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LineHighlightPainter.javaAPI DocExample2520Thu Oct 24 20:14:26 BST 2002None

LineHighlightPainter

public class LineHighlightPainter extends Object implements Highlighter$HighlightPainter

Fields Summary
Constructors Summary
Methods Summary
public static voidmain(java.lang.String[] args)


    // extend DefaultCaret as an anonymous inner class
    Caret lineHighlightPainterCaret = new DefaultCaret() {
      private Highlighter.HighlightPainter lhp = new LineHighlightPainter();
      // override getSelectionPainter to return the LineHighlightPainter
      protected Highlighter.HighlightPainter getSelectionPainter() {
        return lhp;
      }
    };

    JFrame frame = new JFrame("LineHighlightPainter demo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTextArea area = new JTextArea(9, 45);
    area.setCaret(lineHighlightPainterCaret);
    area.setLineWrap(true);
    area.setWrapStyleWord(true);
    area.setText("This is the story\nof the hare who\nlost his spectacles.");
    frame.getContentPane().add(new JScrollPane(area), BorderLayout.CENTER);
    frame.pack();
    frame.setVisible(true);
public voidpaint(java.awt.Graphics g, int p0, int p1, java.awt.Shape bounds, javax.swing.text.JTextComponent c)


    Rectangle r0 = null, r1 = null, rbounds = bounds.getBounds();
    int xmax = rbounds.x + rbounds.width; // x coordinate of right edge
    try {  // convert positions to pixel coordinates
      r0 = c.modelToView(p0);
      r1 = c.modelToView(p1);
    } catch (BadLocationException ex) { return; }
    if ((r0 == null) || (r1 == null)) return;

    g.setColor( c.getSelectionColor() );

    // special case if p0 and p1 are on the same line
    if (r0.y == r1.y) {
      paintLine(g, r0, r1.x);
      return;
    }

    // first line, from p1 to end-of-line
    paintLine(g, r0, xmax);

    // all the full lines in between, if any (assumes that all lines have
    // the same height--not a good assumption with JEditorPane/JTextPane)
    r0.y += r0.height; // move r0 to next line 
    r0.x = rbounds.x; // move r0 to left edge
    while (r0.y < r1.y) {
      paintLine(g, r0, xmax);
      r0.y += r0.height; // move r0 to next line
    }

    // last line, from beginning-of-line to p1
    paintLine(g, r0, r1.x);
private voidpaintLine(java.awt.Graphics g, java.awt.Rectangle r, int x2)

    int ytop = r.y + r.height - 3;
    g.fillRect(r.x, ytop, x2 - r.x, 3);