- /*
- * @(#)Spring.java 1.9 03/12/19
- *
- * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
- * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- */
- package javax.swing;
-
- import java.awt.Component;
- import java.util.*;
-
- /**
- * An instance of the <code>Spring</code> class holds three properties that
- * characterize its behavior: the <em>minimum</em>, <em>preferred</em>, and
- * <em>maximum</em> values. Each of these properties may be involved in
- * defining its fourth, <em>value</em>, property based on a series of rules.
- * <p>
- * An instance of the <code>Spring</code> class can be visualized as a
- * mechanical spring that provides a corrective force as the spring is compressed
- * or stretched away from its preferred value. This force is modelled
- * as linear function of the distance from the preferred value, but with
- * two different constants -- one for the compressional force and one for the
- * tensional one. Those constants are specified by the minimum and maximum
- * values of the spring such that a spring at its minimum value produces an
- * equal and opposite force to that which is created when it is at its
- * maximum value. The difference between the <em>preferred</em> and
- * <em>minimum</em> values, therefore, represents the ease with which the
- * spring can be compressed and the difference between its <em>maximum</em>
- * and <em>preferred</em> values, indicates the ease with which the
- * <code>Spring</code> can be extended.
- * See the {@link #sum} method for details.
- *
- * <p>
- * By defining simple arithmetic operations on <code>Spring</code>s,
- * the behavior of a collection of <code>Spring</code>s
- * can be reduced to that of an ordinary (non-compound) <code>Spring</code>. We define
- * the "+", "-", <em>max</em>, and <em>min</em> operators on
- * <code>Spring</code>s so that, in each case, the result is a <code>Spring</code>
- * whose characteristics bear a useful mathematical relationship to its constituent
- * springs.
- *
- * <p>
- * A <code>Spring</code> can be treated as a pair of intervals
- * with a single common point: the preferred value.
- * The following rules define some of the
- * arithmetic operators that can be applied to intervals
- * (<code>[a, b]</code> refers to the interval
- * from <code>a</code>
- * to <code>b</code>,
- * where <code>a <= b</code>).
- * <p>
- * <pre>
- * [a1, b1] + [a2, b2] = [a1 + a2, b1 + b2]
- *
- * -[a, b] = [-b, -a]
- *
- * max([a1, b1], [a2, b2]) = [max(a1, a2), max(b1, b2)]
- * </pre>
- * <p>
- *
- * If we denote <code>Spring</code>s as <code>[a, b, c]</code>,
- * where <code>a <= b <= c</code>, we can define the same
- * arithmetic operators on <code>Spring</code>s:
- * <p>
- * <pre>
- * [a1, b1, c1] + [a2, b2, c2] = [a1 + a2, b1 + b2, c1 + c2]
- *
- * -[a, b, c] = [-c, -b, -a]
- *
- * max([a1, b1, c1], [a2, b2, c2]) = [max(a1, a2), max(b1, b2), max(c1, c2)]
- * </pre>
- * <p>
- * With both intervals and <code>Spring</code>s we can define "-" and <em>min</em>
- * in terms of negation:
- * <p>
- * <pre>
- * X - Y = X + (-Y)
- *
- * min(X, Y) = -max(-X, -Y)
- * </pre>
- * <p>
- * For the static methods in this class that embody the arithmetic
- * operators, we do not actually perform the operation in question as
- * that would snapshot the values of the properties of the method's arguments
- * at the time the static method is called. Instead, the static methods
- * create a new <code>Spring</code> instance containing references to
- * the method's arguments so that the characteristics of the new spring track the
- * potentially changing characteristics of the springs from which it
- * was made. This is a little like the idea of a <em>lazy value</em>
- * in a functional language.
- * <p>
- * If you are implementing a <code>SpringLayout</code> you
- * can find further information and examples in
- * <a
- href="http://java.sun.com/docs/books/tutorial/uiswing/layout/spring.html">How to Use SpringLayout</a>,
- * a section in <em>The Java Tutorial.</em>
- * <p>
- * <strong>Warning:</strong>
- * Serialized objects of this class will not be compatible with
- * future Swing releases. The current serialization support is
- * appropriate for short term storage or RMI between applications running
- * the same version of Swing. As of 1.4, support for long term storage
- * of all JavaBeans<sup><font size="-2">TM</font></sup>
- * has been added to the <code>java.beans</code> package.
