Source for javax.swing.BoxLayout

   1: /* BoxLayout.java -- A layout for swing components.
   2:    Copyright (C) 2002, 2003, 2005 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: package javax.swing;
  39: 
  40: import java.awt.AWTError;
  41: import java.awt.Component;
  42: import java.awt.ComponentOrientation;
  43: import java.awt.Container;
  44: import java.awt.Dimension;
  45: import java.awt.Insets;
  46: import java.awt.LayoutManager2;
  47: import java.io.Serializable;
  48: 
  49: /**
  50:  * A layout that stacks the children of a container in a Box, either
  51:  * horizontally or vertically.
  52:  *
  53:  * @author Ronald Veldema (rveldema@cs.vu.nl)
  54:  * @author Roman Kennke (roman@kennke.org)
  55:  */
  56: public class BoxLayout implements LayoutManager2, Serializable
  57: {
  58: 
  59:   /**
  60:    * Specifies that components are laid out left to right.
  61:    */
  62:   public static final int X_AXIS = 0;
  63: 
  64:   /**
  65:    * Specifies that components are laid out top to bottom.
  66:    */
  67:   public static final int Y_AXIS = 1;
  68: 
  69:   /**
  70:    * Specifies that components are laid out in the direction of a line of text.
  71:    */
  72:   public static final int LINE_AXIS = 2;
  73: 
  74:   /**
  75:    * Sepcifies that components are laid out in the direction of the line flow.
  76:    */
  77:   public static final int PAGE_AXIS = 3;
  78: 
  79:   /*
  80:    * Needed for serialization.
  81:    */
  82:   private static final long serialVersionUID = -2474455742719112368L;
  83: 
  84:   /*
  85:    * The container given to the constructor.
  86:    */
  87:   private Container container;
  88:   
  89:   /**
  90:    * Current type of component layouting. Defaults to X_AXIS.
  91:    */
  92:   private int way = X_AXIS;
  93: 
  94:   /**
  95:    * The size requirements of the containers children for the X direction.
  96:    */
  97:   private SizeRequirements[] xChildren;
  98: 
  99:   /**
 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: }