JTextPane Highlight Example
/*
Core SWING Advanced Programming
By Kim Topley
ISBN: 0 13 083292 8
Publisher: Prentice Hall
*/
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Shape;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.FileReader;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.JTextPane;
import javax.swing.UIManager;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;
import javax.swing.text.Document;
import javax.swing.text.Highlighter;
import javax.swing.text.JTextComponent;
import javax.swing.text.LayeredHighlighter;
import javax.swing.text.Position;
import javax.swing.text.View;
public class HighlightExample {
public static void main(String[] args) {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
} catch (Exception evt) {}
JFrame f = new JFrame("Highlight example");
final JTextPane textPane = new JTextPane();
textPane.setHighlighter(highlighter);
JPanel pane = new JPanel();
pane.setLayout(new BorderLayout());
pane.add(new JLabel("Enter word: "), "West");
final JTextField tf = new JTextField();
pane.add(tf, "Center");
f.getContentPane().add(pane, "South");
f.getContentPane().add(new JScrollPane(textPane), "Center");
try {
textPane.read(new FileReader("links1.html"), null);
} catch (Exception e) {
System.out.println("Failed to load file " + args[0]);
System.out.println(e);
}
final WordSearcher searcher = new WordSearcher(textPane);
tf.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
word = tf.getText().trim();
int offset = searcher.search(word);
if (offset != -1) {
try {
textPane.scrollRectToVisible(textPane
.modelToView(offset));
} catch (BadLocationException e) {
}
}
}
});
textPane.getDocument().addDocumentListener(new DocumentListener() {
public void insertUpdate(DocumentEvent evt) {
searcher.search(word);
}
public void removeUpdate(DocumentEvent evt) {
searcher.search(word);
}
public void changedUpdate(DocumentEvent evt) {
}
});
f.setSize(400, 400);
f.setVisible(true);
}
public static String word;
public static Highlighter highlighter = new UnderlineHighlighter(null);
}
// A simple class that searches for a word in
// a document and highlights occurrences of that word
class WordSearcher {
public WordSearcher(JTextComponent comp) {
this.comp = comp;
this.painter = new UnderlineHighlighter.UnderlineHighlightPainter(
Color.red);
}
// Search for a word and return the offset of the
// first occurrence. Highlights are added for all
// occurrences found.
public int search(String word) {
int firstOffset = -1;
Highlighter highlighter = comp.getHighlighter();
// Remove any existing highlights for last word
Highlighter.Highlight[] highlights = highlighter.getHighlights();
for (int i = 0; i < highlights.length; i++) {
Highlighter.Highlight h = highlights[i];
if (h.getPainter() instanceof UnderlineHighlighter.UnderlineHighlightPainter) {
highlighter.removeHighlight(h);
}
}
if (word == null || word.equals("")) {
return -1;
}
// Look for the word we are given - insensitive search
String content = null;
try {
Document d = comp.getDocument();
content = d.getText(0, d.getLength()).toLowerCase();
} catch (BadLocationException e) {
// Cannot happen
return -1;
}
word = word.toLowerCase();
int lastIndex = 0;
int wordSize = word.length();
while ((lastIndex = content.indexOf(word, lastIndex)) != -1) {
int endIndex = lastIndex + wordSize;
try {
highlighter.addHighlight(lastIndex, endIndex, painter);
} catch (BadLocationException e) {
// Nothing to do
}
if (firstOffset == -1) {
firstOffset = lastIndex;
}
lastIndex = endIndex;
}
return firstOffset;
}
protected JTextComponent comp;
protected Highlighter.HighlightPainter painter;
}
class UnderlineHighlighter extends DefaultHighlighter {
public UnderlineHighlighter(Color c) {
painter = (c == null ? sharedPainter : new UnderlineHighlightPainter(c));
}
// Convenience method to add a highlight with
// the default painter.
public Object addHighlight(int p0, int p1) throws BadLocationException {
return addHighlight(p0, p1, painter);
}
public void setDrawsLayeredHighlights(boolean newValue) {
// Illegal if false - we only support layered highlights
if (newValue == false) {
throw new IllegalArgumentException(
"UnderlineHighlighter only draws layered highlights");
}
super.setDrawsLayeredHighlights(true);
}
// Painter for underlined highlights
public static class UnderlineHighlightPainter extends
LayeredHighlighter.LayerPainter {
public UnderlineHighlightPainter(Color c) {
color = c;
}
public void paint(Graphics g, int offs0, int offs1, Shape bounds,
JTextComponent c) {
// Do nothing: this method will never be called
}
public Shape paintLayer(Graphics g, int offs0, int offs1, Shape bounds,
JTextComponent c, View view) {
g.setColor(color == null ? c.getSelectionColor() : color);
Rectangle alloc = null;
if (offs0 == view.getStartOffset() && offs1 == view.getEndOffset()) {
if (bounds instanceof Rectangle) {
alloc = (Rectangle) bounds;
} else {
alloc = bounds.getBounds();
}
} else {
try {
Shape shape = view.modelToView(offs0,
Position.Bias.Forward, offs1,
Position.Bias.Backward, bounds);
alloc = (shape instanceof Rectangle) ? (Rectangle) shape
: shape.getBounds();
} catch (BadLocationException e) {
return null;
}
}
FontMetrics fm = c.getFontMetrics(c.getFont());
int baseline = alloc.y + alloc.height - fm.getDescent() + 1;
g.drawLine(alloc.x, baseline, alloc.x + alloc.width, baseline);
g.drawLine(alloc.x, baseline + 1, alloc.x + alloc.width,
baseline + 1);
return alloc;
}
protected Color color; // The color for the underline
}
// Shared painter used for default highlighting
protected static final Highlighter.HighlightPainter sharedPainter = new UnderlineHighlightPainter(
null);
// Painter used for this highlighter
protected Highlighter.HighlightPainter painter;
}
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