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      1 /*
      2  * Copyright (C) 2010 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.list;
     18 
     19 import android.text.TextUtils;
     20 import android.widget.SectionIndexer;
     21 
     22 import java.util.Arrays;
     23 
     24 /**
     25  * A section indexer that is configured with precomputed section titles and
     26  * their respective counts.
     27  */
     28 public class ContactsSectionIndexer implements SectionIndexer {
     29 
     30     private String[] mSections;
     31     private int[] mPositions;
     32     private int mCount;
     33     private static final String BLANK_HEADER_STRING = " ";
     34 
     35     /**
     36      * Constructor.
     37      *
     38      * @param sections a non-null array
     39      * @param counts a non-null array of the same size as <code>sections</code>
     40      */
     41     public ContactsSectionIndexer(String[] sections, int[] counts) {
     42         if (sections == null || counts == null) {
     43             throw new NullPointerException();
     44         }
     45 
     46         if (sections.length != counts.length) {
     47             throw new IllegalArgumentException(
     48                     "The sections and counts arrays must have the same length");
     49         }
     50 
     51         // TODO process sections/counts based on current locale and/or specific section titles
     52 
     53         this.mSections = sections;
     54         mPositions = new int[counts.length];
     55         int position = 0;
     56         for (int i = 0; i < counts.length; i++) {
     57             if (TextUtils.isEmpty(mSections[i])) {
     58                 mSections[i] = BLANK_HEADER_STRING;
     59             } else if (!mSections[i].equals(BLANK_HEADER_STRING)) {
     60                 mSections[i] = mSections[i].trim();
     61             }
     62 
     63             mPositions[i] = position;
     64             position += counts[i];
     65         }
     66         mCount = position;
     67     }
     68 
     69     public Object[] getSections() {
     70         return mSections;
     71     }
     72 
     73     public int getPositionForSection(int section) {
     74         if (section < 0 || section >= mSections.length) {
     75             return -1;
     76         }
     77 
     78         return mPositions[section];
     79     }
     80 
     81     public int getSectionForPosition(int position) {
     82         if (position < 0 || position >= mCount) {
     83             return -1;
     84         }
     85 
     86         int index = Arrays.binarySearch(mPositions, position);
     87 
     88         /*
     89          * Consider this example: section positions are 0, 3, 5; the supplied
     90          * position is 4. The section corresponding to position 4 starts at
     91          * position 3, so the expected return value is 1. Binary search will not
     92          * find 4 in the array and thus will return -insertPosition-1, i.e. -3.
     93          * To get from that number to the expected value of 1 we need to negate
     94          * and subtract 2.
     95          */
     96         return index >= 0 ? index : -index - 2;
     97     }
     98 
     99     public void setProfileHeader(String header) {
    100         if (mSections != null) {
    101             // Don't do anything if the header is already set properly.
    102             if (mSections.length > 0 && header.equals(mSections[0])) {
    103                 return;
    104             }
    105 
    106             // Since the section indexer isn't aware of the profile at the top, we need to add a
    107             // special section at the top for it and shift everything else down.
    108             String[] tempSections = new String[mSections.length + 1];
    109             int[] tempPositions = new int[mPositions.length + 1];
    110             tempSections[0] = header;
    111             tempPositions[0] = 0;
    112             for (int i = 1; i <= mPositions.length; i++) {
    113                 tempSections[i] = mSections[i - 1];
    114                 tempPositions[i] = mPositions[i - 1] + 1;
    115             }
    116             mSections = tempSections;
    117             mPositions = tempPositions;
    118             mCount++;
    119         }
    120     }
    121 }
    122