001/* ComponentOrientation.java -- describes a component's orientation 002 Copyright (C) 2000, 2001, 2002 Free Software Foundation 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. */ 037 038 039package java.awt; 040 041import java.io.Serializable; 042import java.util.Locale; 043import java.util.MissingResourceException; 044import java.util.ResourceBundle; 045 046/** 047 * This class is used to differentiate different orientations for text layout. 048 * It controls whether text flows left-to-right or right-to-left, and whether 049 * lines are horizontal or vertical, as in this table:<br> 050 * <pre> 051 * LT RT TL TR 052 * A B C C B A A D G G D A 053 * D E F F E D B E H H E B 054 * G H I I H G C F I I F C 055 * </pre> 056 * <b>LT</b> languages are most common (left-to-right lines, top-to-bottom). 057 * This includes Western European languages, and optionally includes Japanese, 058 * Chinese, and Korean. <b>RT</b> languages (right-to-left lines, 059 * top-to-bottom) are mainly middle eastern, such as Hebrew and Arabic. 060 * <b>TR</b> languages flow top-to-bottom in a line, right-to-left, and are 061 * the basis of Japanese, Chinese, and Korean. Finally, <b>TL</b> languages 062 * flow top-to-bottom in a line, left-to-right, as in Mongolian. 063 * 064 * <p>This is a pretty poor excuse for a type-safe enum, since it is not 065 * guaranteed that orientation objects are unique (thanks to serialization), 066 * yet there is no equals() method. You would be wise to compare the output 067 * of isHorizontal() and isLeftToRight() rather than comparing objects with 068 * ==, especially since more constants may be added in the future. 069 * 070 * @author Bryce McKinlay (bryce@albatross.co.nz) 071 * @since 1.0 072 * @status updated to 1.4 073 */ 074public final class ComponentOrientation implements Serializable 075{ 076 /** 077 * Compatible with JDK 1.0+. 078 */ 079 private static final long serialVersionUID = -4113291392143563828L; 080 081 /** Constant for unknown orientation. */ 082 private static final int UNKNOWN_ID = 1; 083 084 /** Constant for horizontal line orientation. */ 085 private static final int HORIZONTAL_ID = 2; 086 087 /** Constant for left-to-right orientation. */ 088 private static final int LEFT_TO_RIGHT_ID = 4; 089 090 /** 091 * Items run left to right, and lines flow top to bottom. Examples: English, 092 * French. 093 */ 094 public static final ComponentOrientation LEFT_TO_RIGHT 095 = new ComponentOrientation(HORIZONTAL_ID | LEFT_TO_RIGHT_ID); 096 097 /** 098 * Items run right to left, and lines flow top to bottom. Examples: Arabic, 099 * Hebrew. 100 */ 101 public static final ComponentOrientation RIGHT_TO_LEFT 102 = new ComponentOrientation(HORIZONTAL_ID); 103 104 /** 105 * The orientation is unknown for the locale. For backwards compatibility, 106 * this behaves like LEFT_TO_RIGHT in the instance methods. 107 */ 108 public static final ComponentOrientation UNKNOWN 109 = new ComponentOrientation(UNKNOWN_ID | HORIZONTAL_ID | LEFT_TO_RIGHT_ID); 110 111 /** 112 * The orientation of this object; bitwise-or of unknown (1), horizontal (2), 113 * and left-to-right (4). 114 * 115 * @serial the orientation 116 */ 117 private final int orientation; 118 119 /** 120 * Construct a given orientation. 121 * 122 * @param orientation the orientation 123 */ 124 private ComponentOrientation(int orientation) 125 { 126 this.orientation = orientation; 127 } 128 129 /** 130 * Returns true if the lines are horizontal, in which case lines flow 131 * top-to-bottom. For example, English, Hebrew. Counterexamples: Japanese, 132 * Chinese, Korean, Mongolian. 133 * 134 * @return true if this orientation has horizontal lines 135 */ 136 public boolean isHorizontal() 137 { 138 return (orientation & HORIZONTAL_ID) != 0; 139 } 140 141 /** 142 * If isHorizontal() returns true, then this determines whether items in 143 * the line flow left-to-right. If isHorizontal() returns false, items in 144 * a line flow top-to-bottom, and this determines if lines flow 145 * left-to-right. 146 * 147 * @return true if this orientation flows left-to-right 148 */ 149 public boolean isLeftToRight() 150 { 151 return (orientation & LEFT_TO_RIGHT_ID) != 0; 152 } 153 154 /** 155 * Gets an orientation appropriate for the locale. 156 * 157 * @param locale the locale 158 * @return the orientation for that locale 159 * @throws NullPointerException if locale is null 160 */ 161 public static ComponentOrientation getOrientation(Locale locale) 162 { 163 // Based on iterating over all languages defined in JDK 1.4, this behavior 164 // matches Sun's. However, it makes me wonder if any non-horizontal 165 // orientations even exist, as it sure contradicts their documentation. 166 String language = locale.getLanguage(); 167 if ("ar".equals(language) || "fa".equals(language) || "iw".equals(language) 168 || "ur".equals(language)) 169 return RIGHT_TO_LEFT; 170 return LEFT_TO_RIGHT; 171 } 172 173 /** 174 * Gets an orientation from a resource bundle. This tries the following: 175 * 176 * <ul> 177 * <li>Use the key "Orientation" to find an instance of ComponentOrientation 178 * in the bundle.</li> 179 * <li>Get the locale of the resource bundle, and get the orientation of 180 * that locale.</li> 181 * <li>Give up and get the orientation of the default locale.</li> 182 * </ul> 183 * 184 * @param bdl the bundle to use 185 * @return the orientation 186 * @throws NullPointerException if bdl is null 187 * @deprecated use {@link #getOrientation(Locale)} instead 188 */ 189 public static ComponentOrientation getOrientation(ResourceBundle bdl) 190 { 191 ComponentOrientation r; 192 try 193 { 194 r = (ComponentOrientation) bdl.getObject("Orientation"); 195 if (r != null) 196 return r; 197 } 198 catch (MissingResourceException ignored) 199 { 200 } 201 catch (ClassCastException ignored) 202 { 203 } 204 try 205 { 206 r = getOrientation(bdl.getLocale()); 207 if (r != null) 208 return r; 209 } 210 catch (Exception ignored) 211 { 212 } 213 return getOrientation(Locale.getDefault()); 214 } 215} // class ComponentOrientation