我的可打印Swing组件的所有部分都不打印

Question

我正在尝试做一个可打印的组件(发票文档)。我使用JComponent而不是JPanel，因为我不想要背景。该组件有许多子组件。

主组件实现可打印，并具有一个调用print-method的printAll(g)，以便打印所有子组件。但我的子组件不打印。

我遗漏了什么？所有子组件也必须实现可打印吗？

在下面的代码中，没有打印TopHeader。

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.print.PageFormat;
import java.awt.print.Printable;
import java.awt.print.PrinterException;
import java.awt.print.PrinterJob;

import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class PPanel extends JComponent implements Printable {
    static double w;
    static double h;

    public PPanel() {
        this.setLayout(new BorderLayout());

        this.add(new JLabel("Document Body"), BorderLayout.CENTER);
        this.add(new TopHeader(), BorderLayout.NORTH);
    }

    class TopHeader extends JComponent {
        public TopHeader() {
            this.setLayout(new BorderLayout());
            JLabel companyName = new JLabel("Company name");
            JLabel docType = new JLabel("Document type");
            this.add(companyName, BorderLayout.WEST);
            this.add(docType, BorderLayout.EAST);
        }
    }

    public static void main(String[] args) {
        final PPanel p = new PPanel();
        PrinterJob job = PrinterJob.getPrinterJob();
        job.setPrintable(p);
        try {
            job.print();
        } catch (PrinterException ex) {
            // print failed
        }
            // Preview
        new JFrame() {{ getContentPane().add(p); this.setSize((int)w, (int)h); setVisible(true); }};

    }

    @Override
    public int print(Graphics g, PageFormat pf, int page)
            throws PrinterException {
        if (page > 0) {
            return NO_SUCH_PAGE;
        }

        Graphics2D g2d = (Graphics2D)g;
        g2d.translate(pf.getImageableX(), pf.getImageableY());

        w = pf.getImageableWidth();
        h = pf.getHeight();

        this.setSize((int)w, (int)h);
        this.setPreferredSize(new Dimension((int)w, (int)h));
        this.doLayout();

        this.printAll(g);
        return PAGE_EXISTS;
    }
}

Answer 1

您可能可以遍历由Component[]返回的getComponents()，但是下面显示了一个简单的权宜之计。注意屏幕预览和打印输出之间的区别。另外，注意validate()的使用优先于doLayout()。最后，为了方便预览，本例实现了。

增编:您也可以看看，比较一下在这个example中采用的方法。

import java.awt.*;
import java.awt.print.*;
import javax.swing.*;

public class PPanel extends JComponent implements Printable {

    private JComponent top = new TopHeader();
    private JComponent mid = new JLabel("Document Body");

    public PPanel() {
        this.setLayout(new BorderLayout());
        this.add(top, BorderLayout.NORTH);
        this.add(mid, BorderLayout.CENTER);
    }

    private static class TopHeader extends JComponent {

        public TopHeader() {
            this.setLayout(new BorderLayout());
            JLabel companyName = new JLabel("Company name");
            JLabel docType = new JLabel("Document type");
            this.add(companyName, BorderLayout.WEST);
            this.add(docType, BorderLayout.EAST);
        }
    }

    @Override
    public int print(Graphics g, PageFormat pf, int page)
        throws PrinterException {
        if (page > 0) {
            return NO_SUCH_PAGE;
        }
        Graphics2D g2d = (Graphics2D)g;
        g2d.translate(pf.getImageableX(), pf.getImageableY());
        int w = (int)pf.getImageableWidth();
        int h = (int)pf.getImageableHeight();
        top.setSize(new Dimension(w, top.getPreferredSize().height));
        this.setSize(w, h);
        this.validate();
        this.printAll(g2d);
        return PAGE_EXISTS;
    }

    public static void main(String[] args) {
        final PPanel p = new PPanel();
        // Preview before print()
        new JFrame() {
            {
                this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                this.add(p);
                this.pack();
                this.setVisible(true);
            }
        };
        PrinterJob pj = PrinterJob.getPrinterJob();
        PageFormat pf = pj.pageDialog(pj.defaultPage());
        pj.setPrintable(p, pf);
        if (pj.printDialog()) {
            try {
                pj.print();
            } catch (PrinterException pe) {
                pe.printStackTrace();
            }
        }
    }
}