zxing-js/library

/*
 * 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.
 */

/*namespace com.google.zxing {*/

import MathUtils from './common/detector/MathUtils';
import Float from './util/Float';
import { float, int } from '../customTypings';

/**
 * <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
 */
export default class ResultPoint {

    public constructor(private x: float, private y: float) { }

    public getX(): float {
        return this.x;
    }

    public getY(): float {
        return this.y;
    }

    /*@Override*/
    public equals(other: Object): boolean {
        if (other instanceof ResultPoint) {
            const otherPoint = <ResultPoint>other;
            return this.x === otherPoint.x && this.y === otherPoint.y;
        }
        return false;
    }

    /*@Override*/
    public hashCode(): int {
        return 31 * Float.floatToIntBits(this.x) + Float.floatToIntBits(this.y);
    }

    /*@Override*/
    public toString(): string {
        return '(' + this.x + ',' + this.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 orderBestPatterns(patterns: Array<ResultPoint>): void {

        // Find distances between pattern centers
        const zeroOneDistance = this.distance(patterns[0], patterns[1]);
        const oneTwoDistance = this.distance(patterns[1], patterns[2]);
        const zeroTwoDistance = this.distance(patterns[0], patterns[2]);

        let pointA: ResultPoint;
        let pointB: ResultPoint;
        let pointC: ResultPoint;
        // 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 (this.crossProductZ(pointA, pointB, pointC) < 0.0) {
            const 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 distance(pattern1: ResultPoint, pattern2: ResultPoint): float {
        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 crossProductZ(pointA: ResultPoint,
        pointB: ResultPoint,
        pointC: ResultPoint): float {
        const bX = pointB.x;
        const bY = pointB.y;
        return ((pointC.x - bX) * (pointA.y - bY)) - ((pointC.y - bY) * (pointA.x - bX));
    }

}