/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.contacts;
import android.widget.SectionIndexer;
import java.util.Arrays;
/**
* A section indexer that is configured with precomputed section titles and
* their respective counts.
*/
public class ContactsSectionIndexer implements SectionIndexer {
private final String[] mSections;
private final int[] mPositions;
private final int mCount;
/**
* Constructor.
*
* @param sections a non-null array
* @param counts a non-null array of the same size as <code>sections</code>
*/
public ContactsSectionIndexer(String[] sections, int[] counts) {
if (sections == null || counts == null) {
throw new NullPointerException();
}
if (sections.length != counts.length) {
throw new IllegalArgumentException(
"The sections and counts arrays must have the same length");
}
// TODO process sections/counts based on current locale and/or specific section titles
this.mSections = sections;
mPositions = new int[counts.length];
int position = 0;
for (int i = 0; i < counts.length; i++) {
if (mSections[i] == null) {
mSections[i] = " ";
} else {
mSections[i] = mSections[i].trim();
}
mPositions[i] = position;
position += counts[i];
}
mCount = position;
}
public Object[] getSections() {
return mSections;
}
public int getPositionForSection(int section) {
if (section < 0 || section >= mSections.length) {
return -1;
}
return mPositions[section];
}
public int getSectionForPosition(int position) {
if (position < 0 || position >= mCount) {
return -1;
}
int index = Arrays.binarySearch(mPositions, position);
/*
* Consider this example: section positions are 0, 3, 5; the supplied
* position is 4. The section corresponding to position 4 starts at
* position 3, so the expected return value is 1. Binary search will not
* find 4 in the array and thus will return -insertPosition-1, i.e. -3.
* To get from that number to the expected value of 1 we need to negate
* and subtract 2.
*/
return index >= 0 ? index : -index - 2;
}
}