001/* BoxLayout.java -- A layout for swing components. 002 Copyright (C) 2002, 2003, 2005 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038package javax.swing; 039 040import java.awt.AWTError; 041import java.awt.Component; 042import java.awt.ComponentOrientation; 043import java.awt.Container; 044import java.awt.Dimension; 045import java.awt.Insets; 046import java.awt.LayoutManager2; 047import java.io.Serializable; 048 049/** 050 * A layout that stacks the children of a container in a Box, either 051 * horizontally or vertically. 052 * 053 * @author Ronald Veldema (rveldema@cs.vu.nl) 054 * @author Roman Kennke (roman@kennke.org) 055 */ 056public class BoxLayout implements LayoutManager2, Serializable 057{ 058 059 /** 060 * Specifies that components are laid out left to right. 061 */ 062 public static final int X_AXIS = 0; 063 064 /** 065 * Specifies that components are laid out top to bottom. 066 */ 067 public static final int Y_AXIS = 1; 068 069 /** 070 * Specifies that components are laid out in the direction of a line of text. 071 */ 072 public static final int LINE_AXIS = 2; 073 074 /** 075 * Sepcifies that components are laid out in the direction of the line flow. 076 */ 077 public static final int PAGE_AXIS = 3; 078 079 /* 080 * Needed for serialization. 081 */ 082 private static final long serialVersionUID = -2474455742719112368L; 083 084 /* 085 * The container given to the constructor. 086 */ 087 private Container container; 088 089 /** 090 * Current type of component layouting. Defaults to X_AXIS. 091 */ 092 private int way = X_AXIS; 093 094 /** 095 * The size requirements of the containers children for the X direction. 096 */ 097 private SizeRequirements[] xChildren; 098 099 /** 100 * The size requirements of the containers children for the Y direction. 101 */ 102 private SizeRequirements[] yChildren; 103 104 /** 105 * The size requirements of the container to be laid out for the X direction. 106 */ 107 private SizeRequirements xTotal; 108 109 /** 110 * The size requirements of the container to be laid out for the Y direction. 111 */ 112 private SizeRequirements yTotal; 113 114 /** 115 * The offsets of the child components in the X direction. 116 */ 117 private int[] offsetsX; 118 119 /** 120 * The offsets of the child components in the Y direction. 121 */ 122 private int[] offsetsY; 123 124 /** 125 * The spans of the child components in the X direction. 126 */ 127 private int[] spansX; 128 129 /** 130 * The spans of the child components in the Y direction. 131 */ 132 private int[] spansY; 133 134 /** 135 * Constructs a <code>BoxLayout</code> object. 136 * 137 * @param container The container that needs to be laid out. 138 * @param way The orientation of the components. 139 * 140 * @exception AWTError If way has an invalid value. 141 */ 142 public BoxLayout(Container container, int way) 143 { 144 if (way != X_AXIS && way != Y_AXIS && way != LINE_AXIS && way != PAGE_AXIS) 145 throw new AWTError("Invalid axis"); 146 147 int width = 0; 148 int height = 0; 149 this.container = container; 150 this.way = way; 151 } 152 153 /** 154 * Adds a component to the layout. Not used in BoxLayout. 155 * 156 * @param name The name of the component to add. 157 * @param component the component to add to the layout. 158 */ 159 public void addLayoutComponent(String name, Component component) 160 { 161 // Nothing to do here. 162 } 163 164 /** 165 * Removes a component from the layout. Not used in BoxLayout. 166 * 167 * @param component The component to remove from the layout. 