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| 1 | /* | ||
| 2 | * Copyright (c) 1995, 2006, 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 | |||
| 26 | package java.awt; | ||
| 27 | |||
| 28 | import java.util.Hashtable; | ||
| 29 | |||
| 30 | /** | ||
| 31 | * A border layout lays out a container, arranging and resizing | ||
| 32 | * its components to fit in five regions: | ||
| 33 | * north, south, east, west, and center. | ||
| 34 | * Each region may contain no more than one component, and | ||
| 35 | * is identified by a corresponding constant: | ||
| 36 | * <code>NORTH</code>, <code>SOUTH</code>, <code>EAST</code>, | ||
| 37 | * <code>WEST</code>, and <code>CENTER</code>. When adding a | ||
| 38 | * component to a container with a border layout, use one of these | ||
| 39 | * five constants, for example: | ||
| 40 | * <pre> | ||
| 41 | * Panel p = new Panel(); | ||
| 42 | * p.setLayout(new BorderLayout()); | ||
| 43 | * p.add(new Button("Okay"), BorderLayout.SOUTH); | ||
| 44 | * </pre> | ||
| 45 | * As a convenience, <code>BorderLayout</code> interprets the | ||
| 46 | * absence of a string specification the same as the constant | ||
| 47 | * <code>CENTER</code>: | ||
| 48 | * <pre> | ||
| 49 | * Panel p2 = new Panel(); | ||
| 50 | * p2.setLayout(new BorderLayout()); | ||
| 51 | * p2.add(new TextArea()); // Same as p.add(new TextArea(), BorderLayout.CENTER); | ||
| 52 | * </pre> | ||
| 53 | * <p> | ||
| 54 | * In addition, <code>BorderLayout</code> supports the relative | ||
| 55 | * positioning constants, <code>PAGE_START</code>, <code>PAGE_END</code>, | ||
| 56 | * <code>LINE_START</code>, and <code>LINE_END</code>. | ||
| 57 | * In a container whose <code>ComponentOrientation</code> is set to | ||
| 58 | * <code>ComponentOrientation.LEFT_TO_RIGHT</code>, these constants map to | ||
| 59 | * <code>NORTH</code>, <code>SOUTH</code>, <code>WEST</code>, and | ||
| 60 | * <code>EAST</code>, respectively. | ||
| 61 | * <p> | ||
| 62 | * For compatibility with previous releases, <code>BorderLayout</code> | ||
| 63 | * also includes the relative positioning constants <code>BEFORE_FIRST_LINE</code>, | ||
| 64 | * <code>AFTER_LAST_LINE</code>, <code>BEFORE_LINE_BEGINS</code> and | ||
| 65 | * <code>AFTER_LINE_ENDS</code>. These are equivalent to | ||
| 66 | * <code>PAGE_START</code>, <code>PAGE_END</code>, <code>LINE_START</code> | ||
| 67 | * and <code>LINE_END</code> respectively. For | ||
| 68 | * consistency with the relative positioning constants used by other | ||
| 69 | * components, the latter constants are preferred. | ||
| 70 | * <p> | ||
| 71 | * Mixing both absolute and relative positioning constants can lead to | ||
| 72 | * unpredicable results. If | ||
| 73 | * you use both types, the relative constants will take precedence. | ||
| 74 | * For example, if you add components using both the <code>NORTH</code> | ||
| 75 | * and <code>PAGE_START</code> constants in a container whose | ||
| 76 | * orientation is <code>LEFT_TO_RIGHT</code>, only the | ||
| 77 | * <code>PAGE_START</code> will be layed out. | ||
| 78 | * <p> | ||
| 79 | * NOTE: Currently (in the Java 2 platform v1.2), | ||
| 80 | * <code>BorderLayout</code> does not support vertical | ||
| 81 | * orientations. The <code>isVertical</code> setting on the container's | ||
| 82 | * <code>ComponentOrientation</code> is not respected. | ||
| 83 | * <p> | ||
| 84 | * The components are laid out according to their | ||
| 85 | * preferred sizes and the constraints of the container's size. | ||
| 86 | * The <code>NORTH</code> and <code>SOUTH</code> components may | ||
| 87 | * be stretched horizontally; the <code>EAST</code> and | ||
| 88 | * <code>WEST</code> components may be stretched vertically; | ||
| 89 | * the <code>CENTER</code> component may stretch both horizontally | ||
| 90 | * and vertically to fill any space left over. | ||
| 91 | * <p> | ||
| 92 | * Here is an example of five buttons in an applet laid out using | ||
| 93 | * the <code>BorderLayout</code> layout manager: | ||
| 94 | * <p> | ||
| 95 | * <img src="doc-files/BorderLayout-1.gif" | ||
| 96 | * alt="Diagram of an applet demonstrating BorderLayout. | ||
| 97 | * Each section of the BorderLayout contains a Button corresponding to its position in the layout, one of: | ||
| 98 | * North, West, Center, East, or South." | ||
| 99 | * ALIGN=center HSPACE=10 VSPACE=7> | ||
| 100 | * <p> | ||
| 101 | * The code for this applet is as follows: | ||
| 102 | * <p> | ||
| 103 | * <hr><blockquote><pre> | ||
| 104 | * import java.awt.*; | ||
