Java tutorial
/* * Copyright (c) 1995, 2013, 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; /** * The {@code GridBagConstraints} class specifies constraints * for components that are laid out using the * {@code GridBagLayout} class. * * @author Doug Stein * @author Bill Spitzak (orignial NeWS & OLIT implementation) * @see java.awt.GridBagLayout * @since 1.0 */ public class GridBagConstraints implements Cloneable, java.io.Serializable { /** * Specifies that this component is the next-to-last component in its * column or row ({@code gridwidth}, {@code gridheight}), * or that this component be placed next to the previously added * component ({@code gridx}, {@code gridy}). * @see java.awt.GridBagConstraints#gridwidth * @see java.awt.GridBagConstraints#gridheight * @see java.awt.GridBagConstraints#gridx * @see java.awt.GridBagConstraints#gridy */ public static final int RELATIVE = -1; /** * Specifies that this component is the * last component in its column or row. */ public static final int REMAINDER = 0; /** * Do not resize the component. */ public static final int NONE = 0; /** * Resize the component both horizontally and vertically. */ public static final int BOTH = 1; /** * Resize the component horizontally but not vertically. */ public static final int HORIZONTAL = 2; /** * Resize the component vertically but not horizontally. */ public static final int VERTICAL = 3; /** * Put the component in the center of its display area. */ public static final int CENTER = 10; /** * Put the component at the top of its display area, * centered horizontally. */ public static final int NORTH = 11; /** * Put the component at the top-right corner of its display area. */ public static final int NORTHEAST = 12; /** * Put the component on the right side of its display area, * centered vertically. */ public static final int EAST = 13; /** * Put the component at the bottom-right corner of its display area. */ public static final int SOUTHEAST = 14; /** * Put the component at the bottom of its display area, centered * horizontally. */ public static final int SOUTH = 15; /** * Put the component at the bottom-left corner of its display area. */ public static final int SOUTHWEST = 16; /** * Put the component on the left side of its display area, * centered vertically. */ public static final int WEST = 17; /** * Put the component at the top-left corner of its display area. */ public static final int NORTHWEST = 18; /** * Place the component centered along the edge of its display area * associated with the start of a page for the current * {@code ComponentOrientation}. Equal to NORTH for horizontal * orientations. */ public static final int PAGE_START = 19; /** * Place the component centered along the edge of its display area * associated with the end of a page for the current * {@code ComponentOrientation}. Equal to SOUTH for horizontal * orientations. */ public static final int PAGE_END = 20; /** * Place the component centered along the edge of its display area where * lines of text would normally begin for the current * {@code ComponentOrientation}. Equal to WEST for horizontal, * left-to-right orientations and EAST for horizontal, right-to-left * orientations. */ public static final int LINE_START = 21; /** * Place the component centered along the edge of its display area where * lines of text would normally end for the current * {@code ComponentOrientation}. Equal to EAST for horizontal, * left-to-right orientations and WEST for horizontal, right-to-left * orientations. */ public static final int LINE_END = 22; /** * Place the component in the corner of its display area where * the first line of text on a page would normally begin for the current * {@code ComponentOrientation}. Equal to NORTHWEST for horizontal, * left-to-right orientations and NORTHEAST for horizontal, right-to-left * orientations. */ public static final int FIRST_LINE_START = 23; /** * Place the component in the corner of its display area where * the first line of text on a page would normally end for the current * {@code ComponentOrientation}. Equal to NORTHEAST for horizontal, * left-to-right orientations and NORTHWEST for horizontal, right-to-left * orientations. */ public static final int FIRST_LINE_END = 24; /** * Place the component in the corner of its display area where * the last line of text on a page would normally start for the current * {@code ComponentOrientation}. Equal to SOUTHWEST for horizontal, * left-to-right orientations and SOUTHEAST for horizontal, right-to-left * orientations. */ public static final int LAST_LINE_START = 25; /** * Place the component in the corner of its display area where * the last line of text on a page would normally end for the current * {@code ComponentOrientation}. Equal to SOUTHEAST for horizontal, * left-to-right orientations and