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| 1 | /* | ||
| 2 | * Copyright (c) 2001, 2005, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | package javax.swing; | ||
| 26 | |||
| 27 | import java.awt.Component; | ||
| 28 | |||
| 29 | /** | ||
| 30 | * An instance of the <code>Spring</code> class holds three properties that | ||
| 31 | * characterize its behavior: the <em>minimum</em>, <em>preferred</em>, and | ||
| 32 | * <em>maximum</em> values. Each of these properties may be involved in | ||
| 33 | * defining its fourth, <em>value</em>, property based on a series of rules. | ||
| 34 | * <p> | ||
| 35 | * An instance of the <code>Spring</code> class can be visualized as a | ||
| 36 | * mechanical spring that provides a corrective force as the spring is compressed | ||
| 37 | * or stretched away from its preferred value. This force is modelled | ||
| 38 | * as linear function of the distance from the preferred value, but with | ||
| 39 | * two different constants -- one for the compressional force and one for the | ||
| 40 | * tensional one. Those constants are specified by the minimum and maximum | ||
| 41 | * values of the spring such that a spring at its minimum value produces an | ||
| 42 | * equal and opposite force to that which is created when it is at its | ||
| 43 | * maximum value. The difference between the <em>preferred</em> and | ||
| 44 | * <em>minimum</em> values, therefore, represents the ease with which the | ||
| 45 | * spring can be compressed and the difference between its <em>maximum</em> | ||
| 46 | * and <em>preferred</em> values, indicates the ease with which the | ||
| 47 | * <code>Spring</code> can be extended. | ||
| 48 | * See the {@link #sum} method for details. | ||
| 49 | * | ||
| 50 | * <p> | ||
| 51 | * By defining simple arithmetic operations on <code>Spring</code>s, | ||
| 52 | * the behavior of a collection of <code>Spring</code>s | ||
| 53 | * can be reduced to that of an ordinary (non-compound) <code>Spring</code>. We define | ||
| 54 | * the "+", "-", <em>max</em>, and <em>min</em> operators on | ||
| 55 | * <code>Spring</code>s so that, in each case, the result is a <code>Spring</code> | ||
| 56 | * whose characteristics bear a useful mathematical relationship to its constituent | ||
| 57 | * springs. | ||
| 58 | * | ||
| 59 | * <p> | ||
| 60 | * A <code>Spring</code> can be treated as a pair of intervals | ||
| 61 | * with a single common point: the preferred value. | ||
| 62 | * The following rules define some of the | ||
| 63 | * arithmetic operators that can be applied to intervals | ||
| 64 | * (<code>[a, b]</code> refers to the interval | ||
| 65 | * from <code>a</code> | ||
| 66 | * to <code>b</code>, | ||
| 67 | * where <code>a <= b</code>). | ||
| 68 | * <p> | ||
| 69 | * <pre> | ||
| 70 | * [a1, b1] + [a2, b2] = [a1 + a2, b1 + b2] | ||
| 71 | * | ||
| 72 | * -[a, b] = [-b, -a] | ||
| 73 | * | ||
| 74 | * max([a1, b1], [a2, b2]) = [max(a1, a2), max(b1, b2)] | ||
| 75 | * </pre> | ||
| 76 | * <p> | ||
| 77 | * | ||
| 78 | * If we denote <code>Spring</code>s as <code>[a, b, c]</code>, | ||
| 79 | * where <code>a <= b <= c</code>, we can define the same | ||
| 80 | * arithmetic operators on <code>Spring</code>s: | ||
| 81 | * <p> | ||
| 82 | * <pre> | ||
| 83 | * [a1, b1, c1] + [a2, b2, c2] = [a1 + a2, b1 + b2, c1 + c2] | ||
| 84 | * | ||
| 85 | * -[a, b, c] = [-c, -b, -a] | ||
| 86 | * | ||
| 87 | * max([a1, b1, c1], [a2, b2, c2]) = [max(a1, a2), max(b1, b2), max(c1, c2)] | ||
| 88 | * </pre> | ||
| 89 | * <p> | ||
| 90 | * With both intervals and <code>Spring</code>s we can define "-" and <em>min</em> | ||
| 91 | * in terms of negation: | ||
| 92 | * <p> | ||
| 93 | * <pre> | ||
| 94 | * X - Y = X + (-Y) | ||
| 95 | * | ||
| 96 | * min(X, Y) = -max(-X, -Y) | ||
| 97 | * </pre> | ||
| 98 | * <p> | ||
| 99 | * For the static methods in this class that embody the arithmetic | ||