| 105 | * import java.applet.Applet; | ||
| 106 | * | ||
| 107 | * public class buttonDir extends Applet { | ||
| 108 | * public void init() { | ||
| 109 | * setLayout(new BorderLayout()); | ||
| 110 | * add(new Button("North"), BorderLayout.NORTH); | ||
| 111 | * add(new Button("South"), BorderLayout.SOUTH); | ||
| 112 | * add(new Button("East"), BorderLayout.EAST); | ||
| 113 | * add(new Button("West"), BorderLayout.WEST); | ||
| 114 | * add(new Button("Center"), BorderLayout.CENTER); | ||
| 115 | * } | ||
| 116 | * } | ||
| 117 | * </pre></blockquote><hr> | ||
| 118 | * <p> | ||
| 119 | * @author Arthur van Hoff | ||
| 120 | * @see java.awt.Container#add(String, Component) | ||
| 121 | * @see java.awt.ComponentOrientation | ||
| 122 | * @since JDK1.0 | ||
| 123 | */ | ||
| 124 | public class BorderLayout implements LayoutManager2, | ||
| 125 | java.io.Serializable { | ||
| 126 | /** | ||
| 127 | * Constructs a border layout with the horizontal gaps | ||
| 128 | * between components. | ||
| 129 | * The horizontal gap is specified by <code>hgap</code>. | ||
| 130 | * | ||
| 131 | * @see #getHgap() | ||
| 132 | * @see #setHgap(int) | ||
| 133 | * | ||
| 134 | * @serial | ||
| 135 | */ | ||
| 136 | int hgap; | ||
| 137 | |||
| 138 | /** | ||
| 139 | * Constructs a border layout with the vertical gaps | ||
| 140 | * between components. | ||
| 141 | * The vertical gap is specified by <code>vgap</code>. | ||
| 142 | * | ||
| 143 | * @see #getVgap() | ||
| 144 | * @see #setVgap(int) | ||
| 145 | * @serial | ||
| 146 | */ | ||
| 147 | int vgap; | ||
| 148 | |||
| 149 | /** | ||
| 150 | * Constant to specify components location to be the | ||
| 151 | * north portion of the border layout. | ||
| 152 | * @serial | ||
| 153 | * @see #getChild(String, boolean) | ||
| 154 | * @see #addLayoutComponent | ||
| 155 | * @see #getLayoutAlignmentX | ||
| 156 | * @see #getLayoutAlignmentY | ||
| 157 | * @see #removeLayoutComponent | ||
| 158 | */ | ||
| 159 | Component north; | ||
| 160 | /** | ||
| 161 | * Constant to specify components location to be the | ||
| 162 | * west portion of the border layout. | ||
| 163 | * @serial | ||
| 164 | * @see #getChild(String, boolean) | ||
| 165 | * @see #addLayoutComponent | ||
| 166 | * @see #getLayoutAlignmentX | ||
| 167 | * @see #getLayoutAlignmentY | ||
| 168 | * @see #removeLayoutComponent | ||
| 169 | */ | ||
| 170 | Component west; | ||
| 171 | /** | ||
| 172 | * Constant to specify components location to be the | ||
| 173 | * east portion of the border layout. | ||
| 174 | * @serial | ||
| 175 | * @see #getChild(String, boolean) | ||
| 176 | * @see #addLayoutComponent | ||
| 177 | * @see #getLayoutAlignmentX | ||
| 178 | * @see #getLayoutAlignmentY | ||
| 179 | * @see #removeLayoutComponent | ||
| 180 | */ | ||
| 181 | Component east; | ||
| 182 | /** | ||
| 183 | * Constant to specify components location to be the | ||
| 184 | * south portion of the border layout. | ||
| 185 | * @serial | ||
| 186 | * @see #getChild(String, boolean) | ||
| 187 | * @see #addLayoutComponent | ||
| 188 | * @see #getLayoutAlignmentX | ||
| 189 | * @see #getLayoutAlignmentY | ||
| 190 | * @see #removeLayoutComponent | ||
| 191 | */ | ||
| 192 | Component south; | ||
| 193 | /** | ||
| 194 | * Constant to specify components location to be the | ||
| 195 | * center portion of the border layout. | ||
| 196 | * @serial | ||
| 197 | * @see #getChild(String, boolean) | ||
| 198 | * @see #addLayoutComponent | ||
| 199 | * @see #getLayoutAlignmentX | ||
| 200 | * @see #getLayoutAlignmentY | ||
| 201 | * @see #removeLayoutComponent | ||
| 202 | */ | ||
| 203 | Component center; | ||
| 204 | |||
| 205 | /** | ||
| 206 | * | ||
| 207 | * A relative positioning constant, that can be used instead of | ||
| 208 | * north, south, east, west or center. | ||
| 209 | * mixing the two types of constants can lead to unpredicable results. If | ||
| 210 | * you use both types, the relative constants will take precedence. | ||
| 211 | * For example, if you add components using both the <code>NORTH</code> | ||
| 212 | * and <code>BEFORE_FIRST_LINE</code> constants in a container whose | ||
| 213 | * orientation is <code>LEFT_TO_RIGHT</code>, only the | ||
| 214 | * <code>BEFORE_FIRST_LINE</code> will be layed out. | ||
| 215 | * This will be the same for lastLine, firstItem, lastItem. | ||
| 216 | * @serial | ||
| 217 | */ | ||
| 218 | Component firstLine; | ||
| 219 | /** | ||
| 220 | * A relative positioning constant, that can be used instead of | ||
| 221 | * north, south, east, west or center. | ||