- * Please see {@link java.beans.XMLEncoder}.
- *
- * @see SpringLayout
- * @see SpringLayout.Constraints
- *
- * @version 1.9 12/19/03
- * @author Philip Milne
- * @since 1.4
- */
- public abstract class Spring {
-
- /**
- * An integer value signifying that a property value has not yet been calculated.
- */
- public static final int UNSET = Integer.MIN_VALUE;
-
- /**
- * Used by factory methods to create a <code>Spring</code>.
- *
- * @see #constant(int)
- * @see #constant(int, int, int)
- * @see #max
- * @see #minus
- * @see #sum
- * @see SpringLayout.Constraints
- */
- protected Spring() {}
-
- /**
- * Returns the <em>minimum</em> value of this <code>Spring</code>.
- *
- * @return the <code>minimumValue</code> property of this <code>Spring</code>
- */
- public abstract int getMinimumValue();
-
- /**
- * Returns the <em>preferred</em> value of this <code>Spring</code>.
- *
- * @return the <code>preferredValue</code> of this <code>Spring</code>
- */
- public abstract int getPreferredValue();
-
- /**
- * Returns the <em>maximum</em> value of this <code>Spring</code>.
- *
- * @return the <code>maximumValue</code> property of this <code>Spring</code>
- */
- public abstract int getMaximumValue();
-
- /**
- * Returns the current <em>value</em> of this <code>Spring</code>.
- *
- * @return the <code>value</code> property of this <code>Spring</code>
- *
- * @see #setValue
- */
- public abstract int getValue();
-
- /**
- * Sets the current <em>value</em> of this <code>Spring</code> to <code>value</code>.
- *
- * @param value the new setting of the <code>value</code> property
- *
- * @see #getValue
- */
- public abstract void setValue(int value);
-
- private double range(boolean contract) {
- return contract ? (getPreferredValue() - getMinimumValue()) :
- (getMaximumValue() - getPreferredValue());
- }
-
- /*pp*/ double getStrain() {
- double delta = (getValue() - getPreferredValue());
- return deltarange(getValue() < getPreferredValue());
- }
-
- /*pp*/ void setStrain(double strain) {
- setValue(getPreferredValue() + (int)(strain * range(strain < 0)));
- }
-
- /*pp*/ boolean isCyclic(SpringLayout l) {
- return false;
- }
-
- /*pp*/ static abstract class AbstractSpring extends Spring {
- protected int size = UNSET;
-
- public int getValue() {
- return size != UNSET ? size : getPreferredValue();
- }
-
- public void setValue(int size) {
- if (size == UNSET) {
- clear();
- return;
- }
- this.size = size;
- }
-
- protected void clear() {
- size = UNSET;
- }
- }
-
- private static class StaticSpring extends AbstractSpring {
- protected int min;
- protected int pref;
- protected int max;
-
- public StaticSpring() {}
-
- public StaticSpring(int pref) {
- this(pref, pref, pref);
- }
-
- public StaticSpring(int min, int pref, int max) {
- this.min = min;
- this.pref = pref;
- this.max = max;
- this.size = pref;
- }
-
- public String toString() {
- return "StaticSpring [" + min + ", " + pref + ", " + max + "]";
- }
-
- public int getMinimumValue() {
- return min;
- }
-
- public int getPreferredValue() {
- return pref;
- }
-
- public int getMaximumValue() {
- return max;
- }
- }
-
- private static class NegativeSpring extends Spring {
- private Spring s;
-
- public NegativeSpring(Spring s) {
- this.s = s;
- }
-
- // Note the use of max value rather than minimum value here.
- // See the opening preamble on arithmetic with springs.
