/*
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* Copyright 2008 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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import BitArray from '../common/BitArray';
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import DecodeHintType from '../DecodeHintType';
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import ResultMetadataType from '../ResultMetadataType';
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import ResultPoint from '../ResultPoint';
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import NotFoundException from '../NotFoundException';
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/**
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* Encapsulates functionality and implementation that is common to all families
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* of one-dimensional barcodes.
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*
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* @author dswitkin@google.com (Daniel Switkin)
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* @author Sean Owen
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*/
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export default class OneDReader {
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/*
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@Override
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public Result decode(BinaryBitmap image) throws NotFoundException, FormatException {
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return decode(image, null);
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}
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*/
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// Note that we don't try rotation without the try harder flag, even if rotation was supported.
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// @Override
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decode(image, hints) {
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try {
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return this.doDecode(image, hints);
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}
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catch (nfe) {
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const tryHarder = hints && (hints.get(DecodeHintType.TRY_HARDER) === true);
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if (tryHarder && image.isRotateSupported()) {
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const rotatedImage = image.rotateCounterClockwise();
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const result = this.doDecode(rotatedImage, hints);
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// Record that we found it rotated 90 degrees CCW / 270 degrees CW
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const metadata = result.getResultMetadata();
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let orientation = 270;
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if (metadata !== null && (metadata.get(ResultMetadataType.ORIENTATION) === true)) {
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// But if we found it reversed in doDecode(), add in that result here:
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orientation = (orientation + metadata.get(ResultMetadataType.ORIENTATION) % 360);
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}
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result.putMetadata(ResultMetadataType.ORIENTATION, orientation);
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// Update result points
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const points = result.getResultPoints();
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if (points !== null) {
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const height = rotatedImage.getHeight();
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for (let i = 0; i < points.length; i++) {
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points[i] = new ResultPoint(height - points[i].getY() - 1, points[i].getX());
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}
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}
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return result;
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}
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else {
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throw new NotFoundException();
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}
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}
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}
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// @Override
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reset() {
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// do nothing
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}
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/**
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* We're going to examine rows from the middle outward, searching alternately above and below the
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* middle, and farther out each time. rowStep is the number of rows between each successive
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* attempt above and below the middle. So we'd scan row middle, then middle - rowStep, then
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* middle + rowStep, then middle - (2 * rowStep), etc.
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* rowStep is bigger as the image is taller, but is always at least 1. We've somewhat arbitrarily
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* decided that moving up and down by about 1/16 of the image is pretty good; we try more of the
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* image if "trying harder".
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*
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* @param image The image to decode
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* @param hints Any hints that were requested
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* @return The contents of the decoded barcode
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* @throws NotFoundException Any spontaneous errors which occur
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*/
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doDecode(image, hints) {
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const width = image.getWidth();
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const height = image.getHeight();
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let row = new BitArray(width);
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const tryHarder = hints && (hints.get(DecodeHintType.TRY_HARDER) === true);
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const rowStep = Math.max(1, height >> (tryHarder ? 8 : 5));
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let maxLines;
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if (tryHarder) {
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maxLines = height; // Look at the whole image, not just the center
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}
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else {
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maxLines = 15; // 15 rows spaced 1/32 apart is roughly the middle half of the image
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}
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const middle = Math.trunc(height / 2);
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for (let x = 0; x < maxLines; x++) {
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// Scanning from the middle out. Determine which row we're looking at next:
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const rowStepsAboveOrBelow = Math.trunc((x + 1) / 2);
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const isAbove = (x & 0x01) === 0; // i.e. is x even?
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const rowNumber = middle + rowStep * (isAbove ? rowStepsAboveOrBelow : -rowStepsAboveOrBelow);
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if (rowNumber < 0 || rowNumber >= height) {
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// Oops, if we run off the top or bottom, stop
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break;
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}
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// Estimate black point for this row and load it:
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try {
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row = image.getBlackRow(rowNumber, row);
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}
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catch (ignored) {
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continue;
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}
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// While we have the image data in a BitArray, it's fairly cheap to reverse it in place to
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// handle decoding upside down barcodes.
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for (let attempt = 0; attempt < 2; attempt++) {
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if (attempt === 1) { // trying again?
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row.reverse(); // reverse the row and continue
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// This means we will only ever draw result points *once* in the life of this method
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// since we want to avoid drawing the wrong points after flipping the row, and,
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// don't want to clutter with noise from every single row scan -- just the scans
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// that start on the center line.
