1 /* EmptyBorder.java -- 2 Copyright (C) 2003 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 39 package javax.swing.border; 40 41 import java.awt.Component; 42 import java.awt.Graphics; 43 import java.awt.Insets; 44 45 46 /** 47 * A border for leaving a specifiable number of pixels empty around 48 * the enclosed component. An EmptyBorder requires some space on each 49 * edge, but does not perform any drawing. 50 * 51 * <p><img src="EmptyBorder-1.png" width="290" height="200" 52 * alt="[An illustration of EmptyBorder]" /> 53 * 54 * @author Sascha Brawer (brawer@dandelis.ch) 55 */ 56 public class EmptyBorder extends AbstractBorder 57 { 58 /** 59 * Determined using the <code>serialver</code> tool 60 * of Apple/Sun JDK 1.3.1 on MacOS X 10.1.5. 61 */ 62 static final long serialVersionUID = -8116076291731988694L; 63 64 65 /** 66 * The number of pixels required at the left edge. 67 */ 68 protected int left; 69 70 71 /** 72 * The number of pixels required at the right edge. 73 */ 74 protected int right; 75 76 77 /** 78 * The number of pixels required at the top edge. 79 */ 80 protected int top; 81 82 83 /** 84 * The number of pixels required at the bottom edge. 85 */ 86 protected int bottom; 87 88 89 /** 90 * Constructs an empty border given the number of pixels required 91 * on each side. 92 * 93 * @param top the number of pixels that the border will need 94 * for its top edge. 95 * 96 * @param left the number of pixels that the border will need 97 * for its left edge. 98 * 99 * @param bottom the number of pixels that the border will need 100 * for its bottom edge. 101 * 102 * @param right the number of pixels that the border will need 103 * for its right edge. 104 */ EmptyBorder(int top, int left, int bottom, int right)105 public EmptyBorder(int top, int left, int bottom, int right) 106 { 107 this.top = top; 108 this.left = left; 109 this.bottom = bottom; 110 this.right = right; 111 } 112 113 114 /** 115 * Constructs an empty border given the number of pixels required 116 * on each side, passed in an Insets object. 117 * 118 * @param borderInsets the Insets for the new border. 119 */ EmptyBorder(Insets borderInsets)120 public EmptyBorder(Insets borderInsets) 121 { 122 this(borderInsets.top, borderInsets.left, 123 borderInsets.bottom, borderInsets.right); 124 } 125 126 127 /** 128 * Performs nothing because an EmptyBorder does not paint any 129 * pixels. While the inherited implementation provided by 130 * {@link AbstractBorder#paintBorder} is a no-op as well, 131 * it is overwritten in order to match the API of the Sun 132 * reference implementation. 133 * 134 * @param c the component whose border is to be painted. 135 * @param g the graphics for painting. 136 * @param x the horizontal position for painting the border. 137 * @param y the vertical position for painting the border. 138 * @param width the width of the available area for painting the border. 139 * @param height the height of the available area for painting the border. 140 */ paintBorder(Component c, Graphics g, int x, int y, int width, int height)141 public void paintBorder(Component c, Graphics g, 142 int x, int y, int width, int height) 143 { 144 // Nothing to do here. 145 } 146 147 148 /** 149 * Measures the width of this border. 150 * 151 * @param c the component whose border is to be measured. 152 * 153 * @return an Insets object whose <code>left</code>, <code>right</code>, 154 * <code>top</code> and <code>bottom</code> fields indicate the 155 * width of the border at the respective edge. 156 * 157 * @see #getBorderInsets(java.awt.Component, java.awt.Insets) 158 */ getBorderInsets(Component c)159 public Insets getBorderInsets(Component c) 160 { 161 return getBorderInsets(c, null); 162 } 163 164 165 /** 166 * Measures the width of this border, storing the results into a 167 * pre-existing Insets object. 168 * 169 * @param insets an Insets object for holding the result values. 170 * After invoking this method, the <code>left</code>, 171 * <code>right</code>, <code>top</code> and 172 * <code>bottom</code> fields indicate the width of the 173 * border at the respective edge. 174 * 175 * @return the same object that was passed for <code>insets</code>. 176 * 177 * @see #getBorderInsets() 178 */ getBorderInsets(Component c, Insets insets)179 public Insets getBorderInsets(Component c, Insets insets) 180 { 181 if (insets == null) 182 insets = new Insets(0, 0, 0, 0); 183 184 insets.left = left; 185 insets.right = right; 186 insets.top = top; 187 insets.bottom = bottom; 188 return insets; 189 } 190 191 192 /** 193 * Measures the width of this border. 194 * 195 * @return an Insets object whose <code>left</code>, <code>right</code>, 196 * <code>top</code> and <code>bottom</code> fields indicate the 197 * width of the border at the respective edge. 198 * 199 * @see #getBorderInsets(java.awt.Component, java.awt.Insets) 200 */ getBorderInsets()201 public Insets getBorderInsets() 202 { 203 return getBorderInsets(null, null); 204 } 205 206 207 /** 208 * Determines whether this border fills every pixel in its area 209 * when painting. Since an empty border does not paint any pixels 210 * whatsoever, the result is <code>false</code>. 211 * 212 * @return <code>false</code>. 213 */ isBorderOpaque()214 public boolean isBorderOpaque() 215 { 216 /* The inherited implementation of AbstractBorder.isBorderOpaque() 217 * would also return false. It is not clear why this is overriden 218 * in the Sun implementation, at least not from just reading the 219 * JavaDoc. 220 */ 221 return false; 222 } 223 } 224