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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.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 /**
     25  * Highlights the text in a text field.
     26  */
     27 public class TextHighlighter {
     28     private final String TAG = TextHighlighter.class.getSimpleName();
     29     private final static boolean DEBUG = false;
     30 
     31     private int mTextStyle;
     32 
     33     private CharacterStyle mTextStyleSpan;
     34 
     35     public TextHighlighter(int textStyle) {
     36         mTextStyle = textStyle;
     37         mTextStyleSpan = getStyleSpan();
     38     }
     39 
     40     /**
     41      * Sets the text on the given text view, highlighting the word that matches the given prefix.
     42      *
     43      * @param view the view on which to set the text
     44      * @param text the string to use as the text
     45      * @param prefix the prefix to look for
     46      */
     47     public void setPrefixText(TextView view, String text, String prefix) {
     48         view.setText(applyPrefixHighlight(text, prefix));
     49     }
     50 
     51     private CharacterStyle getStyleSpan() {
     52         return new StyleSpan(mTextStyle);
     53     }
     54 
     55     /**
     56      * Applies highlight span to the text.
     57      * @param text Text sequence to be highlighted.
     58      * @param start Start position of the highlight sequence.
     59      * @param end End position of the highlight sequence.
     60      */
     61     public void applyMaskingHighlight(SpannableString text, int start, int end) {
     62         /** Sets text color of the masked locations to be highlighted. */
     63         text.setSpan(getStyleSpan(), start, end, 0);
     64     }
     65 
     66     /**
     67      * Returns a CharSequence which highlights the given prefix if found in the given text.
     68      *
     69      * @param text the text to which to apply the highlight
     70      * @param prefix the prefix to look for
     71      */
     72     public CharSequence applyPrefixHighlight(CharSequence text, String prefix) {
     73         if (prefix == null) {
     74             return text;
     75         }
     76 
     77         // Skip non-word characters at the beginning of prefix.
     78         int prefixStart = 0;
     79         while (prefixStart < prefix.length() &&
     80                 !Character.isLetterOrDigit(prefix.charAt(prefixStart))) {
     81             prefixStart++;
     82         }
     83         final String trimmedPrefix = prefix.substring(prefixStart);
     84 
     85         int index = FormatUtils.indexOfWordPrefix(text, trimmedPrefix);
     86         if (index != -1) {
     87             final SpannableString result = new SpannableString(text);
     88             result.setSpan(mTextStyleSpan, index, index + trimmedPrefix.length(), 0 /* flags */);
     89             return result;
     90         } else {
     91             return text;
     92         }
     93     }
     94 }
     95