COMPONENT JAVAJava 2 Printing

• By Matthew Robinson and Pavel Vorobiev
• May 13, 2000

Listing 2. Swing component allowing print preview of any Printable job.

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.util.*;
import java.awt.print.*;

import javax.swing.*;
import javax.swing.border.*;
import javax.swing.event.*;

public class PrintPreview extends JFrame 
{
  protected int m_wPage;
  protected int m_hPage;
  protected Printable m_target;
  protected JComboBox m_cbScale;
  protected PreviewContainer m_preview;

  public PrintPreview(Printable target) {
    this(target, "Print Preview");
  }

  public PrintPreview(Printable target, String title) {
    super(title);
    setSize(600, 400);
    m_target = target;

    JToolBar tb = new JToolBar();
    JButton bt = new JButton("Print", new ImageIcon("print.gif"));
    ActionListener lst = new ActionListener() { 
      public void actionPerformed(ActionEvent e) { 
        try {
          // Use default printer, no dialog
          PrinterJob prnJob = PrinterJob.getPrinterJob();
          prnJob.setPrintable(m_target);
          setCursor( Cursor.getPredefinedCursor(
            Cursor.WAIT_CURSOR));
          prnJob.print();
          setCursor( Cursor.getPredefinedCursor(
            Cursor.DEFAULT_CURSOR));
          dispose();
        }
        catch (PrinterException ex) {
          ex.printStackTrace();
          System.err.println("Printing error: "+ex.toString());
        }
      }
    };
    bt.addActionListener(lst);
    bt.setAlignmentY(0.5f);
    bt.setMargin(new Insets(4,6,4,6));
    tb.add(bt);

    bt = new JButton("Close");
    lst = new ActionListener() { 
      public void actionPerformed(ActionEvent e) { 
        dispose();
      }
    };
    bt.addActionListener(lst);
    bt.setAlignmentY(0.5f);
    bt.setMargin(new Insets(2,6,2,6));
    tb.add(bt);

    String[] scales = { "10 %", "25 %", "50 %", "100 %" };
    m_cbScale = new JComboBox(scales);
    lst = new ActionListener() { 
      public void actionPerformed(ActionEvent e) { 
        Thread runner = new Thread() {
          public void run() {
            String str = m_cbScale.getSelectedItem().
              toString();
            if (str.endsWith("%"))
              str = str.substring(0, str.length()-1);
            str = str.trim();
              int scale = 0;
            try { scale = Integer.parseInt(str); }
            catch (NumberFormatException ex) { return; }
            int w = (int)(m_wPage*scale/100);
            int h = (int)(m_hPage*scale/100);

            Component[] comps = m_preview.getComponents();
            for (int k=0; k<comps.length; k++) {
              if (!(comps[k] instanceof PagePreview))
                continue;
              PagePreview pp = (PagePreview)comps[k];
                pp.setScaledSize(w, h);
            }
            m_preview.doLayout();
            m_preview.getParent().getParent().validate();
          }
        };
        runner.start();
      }
    };
    m_cbScale.addActionListener(lst);
    m_cbScale.setMaximumSize(m_cbScale.getPreferredSize());
    m_cbScale.setEditable(true);
    tb.addSeparator();
    tb.add(m_cbScale);
    getContentPane().add(tb, BorderLayout.NORTH);

    m_preview = new PreviewContainer();
    PrinterJob prnJob = PrinterJob.getPrinterJob();
    PageFormat pageFormat = prnJob.defaultPage();
    if (pageFormat.getHeight()==0 || pageFormat.getWidth()==0) {
      System.err.println("Unable to determine default page size");
        return;
    }
    m_wPage = (int)(pageFormat.getWidth());
    m_hPage = (int)(pageFormat.getHeight());
    int scale = 10;
    int w = (int)(m_wPage*scale/100);
    int h = (int)(m_hPage*scale/100);

    int pageIndex = 0;
    try {
      while (true) {
        BufferedImage img = new BufferedImage(m_wPage, 
          m_hPage, BufferedImage.TYPE_INT_RGB);
        Graphics g = img.getGraphics();
        g.setColor(Color.white);
        g.fillRect(0, 0, m_wPage, m_hPage);
        if (target.print(g, pageFormat, pageIndex) != 
         Printable.PAGE_EXISTS)
          break;
        PagePreview pp = new PagePreview(w, h, img);
        m_preview.add(pp);
        pageIndex++;
      }
    }
    catch (PrinterException e) {
      e.printStackTrace();
      System.err.println("Printing error: "+e.toString());
    }

