wmf) don't have a header, i.e. an identifiable file magic
-textAsShapes text elements are saved as shapes in SVG, necessary for variable spacing
often found in math formulas
-charset <cs> sets the default charset to be used, defaults to Windows-1252
-emfHeaderBounds force the usage of the emf header bounds to calculate the bounding box
-fontdir <dir> (PDF only) font directories separated by ";" - use $HOME for current users home dir
defaults to the usual plattform directories
-fontTtf <regex> (PDF only) regex to match the .ttf filenames
-fontMap <map> ";"-separated list of font mappings <typeface from>:<typeface to>

Instructions to run

Download the current nightly and for SVG/PDF the additional dependencies.

Execute the java command (Unix-paths needs to be replaced for Windows - use "-charset" for non-western WMF/EMFs):

java -cp poi-5.0.0-SNAPSHOT.jar:poi-ooxml-5.0.0-SNAPSHOT.jar:poi-ooxml-schemas-5.0.0-SNAPSHOT.jar:poi-scratchpad-5.0.0-SNAPSHOT.jar:lib/*:ooxml-lib/*:auxiliary/* org.apache.poi.xslf.util.PPTX2PNG -format png -fixside long -scale 1000 -charset GBK file.pptx
Note
JDK 1.8 is by default using the PiscesRenderingEngine and affected by Busy loop hangs. To workaround thise, use the MarlinRenderingEngine which is experimental provided starting from openjdk8u252 (JDK-8143849) via -Dsun.java2d.renderer=sun.java2d.marlin.MarlinRenderingEngine or for older jdk builds, preload the marlin jar.

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,svg 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();
}
}