Java tutorial
/* * This library is part of OpenCms - * the Open Source Content Management System * * Copyright (c) Alkacon Software GmbH & Co. KG (http://www.alkacon.com) * * This library 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 2.1 of the License, or (at your option) any later version. * * This library 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. * * For further information about Alkacon Software, please see the * company website: http://www.alkacon.com * * For further information about OpenCms, please see the * project website: http://www.opencms.org * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ package org.opencms.pdftools; import org.opencms.loader.CmsImageScaler; import org.opencms.main.OpenCms; import org.opencms.util.CmsFileUtil; import java.awt.Color; import java.awt.Graphics2D; import java.awt.geom.AffineTransform; import java.awt.image.AffineTransformOp; import java.awt.image.BufferedImage; import java.io.File; import java.io.InputStream; import org.apache.commons.io.output.ByteArrayOutputStream; import org.apache.pdfbox.util.ImageIOUtil; import org.jpedal.PdfDecoder; import org.jpedal.fonts.FontMappings; import org.jpedal.objects.PdfPageData; /** * Class for generating thumbnails from PDF documents using the PDFBox library.<p> */ public class CmsPdfThumbnailGenerator { /** A multiplier used for the input to calculateDimensions. */ private static final int FAKE_PIXEL_MULTIPLIER = 10000; static { FontMappings.setFontReplacements(); } /** * Generates the image data for a thumbnail from a PDF.<p> * * The given width and height determine the box in which the thumbnail should fit. * The resulting image will always have these dimensions, even if the aspect ratio of the actual PDF * page is different from the ratio of the given width and height. In this case, the size of the rendered * page will be reduced, and the rest of the image will be filled with blank space.<p> * * If one of width or height is negative, then that dimension is chosen so the resulting aspect ratio is the * aspect ratio of the PDF page. * * @param pdfInputStream the input stream for reading the PDF data * @param boxWidth the width of the box in which the thumbnail should fit * @param boxHeight the height of the box in which the thumbnail should fit * @param imageFormat the image format (png, jpg, gif) * @param pageIndex the index of the page for which to render the thumbnail (starting at 0) * * @return the image data for the thumbnail, in the given image format * @throws Exception if something goes wrong */ public byte[] generateThumbnail(InputStream pdfInputStream, int boxWidth, int boxHeight, String imageFormat, int pageIndex) throws Exception { org.jpedal.io.ObjectStore.temp_dir = CmsFileUtil.normalizePath(OpenCms.getSystemInfo().getWebInfRfsPath() + CmsPdfThumbnailCache.PDF_CACHE_FOLDER + File.separatorChar); PdfDecoder decoder = new PdfDecoder(true); try { decoder.openPdfFileFromInputStream(pdfInputStream, false); int numPages = decoder.getPageCount(); if (pageIndex >= numPages) { pageIndex = numPages - 1; } else if (pageIndex < 0) { pageIndex = 0; } // width/height are in points (1/72 of an inch) PdfPageData pageData = decoder.getPdfPageData(); double aspectRatio = (pageData.getCropBoxWidth(1 + pageIndex) * 1.0) / pageData.getCropBoxHeight(1 + pageIndex); int rotation = pageData.getRotation(1 + pageIndex); if ((rotation == 90) || (rotation == 270)) { // landscape aspectRatio = 1 / aspectRatio; } if ((boxWidth < 0) && (boxHeight < 0)) { throw new IllegalArgumentException("At least one of width / height must be positive!"); } else if ((boxWidth < 0) && (boxHeight > 0)) { boxWidth = (int) Math.round(aspectRatio * boxHeight); } else if ((boxWidth > 0) && (boxHeight < 0)) { boxHeight = (int) Math.round(boxWidth / aspectRatio); } // calculateDimensions only takes integers, but only their ratio matters, we multiply the box width with a big number int fakePixelWidth = (int) (FAKE_PIXEL_MULTIPLIER * aspectRatio); int fakePixelHeight = (FAKE_PIXEL_MULTIPLIER); int[] unpaddedThumbnailDimensions = CmsImageScaler.calculateDimension(fakePixelWidth, fakePixelHeight, boxWidth, boxHeight); decoder.decodePage(1 + pageIndex); BufferedImage pageImage = decoder.getPageAsImage(1 + pageIndex); BufferedImage paddedImage = new BufferedImage(boxWidth, boxHeight, BufferedImage.TYPE_3BYTE_BGR); Graphics2D g = paddedImage.createGraphics(); int uw = unpaddedThumbnailDimensions[0]; int uh = unpaddedThumbnailDimensions[1]; // Scale to fit in the box AffineTransformOp op = new AffineTransformOp(AffineTransform .getScaleInstance((uw * 1.0) / pageImage.getWidth(), (uh * 1.0) / pageImage.getHeight()), AffineTransformOp.TYPE_BILINEAR); g.setColor(Color.WHITE); // Fill box image with white, then draw the image data for the PDF in the middle g.fillRect(0, 0, paddedImage.getWidth(), paddedImage.getHeight()); //g.drawImage(pageImage, (boxWidth - pageImage.getWidth()) / 2, (boxHeight - pageImage.getHeight()) / 2, null); g.drawImage(pageImage, op, (boxWidth - uw) / 2, (boxHeight - uh) / 2); BufferedImage pageThumbnail = paddedImage; ByteArrayOutputStream out = new ByteArrayOutputStream(); ImageIOUtil.writeImage(pageThumbnail, imageFormat, out); byte[] imageData = out.toByteArray(); return imageData; } finally { if (decoder.isOpen()) { decoder.closePdfFile(); } pdfInputStream.close(); } } }