/* * Copyright (c) 1995, 2006, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */package java.awt; import java.util.Hashtable;import java.util.Arrays; /** * The <code>GridBagLayout</code> class is a flexible layout * manager that aligns components vertically, horizontally or along their * baseline without requiring that the components be of the same size. * Each <code>GridBagLayout</code> object maintains a dynamic, * rectangular grid of cells, with each component occupying * one or more cells, called its <em>display area</em>. * <p> * Each component managed by a <code>GridBagLayout</code> is associated with * an instance of {@link GridBagConstraints}.  The constraints object * specifies where a component's display area should be located on the grid * and how the component should be positioned within its display area.  In * addition to its constraints object, the <code>GridBagLayout</code> also * considers each component's minimum and preferred sizes in order to * determine a component's size. * <p> * The overall orientation of the grid depends on the container's * {@link ComponentOrientation} property.  For horizontal left-to-right * orientations, grid coordinate (0,0) is in the upper left corner of the * container with x increasing to the right and y increasing downward.  For * horizontal right-to-left orientations, grid coordinate (0,0) is in the upper * right corner of the container with x increasing to the left and y * increasing downward. * <p> * To use a grid bag layout effectively, you must customize one or more * of the <code>GridBagConstraints</code> objects that are associated * with its components. You customize a <code>GridBagConstraints</code> * object by setting one or more of its instance variables: * <p> * <dl> * <dt>{@link GridBagConstraints#gridx}, * {@link GridBagConstraints#gridy} * <dd>Specifies the cell containing the leading corner of the component's * display area, where the cell at the origin of the grid has address * <code>gridx&nbsp;=&nbsp;0</code>, * <code>gridy&nbsp;=&nbsp;0</code>.  For horizontal left-to-right layout, * a component's leading corner is its upper left.  For horizontal * right-to-left layout, a component's leading corner is its upper right. * Use <code>GridBagConstraints.RELATIVE</code> (the default value) * to specify that the component be placed immediately following * (along the x axis for <code>gridx</code> or the y axis for * <code>gridy</code>) the component that was added to the container * just before this component was added. * <dt>{@link GridBagConstraints#gridwidth}, * {@link GridBagConstraints#gridheight} * <dd>Specifies the number of cells in a row (for <code>gridwidth</code>) * or column (for <code>gridheight</code>) * in the component's display area. * The default value is 1. * Use <code>GridBagConstraints.REMAINDER</code> to specify * that the component's display area will be from <code>gridx</code> * to the last cell in the row (for <code>gridwidth</code>) * or from <code>gridy</code> to the last cell in the column * (for <code>gridheight</code>). * * Use <code>GridBagConstraints.RELATIVE</code> to specify * that the component's display area will be from <code>gridx</code> * to the next to the last cell in its row (for <code>gridwidth</code> * or from <code>gridy</code> to the next to the last cell in its * column (for <code>gridheight</code>). * * <dt>{@link GridBagConstraints#fill} * <dd>Used when the component's display area * is larger than the component's requested size * to determine whether (and how) to resize the component. * Possible values are * <code>GridBagConstraints.NONE</code> (the default), * <code>GridBagConstraints.HORIZONTAL</code> * (make the component wide enough to fill its display area * horizontally, but don't change its height), * <code>GridBagConstraints.VERTICAL</code> * (make the component tall enough to fill its display area * vertically, but don't change its width), and * <code>GridBagConstraints.BOTH</code> * (make the component fill its display area entirely). * <dt>{@link GridBagConstraints#ipadx}, * {@link GridBagConstraints#ipady} * <dd>Specifies the component's internal padding within the layout, * how much to add to the minimum size of the component. * The width of the component will be at least its minimum width * plus <code>ipadx</code> pixels. Similarly, the height of * the component will be at least the minimum height plus * <code>ipady</code> pixels. * <dt>{@link GridBagConstraints#insets} * <dd>Specifies the component's external padding, the minimum * amount of space between the component and the edges of its display area. * <dt>{@link GridBagConstraints#anchor} * <dd>Specifies where the component should be positioned in its display area. * There are three kinds of possible values: absolute, orientation-relative, * and baseline-relative * Orientation relative values are interpreted relative to the container's * <code>ComponentOrientation</code> property while absolute values * are not.  