| 222 | * Please read Description for firstLine. | ||
| 223 | * @serial | ||
| 224 | */ | ||
| 225 | Component lastLine; | ||
| 226 | /** | ||
| 227 | * A relative positioning constant, that can be used instead of | ||
| 228 | * north, south, east, west or center. | ||
| 229 | * Please read Description for firstLine. | ||
| 230 | * @serial | ||
| 231 | */ | ||
| 232 | Component firstItem; | ||
| 233 | /** | ||
| 234 | * A relative positioning constant, that can be used instead of | ||
| 235 | * north, south, east, west or center. | ||
| 236 | * Please read Description for firstLine. | ||
| 237 | * @serial | ||
| 238 | */ | ||
| 239 | Component lastItem; | ||
| 240 | |||
| 241 | /** | ||
| 242 | * The north layout constraint (top of container). | ||
| 243 | */ | ||
| 244 | public static final String NORTH = "North"; | ||
| 245 | |||
| 246 | /** | ||
| 247 | * The south layout constraint (bottom of container). | ||
| 248 | */ | ||
| 249 | public static final String SOUTH = "South"; | ||
| 250 | |||
| 251 | /** | ||
| 252 | * The east layout constraint (right side of container). | ||
| 253 | */ | ||
| 254 | public static final String EAST = "East"; | ||
| 255 | |||
| 256 | /** | ||
| 257 | * The west layout constraint (left side of container). | ||
| 258 | */ | ||
| 259 | public static final String WEST = "West"; | ||
| 260 | |||
| 261 | /** | ||
| 262 | * The center layout constraint (middle of container). | ||
| 263 | */ | ||
| 264 | public static final String CENTER = "Center"; | ||
| 265 | |||
| 266 | /** | ||
| 267 | * Synonym for PAGE_START. Exists for compatibility with previous | ||
| 268 | * versions. PAGE_START is preferred. | ||
| 269 | * | ||
| 270 | * @see #PAGE_START | ||
| 271 | * @since 1.2 | ||
| 272 | */ | ||
| 273 | public static final String BEFORE_FIRST_LINE = "First"; | ||
| 274 | |||
| 275 | /** | ||
| 276 | * Synonym for PAGE_END. Exists for compatibility with previous | ||
| 277 | * versions. PAGE_END is preferred. | ||
| 278 | * | ||
| 279 | * @see #PAGE_END | ||
| 280 | * @since 1.2 | ||
| 281 | */ | ||
| 282 | public static final String AFTER_LAST_LINE = "Last"; | ||
| 283 | |||
| 284 | /** | ||
| 285 | * Synonym for LINE_START. Exists for compatibility with previous | ||
| 286 | * versions. LINE_START is preferred. | ||
| 287 | * | ||
| 288 | * @see #LINE_START | ||
| 289 | * @since 1.2 | ||
| 290 | */ | ||
| 291 | public static final String BEFORE_LINE_BEGINS = "Before"; | ||
| 292 | |||
| 293 | /** | ||
| 294 | * Synonym for LINE_END. Exists for compatibility with previous | ||
| 295 | * versions. LINE_END is preferred. | ||
| 296 | * | ||
| 297 | * @see #LINE_END | ||
| 298 | * @since 1.2 | ||
| 299 | */ | ||
| 300 | public static final String AFTER_LINE_ENDS = "After"; | ||
| 301 | |||
| 302 | /** | ||
| 303 | * The component comes before the first line of the layout's content. | ||
| 304 | * For Western, left-to-right and top-to-bottom orientations, this is | ||
| 305 | * equivalent to NORTH. | ||
| 306 | * | ||
| 307 | * @see java.awt.Component#getComponentOrientation | ||
| 308 | * @since 1.4 | ||
| 309 | */ | ||
| 310 | public static final String PAGE_START = BEFORE_FIRST_LINE; | ||
| 311 | |||
| 312 | /** | ||
| 313 | * The component comes after the last line of the layout's content. | ||
| 314 | * For Western, left-to-right and top-to-bottom orientations, this is | ||
| 315 | * equivalent to SOUTH. | ||
| 316 | * | ||
| 317 | * @see java.awt.Component#getComponentOrientation | ||
| 318 | * @since 1.4 | ||
| 319 | */ | ||
| 320 | public static final String PAGE_END = AFTER_LAST_LINE; | ||
| 321 | |||
| 322 | /** | ||
| 323 | * The component goes at the beginning of the line direction for the | ||
| 324 | * layout. For Western, left-to-right and top-to-bottom orientations, | ||
| 325 | * this is equivalent to WEST. | ||
| 326 | * | ||
| 327 | * @see java.awt.Component#getComponentOrientation | ||
| 328 | * @since 1.4 | ||
| 329 | */ | ||
| 330 | public static final String LINE_START = BEFORE_LINE_BEGINS; | ||
| 331 | |||
| 332 | /** | ||
| 333 | * The component goes at the end of the line direction for the | ||
| 334 | * layout. For Western, left-to-right and top-to-bottom orientations, | ||
| 335 | * this is equivalent to EAST. | ||
| 336 | * | ||
| 337 | * @see java.awt.Component#getComponentOrientation | ||
| 338 | * @since 1.4 | ||
| 339 | */ | ||
| 340 | public static final String LINE_END = AFTER_LINE_ENDS; | ||
| 341 | |||
| 342 | /* | ||
| 343 | * JDK 1.1 serialVersionUID | ||
| 344 | */ | ||
