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}