SOUTHWEST for horizontal, right-to-left * orientations. */ public static final int LAST_LINE_END = 26; /** * Possible value for the {@code anchor} field. Specifies * that the component should be horizontally centered and * vertically aligned along the baseline of the prevailing row. * If the component does not have a baseline it will be vertically * centered. * * @since 1.6 */ public static final int BASELINE = 0x100; /** * Possible value for the {@code anchor} field. Specifies * that the component should be horizontally placed along the * leading edge. For components with a left-to-right orientation, * the leading edge is the left edge. Vertically the component is * aligned along the baseline of the prevailing row. If the * component does not have a baseline it will be vertically * centered. * * @since 1.6 */ public static final int BASELINE_LEADING = 0x200; /** * Possible value for the {@code anchor} field. Specifies * that the component should be horizontally placed along the * trailing edge. For components with a left-to-right * orientation, the trailing edge is the right edge. Vertically * the component is aligned along the baseline of the prevailing * row. If the component does not have a baseline it will be * vertically centered. * * @since 1.6 */ public static final int BASELINE_TRAILING = 0x300; /** * Possible value for the {@code anchor} field. Specifies * that the component should be horizontally centered. Vertically * the component is positioned so that its bottom edge touches * the baseline of the starting row. If the starting row does not * have a baseline it will be vertically centered. * * @since 1.6 */ public static final int ABOVE_BASELINE = 0x400; /** * Possible value for the {@code anchor} field. Specifies * that the component should be horizontally placed along the * leading edge. For components with a left-to-right orientation, * the leading edge is the left edge. Vertically the component is * positioned so that its bottom edge touches the baseline of the * starting row. If the starting row does not have a baseline it * will be vertically centered. * * @since 1.6 */ public static final int ABOVE_BASELINE_LEADING = 0x500; /** * Possible value for the {@code anchor} field. Specifies * that the component should be horizontally placed along the * trailing edge. For components with a left-to-right * orientation, the trailing edge is the right edge. Vertically * the component is positioned so that its bottom edge touches * the baseline of the starting row. If the starting row does not * have a baseline it will be vertically centered. * * @since 1.6 */ public static final int ABOVE_BASELINE_TRAILING = 0x600; /** * Possible value for the {@code anchor} field. Specifies * that the component should be horizontally centered. Vertically * the component is positioned so that its top edge touches the * baseline of the starting row. If the starting row does not * have a baseline it will be vertically centered. * * @since 1.6 */ public static final int BELOW_BASELINE = 0x700; /** * Possible value for the {@code anchor} field. Specifies * that the component should be horizontally placed along the * leading edge. For components with a left-to-right orientation, * the leading edge is the left edge. Vertically the component is * positioned so that its top edge touches the baseline of the * starting row. If the starting row does not have a baseline it * will be vertically centered. * * @since 1.6 */ public static final int BELOW_BASELINE_LEADING = 0x800; /** * Possible value for the {@code anchor} field. Specifies * that the component should be horizontally placed along the * trailing edge. For components with a left-to-right * orientation, the trailing edge is the right edge. Vertically * the component is positioned so that its top edge touches the * baseline of the starting row. If the starting row does not * have a baseline it will be vertically centered. * * @since 1.6 */ public static final int BELOW_BASELINE_TRAILING = 0x900; /** * Specifies the cell containing the leading edge of the component's * display area, where the first cell in a row has {@code gridx=0}. * The leading edge of a component's display area is its left edge for * a horizontal, left-to-right container and its right edge for a * horizontal, right-to-left container. * The value * {@code RELATIVE} specifies that the component be placed * immediately following the component that was added to the container * just before this component was added. * <p> * The default value is {@code RELATIVE}. * {@code gridx} should be a non-negative value. * @serial * @see #clone() * @see java.awt.GridBagConstraints#gridy * @see java.awt.ComponentOrientation */ public int gridx; /** * Specifies the cell at the top of the component's display area, * where the topmost cell has {@code