@zxing/library
Version:
TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
340 lines (339 loc) • 16.3 kB
JavaScript
;
/*
* 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.
*/
var __values = (this && this.__values) || function(o) {
var s = typeof Symbol === "function" && Symbol.iterator, m = s && o[s], i = 0;
if (m) return m.call(o);
if (o && typeof o.length === "number") return {
next: function () {
if (o && i >= o.length) o = void 0;
return { value: o && o[i++], done: !o };
}
};
throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
};
Object.defineProperty(exports, "__esModule", { value: true });
// import com.google.zxing.NotFoundException;
// import com.google.zxing.ResultPoint;
var ResultPoint_1 = require("../../ResultPoint");
var System_1 = require("../../util/System");
var Arrays_1 = require("../../util/Arrays");
var PDF417DetectorResult_1 = require("./PDF417DetectorResult");
// 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
*/
var Detector = /** @class */ (function () {
function Detector() {
}
/**
* <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
*/
Detector.detectMultiple = function (image, hints, multiple) {
// TODO detection improvement, tryHarder could try several different luminance thresholds/blackpoints or even
// different binarizers
// boolean tryHarder = hints != null && hints.containsKey(DecodeHintType.TRY_HARDER);
var bitMatrix = image.getBlackMatrix();
var barcodeCoordinates = Detector.detect(multiple, bitMatrix);
if (!barcodeCoordinates.length) {
bitMatrix = bitMatrix.clone();
bitMatrix.rotate180();
barcodeCoordinates = Detector.detect(multiple, bitMatrix);
}
return new PDF417DetectorResult_1.default(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
*/
Detector.detect = function (multiple, bitMatrix) {
var e_1, _a;
var barcodeCoordinates = new Array();
var row = 0;
var column = 0;
var foundBarcodeInRow = false;
while (row < bitMatrix.getHeight()) {
var 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;
try {
for (var barcodeCoordinates_1 = (e_1 = void 0, __values(barcodeCoordinates)), barcodeCoordinates_1_1 = barcodeCoordinates_1.next(); !barcodeCoordinates_1_1.done; barcodeCoordinates_1_1 = barcodeCoordinates_1.next()) {
var barcodeCoordinate = barcodeCoordinates_1_1.value;
if (barcodeCoordinate[1] != null) {
row = Math.trunc(Math.max(row, barcodeCoordinate[1].getY()));
}
if (barcodeCoordinate[3] != null) {
row = Math.max(row, Math.trunc(barcodeCoordinate[3].getY()));
}
}
}
catch (e_1_1) { e_1 = { error: e_1_1 }; }
finally {
try {
if (barcodeCoordinates_1_1 && !barcodeCoordinates_1_1.done && (_a = barcodeCoordinates_1.return)) _a.call(barcodeCoordinates_1);
}
finally { if (e_1) throw e_1.error; }
}
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 = Math.trunc(vertices[2].getX());
row = Math.trunc(vertices[2].getY());
}
else {
column = Math.trunc(vertices[4].getX());
row = 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
*/
Detector.findVertices = function (matrix, startRow, startColumn) {
var height = matrix.getHeight();
var width = matrix.getWidth();
// const result = new ResultPoint[8];
var result = new Array(8);
Detector.copyToResult(result, Detector.findRowsWithPattern(matrix, height, width, startRow, startColumn, Detector.START_PATTERN), Detector.INDEXES_START_PATTERN);
if (result[4] != null) {
startColumn = Math.trunc(result[4].getX());
startRow = Math.trunc(result[4].getY());
}
Detector.copyToResult(result, Detector.findRowsWithPattern(matrix, height, width, startRow, startColumn, Detector.STOP_PATTERN), Detector.INDEXES_STOP_PATTERN);
return result;
};
Detector.copyToResult = function (result, tmpResult, destinationIndexes) {
for (var i = 0; i < destinationIndexes.length; i++) {
result[destinationIndexes[i]] = tmpResult[i];
}
};
Detector.findRowsWithPattern = function (matrix, height, width, startRow, startColumn, pattern) {
// const result = new ResultPoint[4];
var result = new Array(4);
var found = false;
var counters = new Int32Array(pattern.length);
for (; startRow < height; startRow += Detector.ROW_STEP) {
var loc = Detector.findGuardPattern(matrix, startColumn, startRow, width, false, pattern, counters);
if (loc != null) {
while (startRow > 0) {
var previousRowLoc = Detector.findGuardPattern(matrix, startColumn, --startRow, width, false, pattern, counters);
if (previousRowLoc != null) {
loc = previousRowLoc;
}
else {
startRow++;
break;
}
}
result[0] = new ResultPoint_1.default(loc[0], startRow);
result[1] = new ResultPoint_1.default(loc[1], startRow);
found = true;
break;
}
}
var stopRow = startRow + 1;
// Last row of the current symbol that contains pattern
if (found) {
var skippedRowCount = 0;
var previousRowLoc = Int32Array.from([Math.trunc(result[0].getX()), Math.trunc(result[1].getX())]);
for (; stopRow < height; stopRow++) {
var 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_1.default(previousRowLoc[0], stopRow);
result[3] = new ResultPoint_1.default(previousRowLoc[1], stopRow);
}
if (stopRow - startRow < Detector.BARCODE_MIN_HEIGHT) {
Arrays_1.default.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.
*/
Detector.findGuardPattern = function (matrix, column, row, width, whiteFirst, pattern, counters) {
Arrays_1.default.fillWithin(counters, 0, counters.length, 0);
var patternStart = column;
var 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--;
}
var x = patternStart;
var counterPosition = 0;
var patternLength = pattern.length;
for (var isWhite = whiteFirst; x < width; x++) {
var 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_1.default.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
*/
Detector.patternMatchVariance = function (counters, pattern, maxIndividualVariance) {
var numCounters = counters.length;
var total = 0;
var patternLength = 0;
for (var 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".
var unitBarWidth = total / patternLength;
maxIndividualVariance *= unitBarWidth;
var totalVariance = 0.0;
for (var x = 0; x < numCounters; x++) {
var counter = counters[x];
var scaledPattern = pattern[x] * unitBarWidth;
var variance = counter > scaledPattern ? counter - scaledPattern : scaledPattern - counter;
if (variance > maxIndividualVariance) {
return /*Float.POSITIVE_INFINITY*/ Infinity;
}
totalVariance += variance;
}
return totalVariance / total;
};
Detector.INDEXES_START_PATTERN = Int32Array.from([0, 4, 1, 5]);
Detector.INDEXES_STOP_PATTERN = Int32Array.from([6, 2, 7, 3]);
Detector.MAX_AVG_VARIANCE = 0.42;
Detector.MAX_INDIVIDUAL_VARIANCE = 0.8;
// B S B S B S B S Bar/Space pattern
// 11111111 0 1 0 1 0 1 000
Detector.START_PATTERN = Int32Array.from([8, 1, 1, 1, 1, 1, 1, 3]);
// 1111111 0 1 000 1 0 1 00 1
Detector.STOP_PATTERN = Int32Array.from([7, 1, 1, 3, 1, 1, 1, 2, 1]);
Detector.MAX_PIXEL_DRIFT = 3;
Detector.MAX_PATTERN_DRIFT = 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.
Detector.SKIPPED_ROW_COUNT_MAX = 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.
Detector.ROW_STEP = 5;
Detector.BARCODE_MIN_HEIGHT = 10;
return Detector;
}());
exports.default = Detector;