/*
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* Copyright 2007 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*namespace com.google.zxing.qrcode.detector {*/
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import DecodeHintType from '../../DecodeHintType';
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import ResultPoint from '../../ResultPoint';
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import FinderPattern from './FinderPattern';
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import FinderPatternInfo from './FinderPatternInfo';
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import NotFoundException from '../../NotFoundException';
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/*import java.io.Serializable;*/
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/*import java.util.ArrayList;*/
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/*import java.util.Collections;*/
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/*import java.util.Comparator;*/
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/*import java.util.List;*/
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/*import java.util.Map;*/
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/**
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* <p>This class attempts to find finder patterns in a QR Code. Finder patterns are the square
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* markers at three corners of a QR Code.</p>
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*
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* <p>This class is thread-safe but not reentrant. Each thread must allocate its own object.
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*
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* @author Sean Owen
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*/
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export default class FinderPatternFinder {
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/**
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* <p>Creates a finder that will search the image for three finder patterns.</p>
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*
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* @param image image to search
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*/
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// public constructor(image: BitMatrix) {
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// this(image, null)
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// }
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constructor(image, resultPointCallback) {
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this.image = image;
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this.resultPointCallback = resultPointCallback;
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this.possibleCenters = [];
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this.crossCheckStateCount = new Int32Array(5);
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this.resultPointCallback = resultPointCallback;
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}
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getImage() {
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return this.image;
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}
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getPossibleCenters() {
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return this.possibleCenters;
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}
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find(hints) {
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const tryHarder = (hints !== null && hints !== undefined) && undefined !== hints.get(DecodeHintType.TRY_HARDER);
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const pureBarcode = (hints !== null && hints !== undefined) && undefined !== hints.get(DecodeHintType.PURE_BARCODE);
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const image = this.image;
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const maxI = image.getHeight();
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const maxJ = image.getWidth();
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// We are looking for black/white/black/white/black modules in
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// 1:1:3:1:1 ratio; this tracks the number of such modules seen so far
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// Let's assume that the maximum version QR Code we support takes up 1/4 the height of the
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// image, and then account for the center being 3 modules in size. This gives the smallest
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// number of pixels the center could be, so skip this often. When trying harder, look for all
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// QR versions regardless of how dense they are.
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let iSkip = Math.floor((3 * maxI) / (4 * FinderPatternFinder.MAX_MODULES));
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if (iSkip < FinderPatternFinder.MIN_SKIP || tryHarder) {
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iSkip = FinderPatternFinder.MIN_SKIP;
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}
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let done = false;
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const stateCount = new Int32Array(5);
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for (let i = iSkip - 1; i < maxI && !done; i += iSkip) {
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// Get a row of black/white values
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stateCount[0] = 0;
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stateCount[1] = 0;
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stateCount[2] = 0;
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stateCount[3] = 0;
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stateCount[4] = 0;
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let currentState = 0;
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for (let j = 0; j < maxJ; j++) {
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if (image.get(j, i)) {
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// Black pixel
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if ((currentState & 1) === 1) { // Counting white pixels
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currentState++;
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}
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stateCount[currentState]++;
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}
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else { // White pixel
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if ((currentState & 1) === 0) { // Counting black pixels
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if (currentState === 4) { // A winner?
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if (FinderPatternFinder.foundPatternCross(stateCount)) { // Yes
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const confirmed = this.handlePossibleCenter(stateCount, i, j, pureBarcode);
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if (confirmed === true) {
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// Start examining every other line. Checking each line turned out to be too
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// expensive and didn't improve performance.