    JScrollPane ps = new JScrollPane(m_preview);
    getContentPane().add(ps, BorderLayout.CENTER);

    setDefaultCloseOperation(DISPOSE_ON_CLOSE);
    setVisible(true);
  }

  class PreviewContainer extends JPanel
  {
    protected int H_GAP = 16;
    protected int V_GAP = 10;

    public Dimension getPreferredSize() {
      int n = getComponentCount();
      if (n == 0)
        return new Dimension(H_GAP, V_GAP);
      Component comp = getComponent(0);
      Dimension dc = comp.getPreferredSize();
      int w = dc.width;
      int h = dc.height;
           
      Dimension dp = getParent().getSize();
      int nCol = Math.max((dp.width-H_GAP)/(w+H_GAP), 1);
      int nRow = n/nCol;
      if (nRow*nCol < n)
        nRow++;
      int ww = nCol*(w+H_GAP) + H_GAP;
      int hh = nRow*(h+V_GAP) + V_GAP;
      Insets ins = getInsets();
      return new Dimension(ww+ins.left+ins.right, 
        hh+ins.top+ins.bottom);
    }

    public Dimension getMaximumSize() {
      return getPreferredSize();
    }

    public Dimension getMinimumSize() {
      return getPreferredSize();
    }

    public void doLayout() {
      Insets ins = getInsets();
      int x = ins.left + H_GAP;
      int y = ins.top + V_GAP;

      int n = getComponentCount();
      if (n == 0)
        return;
      Component comp = getComponent(0);
      Dimension dc = comp.getPreferredSize();
      int w = dc.width;
      int h = dc.height;
            
      Dimension dp = getParent().getSize();
      int nCol = Math.max((dp.width-H_GAP)/(w+H_GAP), 1);
      int nRow = n/nCol;
      if (nRow*nCol < n)
        nRow++;
      int index = 0;
      for (int k = 0; k<nRow; k++) {
        for (int m = 0; m<nCol; m++) {
          if (index >= n)
            return;
          comp = getComponent(index++);
          comp.setBounds(x, y, w, h);
          x += w+H_GAP;
        }
        y += h+V_GAP;
        x = ins.left + H_GAP;
      }
    }
  }

  class PagePreview extends JPanel
  {
    protected int m_w;
    protected int m_h;
    protected Image m_source;
    protected Image m_img;

    public PagePreview(int w, int h, Image source) {
      m_w = w;
      m_h = h;
      m_source= source;
      m_img = m_source.getScaledInstance(m_w, m_h, 
        Image.SCALE_SMOOTH);
      m_img.flush();
      setBackground(Color.white);
      setBorder(new MatteBorder(1, 1, 2, 2, Color.black));
    }

    public void setScaledSize(int w, int h) {
      m_w = w;
      m_h = h;
      m_img = m_source.getScaledInstance(m_w, m_h, 
        Image.SCALE_SMOOTH);
      repaint();
    }

    public Dimension getPreferredSize() {
      Insets ins = getInsets();
      return new Dimension(m_w+ins.left+ins.right, 
        m_h+ins.top+ins.bottom);
    }

    public Dimension getMaximumSize() {
      return getPreferredSize();
    }

    public Dimension getMinimumSize() {
      return getPreferredSize();
    }

    public void paint(Graphics g) {
      g.setColor(getBackground());
      g.fillRect(0, 0, getWidth(), getHeight());
      g.drawImage(m_img, 0, 0, this);
      paintBorder(g);
    }
  }
}