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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 com.android.contacts.common.format;
     18 
     19 import android.text.SpannableString;
     20 import android.text.style.CharacterStyle;
     21 import android.text.style.StyleSpan;
     22 import android.widget.TextView;
     23 
     24 /** Highlights the text in a text field. */
     25 public class TextHighlighter {
     26 
     27   private int mTextStyle;
     28 
     29   private CharacterStyle mTextStyleSpan;
     30 
     31   public TextHighlighter(int textStyle) {
     32     mTextStyle = textStyle;
     33     mTextStyleSpan = getStyleSpan();
     34   }
     35 
     36   /**
     37    * Sets the text on the given text view, highlighting the word that matches the given prefix.
     38    *
     39    * @param view the view on which to set the text
     40    * @param text the string to use as the text
     41    * @param prefix the prefix to look for
     42    */
     43   public void setPrefixText(TextView view, String text, String prefix) {
     44     view.setText(applyPrefixHighlight(text, prefix));
     45   }
     46 
     47   private CharacterStyle getStyleSpan() {
     48     return new StyleSpan(mTextStyle);
     49   }
     50 
     51   /**
     52    * Applies highlight span to the text.
     53    *
     54    * @param text Text sequence to be highlighted.
     55    * @param start Start position of the highlight sequence.
     56    * @param end End position of the highlight sequence.
     57    */
     58   public void applyMaskingHighlight(SpannableString text, int start, int end) {
     59     /** Sets text color of the masked locations to be highlighted. */
     60     text.setSpan(getStyleSpan(), start, end, 0);
     61   }
     62 
     63   /**
     64    * Returns a CharSequence which highlights the given prefix if found in the given text.
     65    *
     66    * @param text the text to which to apply the highlight
     67    * @param prefix the prefix to look for
     68    */
     69   public CharSequence applyPrefixHighlight(CharSequence text, String prefix) {
     70     if (prefix == null) {
     71       return text;
     72     }
     73 
     74     // Skip non-word characters at the beginning of prefix.
     75     int prefixStart = 0;
     76     while (prefixStart < prefix.length()
     77         && !Character.isLetterOrDigit(prefix.charAt(prefixStart))) {
     78       prefixStart++;
     79     }
     80     final String trimmedPrefix = prefix.substring(prefixStart);
     81 
     82     int index = indexOfWordPrefix(text, trimmedPrefix);
     83     if (index != -1) {
     84       final SpannableString result = new SpannableString(text);
     85       result.setSpan(mTextStyleSpan, index, index + trimmedPrefix.length(), 0 /* flags */);
     86       return result;
     87     } else {
     88       return text;
     89     }
     90   }
     91 
     92   /**
     93    * Finds the index of the first word that starts with the given prefix.
     94    *
     95    * <p>If not found, returns -1.
     96    *
     97    * @param text the text in which to search for the prefix
     98    * @param prefix the text to find, in upper case letters
     99    */
    100   public static int indexOfWordPrefix(CharSequence text, String prefix) {
    101     if (prefix == null || text == null) {
    102       return -1;
    103     }
    104 
    105     int textLength = text.length();
    106     int prefixLength = prefix.length();
    107 
    108     if (prefixLength == 0 || textLength < prefixLength) {
    109       return -1;
    110     }
    111 
    112     int i = 0;
    113     while (i < textLength) {
    114       // Skip non-word characters
    115       while (i < textLength && !Character.isLetterOrDigit(text.charAt(i))) {
    116         i++;
    117       }
    118 
    119       if (i + prefixLength > textLength) {
    120         return -1;
    121       }
    122 
    123       // Compare the prefixes
    124       int j;
    125       for (j = 0; j < prefixLength; j++) {
    126         if (Character.toUpperCase(text.charAt(i + j)) != prefix.charAt(j)) {
    127           break;
    128         }
    129       }
    130       if (j == prefixLength) {
    131         return i;
    132       }
    133 
    134       // Skip this word
    135       while (i < textLength && Character.isLetterOrDigit(text.charAt(i))) {
    136         i++;
    137       }
    138     }
    139 
    140     return -1;
    141   }
    142 }
    143