gridy=0}. The value * {@code RELATIVE} specifies that the component be placed just * below the component that was added to the container just before * this component was added. * <p> * The default value is {@code RELATIVE}. * {@code gridy} should be a non-negative value. * @serial * @see #clone() * @see java.awt.GridBagConstraints#gridx */ public int gridy; /** * Specifies the number of cells in a row for the component's * display area. * <p> * Use {@code REMAINDER} to specify that the component's * display area will be from {@code gridx} to the last * cell in the row. * Use {@code RELATIVE} to specify that the component's * display area will be from {@code gridx} to the next * to the last one in its row. * <p> * {@code gridwidth} should be non-negative and the default * value is 1. * @serial * @see #clone() * @see java.awt.GridBagConstraints#gridheight */ public int gridwidth; /** * Specifies the number of cells in a column for the component's * display area. * <p> * Use {@code REMAINDER} to specify that the component's * display area will be from {@code gridy} to the last * cell in the column. * Use {@code RELATIVE} to specify that the component's * display area will be from {@code gridy} to the next * to the last one in its column. * <p> * {@code gridheight} should be a non-negative value and the * default value is 1. * @serial * @see #clone() * @see java.awt.GridBagConstraints#gridwidth */ public int gridheight; /** * Specifies how to distribute extra horizontal space. * <p> * The grid bag layout manager calculates the weight of a column to * be the maximum {@code weightx} of all the components in a * column. If the resulting layout is smaller horizontally than the area * it needs to fill, the extra space is distributed to each column in * proportion to its weight. A column that has a weight of zero receives * no extra space. * <p> * If all the weights are zero, all the extra space appears between * the grids of the cell and the left and right edges. * <p> * The default value of this field is {@code 0}. * {@code weightx} should be a non-negative value. * @serial * @see #clone() * @see java.awt.GridBagConstraints#weighty */ public double weightx; /** * Specifies how to distribute extra vertical space. * <p> * The grid bag layout manager calculates the weight of a row to be * the maximum {@code weighty} of all the components in a row. * If the resulting layout is smaller vertically than the area it * needs to fill, the extra space is distributed to each row in * proportion to its weight. A row that has a weight of zero receives no * extra space. * <p> * If all the weights are zero, all the extra space appears between * the grids of the cell and the top and bottom edges. * <p> * The default value of this field is {@code 0}. * {@code weighty} should be a non-negative value. * @serial * @see #clone() * @see java.awt.GridBagConstraints#weightx */ public double weighty; /** * This field is used when the component is smaller than its * display area. It determines where, within the display area, to * place the component. * <p> There are three kinds of possible values: orientation * relative, baseline relative and absolute. Orientation relative * values are interpreted relative to the container's component * orientation property, baseline relative values are interpreted * relative to the baseline and absolute values are not. The * absolute values are: * {@code CENTER}, {@code NORTH}, {@code NORTHEAST}, * {@code EAST}, {@code SOUTHEAST}, {@code SOUTH}, * {@code SOUTHWEST}, {@code WEST}, and {@code NORTHWEST}. * The orientation relative values are: {@code PAGE_START}, * {@code PAGE_END}, * {@code LINE_START}, {@code LINE_END}, * {@code FIRST_LINE_START}, {@code FIRST_LINE_END}, * {@code LAST_LINE_START} and {@code LAST_LINE_END}. The * baseline relative values are: * {@code BASELINE}, {@code BASELINE_LEADING}, * {@code BASELINE_TRAILING}, * {@code ABOVE_BASELINE}, {@code ABOVE_BASELINE_LEADING}, * {@code ABOVE_BASELINE_TRAILING}, * {@code BELOW_BASELINE}, {@code BELOW_BASELINE_LEADING}, * and {@code BELOW_BASELINE_TRAILING}. * The default value is {@code CENTER}. * @serial * @see #clone() * @see java.awt.ComponentOrientation */ public int anchor; /** * This field is used when the component's display area is larger * than the component's requested size. It determines whether to * resize the component, and if so, how. * <p> * The following values are valid for {@code fill}: * * <ul> * <li> * {@code NONE}: Do not resize the component. * <li> * {@code HORIZONTAL}: Make the component wide enough to fill * its display area horizontally, but do not change its height. * <li> * {@code VERTICAL}: Make the component tall enough to fill its * display area vertically, but do not change its width. * <li> * {@code BOTH}: Make the component fill its display