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BoofCV is an open source Java library for real-time computer vision and robotics applications.
/*
* Copyright (c) 2011-2017, Peter Abeles. All Rights Reserved.
*
* This file is part of BoofCV (http://boofcv.org).
*
* 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 boofcv.misc;
/**
* Function for use when referencing the index in a circular list
*
* @author Peter Abeles
*/
public class CircularIndex {
/**
* Adds a positive offset to index in a circular buffer.
* @param index element in circular buffer
* @param offset integer which is positive and less than size
* @param size size of the circular buffer
* @return new index
*/
public static int plusPOffset(int index, int offset, int size) {
return (index+offset)%size;
}
/**
* Subtracts a positive offset to index in a circular buffer.
* @param index element in circular buffer
* @param offset integer which is positive and less than size
* @param size size of the circular buffer
* @return new index
*/
public static int minusPOffset(int index, int offset, int size) {
index -= offset;
if( index < 0 ) {
return size + index;
} else {
return index;
}
}
/**
* Adds offset (positive or negative) to index in a circular buffer.
* @param index element in circular buffer
* @param offset offset. |offset| < size
* @param size size of the circular buffer
* @return new index
*/
public static int addOffset(int index, int offset, int size) {
index += offset;
if( index < 0 ) {
return size + index;
} else {
return index%size;
}
}
/**
* Returns how many elements away in the positive direction you need to travel to get from
* index0 to index1.
*
* @param index0 element in circular buffer
* @param index1 element in circular buffer
* @param size size of the circular buffer
* @return positive distance
*/
public static int distanceP(int index0, int index1, int size) {
int difference = index1-index0;
if( difference < 0 ) {
difference = size+difference;
}
return difference;
}
/**
* Returns the smallest distance you would need to travel (positive or negative) to go from index0 to index1.
*
* @param index0 element in circular buffer
* @param index1 element in circular buffer
* @param size size of the circular buffer
* @return smallest distance
*/
public static int distance(int index0, int index1, int size) {
if( index0 > index1 ) {
int tmp = index0;
index0 = index1;
index1 = tmp;
}
int distance0 = index1-index0;
int distance1 = index0 + size-index1;
if( distance0 < distance1)
return distance0;
else
return distance1;
}
/**
* Subtracts index1 from index0. positive number if its closer in the positive
* direction or negative if closer in the negative direction. if equal distance then
* it will return a negative number.
*
* @param index0 element in circular buffer
* @param index1 element in circular buffer
* @param size size of the circular buffer
* @return new index
*/
public static int subtract(int index0, int index1, int size) {
int distance = distanceP(index0, index1, size);
if( distance >= size/2+size%2 ) {
return distance-size;
} else {
return distance;
}
}
}