src/core/pdf417/detector/Detector.ts
/*
* Copyright 2009 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.pdf417.detector;
// import com.google.zxing.BinaryBitmap;
import BinaryBitmap from '../../BinaryBitmap';
// import com.google.zxing.DecodeHintType;
import DecodeHintType from '../../DecodeHintType';
// import com.google.zxing.NotFoundException;
// import com.google.zxing.ResultPoint;
import ResultPoint from '../../ResultPoint';
// import com.google.zxing.common.BitMatrix;
import BitMatrix from '../../common/BitMatrix';
import System from '../../util/System';
import Arrays from '../../util/Arrays';
import PDF417DetectorResult from './PDF417DetectorResult';
import { float, int } from '../../../customTypings';
// import java.util.ArrayList;
// import java.util.Arrays;
// import java.util.List;
// import java.util.Map;
/**
* <p>Encapsulates logic that can detect a PDF417 Code in an image, even if the
* PDF417 Code is rotated or skewed, or partially obscured.</p>
*
* @author SITA Lab (kevin.osullivan@sita.aero)
* @author dswitkin@google.com (Daniel Switkin)
* @author Guenther Grau
*/
export default /*public*/ /*final*/ class Detector {
private static /*final*/ INDEXES_START_PATTERN = Int32Array.from([0, 4, 1, 5]);
private static /*final*/ INDEXES_STOP_PATTERN = Int32Array.from([6, 2, 7, 3]);
private static /*final*/ MAX_AVG_VARIANCE: float = /*0.42f*/ 0.42;
private static /*final*/ MAX_INDIVIDUAL_VARIANCE: float = /*0.8f*/ 0.8;
// B S B S B S B S Bar/Space pattern
// 11111111 0 1 0 1 0 1 000
private static /*final*/ START_PATTERN = Int32Array.from([8, 1, 1, 1, 1, 1, 1, 3]);
// 1111111 0 1 000 1 0 1 00 1
private static /*final*/ STOP_PATTERN = Int32Array.from([7, 1, 1, 3, 1, 1, 1, 2, 1]);
private static /*final*/ MAX_PIXEL_DRIFT: /*int*/ number = 3;
private static /*final*/ MAX_PATTERN_DRIFT: /*int*/ number = 5;
// if we set the value too low, then we don't detect the correct height of the bar if the start patterns are damaged.
// if we set the value too high, then we might detect the start pattern from a neighbor barcode.
private static /*final*/ SKIPPED_ROW_COUNT_MAX: /*int*/ number = 25;
// A PDF471 barcode should have at least 3 rows, with each row being >= 3 times the module width. Therefore it should be at least
// 9 pixels tall. To be conservative, we use about half the size to ensure we don't miss it.
private static /*final*/ ROW_STEP: /*int*/ number = 5;
private static /*final*/ BARCODE_MIN_HEIGHT: /*int*/ number = 10;
/**
* <p>Detects a PDF417 Code in an image. Only checks 0 and 180 degree rotations.</p>
*
* @param image barcode image to decode
* @param hints optional hints to detector
* @param multiple if true, then the image is searched for multiple codes. If false, then at most one code will
* be found and returned
* @return {@link PDF417DetectorResult} encapsulating results of detecting a PDF417 code
* @throws NotFoundException if no PDF417 Code can be found
*/
public static detectMultiple( image: BinaryBitmap, hints: Map<DecodeHintType, any>, multiple: boolean): PDF417DetectorResult {
// TODO detection improvement, tryHarder could try several different luminance thresholds/blackpoints or even
// different binarizers
// boolean tryHarder = hints != null && hints.containsKey(DecodeHintType.TRY_HARDER);
let bitMatrix = image.getBlackMatrix();
let barcodeCoordinates = Detector.detect(multiple, bitMatrix);
if (!barcodeCoordinates.length) {
bitMatrix = bitMatrix.clone();
bitMatrix.rotate180();
barcodeCoordinates = Detector.detect(multiple, bitMatrix);
}
return new PDF417DetectorResult(bitMatrix, barcodeCoordinates);
}
/**
* Detects PDF417 codes in an image. Only checks 0 degree rotation
* @param multiple if true, then the image is searched for multiple codes. If false, then at most one code will
* be found and returned
* @param bitMatrix bit matrix to detect barcodes in
* @return List of ResultPoint arrays containing the coordinates of found barcodes
*/
private static detect( multiple: boolean, bitMatrix: BitMatrix): Array<ResultPoint[]> {
const barcodeCoordinates = new Array<ResultPoint[]>();
let row = 0;
let column = 0;
let foundBarcodeInRow = false;
while (row < bitMatrix.getHeight()) {
const vertices = Detector.findVertices(bitMatrix, row, column);
if (vertices[0] == null && vertices[3] == null) {
if (!foundBarcodeInRow) {
// we didn't find any barcode so that's the end of searching
break;
}
// we didn't find a barcode starting at the given column and row. Try again from the first column and slightly
// below the lowest barcode we found so far.