-
- public int getMinimumValue() {
- return -s.getMaximumValue();
- }
-
- public int getPreferredValue() {
- return -s.getPreferredValue();
- }
-
- public int getMaximumValue() {
- return -s.getMinimumValue();
- }
-
- public int getValue() {
- return -s.getValue();
- }
-
- public void setValue(int size) {
- // No need to check for UNSET as
- // Integer.MIN_VALUE == -Integer.MIN_VALUE.
- s.setValue(-size);
- }
-
- /*pp*/ boolean isCyclic(SpringLayout l) {
- return s.isCyclic(l);
- }
- }
-
- private static class ScaleSpring extends Spring {
- private Spring s;
- private float factor;
-
- private ScaleSpring(Spring s, float factor) {
- this.s = s;
- this.factor = factor;
- }
-
- public int getMinimumValue() {
- return Math.round((factor < 0 ? s.getMaximumValue() : s.getMinimumValue()) * factor);
- }
-
- public int getPreferredValue() {
- return Math.round(s.getPreferredValue() * factor);
- }
-
- public int getMaximumValue() {
- return Math.round((factor < 0 ? s.getMinimumValue() : s.getMaximumValue()) * factor);
- }
-
- public int getValue() {
- return Math.round(s.getValue() * factor);
- }
-
- public void setValue(int value) {
- if (value == UNSET) {
- s.setValue(UNSET);
- } else {
- s.setValue(Math.round(value / factor));
- }
- }
-
- /*pp*/ boolean isCyclic(SpringLayout l) {
- return s.isCyclic(l);
- }
- }
-
- /*pp*/ static class WidthSpring extends AbstractSpring {
- /*pp*/ Component c;
-
- public WidthSpring(Component c) {
- this.c = c;
- }
-
- public int getMinimumValue() {
- return c.getMinimumSize().width;
- }
-
- public int getPreferredValue() {
- return c.getPreferredSize().width;
- }
-
- public int getMaximumValue() {
- // We will be doing arithmetic with the results of this call,
- // so if a returned value is Integer.MAX_VALUE we will get
- // arithmetic overflow. Truncate such values.
- return Math.min(Short.MAX_VALUE, c.getMaximumSize().width);
- }
- }
-
- /*pp*/ static class HeightSpring extends AbstractSpring {
- /*pp*/ Component c;
-
- public HeightSpring(Component c) {
- this.c = c;
- }
-
- public int getMinimumValue() {
- return c.getMinimumSize().height;
- }
-
- public int getPreferredValue() {
- return c.getPreferredSize().height;
- }
-
- public int getMaximumValue() {
- return Math.min(Short.MAX_VALUE, c.getMaximumSize().height);
- }
- }
-
- // Use the instance variables of the StaticSpring superclass to
- // cache values that have already been calculated.
- /*pp*/ static abstract class CompoundSpring extends StaticSpring {
- protected Spring s1;
- protected Spring s2;
-
- public CompoundSpring(Spring s1, Spring s2) {
- clear();
- this.s1 = s1;
- this.s2 = s2;
- }
-
- public String toString() {
- return "CompoundSpring of " + s1 + " and " + s2;
- }
-
- protected void clear() {
- min = pref = max = size = UNSET;
- }
-
- public void setValue(int size) {
- if (size == UNSET) {
- if (this.size != UNSET) {
- super.setValue(size);
- s1.setValue(UNSET);
- s2.setValue(UNSET);
- return;
- }
- }
- super.setValue(size);
- }
-
- protected abstract int op(int x, int y);
-
- public int getMinimumValue() {
- if (min == UNSET) {
- min = op(s1.getMinimumValue(), s2.getMinimumValue());
- }
- return min;
- }
-
- public int getPreferredValue() {
- if (pref == UNSET) {
- pref = op(s1.getPreferredValue(), s2.getPreferredValue());
- }
- return pref;
- }
-
- public int getMaximumValue() {
- if (max == UNSET) {
- max = op(s1.getMaximumValue(), s2.getMaximumValue());
- }
- return max;
- }
-
- public int getValue() {
- if (size == UNSET) {
- size = op(s1.getValue(), s2.getValue());
- }
- return size;
- }
-
- /*pp*/ boolean isCyclic(SpringLayout l) {
- return l.isCyclic(s1) || l.isCyclic(s2);
- }
- };
-
- private static class SumSpring extends CompoundSpring {
- public SumSpring(Spring s1, Spring s2) {
- super(s1, s2);
- }
-
- protected int op(int x, int y) {
- return x + y;
- }
-
- public void setValue(int size) {
- super.setValue(size);
- if (size == UNSET) {
- return;
- }
- s1.setStrain(this.getStrain());
- s2.setValue(size - s1.getValue());
- }
- }
-
- private static class MaxSpring extends CompoundSpring {
-
- public MaxSpring(Spring s1, Spring s2) {
- super(s1, s2);
- }
-
- protected int op(int x, int y) {
- return Math.max(x, y);
- }
-
- public void setValue(int size) {
- super.setValue(size);
- if (size == UNSET) {
- return;
- }
- // Pending should also check max bounds here.
