001 /* ComponentOrientation.java -- describes a component's orientation
002 Copyright (C) 2000, 2001, 2002 Free Software Foundation
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
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012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
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019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.awt;
040
041 import java.io.Serializable;
042 import java.util.Locale;
043 import java.util.MissingResourceException;
044 import 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 */
074 public 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