Baseline relative values are calculated relative to the * baseline.  Valid values are:</dd> * <p> * <center><table BORDER=0 COLS=3 WIDTH=800 *        SUMMARY="absolute, relative and baseline values as described above"> * <tr> * <th><P ALIGN="LEFT">Absolute Values</th> * <th><P ALIGN="LEFT">Orientation Relative Values</th> * <th><P ALIGN="LEFT">Baseline Relative Values</th> * </tr> * <tr> * <td> * <li><code>GridBagConstraints.NORTH</code></li> * <li><code>GridBagConstraints.SOUTH</code></li> * <li><code>GridBagConstraints.WEST</code></li> * <li><code>GridBagConstraints.EAST</code></li> * <li><code>GridBagConstraints.NORTHWEST</code></li> * <li><code>GridBagConstraints.NORTHEAST</code></li> * <li><code>GridBagConstraints.SOUTHWEST</code></li> * <li><code>GridBagConstraints.SOUTHEAST</code></li> * <li><code>GridBagConstraints.CENTER</code> (the default)</li> * </td> * <td> * <li><code>GridBagConstraints.PAGE_START</code></li> * <li><code>GridBagConstraints.PAGE_END</code></li> * <li><code>GridBagConstraints.LINE_START</code></li> * <li><code>GridBagConstraints.LINE_END</code></li> * <li><code>GridBagConstraints.FIRST_LINE_START</code></li> * <li><code>GridBagConstraints.FIRST_LINE_END</code></li> * <li><code>GridBagConstraints.LAST_LINE_START</code></li> * <li><code>GridBagConstraints.LAST_LINE_END</code></li> * </td> * <td> * <li><code>GridBagConstraints.BASELINE</code></li> * <li><code>GridBagConstraints.BASELINE_LEADING</code></li> * <li><code>GridBagConstraints.BASELINE_TRAILING</code></li> * <li><code>GridBagConstraints.ABOVE_BASELINE</code></li> * <li><code>GridBagConstraints.ABOVE_BASELINE_LEADING</code></li> * <li><code>GridBagConstraints.ABOVE_BASELINE_TRAILING</code></li> * <li><code>GridBagConstraints.BELOW_BASELINE</code></li> * <li><code>GridBagConstraints.BELOW_BASELINE_LEADING</code></li> * <li><code>GridBagConstraints.BELOW_BASELINE_TRAILING</code></li> * </td> * </tr> * </table></center><p> * <dt>{@link GridBagConstraints#weightx}, * {@link GridBagConstraints#weighty} * <dd>Used to determine how to distribute space, which is * important for specifying resizing behavior. * Unless you specify a weight for at least one component * in a row (<code>weightx</code>) and column (<code>weighty</code>), * all the components clump together in the center of their container. * This is because when the weight is zero (the default), * the <code>GridBagLayout</code> object puts any extra space * between its grid of cells and the edges of the container. * </dl> * <p> * Each row may have a baseline; the baseline is determined by the * components in that row that have a valid baseline and are aligned * along the baseline (the component's anchor value is one of {@code * BASELINE}, {@code BASELINE_LEADING} or {@code BASELINE_TRAILING}). * If none of the components in the row has a valid baseline, the row * does not have a baseline. * <p> * If a component spans rows it is aligned either to the baseline of * the start row (if the baseline-resize behavior is {@code * CONSTANT_ASCENT}) or the end row (if the baseline-resize behavior * is {@code CONSTANT_DESCENT}).  The row that the component is * aligned to is called the <em>prevailing row</em>. * <p> * The following figure shows a baseline layout and includes a * component that spans rows: * <center><table summary="Baseline Layout"> * <tr ALIGN=CENTER> * <td> * <img src="doc-files/GridBagLayout-baseline.png" *  alt="The following text describes this graphic (Figure 1)." ALIGN=center> * </td> * </table></center> * This layout consists of three components: * <ul><li>A panel that starts in row 0 and ends in row 1.  The panel *   has a baseline-resize behavior of <code>CONSTANT_DESCENT</code> and has *   an anchor of <code>BASELINE</code>.  As the baseline-resize behavior *   is <code>CONSTANT_DESCENT</code> the prevailing row for the panel is *   row 1. * <li>Two buttons, each with a baseline-resize behavior of *   <code>CENTER_OFFSET</code> and an anchor of <code>BASELINE</code>. * </ul> * Because the second button and the panel share the same prevailing row, * they are both aligned along their baseline. * <p> * Components positioned using one of the baseline-relative values resize * differently than when positioned using an absolute or orientation-relative * value.  How components change is dictated by how the baseline of the * prevailing row changes.  The baseline is anchored to the * bottom of the display area if any components with the same prevailing row * have a baseline-resize behavior of <code>CONSTANT_DESCENT</code>, * otherwise the baseline is anchored to the top of the display area. * The following rules dictate the resize behavior: * <ul> * <li>Resizable components positioned above the baseline can only * grow as tall as the baseline.  For example, if the baseline is at 100 * and anchored at the top, a resizable component positioned above the * baseline can never grow more than 100 units. * <li>Similarly, resizable components positioned below the baseline can * only grow as high as the difference between the display height and the * baseline. * <li>Resizable components positioned on the baseline with a * baseline-resize behavior of <code>OTHER</code> are only resized if * the baseline at the resized size fits within the display area.  