Name: rmT116609			Date: 09/18/2002


FULL PRODUCT VERSION :
java version "1.4.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92)
Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)

also:

java version "1.4.1"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1-b21)
Java HotSpot(TM) Client VM (build 1.4.1-b21, mixed mode)



DESCRIPTION OF THE PROBLEM :
Centering multiple components with a SpringLayout requires a subclass of Spring which can divide the atrributes of a Spring in half. A "scale" operator
can perform this function and would fit well with the "sum", " minus" and "max" operators the class already provides.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. javac TestCenter2.java
2. java TestCenter2

EXPECTED VERSUS ACTUAL BEHAVIOR :
The provided source shows one way to center components
with a SpringLayout. This is an RFE, so no error is
produced.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------

import javax.swing.*;
import java.awt.*;

public class TestCenter2 {
    public static class ScaleSpring extends Spring {
        private Spring s;
        private double factor;

        private ScaleSpring(Spring s, double factor) {
            this.s = s;
            this.factor = factor;
        }

        public int getMinimumValue() {
            return (int)((factor < 0 ? s.getMaximumValue() : s.getMinimumValue
()) * factor);
        }

        public int getPreferredValue() {
            return (int)(s.getPreferredValue() * factor);
        }

        public int getMaximumValue() {
            return (int)((factor < 0 ? s.getMinimumValue() : s.getMaximumValue
()) * factor);
        }

        public int getValue() {
            return (int)(s.getValue() * factor);
        }

        public void setValue(int value) {
            s.setValue((int)(value / factor));
        }
    }

    public static Spring scale(Spring s, double factor) {
        return new ScaleSpring(s, factor);
    }

    public static void main(String[] args) {
        JFrame f = new JFrame();
        Container p = f.getContentPane();

        JComponent c1 = new JTextField("Spectacular");
        JComponent c2 = new JTextField("Bar");

//        JComponent c1 = new JButton("Foo");
//        c1.setMinimumSize(new Dimension(0, 0));
//        c1.setMaximumSize(new Dimension(Integer.MAX_VALUE,
Integer.MAX_VALUE));
//        JComponent c2 = new JButton("Bar");
//        c1.setMinimumSize(new Dimension(0, 0));
//        c1.setMaximumSize(new Dimension(Integer.MAX_VALUE,
Integer.MAX_VALUE));

        SpringLayout l = new SpringLayout();
        p.setLayout(l);

        p.add(c1);
        p.add(c2);

        SpringLayout.Constraints pc = l.getConstraints(p);
        SpringLayout.Constraints bc1 = l.getConstraints(c1);
        SpringLayout.Constraints bc2 = l.getConstraints(c2);

        Spring middle = scale(pc.getWidth(), 0.5);

        bc1.setX(Spring.sum(middle, Spring.minus(scale(bc1.getWidth(), 0.5))));
        bc2.setX(Spring.sum(middle, Spring.minus(scale(bc2.getWidth(), 0.5))));
        pc.setConstraint("East", Spring.constant(0, 300, 1000));
//        pc.setConstraint("East", Spring.max(bc1.getWidth(), bc2.getWidth()));

        bc1.setY(Spring.constant(0, 10, 100));
        bc2.setY(Spring.sum(Spring.constant(10), bc1.getConstraint("South")));
        pc.setConstraint("South", Spring.sum(Spring.constant(10),
bc2.getConstraint("South")));

        f.pack();
        f.setVisible(true);
    }
}

---------- END SOURCE ----------
(Review ID: 164663) 
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