- if (s1.getPreferredValue() < s2.getPreferredValue()) {
- s1.setValue(Math.min(size, s1.getPreferredValue()));
- s2.setValue(size);
- }
- else {
- s1.setValue(size);
- s2.setValue(Math.min(size, s2.getPreferredValue()));
- }
- }
- }
-
- /**
- * Returns a strut -- a spring whose <em>minimum</em>, <em>preferred</em>, and
- * <em>maximum</em> values each have the value <code>pref</code>.
- *
- * @param pref the <em>minimum</em>, <em>preferred</em>, and
- * <em>maximum</em> values of the new spring
- * @return a spring whose <em>minimum</em>, <em>preferred</em>, and
- * <em>maximum</em> values each have the value <code>pref</code>
- *
- * @see Spring
- */
- public static Spring constant(int pref) {
- return constant(pref, pref, pref);
- }
-
- /**
- * Returns a spring whose <em>minimum</em>, <em>preferred</em>, and
- * <em>maximum</em> values have the values: <code>min</code>, <code>pref</code>,
- * and <code>max</code> respectively.
- *
- * @param min the <em>minimum</em> value of the new spring
- * @param pref the <em>preferred</em> value of the new spring
- * @param max the <em>maximum</em> value of the new spring
- * @return a spring whose <em>minimum</em>, <em>preferred</em>, and
- * <em>maximum</em> values have the values: <code>min</code>, <code>pref</code>,
- * and <code>max</code> respectively
- *
- * @see Spring
- */
- public static Spring constant(int min, int pref, int max) {
- return new StaticSpring(min, pref, max);
- }
-
-
- /**
- * Returns <code>-s</code>: a spring running in the opposite direction to <code>s</code>.
- *
- * @return <code>-s</code>: a spring running in the opposite direction to <code>s</code>
- *
- * @see Spring
- */
- public static Spring minus(Spring s) {
- return new NegativeSpring(s);
- }
-
- /**
- * Returns <code>s1+s2</code>: a spring representing <code>s1</code> and <code>s2</code>
- * in series. In a sum, <code>s3</code>, of two springs, <code>s1</code> and <code>s2</code>,
- * the <em>strains</em> of <code>s1</code>, <code>s2</code>, and <code>s3</code> are maintained
- * at the same level (to within the precision implied by their integer <em>value</em>s).
- * The strain of a spring in compression is:
- * <pre>
- * value - pref
- * ------------
- * pref - min
- * </pre>
- * and the strain of a spring in tension is:
- * <pre>
- * value - pref
- * ------------
- * max - pref
- * </pre>
- * When <code>setValue</code> is called on the sum spring, <code>s3</code>, the strain
- * in <code>s3</code> is calculated using one of the formulas above. Once the strain of
- * the sum is known, the <em>value</em>s of <code>s1</code> and <code>s2</code> are
- * then set so that they are have a strain equal to that of the sum. The formulas are
- * evaluated so as to take rounding errors into account and ensure that the sum of
- * the <em>value</em>s of <code>s1</code> and <code>s2</code> is exactly equal to
- * the <em>value</em> of <code>s3</code>.
