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/*
* Copyright 2007 ZXing authors
*
* 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.google.zxing;
import com.google.zxing.common.detector.MathUtils;
/**
* <p>Encapsulates a point of interest in an image containing a barcode. Typically, this
* would be the location of a finder pattern or the corner of the barcode, for example.</p>
*
* @author Sean Owen
*/
public class ResultPoint {
private final float x;
private final float y;
public ResultPoint(float x, float y) {
this.x = x;
this.y = y;
}
public final float getX() {
return x;
}
public final float getY() {
return y;
}
@Override
public final boolean equals(Object other) {
if (other instanceof ResultPoint) {
ResultPoint otherPoint = (ResultPoint) other;
return x == otherPoint.x && y == otherPoint.y;
}
return false;
}
@Override
public final int hashCode() {
return 31 * Float.floatToIntBits(x) + Float.floatToIntBits(y);
}
@Override
public final String toString() {
return "(" + x + ',' + y + ')';
}
/**
* Orders an array of three ResultPoints in an order [A,B,C] such that AB is less than AC
* and BC is less than AC, and the angle between BC and BA is less than 180 degrees.
*
* @param patterns array of three {@code ResultPoint} to order
*/
public static void orderBestPatterns(ResultPoint[] patterns) {
// Find distances between pattern centers
float zeroOneDistance = distance(patterns[0], patterns[1]);
float oneTwoDistance = distance(patterns[1], patterns[2]);
float zeroTwoDistance = distance(patterns[0], patterns[2]);
ResultPoint pointA;
ResultPoint pointB;
ResultPoint pointC;
// Assume one closest to other two is B; A and C will just be guesses at first
if (oneTwoDistance >= zeroOneDistance && oneTwoDistance >= zeroTwoDistance) {
pointB = patterns[0];
pointA = patterns[1];
pointC = patterns[2];
} else if (zeroTwoDistance >= oneTwoDistance && zeroTwoDistance >= zeroOneDistance) {
pointB = patterns[1];
pointA = patterns[0];
pointC = patterns[2];
} else {
pointB = patterns[2];
pointA = patterns[0];
pointC = patterns[1];
}
// Use cross product to figure out whether A and C are correct or flipped.
// This asks whether BC x BA has a positive z component, which is the arrangement
// we want for A, B, C. If it's negative, then we've got it flipped around and
// should swap A and C.
if (crossProductZ(pointA, pointB, pointC) < 0.0f) {
ResultPoint temp = pointA;
pointA = pointC;
pointC = temp;
}
patterns[0] = pointA;
patterns[1] = pointB;
patterns[2] = pointC;
}
/**
* @param pattern1 first pattern
* @param pattern2 second pattern
* @return distance between two points
*/
public static float distance(ResultPoint pattern1, ResultPoint pattern2) {
return MathUtils.distance(pattern1.x, pattern1.y, pattern2.x, pattern2.y);
}
/**
* Returns the z component of the cross product between vectors BC and BA.
*/
private static float crossProductZ(ResultPoint pointA,
ResultPoint pointB,
ResultPoint pointC) {
float bX = pointB.x;
float bY = pointB.y;
return ((pointC.x - bX) * (pointA.y - bY)) - ((pointC.y - bY) * (pointA.x - bX));
}
}
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