area * entirely. * </ul> * <p> * The default value is {@code NONE}. * @serial * @see #clone() */ public int fill; /** * This field specifies the external padding of the component, the * minimum amount of space between the component and the edges of its * display area. * <p> * The default value is {@code new Insets(0, 0, 0, 0)}. * @serial * @see #clone() */ public Insets insets; /** * This field specifies the internal padding of the component, how much * space to add to the minimum width of the component. The width of * the component is at least its minimum width plus * {@code ipadx} pixels. * <p> * The default value is {@code 0}. * @serial * @see #clone() * @see java.awt.GridBagConstraints#ipady */ public int ipadx; /** * This field specifies the internal padding, that is, how much * space to add to the minimum height of the component. The height of * the component is at least its minimum height plus * {@code ipady} pixels. * <p> * The default value is 0. * @serial * @see #clone() * @see java.awt.GridBagConstraints#ipadx */ public int ipady; /** * Temporary place holder for the x coordinate. * @serial */ int tempX; /** * Temporary place holder for the y coordinate. * @serial */ int tempY; /** * Temporary place holder for the Width of the component. * @serial */ int tempWidth; /** * Temporary place holder for the Height of the component. * @serial */ int tempHeight; /** * The minimum width of the component. It is used to calculate * {@code ipady}, where the default will be 0. * @serial * @see #ipady */ int minWidth; /** * The minimum height of the component. It is used to calculate * {@code ipadx}, where the default will be 0. * @serial * @see #ipadx */ int minHeight; // The following fields are only used if the anchor is // one of BASELINE, BASELINE_LEADING or BASELINE_TRAILING. // ascent and descent include the insets and ipady values. transient int ascent; transient int descent; transient Component.BaselineResizeBehavior baselineResizeBehavior; // The following two fields are used if the baseline type is // CENTER_OFFSET. // centerPadding is either 0 or 1 and indicates if // the height needs to be padded by one when calculating where the // baseline lands transient int centerPadding; // Where the baseline lands relative to the center of the component. transient int centerOffset; /* * JDK 1.1 serialVersionUID */ private static final long serialVersionUID = -1000070633030801713L; /** * Creates a {@code GridBagConstraint} object with * all of its fields set to their default value. */ public GridBagConstraints() { gridx = RELATIVE; gridy = RELATIVE; gridwidth = 1; gridheight = 1; weightx = 0; weighty = 0; anchor = CENTER; fill = NONE; insets = new Insets(0, 0, 0, 0); ipadx = 0; ipady = 0; } /** * Creates a {@code GridBagConstraints} object with * all of its fields set to the passed-in arguments. * * Note: Because the use of this constructor hinders readability * of source code, this constructor should only be used by * automatic source code generation tools. * * @param gridx The initial gridx value. * @param gridy The initial gridy value. * @param gridwidth The initial gridwidth value. * @param gridheight The initial gridheight value. * @param weightx The initial weightx value. * @param weighty The initial weighty value. * @param anchor The initial anchor value. * @param fill The initial fill value. * @param insets The initial insets value. * @param ipadx The initial ipadx value. * @param ipady The initial ipady value. * * @see java.awt.GridBagConstraints#gridx * @see java.awt.GridBagConstraints#gridy * @see java.awt.GridBagConstraints#gridwidth * @see java.awt.GridBagConstraints#gridheight * @see java.awt.GridBagConstraints#weightx * @see java.awt.GridBagConstraints#weighty * @see java.awt.GridBagConstraints#anchor * @see java.awt.GridBagConstraints#fill * @see java.awt.GridBagConstraints#insets * @see java.awt.GridBagConstraints#ipadx * @see java.awt.GridBagConstraints#ipady * * @since 1.2 */ public GridBagConstraints(int gridx, int gridy, int gridwidth, int gridheight, double weightx, double weighty, int anchor, int fill, Insets insets, int ipadx, int ipady) { this.gridx = gridx; this.gridy = gridy; this.gridwidth = gridwidth; this.gridheight = gridheight; this.fill = fill; this.ipadx = ipadx; this.ipady = ipady; this.insets = insets; this.anchor = anchor; this.weightx = weightx; this.weighty = weighty; } /** * Creates a copy of this grid bag constraint. * @return a copy of this grid bag constraint */ public Object clone() { try { GridBagConstraints c = (GridBagConstraints) super.clone(); c.insets = (Insets) insets.clone(); return c; } catch (CloneNotSupportedException e) { // this shouldn't happen, since we are Cloneable throw new InternalError(e); } } boolean isVerticallyResizable() { return (fill == BOTH || fill == VERTICAL); } }