foundBarcodeInRow = false;
column = 0;
for (const barcodeCoordinate of barcodeCoordinates) {
if (barcodeCoordinate[1] != null) {
row = <int> Math.trunc(Math.max(row, barcodeCoordinate[1].getY()));
}
if (barcodeCoordinate[3] != null) {
row = Math.max(row, <int> Math.trunc(barcodeCoordinate[3].getY()));
}
}
row += Detector.ROW_STEP;
continue;
}
foundBarcodeInRow = true;
barcodeCoordinates.push(vertices);
if (!multiple) {
break;
}
// if we didn't find a right row indicator column, then continue the search for the next barcode after the
// start pattern of the barcode just found.
if (vertices[2] != null) {
column = <int> Math.trunc(vertices[2].getX());
row = <int> Math.trunc(vertices[2].getY());
} else {
column = <int> Math.trunc(vertices[4].getX());
row = <int> Math.trunc(vertices[4].getY());
}
}
return barcodeCoordinates;
}
/**
* Locate the vertices and the codewords area of a black blob using the Start
* and Stop patterns as locators.
*
* @param matrix the scanned barcode image.
* @return an array containing the vertices:
* vertices[0] x, y top left barcode
* vertices[1] x, y bottom left barcode
* vertices[2] x, y top right barcode
* vertices[3] x, y bottom right barcode
* vertices[4] x, y top left codeword area
* vertices[5] x, y bottom left codeword area
* vertices[6] x, y top right codeword area
* vertices[7] x, y bottom right codeword area
*/
private static findVertices( matrix: BitMatrix, startRow: /*int*/ number, startColumn: /*int*/ number): ResultPoint[] {
const height = matrix.getHeight();
const width = matrix.getWidth();
// const result = new ResultPoint[8];
const result = new Array<ResultPoint>(8);
Detector.copyToResult(result, Detector.findRowsWithPattern(matrix, height, width, startRow, startColumn, Detector.START_PATTERN),
Detector.INDEXES_START_PATTERN);
if (result[4] != null) {
startColumn = <int> Math.trunc(result[4].getX());
startRow = <int> Math.trunc(result[4].getY());
}
Detector.copyToResult(result, Detector.findRowsWithPattern(matrix, height, width, startRow, startColumn, Detector.STOP_PATTERN),
Detector.INDEXES_STOP_PATTERN);
return result;
}
private static copyToResult(result: ResultPoint[], tmpResult: ResultPoint[], destinationIndexes: Int32Array): void {
for (let i = 0; i < destinationIndexes.length; i++) {
result[destinationIndexes[i]] = tmpResult[i];
}
}
private static findRowsWithPattern( matrix: BitMatrix,
height: /*int*/ number,
width: /*int*/ number,
startRow: /*int*/ number,
startColumn: /*int*/ number,
pattern: Int32Array): ResultPoint[] {
// const result = new ResultPoint[4];
const result = new Array<ResultPoint>(4);
let found = false;
const counters = new Int32Array(pattern.length);
for (; startRow < height; startRow += Detector.ROW_STEP) {
let loc = Detector.findGuardPattern(matrix, startColumn, startRow, width, false, pattern, counters);
if (loc != null) {
while (startRow > 0) {
const previousRowLoc = Detector.findGuardPattern(matrix, startColumn, --startRow, width, false, pattern, counters);
if (previousRowLoc != null) {
loc = previousRowLoc;
} else {
startRow++;
break;
}
}
result[0] = new ResultPoint(loc[0], startRow);
result[1] = new ResultPoint(loc[1], startRow);
found = true;
break;
}
}
let stopRow = startRow + 1;
// Last row of the current symbol that contains pattern
if (found) {
let skippedRowCount = 0;
let previousRowLoc = Int32Array.from([<int> Math.trunc(result[0].getX()), <int> Math.trunc(result[1].getX())]);
for (; stopRow < height; stopRow++) {
const loc = Detector.findGuardPattern(matrix, previousRowLoc[0], stopRow, width, false, pattern, counters);
// a found pattern is only considered to belong to the same barcode if the start and end positions
// don't differ too much. Pattern drift should be not bigger than two for consecutive rows. With
// a higher number of skipped rows drift could be larger. To keep it simple for now, we allow a slightly
// larger drift and don't check for skipped rows.