| 100 | * operators, we do not actually perform the operation in question as | ||
| 101 | * that would snapshot the values of the properties of the method's arguments | ||
| 102 | * at the time the static method is called. Instead, the static methods | ||
| 103 | * create a new <code>Spring</code> instance containing references to | ||
| 104 | * the method's arguments so that the characteristics of the new spring track the | ||
| 105 | * potentially changing characteristics of the springs from which it | ||
| 106 | * was made. This is a little like the idea of a <em>lazy value</em> | ||
| 107 | * in a functional language. | ||
| 108 | * <p> | ||
| 109 | * If you are implementing a <code>SpringLayout</code> you | ||
| 110 | * can find further information and examples in | ||
| 111 | * <a | ||
| 112 | href="http://java.sun.com/docs/books/tutorial/uiswing/layout/spring.html">How to Use SpringLayout</a>, | ||
| 113 | * a section in <em>The Java Tutorial.</em> | ||
| 114 | * <p> | ||
| 115 | * <strong>Warning:</strong> | ||
| 116 | * Serialized objects of this class will not be compatible with | ||
| 117 | * future Swing releases. The current serialization support is | ||
| 118 | * appropriate for short term storage or RMI between applications running | ||
| 119 | * the same version of Swing. As of 1.4, support for long term storage | ||
| 120 | * of all JavaBeans<sup><font size="-2">TM</font></sup> | ||
| 121 | * has been added to the <code>java.beans</code> package. | ||
| 122 | * Please see {@link java.beans.XMLEncoder}. | ||
| 123 | * | ||
| 124 | * @see SpringLayout | ||
| 125 | * @see SpringLayout.Constraints | ||
| 126 | * | ||
| 127 | * @author Philip Milne | ||
| 128 | * @since 1.4 | ||
| 129 | */ | ||
| 130 | public abstract class Spring { | ||
| 131 | |||
| 132 | /** | ||
| 133 | * An integer value signifying that a property value has not yet been calculated. | ||
| 134 | */ | ||
| 135 | public static final int UNSET = Integer.MIN_VALUE; | ||
| 136 | |||
| 137 | /** | ||
| 138 | * Used by factory methods to create a <code>Spring</code>. | ||
| 139 | * | ||
| 140 | * @see #constant(int) | ||
| 141 | * @see #constant(int, int, int) | ||
| 142 | * @see #max | ||
| 143 | * @see #minus | ||
| 144 | * @see #sum | ||
| 145 | * @see SpringLayout.Constraints | ||
| 146 | */ | ||
| 147 | protected Spring() {} | ||
| 148 | |||
| 149 | /** | ||
| 150 | * Returns the <em>minimum</em> value of this <code>Spring</code>. | ||
| 151 | * | ||
| 152 | * @return the <code>minimumValue</code> property of this <code>Spring</code> | ||
| 153 | */ | ||
| 154 | public abstract int getMinimumValue(); | ||
| 155 | |||
| 156 | /** | ||
| 157 | * Returns the <em>preferred</em> value of this <code>Spring</code>. | ||
| 158 | * | ||
| 159 | * @return the <code>preferredValue</code> of this <code>Spring</code> | ||
| 160 | */ | ||
| 161 | public abstract int getPreferredValue(); | ||
| 162 | |||
| 163 | /** | ||
| 164 | * Returns the <em>maximum</em> value of this <code>Spring</code>. | ||
| 165 | * | ||
| 166 | * @return the <code>maximumValue</code> property of this <code>Spring</code> | ||
| 167 | */ | ||
| 168 | public abstract int getMaximumValue(); | ||
| 169 | |||
| 170 | /** | ||
| 171 | * Returns the current <em>value</em> of this <code>Spring</code>. | ||
| 172 | * | ||
| 173 | * @return the <code>value</code> property of this <code>Spring</code> | ||
| 174 | * | ||
| 175 | * @see #setValue | ||
| 176 | */ | ||
| 177 | public abstract int getValue(); | ||
| 178 | |||
| 179 | /** | ||
| 180 | * Sets the current <em>value</em> of this <code>Spring</code> to <code>value</code>. | ||
| 181 | * | ||
| 182 | * @param value the new setting of the <code>value</code> property | ||
| 183 | * | ||
| 184 | * @see #getValue | ||
| 185 | */ | ||
| 186 | public abstract void setValue(int value); | ||
| 187 | |||
