打印大型Swing组件

Question

我有一个Swing表单,在JScrollPane中有一个自定义表(它只是一个JPanel,而不是JTable子类),我试图让它打印出来.如果我只是将整个框架发送到打印机,滚动窗格会切断,如果我将框架的大小调整为滚动窗格内容的大小,某种内部屏障会阻止JFrame变得超过1100像素高.

另一种方法是创建对话框的内容窗格而不将其附加到根JFrame,因为JPanel的大小在这种情况下不受限制.但是为了让组件自行调整并调整到适当的大小,我似乎需要使面板可显示,这意味着至少将它添加到JFrame并调用JFrame.pack(),但同样,1100像素限制回来了.

这是我打印组件的代码:

public static void print(final Component comp) {
    final float SCALE = .5f;
    PrinterJob job = PrinterJob.getPrinterJob();
    job.setPrintable(new Printable() {
        public int print(Graphics g, PageFormat pf, int page)
            throws PrinterException
        {
            if (page * pf.getImageableHeight() >= SCALE * comp.getHeight())
                return NO_SUCH_PAGE;
            ((Graphics2D)g).translate(pf.getImageableX(), pf.getImageableY()
               - page * pf.getImageableHeight());
            ((Graphics2D)g).scale(SCALE, SCALE);
            comp.printAll(g);
            return PAGE_EXISTS;
        }
    });
    if (job.printDialog())
        try { job.print(); }
        catch (PrinterException ex) {}
}

如果我这样做,组件的大小为零:

JPanel c = createPanel(); // This JPanel has a JScrollPane in it with its
                          // preferredSize equal to that of its viewport component
                          // (which is not what I do to show the dialog normally)
print(c);

如果我这样做,组件具有正确的大小,但打印为纯灰色,因为子组件尚未布局:

JPanel c = createPanel();
c.setSize(c.getPeferredSize());
print(c);

这些似乎没有什么区别:

JPanel c = createPanel();
c.validate();
c.revalidate();
c.repaint();
print(c);

这使得面板更大,但它停在大约一页半(1100px):

JPanel c = createPanel();
JFrame f = new JFrame();
f.setContentPane(c);
f.pack();
print(c);

我在这里没有排列.有没有人知道(a)如何更改操作系统最大帧大小,(b)如何布局和绘制离屏组件,或(c)如何直接打印Swing组件,而不必绘制它(？) .感谢帮助.

Answer 1

使用自定义面板的paint()方法,将内容呈现为BufferedImage.

附录:这是一个更完整的方法示例,它只是将组件缩放一半.您需要在实际应用程序中保留纵横比.

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

/** @see https://stackoverflow.com/questions/7026822 */
public class PanelPaint extends JPanel {

    private static final double SCALE = 0.5;

    public PanelPaint() {
        super(new GridLayout(0, 1));
        final MyPanel panel = new MyPanel();
        JScrollPane scroll = new JScrollPane(panel);
        scroll.getViewport().setPreferredSize(new Dimension(320, 240));
        this.add(scroll);
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                add(new JLabel(new ImageIcon(createImage(panel))));
            }
        });
    }

    private BufferedImage createImage(MyPanel panel) {
        Dimension size = panel.getPreferredSize();
        BufferedImage image = new BufferedImage(
            size.width, size.height, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = image.createGraphics();
        panel.paint(g2d);
        g2d.dispose();
        AffineTransform at = new AffineTransform();
        at.scale(SCALE, SCALE);
        AffineTransformOp scaleOp =
            new AffineTransformOp(at, AffineTransformOp.TYPE_BILINEAR);
        return scaleOp.filter(image, null);
    }

    private static class MyPanel extends JPanel {

        private static final int N = 16;

        public MyPanel() {
            super(true);
            this.setLayout(new GridLayout(N, N));
            for (int i = 0; i < N * N; i++) {
                this.add(new JLabel(String.valueOf(i) + " "));
            }
        }
    }

    private void display() {
        JFrame f = new JFrame("PanelPaint");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(this);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new PanelPaint().display();
            }
        });
    }
}

如图所示在这里,你可以扩展渲染以适应目标的MediaPrintableArea,或使用getSubimage()如需要将内容分成页.

Answer 2

由于 JScrollPane 中的组件可以具有任意大小，即使在使其可显示之后也是如此，我的解决方案是尝试以下操作：

JPanel c = createPanel();
JFrame f = new JFrame();
f.getContentPane().add(new JScrollPane(c));
f.pack();
print(c);

这样我就可以验证 JPanel，而不会将其大小限制为 JFrame 的最大大小。它还具有字体和直接打印组件所获得的“无限分辨率”外观，无需像trashgod建议的那样进行双缓冲。