TextPane: DocumentEvent : TextPane « Swing JFC « Java






TextPane: DocumentEvent

TextPane: DocumentEvent
   
/*
Java Swing, 2nd Edition
By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole
ISBN: 0-596-00408-7
Publisher: O'Reilly 
*/
// LiveParenMatcher.java
//Like ParenMatcher but continuously colors as the user edits the document.

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.SwingUtilities;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.Element;
import javax.swing.text.ElementIterator;
import javax.swing.text.Segment;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyleContext;
import javax.swing.text.StyledDocument;

public class LiveParenMatcher extends ParenMatcher implements DocumentListener {

  public LiveParenMatcher() {
    super();
    getDocument().addDocumentListener(this);
  }

  public void changedUpdate(DocumentEvent de) {
    // no insertion or deletion, so do nothing
  }

  public void insertUpdate(DocumentEvent de) {
    SwingUtilities.invokeLater(this); // will call run()
  }

  public void removeUpdate(DocumentEvent de) {
    SwingUtilities.invokeLater(this); // will call run()
  }

  public static void main(String[] args) {
    JFrame frame = new JFrame("LiveParenMatcher");
    frame.setContentPane(new JScrollPane(new LiveParenMatcher()));
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }

  // ---- finished example from "The DocumentListener Interface" ----

  // ---- begin example from "The DocumentEvent Interface" ----
  //      (method renamed to insertUpdate_2)

  public void insertUpdate_2(DocumentEvent de) {
    Document doc = de.getDocument();
    int offset = de.getOffset();
    int length = de.getLength();
    String inserted = "";
    try {
      inserted = doc.getText(offset, length);
    } catch (BadLocationException ble) {
    }

    for (int j = 0; j < inserted.length(); j += 1) {
      char ch = inserted.charAt(j);
      if (ch == '(' || ch == '[' || ch == '{' || ch == ')' || ch == ']'
          || ch == '}') {
        SwingUtilities.invokeLater(this); // will call run()
        return; // no need to check further
      }
    }
  }

  // ---- begin example from "The Segment Class" ----
  //      (method renamed to insertUpdate_3)

  public void insertUpdate_3(DocumentEvent de) {
    Document doc = de.getDocument();
    int offset = de.getOffset();
    int length = de.getLength();
    Segment seg = new Segment();
    try {
      doc.getText(offset, length, seg); // text placed in Segment
    } catch (BadLocationException ble) {
    }

    // iterate through the Segment
    for (char ch = seg.first(); ch != seg.DONE; ch = seg.next())
      if (ch == '(' || ch == '[' || ch == '{' || ch == ')' || ch == ']'
          || ch == '}') {
        SwingUtilities.invokeLater(this); // will call run()
        return; // no need to check further
      }
  }

  // ---- begin example from "The ElementIterator Class" ----
  //      (method renamed to removeUpdate_2)

  public void removeUpdate_2(DocumentEvent de) {
    // print some debugging information before matching the parens
    ElementIterator iter = new ElementIterator(de.getDocument());

    for (Element elem = iter.first(); elem != null; elem = iter.next()) {
      DocumentEvent.ElementChange change = de.getChange(elem);
      if (change != null) { // null means there was no change in elem
        System.out.println("Element " + elem.getName() + " (depth "
            + iter.depth() + ") changed its children: "
            + change.getChildrenRemoved().length
            + " children removed, "
            + change.getChildrenAdded().length
            + " children added.\n");
      }
    }
    SwingUtilities.invokeLater(this); // will call run()
  }

}

class ParenMatcher extends JTextPane implements Runnable {

  public static Color[] matchColor = { Color.blue, Color.magenta, Color.green };

  public static Color badColor = Color.red;

  private AttributeSet[] matchAttrSet;

  private AttributeSet badAttrSet;

  public ParenMatcher() {
    // create an array of AttributeSets from the array of Colors
    StyleContext sc = StyleContext.getDefaultStyleContext();
    badAttrSet = sc.addAttribute(SimpleAttributeSet.EMPTY,
        StyleConstants.Foreground, badColor);
    matchAttrSet = new AttributeSet[matchColor.length];
    for (int j = 0; j < matchColor.length; j += 1)
      matchAttrSet[j] = sc.addAttribute(SimpleAttributeSet.EMPTY,
          StyleConstants.Foreground, matchColor[j]);
  }

  // match and color the parens/brackets/braces
  public void run() {
    StyledDocument doc = getStyledDocument();
    String text = "";
    int len = doc.getLength();
    try {
      text = doc.getText(0, len);
    } catch (BadLocationException ble) {
    }
    java.util.Stack stack = new java.util.Stack();
    for (int j = 0; j < text.length(); j += 1) {
      char ch = text.charAt(j);
      if (ch == '(' || ch == '[' || ch == '{') {
        int depth = stack.size();
        stack.push("" + ch + j); // push a String containg the char and
        // the offset
        AttributeSet aset = matchAttrSet[depth % matchAttrSet.length];
        doc.setCharacterAttributes(j, 1, aset, false);
      }
      if (ch == ')' || ch == ']' || ch == '}') {
        String peek = stack.empty() ? "." : (String) stack.peek();
        if (matches(peek.charAt(0), ch)) { // does it match?
          stack.pop();
          int depth = stack.size();
          AttributeSet aset = matchAttrSet[depth
              % matchAttrSet.length];
          doc.setCharacterAttributes(j, 1, aset, false);
        } else { // mismatch
          doc.setCharacterAttributes(j, 1, badAttrSet, false);
        }
      }
    }

    while (!stack.empty()) { // anything left in the stack is a mismatch
      String pop = (String) stack.pop();
      int offset = Integer.parseInt(pop.substring(1));
      doc.setCharacterAttributes(offset, 1, badAttrSet, false);
    }
  }

  // unset the foreground color (if any) whenever the user enters text
  // (if not for this, text entered after a paren would catch the paren's
  // color)
  public void replaceSelection(String content) {
    getInputAttributes().removeAttribute(StyleConstants.Foreground);
    super.replaceSelection(content);
  }

  // return true if 'left' and 'right' are matching parens/brackets/braces
  public static boolean matches(char left, char right) {
    if (left == '(')
      return (right == ')');
    if (left == '[')
      return (right == ']');
    if (left == '{')
      return (right == '}');
    return false;
  }

  public static void main(String[] args) {
    JFrame frame = new JFrame("ParenMatcher");

    final ParenMatcher matcher = new ParenMatcher();
    matcher.setText("int fact(int n) {\n" + "  if (n <= 1) return 1;\n"
        + "  return(n * fact(n-1));\n" + "}\n");
    frame.getContentPane().add(new JScrollPane(matcher),
        BorderLayout.CENTER);

    JButton matchButton = new JButton("match parens");
    matchButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent ae) {
        matcher.run();
      }
    });
    frame.getContentPane().add(matchButton, BorderLayout.SOUTH);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(200, 150);
    frame.setVisible(true);
  }
}

           
         
    
    
  








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