Name: skT88420 Date: 09/08/99


The program below illustrates a bug in TextLayout.draw. The
program comment describes the problem. Information is lost when
the characters run off the edge of the display area or overlap.

Ray Tomlinson

package com.bbn.tomlinson;

import java.awt.*;
import java.awt.event.*;
import java.awt.font.*;
import java.awt.print.*;
import java.awt.geom.*;
import java.text.*;
import java.util.*;

/**
 * Draw a small window displaying the same text string six different
 * ways: as a TextLayout or ordinary String and with three different x
 * scale factors. The expectation is that each set of three strings
 * would appear the same although offset in y to avoid
 * overlap. Instead, the y positions of the individual characters of
 * the TextLayout are wrong.
 **/
public class Bug2 extends Panel {

  static Map hints = new HashMap();

  static {
    hints.put(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
    hints.put(RenderingHints.KEY_TEXT_ANTIALIASING,
RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
    hints.put(RenderingHints.KEY_FRACTIONALMETRICS,
RenderingHints.VALUE_FRACTIONALMETRICS_ON);
  }
  public Dimension getPreferredSize() {
    return new Dimension(400, 400);
  }

  static String test = "This is only a test";

  static double angle = Math.PI / 6.0; // Rotate 30 degrees

  private void draw(Graphics2D g2d, TextLayout layout,
float x, float y, float scalex)
  {
    AffineTransform saveTransform = g2d.getTransform();
    g2d.translate(x, y);
    g2d.rotate(angle);
    g2d.scale(scalex, 1f);
    layout.draw(g2d, 0f, 0f);
    g2d.setTransform(saveTransform);
  }

  private void draw(Graphics2D g2d, String string,
float x, float y, float scalex) {
    AffineTransform saveTransform = g2d.getTransform();
    g2d.translate(x, y);
    g2d.rotate(angle);
    g2d.scale(scalex, 1f);
    g2d.drawString(string, 0f, 0f);
    g2d.setTransform(saveTransform);
  }

  public void paint(Graphics g) {
    Graphics2D g2d = (Graphics2D) g;
    g2d.scale(1.481f, 1.481); // Convert to 108 dpi
    g2d.addRenderingHints(hints);
    FontRenderContext frc = g2d.getFontRenderContext();
    TextLayout tl1 = new TextLayout(new AttributedString(test).getIterator(), frc);
    draw(g2d, tl1, 10f, 12f, 3.0f);
    draw(g2d, tl1, 10f, 24f, 1.0f);
    draw(g2d, tl1, 10f, 36f, 0.33f);
    draw(g2d, test, 10f, 84f, 3.0f);
    draw(g2d, test, 10f, 96f, 1.0f);
    draw(g2d, test, 10f, 108f, .33f);
  }

  public static void main(String[] args) {
    Frame frame = new Frame("Bug2");
    Bug2 bug2 = new Bug2();
    frame.add(bug2);
    frame.pack();
    frame.show();
    frame.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
System.exit(0);
      }
    });
  }
}
(Review ID: 94995)
======================================================================

This is actually a problem with GlyphVector (which TextLayout uses for drawing). Attached is a modified version of the test which uses GlyphVector instead of TextLayout. The output is the same.
 
john.raley@eng 1999-09-27