workspace-tree-widget/src/main/java/org/gcube/portlets/user/workspace/server/util/ThumbnailGenerator.java

package org.gcube.portlets.user.workspace.server.util;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.imageio.ImageIO;

import org.apache.commons.io.FilenameUtils;
import org.apache.commons.io.IOUtils;


/**
 * The Class ThumbnailGenerator.
 *
 * @author Francesco Mangiacrapa at ISTI-CNR (francesco.mangiacrapa@isti.cnr.it)
 * 
 * Aug 1, 2019
 */
public class ThumbnailGenerator {

	/**
	 * Creates the thumbnail.
	 *
	 * @param originalFile
	 *            the original file
	 * @param thumbWidth
	 *            the thumb width
	 * @param thumbHeight
	 *            the thumb height
	 * @return the input stream
	 * @throws Exception
	 *             the exception
	 */
	public static InputStream generateThumbnail(String originalFile, int thumbWidth, int thumbHeight) throws Exception {

		String baseName = FilenameUtils.getBaseName(originalFile);
		Image image = ImageIO.read(new File(originalFile));
		return createThumb(image, baseName, thumbWidth, thumbHeight);
	}

	/**
	 * Generate thumbnail.
	 *
	 * @param originalFile
	 *            the original file
	 * @param fileName
	 *            the file name
	 * @param thumbWidth
	 *            the thumb width
	 * @param thumbHeight
	 *            the thumb height
	 * @return the input stream
	 * @throws Exception
	 *             the exception
	 */
	public static InputStream generateThumbnail(InputStream originalFile, String fileName, int thumbWidth,
			int thumbHeight) throws Exception {
		Image image = ImageIO.read(originalFile);
		return createThumb(image, fileName, thumbWidth, thumbHeight);
	}

	/**
	 * Creates the thumb.
	 *
	 * @param image
	 *            the image
	 * @param imageName
	 *            the image name
	 * @param thumbWidth
	 *            the thumb width
	 * @param thumbHeight
	 *            the thumb height
	 * @return the input stream
	 * @throws IOException
	 *             error
	 */
	public static InputStream createThumb(Image image, String imageName, int thumbWidth, int thumbHeight)
			throws IOException {
		double thumbRatio = (double) thumbWidth / (double) thumbHeight;
		int imageWidth = image.getWidth(null);
		int imageHeight = image.getHeight(null);
		double imageRatio = (double) imageWidth / (double) imageHeight;
		if (thumbRatio < imageRatio) {
			thumbHeight = (int) (thumbWidth / imageRatio);
		} else {
			thumbWidth = (int) (thumbHeight * imageRatio);
		}
		if (imageWidth < thumbWidth && imageHeight < thumbHeight) {
			thumbWidth = imageWidth;
			thumbHeight = imageHeight;
		} else if (imageWidth < thumbWidth)
			thumbWidth = imageWidth;
		else if (imageHeight < thumbHeight)
			thumbHeight = imageHeight;

		BufferedImage thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);

		Graphics2D graphics2D = thumbImage.createGraphics();
		graphics2D.setBackground(Color.WHITE);
		graphics2D.setPaint(Color.WHITE);
		graphics2D.fillRect(0, 0, thumbWidth, thumbHeight);
		graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
		graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null);

		String ext = FilenameUtils.getExtension(imageName);
		// String baseName = FilenameUtils.getBaseName(originalFile);

		ByteArrayOutputStream os = new ByteArrayOutputStream();
		ImageIO.write(thumbImage, ext, os);
		return new ByteArrayInputStream(os.toByteArray());
	}

	/**
	 * Stream2file.
	 *
	 * @param in
	 *            the in
	 * @param filename
	 *            the filename
	 * @param extension
	 *            the extension
	 * @return the file
	 * @throws IOException
	 *             Signals that an I/O exception has occurred.
	 */
	public static File stream2file(InputStream in, String filename, String extension) throws IOException {

		extension = extension.startsWith(".") ? extension : "." + extension;
		final File tempFile = File.createTempFile(filename, extension);
		tempFile.deleteOnExit();
		try (FileOutputStream out = new FileOutputStream(tempFile)) {
			IOUtils.copy(in, out);
		}
		return tempFile;
	}

	// /**
	// * The main method.
	// *
	// * @param args the arguments
	// * @throws Exception the exception
	// */
	// public static void main(String[] args) throws Exception {
	//
	// String originalFile = "/home/francesco-mangiacrapa/Pictures/Screenshot
	// from 2016-04-11 10:20:43.png";
	// int thumbWidth = 200;
	// int thumbHeight = 200;
	//
	// createThumbnail(originalFile, thumbWidth, thumbHeight);
	//
	// }
}