| 345 | private static final long serialVersionUID = -8658291919501921765L; | ||
| 346 | |||
| 347 | /** | ||
| 348 | * Constructs a new border layout with | ||
| 349 | * no gaps between components. | ||
| 350 | */ | ||
| 351 | public BorderLayout() { | ||
| 352 | this(0, 0); | ||
| 353 | } | ||
| 354 | |||
| 355 | /** | ||
| 356 | * Constructs a border layout with the specified gaps | ||
| 357 | * between components. | ||
| 358 | * The horizontal gap is specified by <code>hgap</code> | ||
| 359 | * and the vertical gap is specified by <code>vgap</code>. | ||
| 360 | * @param hgap the horizontal gap. | ||
| 361 | * @param vgap the vertical gap. | ||
| 362 | */ | ||
| 363 | public BorderLayout(int hgap, int vgap) { | ||
| 364 | this.hgap = hgap; | ||
| 365 | this.vgap = vgap; | ||
| 366 | } | ||
| 367 | |||
| 368 | /** | ||
| 369 | * Returns the horizontal gap between components. | ||
| 370 | * @since JDK1.1 | ||
| 371 | */ | ||
| 372 | public int getHgap() { | ||
| 373 | return hgap; | ||
| 374 | } | ||
| 375 | |||
| 376 | /** | ||
| 377 | * Sets the horizontal gap between components. | ||
| 378 | * @param hgap the horizontal gap between components | ||
| 379 | * @since JDK1.1 | ||
| 380 | */ | ||
| 381 | public void setHgap(int hgap) { | ||
| 382 | this.hgap = hgap; | ||
| 383 | } | ||
| 384 | |||
| 385 | /** | ||
| 386 | * Returns the vertical gap between components. | ||
| 387 | * @since JDK1.1 | ||
| 388 | */ | ||
| 389 | public int getVgap() { | ||
| 390 | return vgap; | ||
| 391 | } | ||
| 392 | |||
| 393 | /** | ||
| 394 | * Sets the vertical gap between components. | ||
| 395 | * @param vgap the vertical gap between components | ||
| 396 | * @since JDK1.1 | ||
| 397 | */ | ||
| 398 | public void setVgap(int vgap) { | ||
| 399 | this.vgap = vgap; | ||
| 400 | } | ||
| 401 | |||
| 402 | /** | ||
| 403 | * Adds the specified component to the layout, using the specified | ||
| 404 | * constraint object. For border layouts, the constraint must be | ||
| 405 | * one of the following constants: <code>NORTH</code>, | ||
| 406 | * <code>SOUTH</code>, <code>EAST</code>, | ||
| 407 | * <code>WEST</code>, or <code>CENTER</code>. | ||
| 408 | * <p> | ||
| 409 | * Most applications do not call this method directly. This method | ||
| 410 | * is called when a component is added to a container using the | ||
| 411 | * <code>Container.add</code> method with the same argument types. | ||
| 412 | * @param comp the component to be added. | ||
| 413 | * @param constraints an object that specifies how and where | ||
| 414 | * the component is added to the layout. | ||
| 415 | * @see java.awt.Container#add(java.awt.Component, java.lang.Object) | ||
| 416 | * @exception IllegalArgumentException if the constraint object is not | ||
| 417 | * a string, or if it not one of the five specified | ||
| 418 | * constants. | ||
| 419 | * @since JDK1.1 | ||
| 420 | */ | ||
| 421 | public void addLayoutComponent(Component comp, Object constraints) { | ||
| 422 | synchronized (comp.getTreeLock()) { | ||
| 423 | if ((constraints == null) || (constraints instanceof String)) { | ||
| 424 | addLayoutComponent((String)constraints, comp); | ||
| 425 | } else { | ||
| 426 | throw new IllegalArgumentException("cannot add to layout: constraint must be a string (or null)"); | ||
| 427 | } | ||
| 428 | } | ||
| 429 | } | ||
| 430 | |||
| 431 | /** | ||
| 432 | * @deprecated replaced by <code>addLayoutComponent(Component, Object)</code>. | ||
| 433 | */ | ||
| 434 | @Deprecated | ||
| 435 | public void addLayoutComponent(String name, Component comp) { | ||
| 436 | synchronized (comp.getTreeLock()) { | ||
| 437 | /* Special case: treat null the same as "Center". */ | ||
| 438 | if (name == null) { | ||
| 439 | name = "Center"; | ||
| 440 | } | ||
| 441 | |||
| 442 | /* Assign the component to one of the known regions of the layout. | ||
| 443 | */ | ||
| 444 | if ("Center".equals(name)) { | ||
| 445 | center = comp; | ||
| 446 | } else if ("North".equals(name)) { | ||
| 447 | north = comp; | ||
| 448 | } else if ("South".equals(name)) { | ||
| 449 | south = comp; | ||
| 450 | } else if ("East".equals(name)) { | ||
| 451 | east = comp; | ||
| 452 | } else if ("West".equals(name)) { | ||
| 453 | west = comp; | ||
| 454 | } else if (BEFORE_FIRST_LINE.equals(name)) { | ||
| 455 | firstLine = comp; | ||
| 456 | } else if (AFTER_LAST_LINE.equals(name)) { | ||
| 457 | lastLine = comp; | ||
| 458 | } else if (BEFORE_LINE_BEGINS.equals(name)) { | ||
| 459 | firstItem = comp; | ||
| 460 | } else if (AFTER_LINE_ENDS.equals(name)) { | ||
| 461 | lastItem = comp; | ||
