org.swiftexplorer.gui.preview.PdfPanel.java Source code

Introduction

Here is the source code for org.swiftexplorer.gui.preview.PdfPanel.java

Source

/*
 * Copyright 2014 Loic Merckel
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package org.swiftexplorer.gui.preview;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDDocumentCatalog;
import org.apache.pdfbox.pdmodel.PDPage;
import org.imgscalr.Scalr;
import org.imgscalr.Scalr.Method;
import org.imgscalr.Scalr.Mode;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.swiftexplorer.gui.preview.PreviewPanel.PreviewComponent;

import javax.swing.JPanel;

public class PdfPanel extends JPanel implements PreviewComponent {

    private static final long serialVersionUID = 1L;

    private final Logger logger = LoggerFactory.getLogger(PdfPanel.class);

    private final int maxPageToPreview = 10;

    private final List<BufferedImage> listImagePages = new ArrayList<BufferedImage>();

    public PdfPanel() {
        super();
    }

    @Override
    public boolean supports(String type) {
        return "application/pdf".equals(type);
    }

    @Override
    public void displayPreview(String contentType, ByteArrayInputStream in) {
        try {
            setPdf(PDDocument.load(in));
        } catch (IOException e) {
            clearPdf();
            logger.error("Error occurred while opening the pdf document", e);
        }
    }

    public synchronized void setPdf(PDDocument pdf) {
        listImagePages.clear();
        if (pdf == null)
            return;
        try {
            if (pdf.isEncrypted()) {
                logger.info("Failed attempt at previewing an encrypted PDF");
                return;
            }
            PDDocumentCatalog cat = pdf.getDocumentCatalog();
            @SuppressWarnings("unchecked")
            List<PDPage> pages = cat.getAllPages();
            if (pages != null && !pages.isEmpty()) {
                for (PDPage page : pages) {
                    listImagePages.add(page.convertToImage());
                    if (listImagePages.size() >= maxPageToPreview)
                        break;
                }
            }
        } catch (IOException e) {
            logger.error("Error occurred while opening the pdf document", e);
        } finally {
            if (pdf != null) {
                try {
                    pdf.close();
                } catch (IOException ex) {
                    logger.error("Error occurred while closing the pdf document", ex);
                }
            }
        }
        repaint();
    }

    public synchronized void clearPdf() {
        listImagePages.clear();
        repaint();
    }

    private BufferedImage getBestFit(BufferedImage bi, int maxWidth, int maxHeight) {
        if (bi == null)
            return null;

        Mode mode = Mode.AUTOMATIC;
        int maxSize = Math.min(maxWidth, maxHeight);
        double dh = (double) bi.getHeight();
        if (dh > Double.MIN_VALUE) {
            double imageAspectRatio = (double) bi.getWidth() / dh;
            if (maxHeight * imageAspectRatio <= maxWidth) {
                maxSize = maxHeight;
                mode = Mode.FIT_TO_HEIGHT;
            } else {
                maxSize = maxWidth;
                mode = Mode.FIT_TO_WIDTH;
            }
        }
        return Scalr.resize(bi, Method.QUALITY, mode, maxSize, Scalr.OP_ANTIALIAS);
    }

    /**
     * {@inheritDoc}.
     */
    @Override
    protected synchronized void paintComponent(Graphics g) {
        g.setColor(Color.LIGHT_GRAY);
        g.fillRect(0, 0, getWidth(), getHeight());
        if (!listImagePages.isEmpty()) {
            int W = this.getWidth();
            int H = this.getHeight();
            int nImg = listImagePages.size();
            int maxImgPerRow = 5;
            int margin = 10;
            int space = 5;
            int nRows = nImg / maxImgPerRow + ((nImg % maxImgPerRow == 0) ? (0) : (1));

            int iW = (W - 2 * margin - (Math.min(maxImgPerRow, nImg) - 1) * space) / Math.min(maxImgPerRow, nImg);
            int iH = (H - 2 * margin - (nRows - 1) * space) / nRows;

            int iX = margin;
            int iY = margin;
            int count = 0;
            for (BufferedImage bi : listImagePages) {
                if (bi == null)
                    continue;

                BufferedImage scaledImg = getBestFit(bi, iW, iH);
                g.drawImage(scaledImg, iX, iY, scaledImg.getWidth(), scaledImg.getHeight(), this);

                ++count;
                iX += (scaledImg.getWidth() + space);
                if (count % maxImgPerRow == 0) {
                    iX = margin;
                    iY += (scaledImg.getHeight() + space);
                }
            }
        }
    }
}