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iSkip = 2;
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if (this.hasSkipped === true) {
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done = this.haveMultiplyConfirmedCenters();
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}
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else {
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const rowSkip = this.findRowSkip();
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if (rowSkip > stateCount[2]) {
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// Skip rows between row of lower confirmed center
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// and top of presumed third confirmed center
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// but back up a bit to get a full chance of detecting
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// it, entire width of center of finder pattern
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// Skip by rowSkip, but back off by stateCount[2] (size of last center
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// of pattern we saw) to be conservative, and also back off by iSkip which
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// is about to be re-added
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i += rowSkip - stateCount[2] - iSkip;
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j = maxJ - 1;
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}
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}
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}
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else {
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stateCount[0] = stateCount[2];
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stateCount[1] = stateCount[3];
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stateCount[2] = stateCount[4];
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stateCount[3] = 1;
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stateCount[4] = 0;
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currentState = 3;
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continue;
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}
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// Clear state to start looking again
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currentState = 0;
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stateCount[0] = 0;
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stateCount[1] = 0;
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stateCount[2] = 0;
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stateCount[3] = 0;
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stateCount[4] = 0;
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}
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else { // No, shift counts back by two
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stateCount[0] = stateCount[2];
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stateCount[1] = stateCount[3];
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stateCount[2] = stateCount[4];
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stateCount[3] = 1;
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stateCount[4] = 0;
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currentState = 3;
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}
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}
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else {
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stateCount[++currentState]++;
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}
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}
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else { // Counting white pixels
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stateCount[currentState]++;
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}
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}
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}
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if (FinderPatternFinder.foundPatternCross(stateCount)) {
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const confirmed = this.handlePossibleCenter(stateCount, i, maxJ, pureBarcode);
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if (confirmed === true) {
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iSkip = stateCount[0];
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if (this.hasSkipped) {
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// Found a third one
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done = this.haveMultiplyConfirmedCenters();
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}
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}
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}
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}
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const patternInfo = this.selectBestPatterns();
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ResultPoint.orderBestPatterns(patternInfo);
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return new FinderPatternInfo(patternInfo);
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}
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/**
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* Given a count of black/white/black/white/black pixels just seen and an end position,
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* figures the location of the center of this run.
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*/
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static centerFromEnd(stateCount, end /*int*/) {
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return (end - stateCount[4] - stateCount[3]) - stateCount[2] / 2.0;
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}
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/**
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* @param stateCount count of black/white/black/white/black pixels just read
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* @return true iff the proportions of the counts is close enough to the 1/1/3/1/1 ratios
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* used by finder patterns to be considered a match
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*/
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static foundPatternCross(stateCount) {
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let totalModuleSize = 0;
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for (let i = 0; i < 5; i++) {
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const count = stateCount[i];
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if (count === 0) {
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return false;
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}
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totalModuleSize += count;
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}
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if (totalModuleSize < 7) {
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return false;
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}
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const moduleSize = totalModuleSize / 7.0;
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const maxVariance = moduleSize / 2.0;
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// Allow less than 50% variance from 1-1-3-1-1 proportions
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return Math.abs(moduleSize - stateCount[0]) < maxVariance &&
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Math.abs(moduleSize - stateCount[1]) < maxVariance &&
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Math.abs(3.0 * moduleSize - stateCount[2]) < 3 * maxVariance &&
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Math.abs(moduleSize - stateCount[3]) < maxVariance &&
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Math.abs(moduleSize - stateCount[4]) < maxVariance;
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}
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getCrossCheckStateCount() {
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const crossCheckStateCount = this.crossCheckStateCount;
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crossCheckStateCount[0] = 0;
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crossCheckStateCount[1] = 0;
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crossCheckStateCount[2] = 0;
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crossCheckStateCount[3] = 0;
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crossCheckStateCount[4] = 0;
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return crossCheckStateCount;
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}
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/**
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* After a vertical and horizontal scan finds a potential finder pattern, this method
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* "cross-cross-cross-checks" by scanning down diagonally through the center of the possible
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* finder pattern to see if the same proportion is detected.
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*
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* @param startI row where a finder pattern was detected
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* @param centerJ center of the section that appears to cross a finder pattern
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* @param maxCount maximum reasonable number of modules that should be
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* observed in any reading state, based on the results of the horizontal scan
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* @param originalStateCountTotal The original state count total.
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* @return true if proportions are withing expected limits
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*/
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crossCheckDiagonal(startI /*int*/, centerJ /*int*/, maxCount /*int*/, originalStateCountTotal /*int*/) {
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const stateCount = this.getCrossCheckStateCount();
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// Start counting up, left from center finding black center mass
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let i = 0;
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const image = this.image;
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while (startI >= i && centerJ >= i && image.get(centerJ - i, startI - i)) {
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stateCount[2]++;
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i++;
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}
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if (startI < i || centerJ < i) {
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return false;
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}
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// Continue up, left finding white space
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while (startI >= i && centerJ >= i && !image.get(centerJ - i, startI - i) &&
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stateCount[1] <= maxCount) {
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stateCount[1]++;
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i++;
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}
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// If already too many modules in this state or ran off the edge:
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if (startI < i || centerJ < i || stateCount[1] > maxCount) {
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return false;
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}
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// Continue up, left finding black border
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while (startI >= i && centerJ >= i && image.get(centerJ - i, startI - i) &&
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stateCount[0] <= maxCount) {
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stateCount[0]++;
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i++;
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}
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if (stateCount[0] > maxCount) {
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return false;
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}
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const maxI = image.getHeight();
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const maxJ = image.getWidth();
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// Now also count down, right from center
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i = 1;
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while (startI + i < maxI && centerJ + i < maxJ && image.get(centerJ + i, startI + i)) {
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stateCount[2]++;
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i++;
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}
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// Ran off the edge?
