apache poi ppt to png emf - apache

Question

I would like to ask about library APACHE POI. I have a .pptx file and with the example which I found on internet I split each slide into separate images. This works great when slide containts .png, .jpeg images but as soon as I have .emf files in slide this image disappear. So I want to have the same copy of slide but with .emf file as well. Is this possible?
version: Apache POI 3.12
Thanks a lot

Answer 1

As mentioned in the comments, EMF is not supported out of the box ... and as FreeHep decided to have a LGPL license it's unlikely that we will include in our release.
In POI you basically have two options to provide a custom image renderer:
implement and register your ImageRenderer implementation in the Graphics2D context via setRenderingHint(Drawable.IMAGE_RENDERER, new MyImageRendener()). The drawback is, that it will be called for any images and you loose the default handling for bitmap/wmf images
or provide a custom DrawFactory which serves your own DrawPictureShape implementation - as in the example below - which only diverts to the EMF renderer when necessary
(looking at this example, the current POI ImageRenderer handling doesn't look flexible and instead of having a global handler, it might be better to register a handler per content-type ...)
Apart of the usual POI component I've included freehep-graphics2d, freehep-graphicsbase, freehep-graphicsio, freehep-graphicsio-emf and freehep-io.
The example is far from being finished, but I guess you get at least a kick-start:
package org.apache.poi.xslf;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import javax.imageio.ImageIO;
import org.apache.poi.sl.draw.DrawFactory;
import org.apache.poi.sl.draw.DrawPictureShape;
import org.apache.poi.sl.draw.Drawable;
import org.apache.poi.sl.draw.ImageRenderer;
import org.apache.poi.sl.usermodel.PictureData;
import org.apache.poi.sl.usermodel.PictureData.PictureType;
import org.apache.poi.sl.usermodel.PictureShape;
import org.apache.poi.util.POILogFactory;
import org.apache.poi.util.POILogger;
import org.apache.poi.xslf.usermodel.XMLSlideShow;
import org.apache.poi.xslf.usermodel.XSLFPictureShape;
import org.apache.poi.xslf.usermodel.XSLFSlide;
import org.freehep.graphicsio.emf.EMFInputStream;
import org.freehep.graphicsio.emf.EMFRenderer;
import org.junit.Test;
public class TestEMFRender {
private final static POILogger LOG = POILogFactory.getLogger(TestEMFRender.class);
#Test
public void render() throws Exception {
XMLSlideShow ppt = getDummy();
Dimension pgsize = ppt.getPageSize();
BufferedImage img = new BufferedImage((int)pgsize.getWidth(), (int)pgsize.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D graphics = initGraphicsCtx(img);
// draw stuff
ppt.getSlides().get(0).draw(graphics);
// save the result
File outfile = new File("bla.png");
ImageIO.write(img, "PNG", outfile);
// cleanup
graphics.dispose();
img.flush();
ppt.close();
}
static XMLSlideShow getDummy() throws IOException {
XMLSlideShow ppt = new XMLSlideShow();
FileInputStream fis = new FileInputStream("kiwilogo.emf");
PictureData pd = ppt.addPicture(fis, PictureType.EMF);
fis.close();
XSLFSlide sl = ppt.createSlide();
XSLFPictureShape ps = sl.createPicture(pd);
ps.setAnchor(new Rectangle2D.Double(100, 100, 100, 100));
return ppt;
}
static Graphics2D initGraphicsCtx(BufferedImage img) {
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);
// custom draw factory
DrawFactory df = new DrawFactory(){
public DrawPictureShape getDrawable(PictureShape<?,?> shape) {
return new DrawPictureShapeEmf(shape);
}
};
graphics.setRenderingHint(Drawable.DRAW_FACTORY, df);
df.fixFonts(graphics);
return graphics;
}
static class DrawPictureShapeEmf extends DrawPictureShape {
public DrawPictureShapeEmf(PictureShape<?,?> shape) {
super(shape);
}
#Override
public void drawContent(Graphics2D graphics) {
PictureData data = getShape().getPictureData();
if(data == null) return;
Rectangle2D anchor = getAnchor(graphics, getShape());
Insets insets = getShape().getClipping();
try {
String contentType = data.getContentType();
ImageRenderer renderer =
PictureType.EMF.contentType.equals(contentType)
? new ImgRenderer()
: super.getImageRenderer(graphics, contentType);
renderer.loadImage(data.getData(), data.getContentType());
renderer.drawImage(graphics, anchor, insets);
} catch (IOException e) {
LOG.log(POILogger.ERROR, "image can't be loaded/rendered.", e);
}
}
}
static class ImgRenderer implements ImageRenderer {
EMFRenderer emfRenderer;
public void loadImage(InputStream data, String contentType) throws IOException {
emfRenderer = new EMFRenderer(new EMFInputStream(data));
}
public void loadImage(byte[] data, String contentType) throws IOException {
loadImage(new ByteArrayInputStream(data), contentType);
}
public Dimension getDimension() {
return emfRenderer.getSize();
}
public void setAlpha(double alpha) {
}
public BufferedImage getImage() {
return null;
}
public BufferedImage getImage(Dimension dim) {
return null;
}
public boolean drawImage(Graphics2D ctx, Rectangle2D graphicsBounds) {
return drawImage(ctx, graphicsBounds, null);
}
public boolean drawImage(Graphics2D ctx, Rectangle2D graphicsBounds, Insets clip) {
AffineTransform at = ctx.getTransform();
try {
Dimension emfDim = emfRenderer.getSize();
// scale output bounds to image bounds
ctx.translate(graphicsBounds.getX(), graphicsBounds.getY());
ctx.scale(graphicsBounds.getWidth()/emfDim.getWidth(), graphicsBounds.getHeight()/emfDim.getHeight());
// TODO: handle clipping
emfRenderer.paint(ctx);
return true;
} catch (RuntimeException e) {
// TODO: logging
return false;
} finally {
ctx.setTransform(at);
}
}
}
}