ddf.catalog.transformer.input.pdf.PdfThumbnailGeneratorImpl.java Source code

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Here is the source code for ddf.catalog.transformer.input.pdf.PdfThumbnailGeneratorImpl.java

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/**
 * Copyright (c) Codice Foundation
 * <p>
 * This is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser
 * General Public License as published by the Free Software Foundation, either version 3 of the
 * License, or any later version.
 * <p>
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 * even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details. A copy of the GNU Lesser General Public License
 * is distributed along with this program and can be found at
 * <http://www.gnu.org/licenses/lgpl.html>.
 */
package ddf.catalog.transformer.input.pdf;

import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Optional;

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.rendering.ImageType;
import org.apache.pdfbox.rendering.PDFRenderer;
import org.apache.pdfbox.tools.imageio.ImageIOUtil;

public class PdfThumbnailGeneratorImpl implements PdfThumbnailGenerator {

    private static final int RESOLUTION_DPI = 44;

    private static final float IMAGE_QUALITY = 1.0f;

    private static final float IMAGE_HEIGHTWIDTH = 128;

    private static final String FORMAT_NAME = "jpg";

    @Override
    public Optional<byte[]> apply(PDDocument pdfDocument) throws IOException {
        PDFRenderer pdfRenderer = new PDFRenderer(pdfDocument);

        if (pdfDocument.getNumberOfPages() < 1) {
            return Optional.empty();
        }

        BufferedImage image = pdfRenderer.renderImageWithDPI(0, RESOLUTION_DPI, ImageType.RGB);

        int largestDimension = Math.max(image.getHeight(), image.getWidth());
        float scalingFactor = IMAGE_HEIGHTWIDTH / largestDimension;
        int scaledHeight = (int) (image.getHeight() * scalingFactor);
        int scaledWidth = (int) (image.getWidth() * scalingFactor);

        BufferedImage scaledImage = new BufferedImage(scaledWidth, scaledHeight, BufferedImage.TYPE_INT_RGB);
        Graphics2D graphics = scaledImage.createGraphics();
        graphics.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        graphics.drawImage(image, 0, 0, scaledWidth, scaledHeight, null);
        graphics.dispose();

        try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) {
            ImageIOUtil.writeImage(scaledImage, FORMAT_NAME, outputStream, RESOLUTION_DPI, IMAGE_QUALITY);
            return Optional.of(outputStream.toByteArray());
        }
    }
}