| 462 | } else { | ||
| 463 | throw new IllegalArgumentException("cannot add to layout: unknown constraint: " + name); | ||
| 464 | } | ||
| 465 | } | ||
| 466 | } | ||
| 467 | |||
| 468 | /** | ||
| 469 | * Removes the specified component from this border layout. This | ||
| 470 | * method is called when a container calls its <code>remove</code> or | ||
| 471 | * <code>removeAll</code> methods. Most applications do not call this | ||
| 472 | * method directly. | ||
| 473 | * @param comp the component to be removed. | ||
| 474 | * @see java.awt.Container#remove(java.awt.Component) | ||
| 475 | * @see java.awt.Container#removeAll() | ||
| 476 | */ | ||
| 477 | public void removeLayoutComponent(Component comp) { | ||
| 478 | synchronized (comp.getTreeLock()) { | ||
| 479 | if (comp == center) { | ||
| 480 | center = null; | ||
| 481 | } else if (comp == north) { | ||
| 482 | north = null; | ||
| 483 | } else if (comp == south) { | ||
| 484 | south = null; | ||
| 485 | } else if (comp == east) { | ||
| 486 | east = null; | ||
| 487 | } else if (comp == west) { | ||
| 488 | west = null; | ||
| 489 | } | ||
| 490 | if (comp == firstLine) { | ||
| 491 | firstLine = null; | ||
| 492 | } else if (comp == lastLine) { | ||
| 493 | lastLine = null; | ||
| 494 | } else if (comp == firstItem) { | ||
| 495 | firstItem = null; | ||
| 496 | } else if (comp == lastItem) { | ||
| 497 | lastItem = null; | ||
| 498 | } | ||
| 499 | } | ||
| 500 | } | ||
| 501 | |||
| 502 | /** | ||
| 503 | * Gets the component that was added using the given constraint | ||
| 504 | * | ||
| 505 | * @param constraints the desired constraint, one of <code>CENTER</code>, | ||
| 506 | * <code>NORTH</code>, <code>SOUTH</code>, | ||
| 507 | * <code>WEST</code>, <code>EAST</code>, | ||
| 508 | * <code>PAGE_START</code>, <code>PAGE_END</code>, | ||
| 509 | * <code>LINE_START</code>, <code>LINE_END</code> | ||
| 510 | * @return the component at the given location, or <code>null</code> if | ||
| 511 | * the location is empty | ||
| 512 | * @exception IllegalArgumentException if the constraint object is | ||
| 513 | * not one of the nine specified constants | ||
| 514 | * @see #addLayoutComponent(java.awt.Component, java.lang.Object) | ||
| 515 | * @since 1.5 | ||
| 516 | */ | ||
| 517 | public Component getLayoutComponent(Object constraints) { | ||
| 518 | if (CENTER.equals(constraints)) { | ||
| 519 | return center; | ||
| 520 | } else if (NORTH.equals(constraints)) { | ||
| 521 | return north; | ||
| 522 | } else if (SOUTH.equals(constraints)) { | ||
| 523 | return south; | ||
| 524 | } else if (WEST.equals(constraints)) { | ||
| 525 | return west; | ||
| 526 | } else if (EAST.equals(constraints)) { | ||
| 527 | return east; | ||
| 528 | } else if (PAGE_START.equals(constraints)) { | ||
| 529 | return firstLine; | ||
| 530 | } else if (PAGE_END.equals(constraints)) { | ||
| 531 | return lastLine; | ||
| 532 | } else if (LINE_START.equals(constraints)) { | ||
| 533 | return firstItem; | ||
| 534 | } else if (LINE_END.equals(constraints)) { | ||
| 535 | return lastItem; | ||
| 536 | } else { | ||
| 537 | throw new IllegalArgumentException("cannot get component: unknown constraint: " + constraints); | ||
| 538 | } | ||
| 539 | } | ||
| 540 | |||
| 541 | |||
| 542 | /** | ||
| 543 | * Returns the component that corresponds to the given constraint location | ||
| 544 | * based on the target <code>Container</code>'s component orientation. | ||
| 545 | * Components added with the relative constraints <code>PAGE_START</code>, | ||
| 546 | * <code>PAGE_END</code>, <code>LINE_START</code>, and <code>LINE_END</code> | ||
| 547 | * take precedence over components added with the explicit constraints | ||
| 548 | * <code>NORTH</code>, <code>SOUTH</code>, <code>WEST</code>, and <code>EAST</code>. | ||
| 549 | * The <code>Container</code>'s component orientation is used to determine the location of components | ||
| 550 | * added with <code>LINE_START</code> and <code>LINE_END</code>. | ||
| 551 | * | ||
| 552 | * @param constraints the desired absolute position, one of <code>CENTER</code>, | ||
| 553 | * <code>NORTH</code>, <code>SOUTH</code>, | ||
| 554 | * <code>EAST</code>, <code>WEST</code> | ||
| 555 | * @param target the {@code Container} used to obtain | ||
| 556 | * the constraint location based on the target | ||
| 557 | * {@code Container}'s component orientation. | ||
| 558 | * @return the component at the given location, or <code>null</code> if | ||
| 559 | * the location is empty | ||
