An ANT Task that repairs the image Metadata for embedding them in an PDF with FOP

RepairImageMetadataTask.java

package imagefixer;

import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;
import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.util.Iterator;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.metadata.IIOMetadataNode;
import javax.imageio.spi.IIORegistry;
import javax.imageio.stream.ImageOutputStream;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Task;
import org.w3c.dom.NodeList;

public class RepairImageMetadataTask extends Task {

	private static final class PNGFilter implements FilenameFilter {

		public boolean accept(File dir, String name) {
			return name.toLowerCase().endsWith(FILE_EXTENSION);
		}

	}

	private static final double DIVISOR = 0.0254;

	private static final String FILE_EXTENSION = "png";

	private static final String PHYS_NODE = "pHYs";

	private static final String PIXELS_PER_UNIT_X_AXIS = "pixelsPerUnitXAxis";

	private static final String PIXELS_PER_UNIT_Y_AXIS = "pixelsPerUnitYAxis";

	private static final String TASK_NAME = "repairImageMetadata";

	private static final String UNIT_SPECIFIER = "unitSpecifier";

	private static final String UNIT_SPECIFIER_DEFAULT = "meter";

	private String folder;

	private int resolution = 72;

	private boolean verbose;

	@Override
	public void execute() throws BuildException {
		IIORegistry.getDefaultInstance().registerApplicationClasspathSpis();
		File file = new File(getFolder());
		if (file.exists()) {

			if (isVerbose()) {
				log("Found Folder : " + file.getAbsolutePath());
			}
			File[] list = file.listFiles(new PNGFilter());

			for (File child : list) {
				try {
					BufferedImage readImage = ImageIO.read(child);
					if (readImage != null) {
						if (isVerbose()) {
							log("Processing Image: " + child.getAbsolutePath());
						}
						String name = child.getAbsolutePath();
						writeFile(readImage, name, getResolution());
					}
				} catch (IOException exception) {
					log(exception, 1);
				}
			}
		}
	}

	public String getFolder() {
		return folder;
	}

	public int getResolution() {
		return resolution;
	}

	@Override
	public String getTaskName() {
		return TASK_NAME;
	}

	@Override
	public String getTaskType() {
		return super.getTaskType();
	}

	public boolean isVerbose() {
		return verbose;
	}

	public void setFolder(String folder) {
		this.folder = folder;
	}

	public void setResolution(int resolution) {
		this.resolution = resolution;
	}

	public void setVerbose(boolean verbose) {
		this.verbose = verbose;
	}

	private void writeFile(RenderedImage image, String filename, int dotsPerInch) {

		String dotsPerMeter = String.valueOf((int) (dotsPerInch / DIVISOR));

		Iterator<ImageWriter> imageWriters = ImageIO.getImageWritersByFormatName(FILE_EXTENSION);

		while (imageWriters.hasNext()) {
			ImageWriter imageWriter = imageWriters.next();

			ImageTypeSpecifier imageType = new ImageTypeSpecifier(image);

			ImageWriteParam writeParam = imageWriter.getDefaultWriteParam();
			IIOMetadata metadata = imageWriter.getDefaultImageMetadata(imageType, writeParam);

			String pngFormatName = metadata.getNativeMetadataFormatName();
			IIOMetadataNode pngNode = (IIOMetadataNode) metadata.getAsTree(pngFormatName);

			IIOMetadataNode physNode = null;
			NodeList childNodes = pngNode.getElementsByTagName(PHYS_NODE);
			if (childNodes.getLength() == 0) {
				physNode = new IIOMetadataNode(PHYS_NODE);
				pngNode.appendChild(physNode);
			} else if (childNodes.getLength() == 1) {
				physNode = (IIOMetadataNode) childNodes.item(0);
			} else {
				throw new IllegalStateException("Don't know what to do with multiple pHYs nodes");
			}

			physNode.setAttribute(PIXELS_PER_UNIT_X_AXIS, dotsPerMeter);
			physNode.setAttribute(PIXELS_PER_UNIT_Y_AXIS, dotsPerMeter);
			physNode.setAttribute(UNIT_SPECIFIER, UNIT_SPECIFIER_DEFAULT);

			try {
				metadata.setFromTree(pngFormatName, pngNode);
				IIOImage iioImage = new IIOImage(image, null, metadata);
				File file = new File(filename);
				ImageOutputStream stream = ImageIO.createImageOutputStream(file);
				imageWriter.setOutput(stream);
				imageWriter.write(iioImage);
				stream.flush();
				stream.close();
			} catch (Exception exception) {
				log(exception, 1);
				continue;
			}
			break;
		}

	}

}