PngIOMetadata.java

/* ========================================================================
 * PlantUML : a free UML diagram generator
 * ========================================================================
 *
 * (C) Copyright 2009-2024, Arnaud Roques
 *
 * Project Info:  https://plantuml.com
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 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
 * License for more details.
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 * You should have received a copy of the GNU General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
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 * Original Author:  Arnaud Roques
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 */
package net.sourceforge.plantuml.png;

import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;
import java.io.IOException;
import java.io.OutputStream;

import javax.imageio.IIOImage;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.metadata.IIOInvalidTreeException;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.metadata.IIOMetadataNode;
import javax.imageio.stream.ImageOutputStream;

import net.sourceforge.plantuml.security.SImageIO;
import net.sourceforge.plantuml.utils.Log;

public class PngIOMetadata {
	// ::remove file when __CORE__

	private static final String copyleft = "Generated by https://plantuml.com";

	public static void writeWithMetadata(RenderedImage image, OutputStream os, String metadata, int dpi,
			String debugData, int level) throws IOException {

		final ImageWriter writer = javax.imageio.ImageIO.getImageWritersByFormatName("png").next();
		try {
			final ImageWriteParam writeParam = writer.getDefaultWriteParam();

			writeParam.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
			writeParam.setCompressionQuality(levelToQuality(level));

			final ImageTypeSpecifier typeSpecifier = ImageTypeSpecifier
					.createFromBufferedImageType(BufferedImage.TYPE_INT_RGB);

			final IIOMetadata meta = writer.getDefaultImageMetadata(typeSpecifier, writeParam);

			if (dpi != 96)
				addDpi(meta, dpi);

			if (debugData != null)
				addText(meta, "debug", debugData);

			addText(meta, "copyleft", copyleft);
			if (metadata != null)
				addiText(meta, "plantuml", metadata);

			Log.debug(() -> "PngIOMetadata pngMetadata=" + meta);

			// Render the PNG to file
			final IIOImage iioImage = new IIOImage(image, null, meta);
			Log.debug(() -> "PngIOMetadata iioImage=" + iioImage);

			try (final ImageOutputStream ios = SImageIO.createImageOutputStream(os)) {
				writer.setOutput(ios);
				writer.write(null, iioImage, writeParam);
			}
		} finally {
			writer.dispose();
		}
	}

	private static float levelToQuality(int level) {
		final int L = Math.max(1, Math.min(9, level));
		 return 1.0f - (L - 1) / 8.0f;
	}

	private static void addDpi(IIOMetadata meta, double dpi) throws IIOInvalidTreeException {
		final IIOMetadataNode dimension = new IIOMetadataNode("Dimension");

		final IIOMetadataNode horizontalPixelSize = new IIOMetadataNode("HorizontalPixelSize");
		final double value = dpi / 0.0254 / 1000;
		horizontalPixelSize.setAttribute("value", Double.toString(value));
		dimension.appendChild(horizontalPixelSize);

		final IIOMetadataNode verticalPixelSize = new IIOMetadataNode("VerticalPixelSize");
		verticalPixelSize.setAttribute("value", Double.toString(value));
		dimension.appendChild(verticalPixelSize);

		final IIOMetadataNode root = new IIOMetadataNode("javax_imageio_1.0");
		root.appendChild(dimension);

		meta.mergeTree("javax_imageio_1.0", root);

	}

	private static void addiText(IIOMetadata meta, String key, String value) throws IIOInvalidTreeException {
		final IIOMetadataNode text = new IIOMetadataNode("iTXt");
		final IIOMetadataNode entry = new IIOMetadataNode("iTXtEntry");
		entry.setAttribute("keyword", key);
		entry.setAttribute("compressionFlag", "true");
		entry.setAttribute("compressionMethod", "0");
		entry.setAttribute("languageTag", "");
		entry.setAttribute("translatedKeyword", "");
		entry.setAttribute("text", value);

		text.appendChild(entry);
		final IIOMetadataNode root = new IIOMetadataNode("javax_imageio_png_1.0");
		root.appendChild(text);

		meta.mergeTree("javax_imageio_png_1.0", root);

	}

	private static void addText(IIOMetadata meta, String key, String value) throws IIOInvalidTreeException {
		final IIOMetadataNode text = new IIOMetadataNode("tEXt");
		final IIOMetadataNode entry = new IIOMetadataNode("tEXtEntry");
		entry.setAttribute("keyword", key);
		entry.setAttribute("value", value);

		text.appendChild(entry);
		final IIOMetadataNode root = new IIOMetadataNode("javax_imageio_png_1.0");
		root.appendChild(text);

		meta.mergeTree("javax_imageio_png_1.0", root);
	}

}