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/*
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* Copyright 2001-2005 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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package javax.swing;
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import java.awt.Component;
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/**
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* An instance of the <code>Spring</code> class holds three properties that
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* characterize its behavior: the <em>minimum</em>, <em>preferred</em>, and
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* <em>maximum</em> values. Each of these properties may be involved in
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* defining its fourth, <em>value</em>, property based on a series of rules.
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* <p>
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* An instance of the <code>Spring</code> class can be visualized as a
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* mechanical spring that provides a corrective force as the spring is compressed
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* or stretched away from its preferred value. This force is modelled
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* as linear function of the distance from the preferred value, but with
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* two different constants -- one for the compressional force and one for the
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* tensional one. Those constants are specified by the minimum and maximum
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* values of the spring such that a spring at its minimum value produces an
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* equal and opposite force to that which is created when it is at its
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* maximum value. The difference between the <em>preferred</em> and
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* <em>minimum</em> values, therefore, represents the ease with which the
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* spring can be compressed and the difference between its <em>maximum</em>
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* and <em>preferred</em> values, indicates the ease with which the
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* <code>Spring</code> can be extended.
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* See the {@link #sum} method for details.
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*
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* <p>
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* By defining simple arithmetic operations on <code>Spring</code>s,
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* the behavior of a collection of <code>Spring</code>s
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* can be reduced to that of an ordinary (non-compound) <code>Spring</code>. We define
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* the "+", "-", <em>max</em>, and <em>min</em> operators on
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* <code>Spring</code>s so that, in each case, the result is a <code>Spring</code>
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* whose characteristics bear a useful mathematical relationship to its constituent
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* springs.
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*
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* <p>
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* A <code>Spring</code> can be treated as a pair of intervals
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* with a single common point: the preferred value.
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* The following rules define some of the
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* arithmetic operators that can be applied to intervals
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* (<code>[a, b]</code> refers to the interval
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* from <code>a</code>
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* to <code>b</code>,
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* where <code>a <= b</code>).
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* <p>
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* <pre>
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* [a1, b1] + [a2, b2] = [a1 + a2, b1 + b2]
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*
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* -[a, b] = [-b, -a]
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*
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* max([a1, b1], [a2, b2]) = [max(a1, a2), max(b1, b2)]
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* </pre>
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* <p>
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*
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* If we denote <code>Spring</code>s as <code>[a, b, c]</code>,
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* where <code>a <= b <= c</code>, we can define the same
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* arithmetic operators on <code>Spring</code>s:
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* <p>
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* <pre>
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* [a1, b1, c1] + [a2, b2, c2] = [a1 + a2, b1 + b2, c1 + c2]
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*
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* -[a, b, c] = [-c, -b, -a]
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*
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* max([a1, b1, c1], [a2, b2, c2]) = [max(a1, a2), max(b1, b2), max(c1, c2)]
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* </pre>
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* <p>
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* With both intervals and <code>Spring</code>s we can define "-" and <em>min</em>
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* in terms of negation:
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* <p>
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* <pre>
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* X - Y = X + (-Y)
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*
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* min(X, Y) = -max(-X, -Y)
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* </pre>
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* <p>
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* For the static methods in this class that embody the arithmetic
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* operators, we do not actually perform the operation in question as
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* that would snapshot the values of the properties of the method's arguments
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* at the time the static method is called. Instead, the static methods
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* create a new <code>Spring</code> instance containing references to
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* the method's arguments so that the characteristics of the new spring track the
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* potentially changing characteristics of the springs from which it
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* was made. This is a little like the idea of a <em>lazy value</em>
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* in a functional language.
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* <p>
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* If you are implementing a <code>SpringLayout</code> you
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* can find further information and examples in
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* <a
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href="http://java.sun.com/docs/books/tutorial/uiswing/layout/spring.html">How to Use SpringLayout</a>,
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* a section in <em>The Java Tutorial.</em>
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* <p>
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* <strong>Warning:</strong>
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* Serialized objects of this class will not be compatible with
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* future Swing releases. The current serialization support is
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* appropriate for short term storage or RMI between applications running
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* the same version of Swing. As of 1.4, support for long term storage
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* of all JavaBeans<sup><font size="-2">TM</font></sup>
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* has been added to the <code>java.beans</code> package.