| 560 | * @exception IllegalArgumentException if the constraint object is | ||
| 561 | * not one of the five specified constants | ||
| 562 | * @exception NullPointerException if the target parameter is null | ||
| 563 | * @see #addLayoutComponent(java.awt.Component, java.lang.Object) | ||
| 564 | * @since 1.5 | ||
| 565 | */ | ||
| 566 | public Component getLayoutComponent(Container target, Object constraints) { | ||
| 567 | boolean ltr = target.getComponentOrientation().isLeftToRight(); | ||
| 568 | Component result = null; | ||
| 569 | |||
| 570 | if (NORTH.equals(constraints)) { | ||
| 571 | result = (firstLine != null) ? firstLine : north; | ||
| 572 | } else if (SOUTH.equals(constraints)) { | ||
| 573 | result = (lastLine != null) ? lastLine : south; | ||
| 574 | } else if (WEST.equals(constraints)) { | ||
| 575 | result = ltr ? firstItem : lastItem; | ||
| 576 | if (result == null) { | ||
| 577 | result = west; | ||
| 578 | } | ||
| 579 | } else if (EAST.equals(constraints)) { | ||
| 580 | result = ltr ? lastItem : firstItem; | ||
| 581 | if (result == null) { | ||
| 582 | result = east; | ||
| 583 | } | ||
| 584 | } else if (CENTER.equals(constraints)) { | ||
| 585 | result = center; | ||
| 586 | } else { | ||
| 587 | throw new IllegalArgumentException("cannot get component: invalid constraint: " + constraints); | ||
| 588 | } | ||
| 589 | |||
| 590 | return result; | ||
| 591 | } | ||
| 592 | |||
| 593 | |||
| 594 | /** | ||
| 595 | * Gets the constraints for the specified component | ||
| 596 | * | ||
| 597 | * @param comp the component to be queried | ||
| 598 | * @return the constraint for the specified component, | ||
| 599 | * or null if component is null or is not present | ||
| 600 | * in this layout | ||
| 601 | * @see #addLayoutComponent(java.awt.Component, java.lang.Object) | ||
| 602 | * @since 1.5 | ||
| 603 | */ | ||
| 604 | public Object getConstraints(Component comp) { | ||
| 605 | //fix for 6242148 : API method java.awt.BorderLayout.getConstraints(null) should return null | ||
| 606 | if (comp == null){ | ||
| 607 | return null; | ||
| 608 | } | ||
| 609 | if (comp == center) { | ||
| 610 | return CENTER; | ||
| 611 | } else if (comp == north) { | ||
| 612 | return NORTH; | ||
| 613 | } else if (comp == south) { | ||
| 614 | return SOUTH; | ||
| 615 | } else if (comp == west) { | ||
| 616 | return WEST; | ||
| 617 | } else if (comp == east) { | ||
| 618 | return EAST; | ||
| 619 | } else if (comp == firstLine) { | ||
| 620 | return PAGE_START; | ||
| 621 | } else if (comp == lastLine) { | ||
| 622 | return PAGE_END; | ||
| 623 | } else if (comp == firstItem) { | ||
| 624 | return LINE_START; | ||
| 625 | } else if (comp == lastItem) { | ||
| 626 | return LINE_END; | ||
| 627 | } | ||
| 628 | return null; | ||
| 629 | } | ||
| 630 | |||
| 631 | /** | ||
| 632 | * Determines the minimum size of the <code>target</code> container | ||
| 633 | * using this layout manager. | ||
| 634 | * <p> | ||
| 635 | * This method is called when a container calls its | ||
| 636 | * <code>getMinimumSize</code> method. Most applications do not call | ||
| 637 | * this method directly. | ||
| 638 | * @param target the container in which to do the layout. | ||
| 639 | * @return the minimum dimensions needed to lay out the subcomponents | ||
| 640 | * of the specified container. | ||
| 641 | * @see java.awt.Container | ||
| 642 | * @see java.awt.BorderLayout#preferredLayoutSize | ||
| 643 | * @see java.awt.Container#getMinimumSize() | ||
| 644 | */ | ||
| 645 | public Dimension minimumLayoutSize(Container target) { | ||
| 646 | synchronized (target.getTreeLock()) { | ||
| 647 | Dimension dim = new Dimension(0, 0); | ||
| 648 | |||
| 649 | boolean ltr = target.getComponentOrientation().isLeftToRight(); | ||
| 650 | Component c = null; | ||
| 651 | |||
| 652 | if ((c=getChild(EAST,ltr)) != null) { | ||
| 653 | Dimension d = c.getMinimumSize(); | ||
| 654 | dim.width += d.width + hgap; | ||
| 655 | dim.height = Math.max(d.height, dim.height); | ||
| 656 | } | ||
| 657 | if ((c=getChild(WEST,ltr)) != null) { | ||
| 658 | Dimension d = c.getMinimumSize(); | ||
| 659 | dim.width += d.width + hgap; | ||
| 660 | dim.height = Math.max(d.height, dim.height); | ||
| 661 | } | ||
| 662 | if ((c=getChild(CENTER,ltr)) != null) { | ||
| 663 | Dimension d = c.getMinimumSize(); | ||
| 664 | dim.width += d.width; | ||
| 665 | dim.height = Math.max(d.height, dim.height); | ||
| 666 | } | ||
| 667 | if ((c=getChild(NORTH,ltr)) != null) { | ||
| 668 | Dimension d = c.getMinimumSize(); | ||
| 669 | dim.width = Math.max(d.width, dim.width); | ||
