在JavaFX中显示pdf

Z时代
2024-01-10
分类：问答

开发JavaFX需要显示pdf 的桌面应用程序。我了解到JavaFX（当前版本）不支持pdf查看/显示，我也了解到JPedal。

现在，问题：

是否有任何外部组件或库可以在JavaFX中查看pdf？它应该是一个免费软件。

（如果必须使用JPedal）如何将其嵌入到我的应用程序中。

回答：

JPedalFX下载提供了有关使用JPedalFX的示例代码。

我有点of脚，但是我只是在这里粘贴从JPedalFX库提供的示例查看器复制的代码段示例代码。该代码依赖于JPedalFX发行版中包含的jpedal_lgpl.jar文件，该文件位于类路径（或应用程序jar清单中引用的库路径）上。

如果您对JPedalFX的使用还有其他疑问，建议您直接与IDR解决方案联系（他们过去一直在响应我）。

// get file path.
FileChooser fc = new FileChooser();
fc.setTitle("Open PDF file...");
fc.getExtensionFilters().add(new FileChooser.ExtensionFilter("PDF Files", "*.pdf"));     
File f = fc.showOpenDialog(stage.getOwner());
String filename = file.getAbsolutePath();
// open file.
PdfDecoder pdf = new PdfDecoder();
pdf.openPdfFile(filename);
showPage(1);
pdf.closePdfFile();
. . .
/**
 * Update the GUI to show a specified page.
 * @param page 
 */
private void showPage(int page) {
    //Check in range
    if (page > pdf.getPageCount())
        return;
    if (page < 1)
        return;
    //Store
    pageNumber = page;
    //Show/hide buttons as neccessary
    if (page == pdf.getPageCount())
        next.setVisible(false);
    else
        next.setVisible(true);
    if (page == 1)
        back.setVisible(false);
    else
        back.setVisible(true);
    //Calculate scale
    int pW = pdf.getPdfPageData().getCropBoxWidth(page);
    int pH = pdf.getPdfPageData().getCropBoxHeight(page);
    Dimension s = Toolkit.getDefaultToolkit().getScreenSize();
    s.width -= 100;
    s.height -= 100;
    double xScale = (double)s.width / pW;
    double yScale = (double)s.height / pH;
    double scale = xScale < yScale ? xScale : yScale;
    //Work out target size
    pW *= scale;
    pH *= scale;
    //Get image and set
    Image i = getPageAsImage(page,pW,pH);
    imageView.setImage(i);
    //Set size of components
    imageView.setFitWidth(pW);
    imageView.setFitHeight(pH);
    stage.setWidth(imageView.getFitWidth()+2);
    stage.setHeight(imageView.getFitHeight()+2);
    stage.centerOnScreen();
}
/**
 * Wrapper for usual method since JFX has no BufferedImage support.
 * @param page
 * @param width
 * @param height
 * @return 
 */
private Image getPageAsImage(int page, int width, int height) {
    BufferedImage img;
    try {
        img = pdf.getPageAsImage(page);
        //Use deprecated method since there's no real alternative 
        //(for JavaFX 2.2+ can use SwingFXUtils instead).
        if (Image.impl_isExternalFormatSupported(BufferedImage.class))
            return javafx.scene.image.Image.impl_fromExternalImage(img);
    } catch(Exception e) {
        e.printStackTrace();
    }
    return null;
}
/**
 * ===========================================
 * Java Pdf Extraction Decoding Access Library
 * ===========================================
 *
 * Project Info:  http://www.jpedal.org
 * (C) Copyright 1997-2008, IDRsolutions and Contributors.
 *
 *  This file is part of JPedal
 *
    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
 *
 * ---------------
 * JPedalFX.java
 * ---------------
 */