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* Please see {@link java.beans.XMLEncoder}.
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*
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* @see SpringLayout
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* @see SpringLayout.Constraints
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*
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* @author Philip Milne
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* @since 1.4
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*/
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public abstract class Spring {
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/**
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* An integer value signifying that a property value has not yet been calculated.
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*/
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public static final int UNSET = Integer.MIN_VALUE;
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/**
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* Used by factory methods to create a <code>Spring</code>.
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*
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* @see #constant(int)
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* @see #constant(int, int, int)
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* @see #max
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* @see #minus
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* @see #sum
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* @see SpringLayout.Constraints
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*/
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protected Spring() {}
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/**
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* Returns the <em>minimum</em> value of this <code>Spring</code>.
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*
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* @return the <code>minimumValue</code> property of this <code>Spring</code>
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*/
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public abstract int getMinimumValue();
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/**
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* Returns the <em>preferred</em> value of this <code>Spring</code>.
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*
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* @return the <code>preferredValue</code> of this <code>Spring</code>
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*/
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public abstract int getPreferredValue();
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/**
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* Returns the <em>maximum</em> value of this <code>Spring</code>.
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*
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* @return the <code>maximumValue</code> property of this <code>Spring</code>
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*/
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public abstract int getMaximumValue();
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/**
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* Returns the current <em>value</em> of this <code>Spring</code>.
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*
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* @return the <code>value</code> property of this <code>Spring</code>
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*
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* @see #setValue
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*/
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public abstract int getValue();
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/**
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* Sets the current <em>value</em> of this <code>Spring</code> to <code>value</code>.
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*
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* @param value the new setting of the <code>value</code> property
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*
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* @see #getValue
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*/
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public abstract void setValue(int value);
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private double range(boolean contract) {
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return contract ? (getPreferredValue() - getMinimumValue()) :
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(getMaximumValue() - getPreferredValue());
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}
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/*pp*/ double getStrain() {
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double delta = (getValue() - getPreferredValue());
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return delta/range(getValue() < getPreferredValue());
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}
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/*pp*/ void setStrain(double strain) {
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setValue(getPreferredValue() + (int)(strain * range(strain < 0)));
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}
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/*pp*/ boolean isCyclic(SpringLayout l) {
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return false;
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}
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/*pp*/ static abstract class AbstractSpring extends Spring {
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protected int size = UNSET;
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public int getValue() {
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return size != UNSET ? size : getPreferredValue();
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}
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public final void setValue(int size) {
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if (this.size == size) {
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return;
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}
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if (size == UNSET) {
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clear();
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} else {
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setNonClearValue(size);
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}
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}
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protected void clear() {
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size = UNSET;
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}
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protected void setNonClearValue(int size) {
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this.size = size;
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}
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}
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private static class StaticSpring extends AbstractSpring {
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protected int min;
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protected int pref;
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protected int max;
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public StaticSpring(int pref) {
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this(pref, pref, pref);
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}
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public StaticSpring(int min, int pref, int max) {
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this.min = min;
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this.pref = pref;
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this.max = max;
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}
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public String toString() {
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return "StaticSpring [" + min + ", " + pref + ", " + max + "]";
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}
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public int getMinimumValue() {
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return min;
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}
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public int getPreferredValue() {
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return pref;
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}
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public int getMaximumValue() {
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return max;
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}
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}
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private static class NegativeSpring extends Spring {
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private Spring s;
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public NegativeSpring(Spring s) {
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this.s = s;
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}
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// Note the use of max value rather than minimum value here.
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// See the opening preamble on arithmetic with springs.
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public int getMinimumValue() {
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return -s.getMaximumValue();
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}
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public int getPreferredValue() {
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return -s.getPreferredValue();
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}
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public int getMaximumValue() {
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return -s.getMinimumValue();
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}
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public int getValue() {
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return -s.getValue();
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}
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public void setValue(int size) {
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// No need to check for UNSET as
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// Integer.MIN_VALUE == -Integer.MIN_VALUE.