| 188 | private double range(boolean contract) { | ||
| 189 | return contract ? (getPreferredValue() - getMinimumValue()) : | ||
| 190 | (getMaximumValue() - getPreferredValue()); | ||
| 191 | } | ||
| 192 | |||
| 193 | /*pp*/ double getStrain() { | ||
| 194 | double delta = (getValue() - getPreferredValue()); | ||
| 195 | return delta/range(getValue() < getPreferredValue()); | ||
| 196 | } | ||
| 197 | |||
| 198 | /*pp*/ void setStrain(double strain) { | ||
| 199 | setValue(getPreferredValue() + (int)(strain * range(strain < 0))); | ||
| 200 | } | ||
| 201 | |||
| 202 | /*pp*/ boolean isCyclic(SpringLayout l) { | ||
| 203 | return false; | ||
| 204 | } | ||
| 205 | |||
| 206 | /*pp*/ static abstract class AbstractSpring extends Spring { | ||
| 207 | protected int size = UNSET; | ||
| 208 | |||
| 209 | public int getValue() { | ||
| 210 | return size != UNSET ? size : getPreferredValue(); | ||
| 211 | } | ||
| 212 | |||
| 213 | public final void setValue(int size) { | ||
| 214 | if (this.size == size) { | ||
| 215 | return; | ||
| 216 | } | ||
| 217 | if (size == UNSET) { | ||
| 218 | clear(); | ||
| 219 | } else { | ||
| 220 | setNonClearValue(size); | ||
| 221 | } | ||
| 222 | } | ||
| 223 | |||
| 224 | protected void clear() { | ||
| 225 | size = UNSET; | ||
| 226 | } | ||
| 227 | |||
| 228 | protected void setNonClearValue(int size) { | ||
| 229 | this.size = size; | ||
| 230 | } | ||
| 231 | } | ||
| 232 | |||
| 233 | private static class StaticSpring extends AbstractSpring { | ||
| 234 | protected int min; | ||
| 235 | protected int pref; | ||
| 236 | protected int max; | ||
| 237 | |||
| 238 | public StaticSpring(int pref) { | ||
| 239 | this(pref, pref, pref); | ||
| 240 | } | ||
| 241 | |||
| 242 | public StaticSpring(int min, int pref, int max) { | ||
| 243 | this.min = min; | ||
| 244 | this.pref = pref; | ||
| 245 | this.max = max; | ||
| 246 | } | ||
| 247 | |||
| 248 | public String toString() { | ||
| 249 | return "StaticSpring [" + min + ", " + pref + ", " + max + "]"; | ||
| 250 | } | ||
| 251 | |||
| 252 | public int getMinimumValue() { | ||
| 253 | return min; | ||
| 254 | } | ||
| 255 | |||
| 256 | public int getPreferredValue() { | ||
| 257 | return pref; | ||
| 258 | } | ||
| 259 | |||
| 260 | public int getMaximumValue() { | ||
| 261 | return max; | ||
| 262 | } | ||
| 263 | } | ||
| 264 | |||
| 265 | private static class NegativeSpring extends Spring { | ||
| 266 | private Spring s; | ||
| 267 | |||
| 268 | public NegativeSpring(Spring s) { | ||
| 269 | this.s = s; | ||
| 270 | } | ||
| 271 | |||
| 272 | // Note the use of max value rather than minimum value here. | ||
| 273 | // See the opening preamble on arithmetic with springs. | ||
| 274 | |||
| 275 | public int getMinimumValue() { | ||
| 276 | return -s.getMaximumValue(); | ||
| 277 | } | ||
| 278 | |||
| 279 | public int getPreferredValue() { | ||
| 280 | return -s.getPreferredValue(); | ||
| 281 | } | ||
| 282 | |||
| 283 | public int getMaximumValue() { | ||
| 284 | return -s.getMinimumValue(); | ||
| 285 | } | ||
| 286 | |||
| 287 | public int getValue() { | ||
| 288 | return -s.getValue(); | ||
| 289 | } | ||
| 290 | |||
| 291 | public void setValue(int size) { | ||
| 292 | // No need to check for UNSET as | ||
| 293 | // Integer.MIN_VALUE == -Integer.MIN_VALUE. | ||
| 294 | s.setValue(-size); | ||
| 295 | } | ||
| 296 | |||
| 297 | /*pp*/ boolean isCyclic(SpringLayout l) { | ||
| 298 | return s.isCyclic(l); | ||
| 299 | } | ||
| 300 | } | ||
| 301 | |||
| 302 | private static class ScaleSpring extends Spring { | ||
| 303 | private Spring s; | ||
| 304 | private float factor; | ||
| 305 | |||
| 306 | private ScaleSpring(Spring s, float factor) { | ||
| 307 | this.s = s; | ||
| 308 | this.factor = factor; | ||
| 309 | } | ||
| 310 | |||
| 311 | public int getMinimumValue() { | ||
| 312 | return Math.round((factor < 0 ? s.getMaximumValue() : s.getMinimumValue()) * factor); | ||
