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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.util;
     18 
     19 import java.util.Locale;
     20 
     21 import libcore.icu.ICU;
     22 
     23 /**
     24  * Various utilities for Locales
     25  *
     26  * @hide
     27  */
     28 public class LocaleUtil {
     29 
     30     private LocaleUtil() { /* cannot be instantiated */ }
     31 
     32     /**
     33      * @hide Do not use. Implementation not finished.
     34      */
     35     public static final int TEXT_LAYOUT_DIRECTION_LTR_DO_NOT_USE = 0;
     36 
     37     /**
     38      * @hide Do not use. Implementation not finished.
     39      */
     40     public static final int TEXT_LAYOUT_DIRECTION_RTL_DO_NOT_USE = 1;
     41 
     42     private static final char UNDERSCORE_CHAR = '_';
     43 
     44     private static String ARAB_SCRIPT_SUBTAG = "Arab";
     45     private static String HEBR_SCRIPT_SUBTAG = "Hebr";
     46 
     47     /**
     48      * Return the layout direction for a given Locale
     49      *
     50      * @param locale the Locale for which we want the layout direction. Can be null.
     51      * @return the layout direction. This may be one of:
     52      * {@link #TEXT_LAYOUT_DIRECTION_LTR_DO_NOT_USE} or
     53      * {@link #TEXT_LAYOUT_DIRECTION_RTL_DO_NOT_USE}.
     54      *
     55      * Be careful: this code will need to be changed when vertical scripts will be supported
     56      *
     57      * @hide
     58      */
     59     public static int getLayoutDirectionFromLocale(Locale locale) {
     60         if (locale != null && !locale.equals(Locale.ROOT)) {
     61             final String scriptSubtag = ICU.getScript(ICU.addLikelySubtags(locale.toString()));
     62             if (scriptSubtag == null) return getLayoutDirectionFromFirstChar(locale);
     63 
     64             if (scriptSubtag.equalsIgnoreCase(ARAB_SCRIPT_SUBTAG) ||
     65                     scriptSubtag.equalsIgnoreCase(HEBR_SCRIPT_SUBTAG)) {
     66                 return TEXT_LAYOUT_DIRECTION_RTL_DO_NOT_USE;
     67             }
     68         }
     69 
     70         return TEXT_LAYOUT_DIRECTION_LTR_DO_NOT_USE;
     71     }
     72 
     73     /**
     74      * Fallback algorithm to detect the locale direction. Rely on the fist char of the
     75      * localized locale name. This will not work if the localized locale name is in English
     76      * (this is the case for ICU 4.4 and "Urdu" script)
     77      *
     78      * @param locale
     79      * @return the layout direction. This may be one of:
     80      * {@link #TEXT_LAYOUT_DIRECTION_LTR_DO_NOT_USE} or
     81      * {@link #TEXT_LAYOUT_DIRECTION_RTL_DO_NOT_USE}.
     82      *
     83      * Be careful: this code will need to be changed when vertical scripts will be supported
     84      *
     85      * @hide
     86      */
     87     private static int getLayoutDirectionFromFirstChar(Locale locale) {
     88         switch(Character.getDirectionality(locale.getDisplayName(locale).charAt(0))) {
     89             case Character.DIRECTIONALITY_RIGHT_TO_LEFT:
     90             case Character.DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC:
     91                 return TEXT_LAYOUT_DIRECTION_RTL_DO_NOT_USE;
     92 
     93             case Character.DIRECTIONALITY_LEFT_TO_RIGHT:
     94             default:
     95                 return TEXT_LAYOUT_DIRECTION_LTR_DO_NOT_USE;
     96         }
     97     }
     98 }
     99