168 */ 169 public void removeLayoutComponent(Component component) 170 { 171 // Nothing to do here. 172 } 173 174 private boolean isHorizontalIn(Container parent) 175 { 176 ComponentOrientation orientation = parent.getComponentOrientation(); 177 return this.way == X_AXIS 178 || (this.way == LINE_AXIS 179 && orientation.isHorizontal()) 180 || (this.way == PAGE_AXIS 181 && (!orientation.isHorizontal())); 182 } 183 184 185 186 /** 187 * Returns the preferred size of the layout. 188 * 189 * @param parent The container that needs to be laid out. 190 * 191 * @return The dimension of the layout. 192 */ 193 public Dimension preferredLayoutSize(Container parent) 194 { 195 synchronized (container.getTreeLock()) 196 { 197 if (container != parent) 198 throw new AWTError("BoxLayout can't be shared"); 199 200 checkTotalRequirements(); 201 Insets i = container.getInsets(); 202 return new Dimension(xTotal.preferred + i.left + i.right, 203 yTotal.preferred + i.top + i.bottom); 204 } 205 } 206 207 /** 208 * Returns the minimum size of the layout. 209 * 210 * @param parent The container that needs to be laid out. 211 * 212 * @return The dimension of the layout. 213 */ 214 public Dimension minimumLayoutSize(Container parent) 215 { 216 synchronized (container.getTreeLock()) 217 { 218 if (container != parent) 219 throw new AWTError("BoxLayout can't be shared"); 220 221 checkTotalRequirements(); 222 Insets i = container.getInsets(); 223 return new Dimension(xTotal.minimum + i.left + i.right, 224 yTotal.minimum + i.top + i.bottom); 225 } 226 } 227 228 /** 229 * Lays out the specified container using this layout. 230 * 231 * @param parent The container that needs to be laid out. 232 */ 233 public void layoutContainer(Container parent) 234 { 235 synchronized (container.getTreeLock()) 236 { 237 if (container != parent) 238 throw new AWTError("BoxLayout can't be shared"); 239 240 checkLayout(); 241 Component[] children = container.getComponents(); 242 Insets in = container.getInsets(); 243 for (int i = 0; i < children.length; i++) 244 children[i].setBounds(offsetsX[i] + in.left, offsetsY[i] + in.top, 245 spansX[i], spansY[i]); 246 } 247 } 248 249 /** 250 * Adds a component to the layout. Not used in BoxLayout 251 * 252 * @param child The component to add to the layout. 253 * @param constraints The constraints for the component in the layout. 254 */ 255 public void addLayoutComponent(Component child, Object constraints) 256 { 257 // Nothing to do here. 258 } 259 260 /** 261 * Returns the alignment along the X axis for the container. 262 * 263 * @param parent The container that needs to be laid out. 264 * 265 * @return The alignment. 266 */ 267 public float getLayoutAlignmentX(Container parent) 268 { 269 synchronized (container.getTreeLock()) 270 { 271 if (container != parent) 272 throw new AWTError("BoxLayout can't be shared"); 273 274 checkTotalRequirements(); 275 return xTotal.alignment; 276 } 277 } 278 279 /** 280 * Returns the alignment along the Y axis for the container. 281 * 282 * @param parent The container that needs to be laid out. 283 * 284 * @return The alignment. 285 */ 286 public float getLayoutAlignmentY(Container parent) 287 { 288 synchronized (container.getTreeLock()) 289 { 290 if (container != parent) 291 throw new AWTError("BoxLayout can't be shared"); 292 293 checkTotalRequirements(); 294 return yTotal.alignment; 295 } 296 } 297 298 /** 299 * Invalidates the layout. 300 * 301 * @param parent The container that needs to be laid out. 302 */ 303 public void invalidateLayout(Container parent) 304 { 305 if (container != parent) 306 throw new AWTError("BoxLayout can't be shared"); 307 308 synchronized (container.getTreeLock()) 309 { 310 xChildren = null; 311 yChildren = null; 312 xTotal = null; 313 yTotal = null; 314 offsetsX = null; 315 offsetsY = null; 316 spansX = null; 317 spansY = null; 318 } 319 } 320 321 /** 322 * Returns the maximum size of the layout gived the components 323 * in the given container. 