| 313 | } | ||
| 314 | |||
| 315 | public int getPreferredValue() { | ||
| 316 | return Math.round(s.getPreferredValue() * factor); | ||
| 317 | } | ||
| 318 | |||
| 319 | public int getMaximumValue() { | ||
| 320 | return Math.round((factor < 0 ? s.getMinimumValue() : s.getMaximumValue()) * factor); | ||
| 321 | } | ||
| 322 | |||
| 323 | public int getValue() { | ||
| 324 | return Math.round(s.getValue() * factor); | ||
| 325 | } | ||
| 326 | |||
| 327 | public void setValue(int value) { | ||
| 328 | if (value == UNSET) { | ||
| 329 | s.setValue(UNSET); | ||
| 330 | } else { | ||
| 331 | s.setValue(Math.round(value / factor)); | ||
| 332 | } | ||
| 333 | } | ||
| 334 | |||
| 335 | /*pp*/ boolean isCyclic(SpringLayout l) { | ||
| 336 | return s.isCyclic(l); | ||
| 337 | } | ||
| 338 | } | ||
| 339 | |||
| 340 | /*pp*/ static class WidthSpring extends AbstractSpring { | ||
| 341 | /*pp*/ Component c; | ||
| 342 | |||
| 343 | public WidthSpring(Component c) { | ||
| 344 | this.c = c; | ||
| 345 | } | ||
| 346 | |||
| 347 | public int getMinimumValue() { | ||
| 348 | return c.getMinimumSize().width; | ||
| 349 | } | ||
| 350 | |||
| 351 | public int getPreferredValue() { | ||
| 352 | return c.getPreferredSize().width; | ||
| 353 | } | ||
| 354 | |||
| 355 | public int getMaximumValue() { | ||
| 356 | // We will be doing arithmetic with the results of this call, | ||
| 357 | // so if a returned value is Integer.MAX_VALUE we will get | ||
| 358 | // arithmetic overflow. Truncate such values. | ||
| 359 | return Math.min(Short.MAX_VALUE, c.getMaximumSize().width); | ||
| 360 | } | ||
| 361 | } | ||
| 362 | |||
| 363 | /*pp*/ static class HeightSpring extends AbstractSpring { | ||
| 364 | /*pp*/ Component c; | ||
| 365 | |||
| 366 | public HeightSpring(Component c) { | ||
| 367 | this.c = c; | ||
| 368 | } | ||
| 369 | |||
| 370 | public int getMinimumValue() { | ||
| 371 | return c.getMinimumSize().height; | ||
| 372 | } | ||
| 373 | |||
| 374 | public int getPreferredValue() { | ||
| 375 | return c.getPreferredSize().height; | ||
| 376 | } | ||
| 377 | |||
| 378 | public int getMaximumValue() { | ||
| 379 | return Math.min(Short.MAX_VALUE, c.getMaximumSize().height); | ||
| 380 | } | ||
| 381 | } | ||
| 382 | |||
| 383 | /*pp*/ static abstract class SpringMap extends Spring { | ||
| 384 | private Spring s; | ||
| 385 | |||
| 386 | public SpringMap(Spring s) { | ||
| 387 | this.s = s; | ||
| 388 | } | ||
| 389 | |||
| 390 | protected abstract int map(int i); | ||
| 391 | |||
| 392 | protected abstract int inv(int i); | ||
| 393 | |||
| 394 | public int getMinimumValue() { | ||
| 395 | return map(s.getMinimumValue()); | ||
| 396 | } | ||
| 397 | |||
| 398 | public int getPreferredValue() { | ||
| 399 | return map(s.getPreferredValue()); | ||
| 400 | } | ||
| 401 | |||
| 402 | public int getMaximumValue() { | ||
| 403 | return Math.min(Short.MAX_VALUE, map(s.getMaximumValue())); | ||
| 404 | } | ||
| 405 | |||
| 406 | public int getValue() { | ||
| 407 | return map(s.getValue()); | ||
| 408 | } | ||
| 409 | |||
| 410 | public void setValue(int value) { | ||
| 411 | if (value == UNSET) { | ||
| 412 | s.setValue(UNSET); | ||
| 413 | } else { | ||
| 414 | s.setValue(inv(value)); | ||
| 415 | } | ||
| 416 | } | ||
| 417 | |||
| 418 | /*pp*/ boolean isCyclic(SpringLayout l) { | ||
| 419 | return s.isCyclic(l); | ||
| 420 | } | ||
| 421 | } | ||
| 422 | |||
| 423 | // Use the instance variables of the StaticSpring superclass to | ||
| 424 | // cache values that have already been calculated. | ||
| 425 | /*pp*/ static abstract class CompoundSpring extends StaticSpring { | ||
| 426 | protected Spring s1; | ||
| 427 | protected Spring s2; | ||
| 428 | |||
| 429 | public CompoundSpring(Spring s1, Spring s2) { | ||
| 430 | super(UNSET); | ||
| 431 | this.s1 = s1; | ||
| 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 | } | ||