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if (startI + i >= maxI || centerJ + i >= maxJ) {
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return false;
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}
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while (startI + i < maxI && centerJ + i < maxJ && !image.get(centerJ + i, startI + i) &&
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stateCount[3] < maxCount) {
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stateCount[3]++;
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i++;
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}
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if (startI + i >= maxI || centerJ + i >= maxJ || stateCount[3] >= maxCount) {
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return false;
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}
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while (startI + i < maxI && centerJ + i < maxJ && image.get(centerJ + i, startI + i) &&
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stateCount[4] < maxCount) {
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stateCount[4]++;
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i++;
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}
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if (stateCount[4] >= maxCount) {
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return false;
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}
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// If we found a finder-pattern-like section, but its size is more than 100% different than
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// the original, assume it's a false positive
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const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];
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return Math.abs(stateCountTotal - originalStateCountTotal) < 2 * originalStateCountTotal &&
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FinderPatternFinder.foundPatternCross(stateCount);
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}
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/**
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* <p>After a horizontal scan finds a potential finder pattern, this method
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* "cross-checks" by scanning down vertically through the center of the possible
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* finder pattern to see if the same proportion is detected.</p>
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*
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* @param startI row where a finder pattern was detected
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* @param centerJ center of the section that appears to cross a finder pattern
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* @param maxCount maximum reasonable number of modules that should be
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* observed in any reading state, based on the results of the horizontal scan
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* @return vertical center of finder pattern, or {@link Float#NaN} if not found
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*/
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crossCheckVertical(startI /*int*/, centerJ /*int*/, maxCount /*int*/, originalStateCountTotal /*int*/) {
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const image = this.image;
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const maxI = image.getHeight();
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const stateCount = this.getCrossCheckStateCount();
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// Start counting up from center
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let i = startI;
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while (i >= 0 && image.get(centerJ, i)) {
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stateCount[2]++;
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i--;
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}
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if (i < 0) {
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return NaN;
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}
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while (i >= 0 && !image.get(centerJ, i) && stateCount[1] <= maxCount) {
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stateCount[1]++;
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i--;
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}
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// If already too many modules in this state or ran off the edge:
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if (i < 0 || stateCount[1] > maxCount) {
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return NaN;
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}
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while (i >= 0 && image.get(centerJ, i) && stateCount[0] <= maxCount) {
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stateCount[0]++;
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i--;
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}
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if (stateCount[0] > maxCount) {
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return NaN;
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}
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// Now also count down from center
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i = startI + 1;
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while (i < maxI && image.get(centerJ, i)) {
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stateCount[2]++;
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i++;
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}
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if (i === maxI) {
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return NaN;
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}
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while (i < maxI && !image.get(centerJ, i) && stateCount[3] < maxCount) {
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stateCount[3]++;
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i++;
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}
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if (i === maxI || stateCount[3] >= maxCount) {
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return NaN;
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}
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while (i < maxI && image.get(centerJ, i) && stateCount[4] < maxCount) {
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stateCount[4]++;
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i++;
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}
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if (stateCount[4] >= maxCount) {
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return NaN;
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}
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// If we found a finder-pattern-like section, but its size is more than 40% different than
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// the original, assume it's a false positive
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const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
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stateCount[4];
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if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal) {
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return NaN;
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}
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return FinderPatternFinder.foundPatternCross(stateCount) ? FinderPatternFinder.centerFromEnd(stateCount, i) : NaN;
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}
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/**
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* <p>Like {@link #crossCheckVertical(int, int, int, int)}, and in fact is basically identical,
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* except it reads horizontally instead of vertically. This is used to cross-cross
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* check a vertical cross check and locate the real center of the alignment pattern.</p>
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*/
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crossCheckHorizontal(startJ /*int*/, centerI /*int*/, maxCount /*int*/, originalStateCountTotal /*int*/) {
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const image = this.image;
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const maxJ = image.getWidth();
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const stateCount = this.getCrossCheckStateCount();
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let j = startJ;
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while (j >= 0 && image.get(j, centerI)) {
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stateCount[2]++;
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j--;
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}
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if (j < 0) {
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return NaN;
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}
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while (j >= 0 && !image.get(j, centerI) && stateCount[1] <= maxCount) {
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stateCount[1]++;
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j--;
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}
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if (j < 0 || stateCount[1] > maxCount) {
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return NaN;
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}