324 * 325 * @param parent The container that needs to be laid out. 326 * 327 * @return The dimension of the layout. 328 */ 329 public Dimension maximumLayoutSize(Container parent) 330 { 331 synchronized (container.getTreeLock()) 332 { 333 if (container != parent) 334 throw new AWTError("BoxLayout can't be shared"); 335 336 checkTotalRequirements(); 337 Insets i = container.getInsets(); 338 int xDim = xTotal.maximum + i.left + i.right; 339 int yDim = yTotal.maximum + i.top + i.bottom; 340 341 // Check for overflow 342 if (xDim < xTotal.maximum) 343 xDim = Integer.MAX_VALUE; 344 if (yDim < yTotal.maximum) 345 yDim = Integer.MAX_VALUE; 346 return new Dimension(xDim, yDim); 347 } 348 } 349 350 /** 351 * Makes sure that the xTotal and yTotal fields are set up correctly. A call 352 * to {@link #invalidateLayout} sets these fields to null and they have to be 353 * recomputed. 354 */ 355 private void checkTotalRequirements() 356 { 357 if (xTotal == null || yTotal == null) 358 { 359 checkRequirements(); 360 if (isHorizontalIn(container)) 361 { 362 xTotal = SizeRequirements.getTiledSizeRequirements(xChildren); 363 yTotal = SizeRequirements.getAlignedSizeRequirements(yChildren); 364 } 365 else 366 { 367 xTotal = SizeRequirements.getAlignedSizeRequirements(xChildren); 368 yTotal = SizeRequirements.getTiledSizeRequirements(yChildren); 369 } 370 } 371 } 372 373 /** 374 * Makes sure that the xChildren and yChildren fields are correctly set up. 375 * A call to {@link #invalidateLayout(Container)} sets these fields to null, 376 * so they have to be set up again. 377 */ 378 private void checkRequirements() 379 { 380 if (xChildren == null || yChildren == null) 381 { 382 Component[] children = container.getComponents(); 383 xChildren = new SizeRequirements[children.length]; 384 yChildren = new SizeRequirements[children.length]; 385 for (int i = 0; i < children.length; i++) 386 { 387 if (! children[i].isVisible()) 388 { 389 xChildren[i] = new SizeRequirements(); 390 yChildren[i] = new SizeRequirements(); 391 } 392 else 393 { 394 xChildren[i] = 395 new SizeRequirements(children[i].getMinimumSize().width, 396 children[i].getPreferredSize().width, 397 children[i].getMaximumSize().width, 398 children[i].getAlignmentX()); 399 yChildren[i] = 400 new SizeRequirements(children[i].getMinimumSize().height, 401 children[i].getPreferredSize().height, 402 children[i].getMaximumSize().height, 403 children[i].getAlignmentY()); 404 } 405 } 406 } 407 } 408 409 /** 410 * Makes sure that the offsetsX, offsetsY, spansX and spansY fields are set 411 * up correctly. A call to {@link #invalidateLayout} sets these fields 412 * to null and they have to be recomputed. 413 */ 414 private void checkLayout() 415 { 416 if (offsetsX == null || offsetsY == null || spansX == null 417 || spansY == null) 418 { 419 checkRequirements(); 420 checkTotalRequirements(); 421 int len = container.getComponents().length; 422 offsetsX = new int[len]; 423 offsetsY = new int[len]; 424 spansX = new int[len]; 425 spansY = new int[len]; 426 427 Insets in = container.getInsets(); 428 int width = container.getWidth() - in.left - in.right; 429 int height = container.getHeight() - in.top - in.bottom; 430 431 if (isHorizontalIn(container)) 432 { 433 SizeRequirements.calculateTiledPositions(width, 434 xTotal, xChildren, 435 offsetsX, spansX); 436 SizeRequirements.calculateAlignedPositions(height, 437 yTotal, yChildren, 438 offsetsY, spansY); 439 } 440 else 441 { 442 SizeRequirements.calculateAlignedPositions(width, 443 xTotal, xChildren, 444 offsetsX, spansX); 445 SizeRequirements.calculateTiledPositions(height, 446 yTotal, yChildren, 447 offsetsY, spansY); 448 } 449 } 450 } 451}