printpreview.java

这个小软件( RealEditor )是同学一起编写的

package com.ecust.swing;

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.awt.print.*;
import javax.swing.*;
import javax.swing.border.*;

public class PrintPreview extends JFrame {
	  /**
     * 
     */
    private static final long serialVersionUID = 633860524327480485L;
    protected int m_wPage;
	  protected int m_hPage;
	  protected Printable m_target;
	  protected JComboBox m_cbScale;
	  protected PreviewContainer m_preview;

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

	  public PrintPreview(Printable target, String title, PrinterJob prnJob) {
	    super(title);
	    setSize(600, 400);
	    m_target = target;
	    this.prnJob = prnJob;
	    JToolBar tb = new JToolBar();
	    JButton bt = new JButton("Print", new ImageIcon("print.gif"));
	    ActionListener lst = new ActionListener() { 
	      public void actionPerformed(ActionEvent e) { 
	        try {
	          PrinterJob prnJob = PrinterJob.getPrinterJob();
	          prnJob.setPrintable(m_target);
	          setCursor( Cursor.getPredefinedCursor(
	            Cursor.WAIT_CURSOR));
	          prnJob.print();
	          setCursor( Cursor.getPredefinedCursor(
	            Cursor.DEFAULT_CURSOR));
	        }
	        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();

	    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
  {
    /**
     * 
     */
    private static final long serialVersionUID = -4952260951955161118L;
    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
  {
    /**
     * 
     */
    private static final long serialVersionUID = 926025838534977094L;
    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);
    }
  }
}