Paint pas fait sur JTextPane+JScrollPane

Voila un exemple.

Code:

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import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
 
public class GoSc {
	public static void main(String a[]) {
		final JFrame frame = new JFrame();
		frame.setSize(300, 200);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		JTextPane editor = new JTextPane() {
			@Override
			public boolean getScrollableTracksViewportWidth() {
				return false;
			}
		};
		editor.setText("mmmmmmmmm\nmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm");
		frame.setContentPane(new JScrollPane(editor));
		frame.setLocationRelativeTo(null);
		frame.setVisible(true);
 
		LineHighlight line = new LineHighlight(editor, Color.YELLOW);
 
		line.resetLineHighlight();
	}
}

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import java.awt.Color;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Shape;
import javax.swing.SwingUtilities;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;
import javax.swing.text.Element;
import javax.swing.text.Highlighter;
import javax.swing.text.JTextComponent;
import javax.swing.text.View;
import javax.swing.text.DefaultHighlighter.DefaultHighlightPainter;
 
public class LineHighlight extends DefaultHighlightPainter {
 
	private JTextComponent theTextComponent = null;
	private Highlighter theHighlighter = null;
	private Object theLastHighlight = null;
	private static Color defaultColor = new Color(230,245,255);
        private boolean active = true;
 
	public LineHighlight(JTextComponent aTextComponent, Color lineHighlightColor) {
		super(lineHighlightColor == null ? defaultColor : lineHighlightColor);
		if (aTextComponent != null) setTextComponent(aTextComponent);
	}
 
	private void setTextComponent(JTextComponent aTextComponent) {
		theTextComponent = aTextComponent;
		DefaultHighlighter defaultHighlighter = (DefaultHighlighter)theTextComponent.getHighlighter();
		defaultHighlighter.setDrawsLayeredHighlights(true);
		theHighlighter = defaultHighlighter;
	}
 
 
	@Override
	public Shape paintLayer(Graphics g, int offs0, int offs1, Shape bounds, JTextComponent c, View view) {
		if (active) {	
			try {
				Rectangle r = c.modelToView(offs0);
				r.width = c.getSize().width;
				g.setColor(getColor());
				g.fillRect(r.x, r.y, r.width, r.height);			
				//c.repaint(r.x, r.y, r.width, r.height);
				return r;
			} 
			catch (BadLocationException e) {
				e.printStackTrace();
			}
		}
		return null;
	}
 
	public void resetLineHighlight() {
		if (theTextComponent != null && active) {
			SwingUtilities.invokeLater(new Runnable() {
				public void run() {
					if (theLastHighlight != null) theHighlighter.removeHighlight(theLastHighlight);
					Element root = theTextComponent.getDocument().getDefaultRootElement();
					int line = root.getElementIndex(theTextComponent.getCaretPosition());
					Element lineElement = root.getElement(line);
					int start = lineElement.getStartOffset();
					int end = lineElement.getEndOffset();
					addHighlight(start, end);
				}
			});
		}
	}
 
	private void addHighlight(int offset, int end) {
		try {
			theLastHighlight = theHighlighter.addHighlight(offset, end, this);
		} 
		catch (BadLocationException ble) {
			ble.printStackTrace();
		}
	}
 
	protected void removeHighlight() {
		theHighlighter.removeHighlight(theLastHighlight);
	}
 
	public boolean isActive() {
		return active;
	}
 
	public void setActive(boolean active) {
		this.active = active;
		theTextComponent.repaint();
	}
 
}