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。 我已经使用 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 组件出口。但一半不出口。 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。 tnx

Answer 1

考虑首先从面板创建一个java.awt.Image（通过将面板绘制为图像）。然后，您可以使用以下方法获取com.itextpdf.text.Image 的实例：

com.itextpdf.text.Image.getInstance(PdfWriter writer, java.awt.Image awtImage, float quality) -
从java.awt.Image 获取com.itextpdf.textImage 的实例。图像被添加为具有用户定义质量的 JPEG。

然后您可以使用com.itextpdf.text.Image API 方法scaleToFit 或scalePercent() 缩放图像（如下例中使用的）。更多关于使用图片的信息（在 iText 中）可以找到here

以下程序创建一个大小为 2000x2000 的面板，其中将 20x20 的正方形（每个 100 像素）绘制到面板上。该面板包含在滚动窗格内。然后将其绘制到图像上，图像将被缩放并添加到 pdf 文档中并打印为 pdf。

_{下图仅显示了如何将整个面板绘制到图像上，然后使用先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();
            }
        });
    }
}