org.jpedal.ThumbnailDecoder Maven / Gradle / Ivy
/*
* ===========================================
* Java Pdf Extraction Decoding Access Library
* ===========================================
*
* Project Info: http://www.idrsolutions.com
* Help section for developers at http://www.idrsolutions.com/support/
*
* (C) Copyright 1997-2017 IDRsolutions and Contributors.
*
* This file is part of JPedal/JPDF2HTML5
*
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.
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
*
* ---------------
* ThumbnailDecoder.java
* ---------------
*/
package org.jpedal;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import org.jpedal.exception.PdfException;
import org.jpedal.objects.acroforms.AcroRenderer;
import org.jpedal.utils.LogWriter;
/**
* generates the thumbnails of pages for display
*/
public class ThumbnailDecoder {
private final PdfDecoderInt decode_pdf;
public ThumbnailDecoder(final PdfDecoderInt decode_pdf) {
this.decode_pdf = decode_pdf;
}
/**
* get pdf as Image of any page scaling is size (100 = full size)
*/
public final synchronized BufferedImage getPageAsThumbnail(final int pageNumber, final int height) {
BufferedImage newImg = null;
//stopDecoding=false;
try {
//this is used in Viewer so we need to over-ride implicit assumption
//forms rendered as components just for thumbnail
final AcroRenderer formRenderer = decode_pdf.getFormRenderer();
final boolean formsAlreadyDecoded = formRenderer.getCompData().getFormList(true)[pageNumber] != null;
//Produce image at 50% scaling to prevent massive memory issues at large scalings
//Also improves thumbnail quality at higher resolutions
float scaling = decode_pdf.getScaling();
if (scaling > 0.5f) {
scaling = 0.5f;
}
final BufferedImage pageImage = decode_pdf.getPageAsImage(pageNumber, scaling);
//If viewer had not decoded forms for that page, reset to null
if (!formsAlreadyDecoded) {
formRenderer.getCompData().getFormList(true)[pageNumber] = null;
formRenderer.getCompData().getFormList(false)[pageNumber] = null;
}
final int imgHeight = pageImage.getHeight();
final double scale = height / (double) imgHeight;
final int width = (int) (pageImage.getWidth() * scale);
newImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
final Graphics g = newImg.getGraphics();
g.drawImage(pageImage, 0, 0, width, height, null);
g.dispose();
} catch (final PdfException e) {
LogWriter.writeLog("Exception: " + e.getMessage());
}
return newImg;
}
}