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while (j >= 0 && image.get(j, centerI) && stateCount[0] <= maxCount) {
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stateCount[0]++;
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j--;
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}
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if (stateCount[0] > maxCount) {
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return NaN;
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}
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j = startJ + 1;
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while (j < maxJ && image.get(j, centerI)) {
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stateCount[2]++;
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j++;
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}
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if (j === maxJ) {
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return NaN;
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}
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while (j < maxJ && !image.get(j, centerI) && stateCount[3] < maxCount) {
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stateCount[3]++;
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j++;
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}
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if (j === maxJ || stateCount[3] >= maxCount) {
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return NaN;
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}
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while (j < maxJ && image.get(j, centerI) && stateCount[4] < maxCount) {
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stateCount[4]++;
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j++;
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}
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if (stateCount[4] >= maxCount) {
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return NaN;
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}
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// If we found a finder-pattern-like section, but its size is significantly different than
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// the original, assume it's a false positive
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const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
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stateCount[4];
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if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {
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return NaN;
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}
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return FinderPatternFinder.foundPatternCross(stateCount) ? FinderPatternFinder.centerFromEnd(stateCount, j) : NaN;
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}
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/**
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* <p>This is called when a horizontal scan finds a possible alignment pattern. It will
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* cross check with a vertical scan, and if successful, will, ah, cross-cross-check
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* with another horizontal scan. This is needed primarily to locate the real horizontal
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* center of the pattern in cases of extreme skew.
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* And then we cross-cross-cross check with another diagonal scan.</p>
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*
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* <p>If that succeeds the finder pattern location is added to a list that tracks
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* the number of times each location has been nearly-matched as a finder pattern.
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* Each additional find is more evidence that the location is in fact a finder
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* pattern center
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*
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* @param stateCount reading state module counts from horizontal scan
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* @param i row where finder pattern may be found
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* @param j end of possible finder pattern in row
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* @param pureBarcode true if in "pure barcode" mode
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* @return true if a finder pattern candidate was found this time
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*/
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handlePossibleCenter(stateCount, i /*int*/, j /*int*/, pureBarcode) {
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const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
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stateCount[4];
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let centerJ = FinderPatternFinder.centerFromEnd(stateCount, j);
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let centerI = this.crossCheckVertical(i, /*(int) */ Math.floor(centerJ), stateCount[2], stateCountTotal);
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if (!isNaN(centerI)) {
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// Re-cross check
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centerJ = this.crossCheckHorizontal(/*(int) */ Math.floor(centerJ), /*(int) */ Math.floor(centerI), stateCount[2], stateCountTotal);
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if (!isNaN(centerJ) &&
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(!pureBarcode || this.crossCheckDiagonal(/*(int) */ Math.floor(centerI), /*(int) */ Math.floor(centerJ), stateCount[2], stateCountTotal))) {
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const estimatedModuleSize = stateCountTotal / 7.0;
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let found = false;
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const possibleCenters = this.possibleCenters;
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for (let index = 0, length = possibleCenters.length; index < length; index++) {
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const center = possibleCenters[index];
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// Look for about the same center and module size:
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if (center.aboutEquals(estimatedModuleSize, centerI, centerJ)) {
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possibleCenters[index] = center.combineEstimate(centerI, centerJ, estimatedModuleSize);
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found = true;
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break;
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}
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}
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if (!found) {
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const point = new FinderPattern(centerJ, centerI, estimatedModuleSize);
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possibleCenters.push(point);
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if (this.resultPointCallback !== null && this.resultPointCallback !== undefined) {
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this.resultPointCallback.foundPossibleResultPoint(point);
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}
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}
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return true;
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}
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}
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return false;
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}
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/**
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* @return number of rows we could safely skip during scanning, based on the first
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* two finder patterns that have been located. In some cases their position will
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* allow us to infer that the third pattern must lie below a certain point farther
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* down in the image.
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*/
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findRowSkip() {
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const max = this.possibleCenters.length;
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if (max <= 1) {
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return 0;
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}
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let firstConfirmedCenter = null;
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for (const center of this.possibleCenters) {
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if (center.getCount() >= FinderPatternFinder.CENTER_QUORUM) {
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if (firstConfirmedCenter == null) {
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firstConfirmedCenter = center;
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}
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else {
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// We have two confirmed centers
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// How far down can we skip before resuming looking for the next
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// pattern? In the worst case, only the difference between the
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// difference in the x / y coordinates of the two centers.
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// This is the case where you find top left last.