- *
- * @return <code>s1+s2</code>: a spring representing <code>s1</code> and <code>s2</code> in series
- *
- * @see Spring
- */
- public static Spring sum(Spring s1, Spring s2) {
- return new SumSpring(s1, s2);
- }
-
- /**
- * Returns <code>max(s1, s2)</code>: a spring whose value is always greater than (or equal to)
- * the values of both <code>s1</code> and <code>s2</code>.
- *
- * @return <code>max(s1, s2)</code>: a spring whose value is always greater than (or equal to)
- * the values of both <code>s1</code> and <code>s2</code>
- * @see Spring
- */
- public static Spring max(Spring s1, Spring s2) {
- return new MaxSpring(s1, s2);
- }
-
- // Remove these, they're not used often and can be created using minus -
- // as per these implementations.
-
- /*pp*/ static Spring difference(Spring s1, Spring s2) {
- return sum(s1, minus(s2));
- }
-
- /*
- public static Spring min(Spring s1, Spring s2) {
- return minus(max(minus(s1), minus(s2)));
- }
- */
-
- /**
- * Returns a spring whose <em>minimum</em>, <em>preferred</em>, <em>maximum</em>
- * and <em>value</em> properties are each multiples of the properties of the
- * argument spring, <code>s</code>. Minimum and maximum properties are
- * swapped when <code>factor</code> is negative (in accordance with the
- * rules of interval arithmetic).
- * <p>
- * When factor is, for example, 0.5f the result represents 'the mid-point'
- * of its input - an operation that is useful for centering components in
- * a container.
- *
- * @param s the spring to scale
- * @param factor amount to scale by.
- * @return a spring whose properties are those of the input spring <code>s</code>
- * multiplied by <code>factor</code>
- * @throws NullPointerException if <code>s</code> is null
- * @since 1.5
- */
- public static Spring scale(Spring s, float factor) {
- checkArg(s);
- return new ScaleSpring(s, factor);
- }
-
- /**
- * Returns a spring whose <em>minimum</em>, <em>preferred</em>, <em>maximum</em>
- * and <em>value</em> properties are defined by the widths of the <em>minimumSize</em>,
- * <em>preferredSize</em>, <em>maximumSize</em> and <em>size</em> properties
- * of the supplied component. The returned spring is a 'wrapper' implementation
- * whose methods call the appropriate size methods of the supplied component.
- * The minimum, preferred, maximum and value properties of the returned spring
- * therefore report the current state of the appropriate properties in the
- * component and track them as they change.
- *
- * @param c Component used for calculating size
- * @return a spring whose properties are defined by the horizontal component
- * of the component's size methods.
- * @throws NullPointerException if <code>c</code> is null
- * @since 1.5
- */
- public static Spring width(Component c) {
- checkArg(c);
- return new WidthSpring(c);
- }
-
- /**
- * Returns a spring whose <em>minimum</em>, <em>preferred</em>, <em>maximum</em>
- * and <em>value</em> properties are defined by the heights of the <em>minimumSize</em>,
- * <em>preferredSize</em>, <em>maximumSize</em> and <em>size</em> properties
- * of the supplied component. The returned spring is a 'wrapper' implementation
- * whose methods call the appropriate size methods of the supplied component.
- * The minimum, preferred, maximum and value properties of the returned spring
- * therefore report the current state of the appropriate properties in the
- * component and track them as they change.
- *
- * @param c Component used for calculating size
- * @return a spring whose properties are defined by the vertical component
- * of the component's size methods.
- * @throws NullPointerException if <code>c</code> is null
- * @since 1.5
- */
- public static Spring height(Component c) {
- checkArg(c);
- return new HeightSpring(c);
- }
-
-
- /**
- * If <code>s</code> is null, this throws an NullPointerException.
- */
- private static void checkArg(Object s) {
- if (s == null) {
- throw new NullPointerException("Argument must not be null");
- }
- }
- }