001 /* BoxLayout.java -- A layout for swing components.
002 Copyright (C) 2002, 2003, 2005 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.ComponentOrientation;
043 import java.awt.Container;
044 import java.awt.Dimension;
045 import java.awt.Insets;
046 import java.awt.LayoutManager2;
047 import 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 */
056 public 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 }