| 670 | dim.height += d.height + vgap; | ||
| 671 | } | ||
| 672 | if ((c=getChild(SOUTH,ltr)) != null) { | ||
| 673 | Dimension d = c.getMinimumSize(); | ||
| 674 | dim.width = Math.max(d.width, dim.width); | ||
| 675 | dim.height += d.height + vgap; | ||
| 676 | } | ||
| 677 | |||
| 678 | Insets insets = target.getInsets(); | ||
| 679 | dim.width += insets.left + insets.right; | ||
| 680 | dim.height += insets.top + insets.bottom; | ||
| 681 | |||
| 682 | return dim; | ||
| 683 | } | ||
| 684 | } | ||
| 685 | |||
| 686 | /** | ||
| 687 | * Determines the preferred size of the <code>target</code> | ||
| 688 | * container using this layout manager, based on the components | ||
| 689 | * in the container. | ||
| 690 | * <p> | ||
| 691 | * Most applications do not call this method directly. This method | ||
| 692 | * is called when a container calls its <code>getPreferredSize</code> | ||
| 693 | * method. | ||
| 694 | * @param target the container in which to do the layout. | ||
| 695 | * @return the preferred dimensions to lay out the subcomponents | ||
| 696 | * of the specified container. | ||
| 697 | * @see java.awt.Container | ||
| 698 | * @see java.awt.BorderLayout#minimumLayoutSize | ||
| 699 | * @see java.awt.Container#getPreferredSize() | ||
| 700 | */ | ||
| 701 | public Dimension preferredLayoutSize(Container target) { | ||
| 702 | synchronized (target.getTreeLock()) { | ||
| 703 | Dimension dim = new Dimension(0, 0); | ||
| 704 | |||
| 705 | boolean ltr = target.getComponentOrientation().isLeftToRight(); | ||
| 706 | Component c = null; | ||
| 707 | |||
| 708 | if ((c=getChild(EAST,ltr)) != null) { | ||
| 709 | Dimension d = c.getPreferredSize(); | ||
| 710 | dim.width += d.width + hgap; | ||
| 711 | dim.height = Math.max(d.height, dim.height); | ||
| 712 | } | ||
| 713 | if ((c=getChild(WEST,ltr)) != null) { | ||
| 714 | Dimension d = c.getPreferredSize(); | ||
| 715 | dim.width += d.width + hgap; | ||
| 716 | dim.height = Math.max(d.height, dim.height); | ||
| 717 | } | ||
| 718 | if ((c=getChild(CENTER,ltr)) != null) { | ||
| 719 | Dimension d = c.getPreferredSize(); | ||
| 720 | dim.width += d.width; | ||
| 721 | dim.height = Math.max(d.height, dim.height); | ||
| 722 | } | ||
| 723 | if ((c=getChild(NORTH,ltr)) != null) { | ||
| 724 | Dimension d = c.getPreferredSize(); | ||
| 725 | dim.width = Math.max(d.width, dim.width); | ||
| 726 | dim.height += d.height + vgap; | ||
| 727 | } | ||
| 728 | if ((c=getChild(SOUTH,ltr)) != null) { | ||
| 729 | Dimension d = c.getPreferredSize(); | ||
| 730 | dim.width = Math.max(d.width, dim.width); | ||
| 731 | dim.height += d.height + vgap; | ||
| 732 | } | ||
| 733 | |||
| 734 | Insets insets = target.getInsets(); | ||
| 735 | dim.width += insets.left + insets.right; | ||
| 736 | dim.height += insets.top + insets.bottom; | ||
| 737 | |||
| 738 | return dim; | ||
| 739 | } | ||
| 740 | } | ||
| 741 | |||
| 742 | /** | ||
| 743 | * Returns the maximum dimensions for this layout given the components | ||
| 744 | * in the specified target container. | ||
| 745 | * @param target the component which needs to be laid out | ||
| 746 | * @see Container | ||
| 747 | * @see #minimumLayoutSize | ||
| 748 | * @see #preferredLayoutSize | ||
| 749 | */ | ||
| 750 | public Dimension maximumLayoutSize(Container target) { | ||
| 751 | return new Dimension(Integer.MAX_VALUE, Integer.MAX_VALUE); | ||
| 752 | } | ||
| 753 | |||
| 754 | /** | ||
| 755 | * Returns the alignment along the x axis. This specifies how | ||
| 756 | * the component would like to be aligned relative to other | ||
| 757 | * components. The value should be a number between 0 and 1 | ||
| 758 | * where 0 represents alignment along the origin, 1 is aligned | ||
| 759 | * the furthest away from the origin, 0.5 is centered, etc. | ||
| 760 | */ | ||
| 761 | public float getLayoutAlignmentX(Container parent) { | ||
| 762 | return 0.5f; | ||
| 763 | } | ||
| 764 | |||
| 765 | /** | ||
| 766 | * Returns the alignment along the y axis. This specifies how | ||
| 767 | * the component would like to be aligned relative to other | ||
| 768 | * components. The value should be a number between 0 and 1 | ||
| 769 | * where 0 represents alignment along the origin, 1 is aligned | ||
| 770 | * the furthest away from the origin, 0.5 is centered, etc. | ||
| 771 | */ | ||
| 772 | public float getLayoutAlignmentY(Container parent) { | ||
| 773 | return 0.5f; | ||
| 774 | } | ||
| 775 | |||
| 776 | /** | ||
| 777 | * Invalidates the layout, indicating that if the layout manager | ||