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s.setValue(-size);
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}
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/*pp*/ boolean isCyclic(SpringLayout l) {
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return s.isCyclic(l);
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}
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}
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private static class ScaleSpring extends Spring {
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private Spring s;
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private float factor;
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private ScaleSpring(Spring s, float factor) {
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this.s = s;
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this.factor = factor;
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}
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public int getMinimumValue() {
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return Math.round((factor < 0 ? s.getMaximumValue() : s.getMinimumValue()) * factor);
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}
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public int getPreferredValue() {
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return Math.round(s.getPreferredValue() * factor);
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}
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public int getMaximumValue() {
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return Math.round((factor < 0 ? s.getMinimumValue() : s.getMaximumValue()) * factor);
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}
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public int getValue() {
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return Math.round(s.getValue() * factor);
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}
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public void setValue(int value) {
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if (value == UNSET) {
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s.setValue(UNSET);
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} else {
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s.setValue(Math.round(value / factor));
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}
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}
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/*pp*/ boolean isCyclic(SpringLayout l) {
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return s.isCyclic(l);
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}
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}
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/*pp*/ static class WidthSpring extends AbstractSpring {
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/*pp*/ Component c;
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public WidthSpring(Component c) {
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this.c = c;
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}
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public int getMinimumValue() {
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return c.getMinimumSize().width;
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}
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public int getPreferredValue() {
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return c.getPreferredSize().width;
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}
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public int getMaximumValue() {
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// We will be doing arithmetic with the results of this call,
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// so if a returned value is Integer.MAX_VALUE we will get
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// arithmetic overflow. Truncate such values.
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return Math.min(Short.MAX_VALUE, c.getMaximumSize().width);
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}
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}
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/*pp*/ static class HeightSpring extends AbstractSpring {
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/*pp*/ Component c;
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public HeightSpring(Component c) {
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this.c = c;
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}
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public int getMinimumValue() {
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return c.getMinimumSize().height;
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}
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public int getPreferredValue() {
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return c.getPreferredSize().height;
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}
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public int getMaximumValue() {
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return Math.min(Short.MAX_VALUE, c.getMaximumSize().height);
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}
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}
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/*pp*/ static abstract class SpringMap extends Spring {
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private Spring s;
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public SpringMap(Spring s) {
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this.s = s;
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}
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protected abstract int map(int i);
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protected abstract int inv(int i);
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public int getMinimumValue() {
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return map(s.getMinimumValue());
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}
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public int getPreferredValue() {
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return map(s.getPreferredValue());
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}
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public int getMaximumValue() {
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return Math.min(Short.MAX_VALUE, map(s.getMaximumValue()));
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}
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public int getValue() {
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return map(s.getValue());
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}
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public void setValue(int value) {
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if (value == UNSET) {
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s.setValue(UNSET);
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} else {
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s.setValue(inv(value));
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}
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}
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/*pp*/ boolean isCyclic(SpringLayout l) {
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return s.isCyclic(l);
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}
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}
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// Use the instance variables of the StaticSpring superclass to
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// cache values that have already been calculated.
