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Commit 463b4820 authored by Roozbeh Pournader's avatar Roozbeh Pournader
Browse files

Support all RTL scripts in getLayoutDirectionFromLocale(). 

Previously, only the languages written in Arabic and Hebrew were
considered right-to-left. Now, ICU is used to return the direction
of the language, which not only support other right-to-left scripts
(such as Thaana), but also has better logic to determine the
direction of the locale and uses caching to improve the speed.

Bug: 22559274
Change-Id: I760be7984a9b35ea77d59ca84a220798e205af36
parent 6e02fa01

core/java/android/text/TextUtils.java

+7 −42
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ package android.text; 


import android.annotation.Nullable;

import android.content.res.Resources;

import android.icu.util.ULocale;

import android.os.Parcel;

import android.os.Parcelable;

import android.os.SystemProperties;
@@ -1754,47 +1755,14 @@ public class TextUtils { 
     * Be careful: this code will need to be updated when vertical scripts will be supported

     */

    public static int getLayoutDirectionFromLocale(Locale locale) {

        if (locale != null && !locale.equals(Locale.ROOT)) {

            final String scriptSubtag = ICU.addLikelySubtags(locale).getScript();

            if (scriptSubtag == null) return getLayoutDirectionFromFirstChar(locale);



            if (scriptSubtag.equalsIgnoreCase(ARAB_SCRIPT_SUBTAG) ||

                    scriptSubtag.equalsIgnoreCase(HEBR_SCRIPT_SUBTAG)) {

                return View.LAYOUT_DIRECTION_RTL;

            }

        }

        // If forcing into RTL layout mode, return RTL as default, else LTR

        return SystemProperties.getBoolean(Settings.Global.DEVELOPMENT_FORCE_RTL, false)

        return ((locale != null && !locale.equals(Locale.ROOT)

                        && ULocale.forLocale(locale).isRightToLeft())

                // If forcing into RTL layout mode, return RTL as default

                || SystemProperties.getBoolean(Settings.Global.DEVELOPMENT_FORCE_RTL, false))

            ? View.LAYOUT_DIRECTION_RTL

            : View.LAYOUT_DIRECTION_LTR;

    }



    /**

     * Fallback algorithm to detect the locale direction. Rely on the fist char of the

     * localized locale name. This will not work if the localized locale name is in English

     * (this is the case for ICU 4.4 and "Urdu" script)

     *

     * @param locale

     * @return the layout direction. This may be one of:

     * {@link View#LAYOUT_DIRECTION_LTR} or

     * {@link View#LAYOUT_DIRECTION_RTL}.

     *

     * Be careful: this code will need to be updated when vertical scripts will be supported

     *

     * @hide

     */

    private static int getLayoutDirectionFromFirstChar(Locale locale) {

        switch(Character.getDirectionality(locale.getDisplayName(locale).charAt(0))) {

            case Character.DIRECTIONALITY_RIGHT_TO_LEFT:

            case Character.DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC:

                return View.LAYOUT_DIRECTION_RTL;



            case Character.DIRECTIONALITY_LEFT_TO_RIGHT:

            default:

                return View.LAYOUT_DIRECTION_LTR;

        }

    }



    /**

     * Return localized string representing the given number of selected items.

     *
@@ -1811,7 +1779,4 @@ public class TextUtils { 
    private static String[] EMPTY_STRING_ARRAY = new String[]{};



    private static final char ZWNBS_CHAR = '\uFEFF';



    private static String ARAB_SCRIPT_SUBTAG = "Arab";

    private static String HEBR_SCRIPT_SUBTAG = "Hebr";

}

core/tests/coretests/src/android/text/TextUtilsTest.java

+44 −0
Original line number Diff line number Diff line
@@ -25,9 +25,11 @@ import android.test.suitebuilder.annotation.SmallTest; 
import android.text.style.StyleSpan;

import android.text.util.Rfc822Token;

import android.text.util.Rfc822Tokenizer;

import android.view.View;



import java.util.ArrayList;

import java.util.List;

import java.util.Locale;



import junit.framework.TestCase;
@@ -519,4 +521,46 @@ public class TextUtilsTest extends TestCase { 
            return 0;

        }

    }



    @SmallTest

    public void testGetLayoutDirectionFromLocale() {

        assertEquals(View.LAYOUT_DIRECTION_LTR, TextUtils.getLayoutDirectionFromLocale(null));

        assertEquals(View.LAYOUT_DIRECTION_LTR,

                TextUtils.getLayoutDirectionFromLocale(Locale.ROOT));

        assertEquals(View.LAYOUT_DIRECTION_LTR,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("en")));

        assertEquals(View.LAYOUT_DIRECTION_LTR,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("en-US")));

        assertEquals(View.LAYOUT_DIRECTION_LTR,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("az")));

        assertEquals(View.LAYOUT_DIRECTION_LTR,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("az-AZ")));

        assertEquals(View.LAYOUT_DIRECTION_LTR,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("az-Latn")));

        assertEquals(View.LAYOUT_DIRECTION_LTR,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("en-EG")));

        assertEquals(View.LAYOUT_DIRECTION_LTR,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("ar-Latn")));



        assertEquals(View.LAYOUT_DIRECTION_RTL,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("ar")));

        assertEquals(View.LAYOUT_DIRECTION_RTL,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("fa")));

        assertEquals(View.LAYOUT_DIRECTION_RTL,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("he")));

        assertEquals(View.LAYOUT_DIRECTION_RTL,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("iw")));

        assertEquals(View.LAYOUT_DIRECTION_RTL,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("ur")));

        assertEquals(View.LAYOUT_DIRECTION_RTL,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("dv")));

        assertEquals(View.LAYOUT_DIRECTION_RTL,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("az-Arab")));

        assertEquals(View.LAYOUT_DIRECTION_RTL,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("az-IR")));

        assertEquals(View.LAYOUT_DIRECTION_RTL,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("fa-US")));

        assertEquals(View.LAYOUT_DIRECTION_RTL,

                TextUtils.getLayoutDirectionFromLocale(Locale.forLanguageTag("tr-Arab")));

    }

}