001 /* OverlayLayout.java -- A layout manager 002 Copyright (C) 2002, 2004, 2005, 2006, Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 package javax.swing; 039 040 import java.awt.AWTError; 041 import java.awt.Component; 042 import java.awt.Container; 043 import java.awt.Dimension; 044 import java.awt.Insets; 045 import java.awt.LayoutManager2; 046 import java.io.Serializable; 047 048 /** 049 * A layout manager that lays out the components of a container one over 050 * another. 051 * 052 * The components take as much space as is available in the container, but not 053 * more than specified by their maximum size. 054 * 055 * The overall layout is mainly affected by the components 056 * <code>alignmentX</code> and <code>alignmentY</code> properties. All 057 * components are aligned, so that their alignment points (for either 058 * direction) are placed in one line (the baseline for this direction). 059 * 060 * For example: An X alignment of 0.0 means that the component's alignment 061 * point is at it's left edge, an X alignment of 0.5 means that the alignment 062 * point is in the middle, an X alignment of 1.0 means, the aligment point is 063 * at the right edge. So if you have three components, the first with 0.0, the 064 * second with 0.5 and the third with 1.0, then they are laid out like this: 065 * 066 * <pre> 067 * +-------+ 068 * | 1 | 069 * +-------+ 070 * +-------+ 071 * | 2 | 072 * +-------+ 073 * +---------+ 074 * | 3 + 075 * +---------+ 076 * </pre> 077 * The above picture shows the X alignment between the components. An Y 078 * alignment like shown above cannot be achieved with this layout manager. The 079 * components are place on top of each other, with the X alignment shown above. 080 * 081 * @author Roman Kennke (kennke@aicas.com) 082 * @author Andrew Selkirk 083 */ 084 public class OverlayLayout implements LayoutManager2, Serializable 085 { 086 private static final long serialVersionUID = 18082829169631543L; 087 088 /** 089 * The container to be laid out. 090 */ 091 private Container target; 092 093 /** 094 * The size requirements of the containers children for the X direction. 095 */ 096 private SizeRequirements[] xChildren; 097 098 /** 099 * The size requirements of the containers children for the Y direction. 100 */ 101 private SizeRequirements[] yChildren; 102 103 /** 104 * The size requirements of the container to be laid out for the X direction. 105 */ 106 private SizeRequirements xTotal; 107 108 /** 109 * The size requirements of the container to be laid out for the Y direction. 110 */ 111 private SizeRequirements yTotal; 112 113 /** 114 * The offsets of the child components in the X direction. 115 */ 116 private int[] offsetsX; 117 118 /** 119 * The offsets of the child components in the Y direction. 120 */ 121 private int[] offsetsY; 122 123 /** 124 * The spans of the child components in the X direction. 125 */ 126 private int[] spansX; 127 128 /** 129 * The spans of the child components in the Y direction. 130 */ 131 private int[] spansY; 132 133 /** 134 * Creates a new OverlayLayout for the specified container. 135 * 136 * @param target the container to be laid out 137 */ 138 public OverlayLayout(Container target) 139 { 140 this.target = target; 141 } 142 143 /** 144 * Notifies the layout manager that the layout has become invalid. It throws 145 * away cached layout information and recomputes it the next time it is 146 * requested. 147 * 148 * @param target not used here 149 */ 150 public void invalidateLayout(Container target) 151 { 152 xChildren = null; 153 yChildren = null; 154 xTotal = null; 155 yTotal = null; 156 offsetsX = null; 157 offsetsY = null; 158 spansX = null; 159 spansY = null; 160 } 161 162 /** 163 * This method is not used in this layout manager. 164 * 165 * @param string not used here 166 * @param component not used here 167 */ 168 public void addLayoutComponent(String string, Component component) 169 { 170 // Nothing to do here. 171 } 172 173 /** 174 * This method is not used in this layout manager. 175 * 176 * @param component not used here 177 * @param constraints not used here 178 */ 179 public void addLayoutComponent(Component component, Object constraints) 180 { 181 // Nothing to do here. 182 } 183 184 /** 185 * This method is not used in this layout manager. 186 * 187 * @param component not used here 188 */ 189 public void removeLayoutComponent(Component component) 190 { 191 // Nothing to do here. 192 } 193 194 /** 195 * Returns the preferred size of the container that is laid out. This is 196 * computed by the children's preferred sizes, taking their alignments into 197 * account. 198 * 199 * @param target not used here 200 * 201 * @return the preferred size of the container that is laid out 202 */ 203 public Dimension preferredLayoutSize(Container target) 204 { 205 if (target != this.target) 206 throw new AWTError("OverlayLayout can't be shared"); 207 208 checkTotalRequirements(); 209 return new Dimension(xTotal.preferred, yTotal.preferred); 210 } 211 212 /** 213 * Returns the minimum size of the container that is laid out. This is 214 * computed by the children's minimum sizes, taking their alignments into 215 * account. 216 * 217 * @param target not used here 218 * 219 * @return the minimum size of the container that is laid out 220 */ 221 public Dimension minimumLayoutSize(Container target) 222 { 223 if (target != this.target) 224 throw new AWTError("OverlayLayout can't be shared"); 225 226 checkTotalRequirements(); 227 return new Dimension(xTotal.minimum, yTotal.minimum); 228 } 229 230 /** 231 * Returns the maximum size of the container that is laid out. This is 232 * computed by the children's maximum sizes, taking their alignments into 233 * account. 