java - 如何将可滚动的 JPanel 导出为 pdf 文件

Question

我设计了一个 jpanel，其中包含许多具有可滚动功能的 Swing 组件。我想将整个 Jpanle 导出到 pdf 文件中。但我无法导出整个 Jpanle。我使用 itext 生成 pdf。我的问题是我无法将整个 jpanel 导出为 pdf。当我导出一半的 Jpanel 时组件导出。但一半不导出。 这是我的代码。

public void PrintFrameToPDF(JPanel c, File file) {
    try {           
        Document d = new Document();
        PdfWriter writer = PdfWriter.getInstance(d, new FileOutputStream("F://newfile.pdf"));
        d.open();

        PdfContentByte cb = writer.getDirectContent();
        PdfTemplate template = cb.createTemplate(800, 1600);
        Graphics2D g2d = template.createGraphics(800, 1600);
        // g2d.translate(1.0, 1.0);
        c.paintAll(g2d);
        // c.addNotify();
        // c.validate();
        g2d.dispose();
        cb.addTemplate(template, 0, 0);
        d.close();          
    } catch (Exception e) {
        //
    }
}

请帮助我。发送

Answer 1

考虑创建一个 java.awt.Image首先从面板(通过将面板绘制到图像)。然后您可以获得 com.itextpdf.text.Image 的实例使用:

com.itextpdf.text.Image.getInstance(PdfWriter writer,
java.awt.Image awtImage,
float quality) -
Gets an instance of a com.itextpdf.textImage from a java.awt.Image. The image is added as a JPEG with a user defined quality.

然后您可以使用 com.itextpdf.text.Image API 缩放图像方法 scaleToFit或 scalePercent() (如以下示例中所用)。有关使用图像(在 iText 中)的更多信息，请参见 here

以下程序创建了一个大小为 2000x2000 的面板，其中在面板上绘制了 20x20(每个 100 像素)的正方形。该面板包含在滚动 Pane 内。然后将其绘制到图像上，图像将被缩放并添加到 pdf 文档并打印为 pdf。

_{下图显示了如何将整个面板绘制到图像上，然后使用之前的面板图像创建另一个面板以绘制到新面板上。然后通过对话框显示新面板。}

import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.FileOutputStream;

import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;

import com.itextpdf.text.Document;
import com.itextpdf.text.Image;
import com.itextpdf.text.pdf.PdfWriter;

/**
 * This example requires iText. I retrieved it from Maven repository
 * 
 *      <dependency>
 *          <groupId>com.itextpdf</groupId>
 *          <artifactId>itextpdf</artifactId>
 *          <version>5.5.2</version>
 *      </dependency>
 *
 * The program can be run without iText if you comment out the entire
 * method printToPDF (and iText imports), along with it's method call in 
 * the class constructor. The result will be the the image above.
 */

public class LargePanelToImageMCVE {

    public LargePanelToImageMCVE() {
        LargeImagePanel panel = new LargeImagePanel();
        JFrame frame = new JFrame();
        frame.add(new JScrollPane(panel));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
        frame.setVisible(true);

        final java.awt.Image image = getImageFromPanel(panel);

        /* This was just a text panel to make sure the full panel was
         * drawn to the panel.
         */
        JPanel newPanel = new JPanel() {
            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.drawImage(image, 0, 0, getWidth(), getHeight(), this);
            }

            @Override
            public Dimension getPreferredSize() {
                return new Dimension(300, 300);
            }
        };

        /* Print Image to PDF */
        String fileName = "D://newfile.pdf";
        printToPDF(image, fileName);

        /* This was just a test to show the newPanel drew the entire
         * original panel (scaled)
         */
        JOptionPane.showMessageDialog(null, newPanel);

    }

    public void printToPDF(java.awt.Image awtImage, String fileName) {
        try {
            Document d = new Document();
            PdfWriter writer = PdfWriter.getInstance(d, new FileOutputStream(
                    fileName));
            d.open();


            Image iTextImage = Image.getInstance(writer, awtImage, 1);
            iTextImage.setAbsolutePosition(50, 50);
            iTextImage.scalePercent(25);
            d.add(iTextImage);

            d.close();

        } catch (Exception e) {
            e.printStackTrace();
        }   
    }

    public static java.awt.Image getImageFromPanel(Component component) {

        BufferedImage image = new BufferedImage(component.getWidth(),
                component.getHeight(), BufferedImage.TYPE_INT_RGB);
        component.paint(image.getGraphics());
        return image;
    }

    /**
     * Demo panel that is 2000x2000 px with alternating squares
     * to check all squares are drawn to image
     */
    public class LargeImagePanel extends JPanel {
        private static final int FULL_SIZE = 2000;
        private static final int PER_ROW_COLUMN = 20;
        private static final int SQUARE_SIZE = FULL_SIZE / PER_ROW_COLUMN;

        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            for (int row = 0; row < PER_ROW_COLUMN; row++) {
                for (int col = 0; col < PER_ROW_COLUMN; col++) {
                    if ((row % 2) == (col % 2)) {
                        g.setColor(Color.BLACK);
                    } else {
                        g.setColor(Color.WHITE);
                    }
                    g.fillRect(col * SQUARE_SIZE, row * SQUARE_SIZE,
                            SQUARE_SIZE, SQUARE_SIZE);
                }
            }
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(FULL_SIZE, FULL_SIZE);
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new LargePanelToImageMCVE();
            }
        });
    }
}