Example usage for android.text TextDirectionHeuristic isRtl

Introduction

In this page you can find the example usage for android.text TextDirectionHeuristic isRtl.

Prototype

boolean isRtl(CharSequence cs, int start, int count);

Source Link

Document

Guess if a CharSequence is in the RTL direction or not.

Usage

From source file:android.text.BidiFormatter.java

/**
 * Returns a Unicode bidi mark matching the context directionality (LRM or RLM) if either the
 * overall or the exit directionality of a given string is opposite to the context directionality.
 * Putting this after the string (including its directionality declaration wrapping) prevents it
 * from "sticking" to other opposite-directionality text or a number appearing after it inline
 * with only neutral content in between. Otherwise returns the empty string. While the exit
 * directionality is determined by scanning the end of the string, the overall directionality is
 * given explicitly by a heuristic to estimate the {@code str}'s directionality.
 *
 * @param str String after which the mark may need to appear.
 * @param heuristic The text direction heuristic that will be used to estimate the {@code str}'s
 *                  directionality.//from   www .  jav  a  2  s. co  m
 * @return LRM for RTL text in LTR context; RLM for LTR text in RTL context;
 *     else, the empty string.
 *
 * @hide
 */
public String markAfter(String str, TextDirectionHeuristic heuristic) {
    final boolean isRtl = heuristic.isRtl(str, 0, str.length());
    // getExitDir() is called only if needed (short-circuit).
    if (!mIsRtlContext && (isRtl || getExitDir(str) == DIR_RTL)) {
        return LRM_STRING;
    }
    if (mIsRtlContext && (!isRtl || getExitDir(str) == DIR_LTR)) {
        return RLM_STRING;
    }
    return EMPTY_STRING;
}

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From source file:android.text.BidiFormatter.java

/**
 * Returns a Unicode bidi mark matching the context directionality (LRM or RLM) if either the
 * overall or the entry directionality of a given string is opposite to the context
 * directionality. Putting this before the string (including its directionality declaration
 * wrapping) prevents it from "sticking" to other opposite-directionality text appearing before
 * it inline with only neutral content in between. Otherwise returns the empty string. While the
 * entry directionality is determined by scanning the beginning of the string, the overall
 * directionality is given explicitly by a heuristic to estimate the {@code str}'s directionality.
 *
 * @param str String before which the mark may need to appear.
 * @param heuristic The text direction heuristic that will be used to estimate the {@code str}'s
 *                  directionality./*from   ww  w. jav a2  s  .  c o  m*/
 * @return LRM for RTL text in LTR context; RLM for LTR text in RTL context;
 *     else, the empty string.
 *
 * @hide
 */
public String markBefore(String str, TextDirectionHeuristic heuristic) {
    final boolean isRtl = heuristic.isRtl(str, 0, str.length());
    // getEntryDir() is called only if needed (short-circuit).
    if (!mIsRtlContext && (isRtl || getEntryDir(str) == DIR_RTL)) {
        return LRM_STRING;
    }
    if (mIsRtlContext && (!isRtl || getEntryDir(str) == DIR_LTR)) {
        return RLM_STRING;
    }
    return EMPTY_STRING;
}

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From source file:android.text.BidiFormatter.java

/**
 * Formats a string of given directionality for use in plain-text output of the context
 * directionality, so an opposite-directionality string is neither garbled nor garbles its
 * surroundings. This makes use of Unicode bidi formatting characters.
 * <p>//from  w w w  .j  ava2  s  . c o m
 * The algorithm: In case the given directionality doesn't match the context directionality, wraps
 * the string with Unicode bidi formatting characters: RLE+{@code str}+PDF for RTL text, or
 * LRE+{@code str}+PDF for LTR text.
 * <p>
 * If {@code isolate}, directionally isolates the string so that it does not garble its
 * surroundings. Currently, this is done by "resetting" the directionality after the string by
 * appending a trailing Unicode bidi mark matching the context directionality (LRM or RLM) when
 * either the overall directionality or the exit directionality of the string is opposite to that
 * of the context. If the formatter was built using {@link Builder#stereoReset(boolean)} and
 * passing "true" as an argument, also prepends a Unicode bidi mark matching the context
 * directionality when either the overall directionality or the entry directionality of the
 * string is opposite to that of the context. Note that as opposed to the overall
 * directionality, the entry and exit directionalities are determined from the string itself.
 * <p>
 * Does *not* do HTML-escaping.
 *
 * @param str The input string.
 * @param heuristic The algorithm to be used to estimate the string's overall direction.
 *        See {@link TextDirectionHeuristics} for pre-defined heuristics.
 * @param isolate Whether to directionally isolate the string to prevent it from garbling the
 *     content around it
 * @return Input string after applying the above processing.
 */
public String unicodeWrap(String str, TextDirectionHeuristic heuristic, boolean isolate) {
    final boolean isRtl = heuristic.isRtl(str, 0, str.length());
    StringBuilder result = new StringBuilder();
    if (getStereoReset() && isolate) {
        result.append(markBefore(str, isRtl ? TextDirectionHeuristics.RTL : TextDirectionHeuristics.LTR));
    }
    if (isRtl != mIsRtlContext) {
        result.append(isRtl ? RLE : LRE);
        result.append(str);
        result.append(PDF);
    } else {
        result.append(str);
    }
    if (isolate) {
        result.append(markAfter(str, isRtl ? TextDirectionHeuristics.RTL : TextDirectionHeuristics.LTR));
    }
    return result.toString();
}

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