| 778 | * has cached information it should be discarded. | ||
| 779 | */ | ||
| 780 | public void invalidateLayout(Container target) { | ||
| 781 | } | ||
| 782 | |||
| 783 | /** | ||
| 784 | * Lays out the container argument using this border layout. | ||
| 785 | * <p> | ||
| 786 | * This method actually reshapes the components in the specified | ||
| 787 | * container in order to satisfy the constraints of this | ||
| 788 | * <code>BorderLayout</code> object. The <code>NORTH</code> | ||
| 789 | * and <code>SOUTH</code> components, if any, are placed at | ||
| 790 | * the top and bottom of the container, respectively. The | ||
| 791 | * <code>WEST</code> and <code>EAST</code> components are | ||
| 792 | * then placed on the left and right, respectively. Finally, | ||
| 793 | * the <code>CENTER</code> object is placed in any remaining | ||
| 794 | * space in the middle. | ||
| 795 | * <p> | ||
| 796 | * Most applications do not call this method directly. This method | ||
| 797 | * is called when a container calls its <code>doLayout</code> method. | ||
| 798 | * @param target the container in which to do the layout. | ||
| 799 | * @see java.awt.Container | ||
| 800 | * @see java.awt.Container#doLayout() | ||
| 801 | */ | ||
| 802 | public void layoutContainer(Container target) { | ||
| 803 | synchronized (target.getTreeLock()) { | ||
| 804 | Insets insets = target.getInsets(); | ||
| 805 | int top = insets.top; | ||
| 806 | int bottom = target.height - insets.bottom; | ||
| 807 | int left = insets.left; | ||
| 808 | int right = target.width - insets.right; | ||
| 809 | |||
| 810 | boolean ltr = target.getComponentOrientation().isLeftToRight(); | ||
| 811 | Component c = null; | ||
| 812 | |||
| 813 | if ((c=getChild(NORTH,ltr)) != null) { | ||
| 814 | c.setSize(right - left, c.height); | ||
| 815 | Dimension d = c.getPreferredSize(); | ||
| 816 | c.setBounds(left, top, right - left, d.height); | ||
| 817 | top += d.height + vgap; | ||
| 818 | } | ||
| 819 | if ((c=getChild(SOUTH,ltr)) != null) { | ||
| 820 | c.setSize(right - left, c.height); | ||
| 821 | Dimension d = c.getPreferredSize(); | ||
| 822 | c.setBounds(left, bottom - d.height, right - left, d.height); | ||
| 823 | bottom -= d.height + vgap; | ||
| 824 | } | ||
| 825 | if ((c=getChild(EAST,ltr)) != null) { | ||
| 826 | c.setSize(c.width, bottom - top); | ||
| 827 | Dimension d = c.getPreferredSize(); | ||
| 828 | c.setBounds(right - d.width, top, d.width, bottom - top); | ||
| 829 | right -= d.width + hgap; | ||
| 830 | } | ||
| 831 | if ((c=getChild(WEST,ltr)) != null) { | ||
| 832 | c.setSize(c.width, bottom - top); | ||
| 833 | Dimension d = c.getPreferredSize(); | ||
| 834 | c.setBounds(left, top, d.width, bottom - top); | ||
| 835 | left += d.width + hgap; | ||
| 836 | } | ||
| 837 | if ((c=getChild(CENTER,ltr)) != null) { | ||
| 838 | c.setBounds(left, top, right - left, bottom - top); | ||
| 839 | } | ||
| 840 | } | ||
| 841 | } | ||
| 842 | |||
| 843 | /** | ||
| 844 | * Get the component that corresponds to the given constraint location | ||
| 845 | * | ||
| 846 | * @param key The desired absolute position, | ||
| 847 | * either NORTH, SOUTH, EAST, or WEST. | ||
| 848 | * @param ltr Is the component line direction left-to-right? | ||
| 849 | */ | ||
| 850 | private Component getChild(String key, boolean ltr) { | ||
| 851 | Component result = null; | ||
| 852 | |||
| 853 | if (key == NORTH) { | ||
| 854 | result = (firstLine != null) ? firstLine : north; | ||
| 855 | } | ||
| 856 | else if (key == SOUTH) { | ||
| 857 | result = (lastLine != null) ? lastLine : south; | ||
| 858 | } | ||
| 859 | else if (key == WEST) { | ||
| 860 | result = ltr ? firstItem : lastItem; | ||
| 861 | if (result == null) { | ||
| 862 | result = west; | ||
| 863 | } | ||
| 864 | } | ||
| 865 | else if (key == EAST) { | ||
| 866 | result = ltr ? lastItem : firstItem; | ||
| 867 | if (result == null) { | ||
| 868 | result = east; | ||
| 869 | } | ||
| 870 | } | ||
| 871 | else if (key == CENTER) { | ||
| 872 | result = center; | ||
| 873 | } | ||
| 874 | if (result != null && !result.visible) { | ||
| 875 | result = null; | ||
| 876 | } | ||
| 877 | return result; | ||
| 878 | } | ||
| 879 | |||
| 880 | /** | ||
| 881 | * Returns a string representation of the state of this border layout. | ||
| 882 | * @return a string representation of this border layout. | ||
| 883 | */ | ||
| 884 | public String toString() { | ||
| 885 | return getClass().getName() + "[hgap=" + hgap + ",vgap=" + vgap + "]"; | ||
| 886 | } | ||
| 887 | } | ||