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/*pp*/ static abstract class CompoundSpring extends StaticSpring {
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protected Spring s1;
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protected Spring s2;
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public CompoundSpring(Spring s1, Spring s2) {
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super(UNSET);
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this.s1 = s1;
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432 |
this.s2 = s2;
|
|
433 |
}
|
|
434 |
|
|
435 |
public String toString() {
|
|
436 |
return "CompoundSpring of " + s1 + " and " + s2;
|
|
437 |
}
|
|
438 |
|
|
439 |
protected void clear() {
|
|
440 |
super.clear();
|
|
441 |
min = pref = max = UNSET;
|
|
442 |
s1.setValue(UNSET);
|
|
443 |
s2.setValue(UNSET);
|
|
444 |
}
|
|
445 |
|
|
446 |
protected abstract int op(int x, int y);
|
|
447 |
|
|
448 |
public int getMinimumValue() {
|
|
449 |
if (min == UNSET) {
|
|
450 |
min = op(s1.getMinimumValue(), s2.getMinimumValue());
|
|
451 |
}
|
|
452 |
return min;
|
|
453 |
}
|
|
454 |
|
|
455 |
public int getPreferredValue() {
|
|
456 |
if (pref == UNSET) {
|
|
457 |
pref = op(s1.getPreferredValue(), s2.getPreferredValue());
|
|
458 |
}
|
|
459 |
return pref;
|
|
460 |
}
|
|
461 |
|
|
462 |
public int getMaximumValue() {
|
|
463 |
if (max == UNSET) {
|
|
464 |
max = op(s1.getMaximumValue(), s2.getMaximumValue());
|
|
465 |
}
|
|
466 |
return max;
|
|
467 |
}
|
|
468 |
|
|
469 |
public int getValue() {
|
|
470 |
if (size == UNSET) {
|
|
471 |
size = op(s1.getValue(), s2.getValue());
|
|
472 |
}
|
|
473 |
return size;
|
|
474 |
}
|
|
475 |
|
|
476 |
/*pp*/ boolean isCyclic(SpringLayout l) {
|
|
477 |
return l.isCyclic(s1) || l.isCyclic(s2);
|
|
478 |
}
|
|
479 |
};
|
|
480 |
|
|
481 |
private static class SumSpring extends CompoundSpring {
|
|
482 |
public SumSpring(Spring s1, Spring s2) {
|
|
483 |
super(s1, s2);
|
|
484 |
}
|
|
485 |
|
|
486 |
protected int op(int x, int y) {
|
|
487 |
return x + y;
|
|
488 |
}
|
|
489 |
|
|
490 |
protected void setNonClearValue(int size) {
|
|
491 |
super.setNonClearValue(size);
|
|
492 |
s1.setStrain(this.getStrain());
|
|
493 |
s2.setValue(size - s1.getValue());
|
|
494 |
}
|
|
495 |
}
|
|
496 |
|
|
497 |
private static class MaxSpring extends CompoundSpring {
|
|
498 |
|
|
499 |
public MaxSpring(Spring s1, Spring s2) {
|
|
500 |
super(s1, s2);
|
|
501 |
}
|
|
502 |
|
|
503 |
protected int op(int x, int y) {
|
|
504 |
return Math.max(x, y);
|
|
505 |
}
|
|
506 |
|
|
507 |
protected void setNonClearValue(int size) {
|
|
508 |
super.setNonClearValue(size);
|
|
509 |
s1.setValue(size);
|
|
510 |
s2.setValue(size);
|
|
511 |
}
|
|
512 |
}
|
|
513 |
|
|
514 |
/**
|
|
515 |
* Returns a strut -- a spring whose <em>minimum</em>, <em>preferred</em>, and
|
|
516 |
* <em>maximum</em> values each have the value <code>pref</code>.
|
|
517 |
*
|
|
518 |
* @param pref the <em>minimum</em>, <em>preferred</em>, and
|
|
519 |
* <em>maximum</em> values of the new spring
|
|
520 |
* @return a spring whose <em>minimum</em>, <em>preferred</em>, and
|
|
521 |
* <em>maximum</em> values each have the value <code>pref</code>
|
|
522 |
*
|
|
523 |
* @see Spring
|
|
524 |
*/
|
|
525 |
public static Spring constant(int pref) {
|
|
526 |
return constant(pref, pref, pref);
|
|
527 |
}
|
|
528 |
|
|
529 |
/**
|
|
530 |
* Returns a spring whose <em>minimum</em>, <em>preferred</em>, and
|
|
531 |
* <em>maximum</em> values have the values: <code>min</code>, <code>pref</code>,
|
|
532 |
* and <code>max</code> respectively.
|
|
533 |
*
|
|
534 |
* @param min the <em>minimum</em> value of the new spring
|
|
535 |
* @param pref the <em>preferred</em> value of the new spring
|
|
536 |
* @param max the <em>maximum</em> value of the new spring
|
|
537 |
* @return a spring whose <em>minimum</em>, <em>preferred</em>, and
|
|
538 |
* <em>maximum</em> values have the values: <code>min</code>, <code>pref</code>,
|
|
539 |
* and <code>max</code> respectively
|
|
540 |
*
|
|
541 |
* @see Spring
|
|
542 |
*/
|
|
543 |
public static Spring constant(int min, int pref, int max) {
|
|
544 |
return new StaticSpring(min, pref, max);
|
|
545 |
}
|
|
546 |
|
|
547 |
|
|
548 |
/**
|
|
549 |
* Returns <code>-s</code>: a spring running in the opposite direction to <code>s</code>.