234 * 235 * @param target not used here 236 * 237 * @return the maximum size of the container that is laid out 238 */ 239 public Dimension maximumLayoutSize(Container target) 240 { 241 if (target != this.target) 242 throw new AWTError("OverlayLayout can't be shared"); 243 244 checkTotalRequirements(); 245 return new Dimension(xTotal.maximum, yTotal.maximum); 246 } 247 248 /** 249 * Returns the X alignment of the container that is laid out. This is 250 * computed by the children's preferred sizes, taking their alignments into 251 * account. 252 * 253 * @param target not used here 254 * 255 * @return the X alignment of the container that is laid out 256 */ 257 public float getLayoutAlignmentX(Container target) 258 { 259 if (target != this.target) 260 throw new AWTError("OverlayLayout can't be shared"); 261 262 checkTotalRequirements(); 263 return xTotal.alignment; 264 } 265 266 /** 267 * Returns the Y alignment of the container that is laid out. This is 268 * computed by the children's preferred sizes, taking their alignments into 269 * account. 270 * 271 * @param target not used here 272 * 273 * @return the X alignment of the container that is laid out 274 */ 275 public float getLayoutAlignmentY(Container target) 276 { 277 if (target != this.target) 278 throw new AWTError("OverlayLayout can't be shared"); 279 280 checkTotalRequirements(); 281 return yTotal.alignment; 282 } 283 284 /** 285 * Lays out the container and it's children. 286 * 287 * The children are laid out one over another. 288 * 289 * The components take as much space as is available in the container, but 290 * not more than specified by their maximum size. 291 * 292 * The overall layout is mainly affected by the components 293 * <code>alignmentX</code> and <code>alignmentY</code> properties. All 294 * components are aligned, so that their alignment points (for either 295 * direction) are placed in one line (the baseline for this direction). 296 * 297 * For example: An X alignment of 0.0 means that the component's alignment 298 * point is at it's left edge, an X alignment of 0.5 means that the alignment 299 * point is in the middle, an X alignment of 1.0 means, the aligment point is 300 * at the right edge. So if you have three components, the first with 0.0, 301 * the second with 0.5 and the third with 1.0, then they are laid out like 302 * this: 303 * 304 * <pre> 305 * +-------+ 306 * | 1 | 307 * +-------+ 308 * +-------+ 309 * | 2 | 310 * +-------+ 311 * +---------+ 312 * | 3 + 313 * +---------+ 314 * </pre> 315 * The above picture shows the X alignment between the components. An Y 316 * alignment like shown above cannot be achieved with this layout manager. 317 * The components are place on top of each other, with the X alignment shown 318 * above. 319 * 320 * @param target not used here 321 */ 322 public void layoutContainer(Container target) 323 { 324 if (target != this.target) 325 throw new AWTError("OverlayLayout can't be shared"); 326 327 checkLayout(); 328 Component[] children = target.getComponents(); 329 for (int i = 0; i < children.length; i++) 330 children[i].setBounds(offsetsX[i], offsetsY[i], spansX[i], spansY[i]); 331 } 332 333 /** 334 * Makes sure that the xChildren and yChildren fields are correctly set up. 335 * A call to {@link #invalidateLayout(Container)} sets these fields to null, 336 * so they have to be set up again. 337 */ 338 private void checkRequirements() 339 { 340 if (xChildren == null || yChildren == null) 341 { 342 Component[] children = target.getComponents(); 343 xChildren = new SizeRequirements[children.length]; 344 yChildren = new SizeRequirements[children.length]; 345 for (int i = 0; i < children.length; i++) 346 { 347 if (! children[i].isVisible()) 348 { 349 xChildren[i] = new SizeRequirements(); 350 yChildren[i] = new SizeRequirements(); 351 } 352 else 353 { 354 xChildren[i] = 355 new SizeRequirements(children[i].getMinimumSize().width, 356 children[i].getPreferredSize().width, 357 children[i].getMaximumSize().width, 358 children[i].getAlignmentX()); 359 yChildren[i] = 360 new SizeRequirements(children[i].getMinimumSize().height, 361 children[i].getPreferredSize().height, 362 children[i].getMaximumSize().height, 363 children[i].getAlignmentY()); 364 } 365 } 366 } 367 } 368 369 /** 370 * Makes sure that the xTotal and yTotal fields are set up correctly. A call 371 * to {@link #invalidateLayout} sets these fields to null and they have to be 372 * recomputed. 373 */ 374 private void checkTotalRequirements() 375 { 376 if (xTotal == null || yTotal == null) 377 { 378 checkRequirements(); 379 xTotal = SizeRequirements.getAlignedSizeRequirements(xChildren); 380 yTotal = SizeRequirements.getAlignedSizeRequirements(yChildren); 381 } 382 } 383 384 /** 385 * Makes sure that the offsetsX, offsetsY, spansX and spansY fields are set 386 * up correctly. A call to {@link #invalidateLayout} sets these fields 387 * to null and they have to be recomputed. 388 */ 389 private void checkLayout() 390 { 391 if (offsetsX == null || offsetsY == null || spansX == null 392 || spansY == null) 393 { 394 checkRequirements(); 395 checkTotalRequirements(); 396 int len = target.getComponents().length; 397 offsetsX = new int[len]; 398 offsetsY = new int[len]; 399 spansX = new int[len]; 400 spansY = new int[len]; 401 402 Insets in = target.getInsets(); 403 int width = target.getWidth() - in.left - in.right; 404 int height = target.getHeight() - in.top - in.bottom; 405 406 SizeRequirements.calculateAlignedPositions(width, xTotal, 407 xChildren, offsetsX, spansX); 408 SizeRequirements.calculateAlignedPositions(height, yTotal, 409 yChildren, offsetsY, spansY); 410 } 411 } 412 }