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if (hints && (hints.get(DecodeHintType.NEED_RESULT_POINT_CALLBACK) === true)) {
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const newHints = new Map();
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hints.forEach((hint, key) => newHints.set(key, hint));
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newHints.delete(DecodeHintType.NEED_RESULT_POINT_CALLBACK);
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hints = newHints;
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}
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}
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try {
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// Look for a barcode
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const result = this.decodeRow(rowNumber, row, hints);
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// We found our barcode
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if (attempt === 1) {
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// But it was upside down, so note that
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result.putMetadata(ResultMetadataType.ORIENTATION, 180);
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// And remember to flip the result points horizontally.
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const points = result.getResultPoints();
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if (points !== null) {
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points[0] = new ResultPoint(width - points[0].getX() - 1, points[0].getY());
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points[1] = new ResultPoint(width - points[1].getX() - 1, points[1].getY());
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}
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}
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return result;
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}
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catch (re) {
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// continue -- just couldn't decode this row
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}
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}
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}
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throw new NotFoundException();
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}
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/**
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* Records the size of successive runs of white and black pixels in a row, starting at a given point.
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* The values are recorded in the given array, and the number of runs recorded is equal to the size
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* of the array. If the row starts on a white pixel at the given start point, then the first count
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* recorded is the run of white pixels starting from that point; likewise it is the count of a run
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* of black pixels if the row begin on a black pixels at that point.
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*
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* @param row row to count from
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* @param start offset into row to start at
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* @param counters array into which to record counts
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* @throws NotFoundException if counters cannot be filled entirely from row before running out
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* of pixels
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*/
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static recordPattern(row, start, counters) {
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const numCounters = counters.length;
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for (let index = 0; index < numCounters; index++)
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counters[index] = 0;
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const end = row.getSize();
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if (start >= end) {
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throw new NotFoundException();
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}
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let isWhite = !row.get(start);
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let counterPosition = 0;
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let i = start;
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while (i < end) {
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if (row.get(i) !== isWhite) {
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counters[counterPosition]++;
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}
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else {
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if (++counterPosition === numCounters) {
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break;
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}
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else {
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counters[counterPosition] = 1;
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isWhite = !isWhite;
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}
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}
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i++;
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}
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// If we read fully the last section of pixels and filled up our counters -- or filled
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// the last counter but ran off the side of the image, OK. Otherwise, a problem.
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if (!(counterPosition === numCounters || (counterPosition === numCounters - 1 && i === end))) {
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throw new NotFoundException();
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}
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}
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static recordPatternInReverse(row, start, counters) {
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// This could be more efficient I guess
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let numTransitionsLeft = counters.length;
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let last = row.get(start);
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while (start > 0 && numTransitionsLeft >= 0) {
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if (row.get(--start) !== last) {
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numTransitionsLeft--;
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last = !last;
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}
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}
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if (numTransitionsLeft >= 0) {
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throw new NotFoundException();
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}
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OneDReader.recordPattern(row, start + 1, counters);
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}
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/**
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* Determines how closely a set of observed counts of runs of black/white values matches a given
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* target pattern. This is reported as the ratio of the total variance from the expected pattern
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* proportions across all pattern elements, to the length of the pattern.
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*
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* @param counters observed counters
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* @param pattern expected pattern
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* @param maxIndividualVariance The most any counter can differ before we give up
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* @return ratio of total variance between counters and pattern compared to total pattern size
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*/
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static patternMatchVariance(counters, pattern, maxIndividualVariance) {
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const numCounters = counters.length;
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let total = 0;
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let patternLength = 0;
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for (let i = 0; i < numCounters; i++) {
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total += counters[i];
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patternLength += pattern[i];
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}
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if (total < patternLength) {
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// If we don't even have one pixel per unit of bar width, assume this is too small
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// to reliably match, so fail:
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return Number.POSITIVE_INFINITY;
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}
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const unitBarWidth = total / patternLength;
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maxIndividualVariance *= unitBarWidth;
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let totalVariance = 0.0;
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for (let x = 0; x < numCounters; x++) {
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const counter = counters[x];
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const scaledPattern = pattern[x] * unitBarWidth;
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const variance = counter > scaledPattern ? counter - scaledPattern : scaledPattern - counter;
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if (variance > maxIndividualVariance) {
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return Number.POSITIVE_INFINITY;
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}
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totalVariance += variance;
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}
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return totalVariance / total;
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}
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}
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