|
|
550 |
*
|
|
551 |
* @return <code>-s</code>: a spring running in the opposite direction to <code>s</code>
|
|
552 |
*
|
|
553 |
* @see Spring
|
|
554 |
*/
|
|
555 |
public static Spring minus(Spring s) {
|
|
556 |
return new NegativeSpring(s);
|
|
557 |
}
|
|
558 |
|
|
559 |
/**
|
|
560 |
* Returns <code>s1+s2</code>: a spring representing <code>s1</code> and <code>s2</code>
|
|
561 |
* in series. In a sum, <code>s3</code>, of two springs, <code>s1</code> and <code>s2</code>,
|
|
562 |
* the <em>strains</em> of <code>s1</code>, <code>s2</code>, and <code>s3</code> are maintained
|
|
563 |
* at the same level (to within the precision implied by their integer <em>value</em>s).
|
|
564 |
* The strain of a spring in compression is:
|
|
565 |
* <pre>
|
|
566 |
* value - pref
|
|
567 |
* ------------
|
|
568 |
* pref - min
|
|
569 |
* </pre>
|
|
570 |
* and the strain of a spring in tension is:
|
|
571 |
* <pre>
|
|
572 |
* value - pref
|
|
573 |
* ------------
|
|
574 |
* max - pref
|
|
575 |
* </pre>
|
|
576 |
* When <code>setValue</code> is called on the sum spring, <code>s3</code>, the strain
|
|
577 |
* in <code>s3</code> is calculated using one of the formulas above. Once the strain of
|
|
578 |
* the sum is known, the <em>value</em>s of <code>s1</code> and <code>s2</code> are
|
|
579 |
* then set so that they are have a strain equal to that of the sum. The formulas are
|
|
580 |
* evaluated so as to take rounding errors into account and ensure that the sum of
|
|
581 |
* the <em>value</em>s of <code>s1</code> and <code>s2</code> is exactly equal to
|
|
582 |
* the <em>value</em> of <code>s3</code>.
|
|
583 |
*
|
|
584 |
* @return <code>s1+s2</code>: a spring representing <code>s1</code> and <code>s2</code> in series
|
|
585 |
*
|
|
586 |
* @see Spring
|
|
587 |
*/
|
|
588 |
public static Spring sum(Spring s1, Spring s2) {
|
|
589 |
return new SumSpring(s1, s2);
|
|
590 |
}
|
|
591 |
|
|
592 |
/**
|
|
593 |
* Returns <code>max(s1, s2)</code>: a spring whose value is always greater than (or equal to)
|
|
594 |
* the values of both <code>s1</code> and <code>s2</code>.
|
|
595 |
*
|
|
596 |
* @return <code>max(s1, s2)</code>: a spring whose value is always greater than (or equal to)
|
|
597 |
* the values of both <code>s1</code> and <code>s2</code>
|
|
598 |
* @see Spring
|
|
599 |
*/
|
|
600 |
public static Spring max(Spring s1, Spring s2) {
|
|
601 |
return new MaxSpring(s1, s2);
|
|
602 |
}
|
|
603 |
|
|
604 |
// Remove these, they're not used often and can be created using minus -
|
|
605 |
// as per these implementations.
|
|
606 |
|
|
607 |
/*pp*/ static Spring difference(Spring s1, Spring s2) {
|
|
608 |
return sum(s1, minus(s2));
|
|
609 |
}
|
|
610 |
|
|
611 |
/*
|
|
612 |
public static Spring min(Spring s1, Spring s2) {
|
|
613 |
return minus(max(minus(s1), minus(s2)));
|
|
614 |
}
|
|
615 |
*/
|
|
616 |
|
|
617 |
/**
|
|
618 |
* Returns a spring whose <em>minimum</em>, <em>preferred</em>, <em>maximum</em>
|
|
619 |
* and <em>value</em> properties are each multiples of the properties of the
|
|
620 |
* argument spring, <code>s</code>. Minimum and maximum properties are
|
|
621 |
* swapped when <code>factor</code> is negative (in accordance with the
|
|
622 |
* rules of interval arithmetic).