if (loc != null &&
Math.abs(previousRowLoc[0] - loc[0]) < Detector.MAX_PATTERN_DRIFT &&
Math.abs(previousRowLoc[1] - loc[1]) < Detector.MAX_PATTERN_DRIFT) {
previousRowLoc = loc;
skippedRowCount = 0;
} else {
if (skippedRowCount > Detector.SKIPPED_ROW_COUNT_MAX) {
break;
} else {
skippedRowCount++;
}
}
}
stopRow -= skippedRowCount + 1;
result[2] = new ResultPoint(previousRowLoc[0], stopRow);
result[3] = new ResultPoint(previousRowLoc[1], stopRow);
}
if (stopRow - startRow < Detector.BARCODE_MIN_HEIGHT) {
Arrays.fill(result, null);
}
return result;
}
/**
* @param matrix row of black/white values to search
* @param column x position to start search
* @param row y position to start search
* @param width the number of pixels to search on this row
* @param pattern pattern of counts of number of black and white pixels that are
* being searched for as a pattern
* @param counters array of counters, as long as pattern, to re-use
* @return start/end horizontal offset of guard pattern, as an array of two ints.
*/
private static findGuardPattern( matrix: BitMatrix,
column: /*int*/ number,
row: /*int*/ number,
width: /*int*/ number,
whiteFirst: boolean,
pattern: Int32Array,
counters: Int32Array): Int32Array {
Arrays.fillWithin(counters, 0, counters.length, 0);
let patternStart = column;
let pixelDrift = 0;
// if there are black pixels left of the current pixel shift to the left, but only for MAX_PIXEL_DRIFT pixels
while (matrix.get(patternStart, row) && patternStart > 0 && pixelDrift++ < Detector.MAX_PIXEL_DRIFT) {
patternStart--;
}
let x = patternStart;
let counterPosition = 0;
let patternLength = pattern.length;
for (let isWhite = whiteFirst; x < width; x++) {
let pixel = matrix.get(x, row);
if (pixel !== isWhite) {
counters[counterPosition]++;
} else {
if (counterPosition === patternLength - 1) {
if (Detector.patternMatchVariance(counters, pattern, Detector.MAX_INDIVIDUAL_VARIANCE) < Detector.MAX_AVG_VARIANCE) {
return new Int32Array([patternStart, x]);
}
patternStart += counters[0] + counters[1];
System.arraycopy(counters, 2, counters, 0, counterPosition - 1);
counters[counterPosition - 1] = 0;
counters[counterPosition] = 0;
counterPosition--;
} else {
counterPosition++;
}
counters[counterPosition] = 1;
isWhite = !isWhite;
}
}
if (counterPosition === patternLength - 1 &&
Detector.patternMatchVariance(counters, pattern, Detector.MAX_INDIVIDUAL_VARIANCE) < Detector.MAX_AVG_VARIANCE) {
return new Int32Array([patternStart, x - 1]);
}
return null;
}
/**
* Determines how closely a set of observed counts of runs of black/white
* values matches a given target pattern. This is reported as the ratio of
* the total variance from the expected pattern proportions across all
* pattern elements, to the length of the pattern.
*
* @param counters observed counters
* @param pattern expected pattern
* @param maxIndividualVariance The most any counter can differ before we give up
* @return ratio of total variance between counters and pattern compared to total pattern size
*/
private static patternMatchVariance( counters: Int32Array, pattern: Int32Array, maxIndividualVariance: float): float {
let numCounters = counters.length;
let total = 0;
let patternLength = 0;
for (let i = 0; i < numCounters; i++) {
total += counters[i];
patternLength += pattern[i];
}
if (total < patternLength) {
// If we don't even have one pixel per unit of bar width, assume this
// is too small to reliably match, so fail:
return /*Float.POSITIVE_INFINITY*/ Infinity;
}
// We're going to fake floating-point math in integers. We just need to use more bits.
// Scale up patternLength so that intermediate values below like scaledCounter will have
// more "significant digits".
let unitBarWidth = <float> total / patternLength;
maxIndividualVariance *= unitBarWidth;
let totalVariance = 0.0;
for (let x = 0; x < numCounters; x++) {
let counter = counters[x];
let scaledPattern = pattern[x] * unitBarWidth;
let variance = counter > scaledPattern ? counter - scaledPattern : scaledPattern - counter;
if (variance > maxIndividualVariance) {
return /*Float.POSITIVE_INFINITY*/ Infinity;
}
totalVariance += variance;
}
return totalVariance / total;
}
}