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this.hasSkipped = true;
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return /*(int) */ Math.floor((Math.abs(firstConfirmedCenter.getX() - center.getX()) -
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Math.abs(firstConfirmedCenter.getY() - center.getY())) / 2);
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}
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}
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}
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return 0;
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}
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/**
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* @return true iff we have found at least 3 finder patterns that have been detected
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* at least {@link #CENTER_QUORUM} times each, and, the estimated module size of the
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* candidates is "pretty similar"
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*/
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haveMultiplyConfirmedCenters() {
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let confirmedCount = 0;
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let totalModuleSize = 0.0;
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const max = this.possibleCenters.length;
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for (const pattern of this.possibleCenters) {
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if (pattern.getCount() >= FinderPatternFinder.CENTER_QUORUM) {
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confirmedCount++;
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totalModuleSize += pattern.getEstimatedModuleSize();
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}
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}
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if (confirmedCount < 3) {
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return false;
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}
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// OK, we have at least 3 confirmed centers, but, it's possible that one is a "false positive"
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// and that we need to keep looking. We detect this by asking if the estimated module sizes
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// vary too much. We arbitrarily say that when the total deviation from average exceeds
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// 5% of the total module size estimates, it's too much.
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const average = totalModuleSize / max;
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let totalDeviation = 0.0;
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for (const pattern of this.possibleCenters) {
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totalDeviation += Math.abs(pattern.getEstimatedModuleSize() - average);
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}
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return totalDeviation <= 0.05 * totalModuleSize;
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}
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/**
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* @return the 3 best {@link FinderPattern}s from our list of candidates. The "best" are
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* those that have been detected at least {@link #CENTER_QUORUM} times, and whose module
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* size differs from the average among those patterns the least
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* @throws NotFoundException if 3 such finder patterns do not exist
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*/
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selectBestPatterns() {
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const startSize = this.possibleCenters.length;
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if (startSize < 3) {
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// Couldn't find enough finder patterns
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throw new NotFoundException();
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}
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const possibleCenters = this.possibleCenters;
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let average;
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// Filter outlier possibilities whose module size is too different
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if (startSize > 3) {
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// But we can only afford to do so if we have at least 4 possibilities to choose from
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let totalModuleSize = 0.0;
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let square = 0.0;
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for (const center of this.possibleCenters) {
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const size = center.getEstimatedModuleSize();
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totalModuleSize += size;
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square += size * size;
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}
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average = totalModuleSize / startSize;
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let stdDev = Math.sqrt(square / startSize - average * average);
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possibleCenters.sort(
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/**
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* <p>Orders by furthest from average</p>
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*/
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// FurthestFromAverageComparator implements Comparator<FinderPattern>
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(center1, center2) => {
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const dA = Math.abs(center2.getEstimatedModuleSize() - average);
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const dB = Math.abs(center1.getEstimatedModuleSize() - average);
|
return dA < dB ? -1 : dA > dB ? 1 : 0;
|
});
|
const limit = Math.max(0.2 * average, stdDev);
|
for (let i = 0; i < possibleCenters.length && possibleCenters.length > 3; i++) {
|
const pattern = possibleCenters[i];
|
if (Math.abs(pattern.getEstimatedModuleSize() - average) > limit) {
|
possibleCenters.splice(i, 1);
|
i--;
|
}
|
}
|
}
|
if (possibleCenters.length > 3) {
|
// Throw away all but those first size candidate points we found.
|
let totalModuleSize = 0.0;
|
for (const possibleCenter of possibleCenters) {
|
totalModuleSize += possibleCenter.getEstimatedModuleSize();
|
}
|
average = totalModuleSize / possibleCenters.length;
|
possibleCenters.sort(
|
/**
|
* <p>Orders by {@link FinderPattern#getCount()}, descending.</p>
|
*/
|
// CenterComparator implements Comparator<FinderPattern>
|
(center1, center2) => {
|
if (center2.getCount() === center1.getCount()) {
|
const dA = Math.abs(center2.getEstimatedModuleSize() - average);
|
const dB = Math.abs(center1.getEstimatedModuleSize() - average);
|
return dA < dB ? 1 : dA > dB ? -1 : 0;
|
}
|
else {
|
return center2.getCount() - center1.getCount();
|
}
|
});
|
possibleCenters.splice(3); // this is not realy necessary as we only return first 3 anyway
|
}
|
return [
|
possibleCenters[0],
|
possibleCenters[1],
|
possibleCenters[2]
|
];
|
}
|
}
|
FinderPatternFinder.CENTER_QUORUM = 2;
|
FinderPatternFinder.MIN_SKIP = 3; // 1 pixel/module times 3 modules/center
|
FinderPatternFinder.MAX_MODULES = 57; // support up to version 10 for mobile clients
|
