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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