If * the baseline is such that it does not fit within the display area * the component is not resized. * <li>Components positioned on the baseline that do not have a * baseline-resize behavior of <code>OTHER</code> * can only grow as tall as {@code display height - baseline + baseline of component}. * </ul> * If you position a component along the baseline, but the * component does not have a valid baseline, it will be vertically centered * in its space.  Similarly if you have positioned a component relative * to the baseline and none of the components in the row have a valid * baseline the component is vertically centered. * <p> * The following figures show ten components (all buttons) * managed by a grid bag layout.  Figure 2 shows the layout for a horizontal, * left-to-right container and Figure 3 shows the layout for a horizontal, * right-to-left container. * <p> * <center><table COLS=2 WIDTH=600 summary="layout"> * <tr ALIGN=CENTER> * <td> * <img src="doc-files/GridBagLayout-1.gif" alt="The preceeding text describes this graphic (Figure 1)." ALIGN=center HSPACE=10 VSPACE=7> * </td> * <td> * <img src="doc-files/GridBagLayout-2.gif" alt="The preceeding text describes this graphic (Figure 2)." ALIGN=center HSPACE=10 VSPACE=7> * </td> * <tr ALIGN=CENTER> * <td>Figure 2: Horizontal, Left-to-Right</td> * <td>Figure 3: Horizontal, Right-to-Left</td> * </tr> * </table></center> * <p> * Each of the ten components has the <code>fill</code> field * of its associated <code>GridBagConstraints</code> object * set to <code>GridBagConstraints.BOTH</code>. * In addition, the components have the following non-default constraints: * <p> * <ul> * <li>Button1, Button2, Button3: <code>weightx&nbsp;=&nbsp;1.0</code> * <li>Button4: <code>weightx&nbsp;=&nbsp;1.0</code>, * <code>gridwidth&nbsp;=&nbsp;GridBagConstraints.REMAINDER</code> * <li>Button5: <code>gridwidth&nbsp;=&nbsp;GridBagConstraints.REMAINDER</code> * <li>Button6: <code>gridwidth&nbsp;=&nbsp;GridBagConstraints.RELATIVE</code> * <li>Button7: <code>gridwidth&nbsp;=&nbsp;GridBagConstraints.REMAINDER</code> * <li>Button8: <code>gridheight&nbsp;=&nbsp;2</code>, * <code>weighty&nbsp;=&nbsp;1.0</code> * <li>Button9, Button 10: * <code>gridwidth&nbsp;=&nbsp;GridBagConstraints.REMAINDER</code> * </ul> * <p> * Here is the code that implements the example shown above: * <p> * <hr><blockquote><pre> * import java.awt.*; * import java.util.*; * import java.applet.Applet; * * public class GridBagEx1 extends Applet { * *     protected void makebutton(String name, *                               GridBagLayout gridbag, *                               GridBagConstraints c) { *         Button button = new Button(name); *         gridbag.setConstraints(button, c); *         add(button); *     } * *     public void init() { *         GridBagLayout gridbag = new GridBagLayout(); *         GridBagConstraints c = new GridBagConstraints(); * *         setFont(new Font("SansSerif", Font.PLAIN, 14)); *         setLayout(gridbag); * *         c.fill = GridBagConstraints.BOTH; *         c.weightx = 1.0; *         makebutton("Button1", gridbag, c); *         makebutton("Button2", gridbag, c); *         makebutton("Button3", gridbag, c); * *         c.gridwidth = GridBagConstraints.REMAINDER; //end row *         makebutton("Button4", gridbag, c); * *         c.weightx = 0.0;                //reset to the default *         makebutton("Button5", gridbag, c); //another row * *         c.gridwidth = GridBagConstraints.RELATIVE; //next-to-last in row *         makebutton("Button6", gridbag, c); * *         c.gridwidth = GridBagConstraints.REMAINDER; //end row *         makebutton("Button7", gridbag, c); * *         c.gridwidth = 1;                //reset to the default *         c.gridheight = 2; *         c.weighty = 1.0; *         makebutton("Button8", gridbag, c); * *         c.weighty = 0.0;                //reset to the default *         c.gridwidth = GridBagConstraints.REMAINDER; //end row *         c.gridheight = 1;               //reset to the default *         makebutton("Button9", gridbag, c); *         makebutton("Button10", gridbag, c); * *         setSize(300, 100); *     } * *     public static void main(String args[]) { *         Frame f = new Frame("GridBag Layout Example"); *         GridBagEx1 ex1 = new GridBagEx1(); * *         ex1.init(); * *         f.add("Center", ex1); *         f.pack(); *         f.setSize(f.getPreferredSize()); *         f.show(); *     } * } * </pre></blockquote><hr> * <p> * @author Doug Stein * @author Bill Spitzak (orignial NeWS & OLIT implementation) * @see       java.awt.GridBagConstraints * @see       java.awt.GridBagLayoutInfo * @see       java.awt.ComponentOrientation * @since JDK1.0 */public class GridBagLayout implements LayoutManager2,java.io.Serializable {     static final int EMPIRICMULTIPLIER = 2;    /**     * This field is no longer used to reserve arrays and keeped for backward     * compatibility. Previously, this was     * the maximum number of grid positions (both horizontal and     * vertical) that could be laid out by the grid bag layout.     * Current implementation doesn't impose any limits     * on the size of a grid.     */    protected static final int MAXGRIDSIZE = 512;     /**     * The smallest grid that can be laid out by the grid bag layout.     */    protected static final int MINSIZE = 1;    /**     * The preferred grid size that can be laid out by the grid bag layout.     */    protected static final int PREFERREDSIZE = 2;     /**     * This hashtable maintains the association between     * a component and its gridbag constraints.     * The Keys in <code>comptable</code> are the components and the     * values are the instances of <code>GridBagConstraints</code>.     *     * @serial     * @see java.awt.GridBagConstraints     */    protected Hashtable<Component,GridBagConstraints> comptable;     /**     * This field holds a gridbag constraints instance     * containing the default values, so if a component     * does not have gridbag constraints associated with     * it, then the component will be assigned a     * copy of the <code>defaultConstraints</code>.     *     * @serial     * @see #getConstraints(Component)     * @see #setConstraints(Component, GridBagConstraints)     * @see #lookupConstraints(Component)     */    protected GridBagConstraints defaultConstraints;     /**     * This field holds the layout information     * for the gridbag.  The information in this field     * is based on the most recent validation of the     * gridbag.     * If <code>layoutInfo</code> is <code>null</code>     * this indicates that there are no components in     * the gridbag or if there are components, they have     * not yet been validated.     *     * @serial     * @see #getLayoutInfo(Container, int)     */    protected GridBagLayoutInfo layoutInfo;     /**     * This field holds the overrides to the column minimum     * width.  If this field is non-<code>null</code> the values are     * applied to the gridbag after all of the minimum columns     * widths have been calculated.     * If columnWidths has more elements than the number of     * columns, columns are added to the gridbag to match     * the number of elements in columnWidth.     *     * @serial     * @see #getLayoutDimensions()     */    public int columnWidths[];     /**     * This field holds the overrides to the row minimum     * heights.  If this field is non-<code>null</code> the values are     * applied to the gridbag after all of the minimum row     * heights have been calculated.     * If <code>rowHeights</code> has more elements than the number of     * rows, rowa are added to the gridbag to match     * the number of elements in <code>rowHeights</code>.     *     * @serial     * @see #getLayoutDimensions()     */    public int rowHeights[];     /**     * This field holds the overrides to the column weights.     * If this field is non-<code>null</code> the values are     * applied to the gridbag after all of the columns     * weights have been calculated.     * If <code>columnWeights[i]</code> &gt; weight for column i, then     * column i is assigned the weight in <code>columnWeights[i]</code>.     * If <code>columnWeights</code> has more elements than the number     * of columns, the excess elements are ignored - they do     * not cause more columns to be created.     *     * @serial     */    public double columnWeights[];     /**     * This field holds the overrides to the row weights.     * If this field is non-<code>null</code> the values are     * applied to the gridbag after all of the rows     * weights have been calculated.     * If <code>rowWeights[i]</code> &gt; weight for row i, then     * row i is assigned the weight in <code>rowWeights[i]</code>.     * If <code>rowWeights</code> has more elements than the number     * of rows, the excess elements are ignored - they do     * not cause more rows to be created.     *     * @serial     */    public double rowWeights[];     /**     * The component being positioned.  This is set before calling into     * <code>adjustForGravity</code>.     */    private Component componentAdjusting;     /**     * Creates a grid bag layout manager.     */    public GridBagLayout () {        comptable = new Hashtable<Component,GridBagConstraints>();        defaultConstraints = new GridBagConstraints();    }     /**     * Sets the constraints for the specified component in this layout.     * @param       comp the component to be modified     * @param       constraints the constraints to be applied     */    public void setConstraints(Component comp, GridBagConstraints constraints) {        comptable.put(comp, (GridBagConstraints)constraints.clone());    }

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