|
|
623 |
* <p>
|
|
624 |
* When factor is, for example, 0.5f the result represents 'the mid-point'
|
|
625 |
* of its input - an operation that is useful for centering components in
|
|
626 |
* a container.
|
|
627 |
*
|
|
628 |
* @param s the spring to scale
|
|
629 |
* @param factor amount to scale by.
|
|
630 |
* @return a spring whose properties are those of the input spring <code>s</code>
|
|
631 |
* multiplied by <code>factor</code>
|
|
632 |
* @throws NullPointerException if <code>s</code> is null
|
|
633 |
* @since 1.5
|
|
634 |
*/
|
|
635 |
public static Spring scale(Spring s, float factor) {
|
|
636 |
checkArg(s);
|
|
637 |
return new ScaleSpring(s, factor);
|
|
638 |
}
|
|
639 |
|
|
640 |
/**
|
|
641 |
* Returns a spring whose <em>minimum</em>, <em>preferred</em>, <em>maximum</em>
|
|
642 |
* and <em>value</em> properties are defined by the widths of the <em>minimumSize</em>,
|
|
643 |
* <em>preferredSize</em>, <em>maximumSize</em> and <em>size</em> properties
|
|
644 |
* of the supplied component. The returned spring is a 'wrapper' implementation
|
|
645 |
* whose methods call the appropriate size methods of the supplied component.
|
|
646 |
* The minimum, preferred, maximum and value properties of the returned spring
|
|
647 |
* therefore report the current state of the appropriate properties in the
|
|
648 |
* component and track them as they change.
|
|
649 |
*
|
|
650 |
* @param c Component used for calculating size
|
|
651 |
* @return a spring whose properties are defined by the horizontal component
|
|
652 |
* of the component's size methods.
|
|
653 |
* @throws NullPointerException if <code>c</code> is null
|
|
654 |
* @since 1.5
|
|
655 |
*/
|
|
656 |
public static Spring width(Component c) {
|
|
657 |
checkArg(c);
|
|
658 |
return new WidthSpring(c);
|
|
659 |
}
|
|
660 |
|
|
661 |
/**
|
|
662 |
* Returns a spring whose <em>minimum</em>, <em>preferred</em>, <em>maximum</em>
|
|
663 |
* and <em>value</em> properties are defined by the heights of the <em>minimumSize</em>,
|
|
664 |
* <em>preferredSize</em>, <em>maximumSize</em> and <em>size</em> properties
|
|
665 |
* of the supplied component. The returned spring is a 'wrapper' implementation
|
|
666 |
* whose methods call the appropriate size methods of the supplied component.
|
|
667 |
* The minimum, preferred, maximum and value properties of the returned spring
|
|
668 |
* therefore report the current state of the appropriate properties in the
|
|
669 |
* component and track them as they change.
|
|
670 |
*
|
|
671 |
* @param c Component used for calculating size
|
|
672 |
* @return a spring whose properties are defined by the vertical component
|
|
673 |
* of the component's size methods.
|
|
674 |
* @throws NullPointerException if <code>c</code> is null
|
|
675 |
* @since 1.5
|
|
676 |
*/
|
|
677 |
public static Spring height(Component c) {
|
|
678 |
checkArg(c);
|
|
679 |
return new HeightSpring(c);
|
|
680 |
}
|
|
681 |
|
|
682 |
|
|
683 |
/**
|
|
684 |
* If <code>s</code> is null, this throws an NullPointerException.
|
|
685 |
*/
|
|
686 |
private static void checkArg(Object s) {
|
|
687 |
if (s == null) {
|
|
688 |
throw new NullPointerException("Argument must not be null");
|
|
689 |
}
|
|
690 |
}
|
|
691 |
}
|