Preparing pdf417 decoding
Christoph Oberhofer
9 years ago
parent
7ec6eb28d3
commit
a8b2d3ed9a
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export function getCenterLineFromBox(box) {
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return [{
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x: (box[1][0] - box[0][0]) / 2 + box[0][0],
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y: (box[1][1] - box[0][1]) / 2 + box[0][1]
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}, {
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x: (box[3][0] - box[2][0]) / 2 + box[2][0],
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y: (box[3][1] - box[2][1]) / 2 + box[2][1]
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}];
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}
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export function getLineLength(line) {
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return Math.sqrt(
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Math.pow(Math.abs(line[1].y - line[0].y), 2) +
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Math.pow(Math.abs(line[1].x - line[0].x), 2));
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}
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export function getLineAngle(line) {
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return Math.atan2(line[1].y - line[0].y, line[1].x - line[0].x);
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}
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function extendLine(line, angle, ext) {
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const extension = {
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y: ext * Math.sin(angle),
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x: ext * Math.cos(angle)
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};
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line[0].y -= extension.y;
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line[0].x -= extension.x;
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line[1].y += extension.y;
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line[1].x += extension.x;
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return line;
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}
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export function getExtendedLine(inputImageWrapper, line, angle, ext) {
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line = extendLine(line, angle, ext);
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while (ext > 1 && (!inputImageWrapper.inImageWithBorder(line[0], 0)
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|| !inputImageWrapper.inImageWithBorder(line[1], 0))) {
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ext -= Math.ceil(ext / 2);
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line = extendLine(line, angle, -ext);
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}
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return line;
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}
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@ -0,0 +1,48 @@
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import {
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getCenterLineFromBox as getLine,
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getLineLength,
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getLineAngle,
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getExtendedLine
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} from '../common/geometric';
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import ImageDebug from '../common/image_debug';
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import Bresenham from '../decoder/bresenham';
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import {findPattern} from '../reader/common';
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const vec2 = {
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clone: require('gl-vec2/clone'),
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dot: require('gl-vec2/dot')
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}
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const START_PATTERN = [8, 1, 1, 1, 1, 1, 1, 3],
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STOP_PATTERN = [7, 1, 1, 3, 1, 1, 1, 2, 1],
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MODULO = START_PATTERN.reduce((sum, i) => (sum + i),0);
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export default function detect(inputImageWrapper, box, ctx) {
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let line = getLine(box),
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lineLength = getLineLength(line),
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lineAngle = getLineAngle(line),
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extendedLine = getExtendedLine(inputImageWrapper, line, lineAngle, Math.floor(lineLength * 0.15)),
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barcodeLine = Bresenham.getBarcodeLine(inputImageWrapper, extendedLine[0], extendedLine[1]);
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if (ENV.development) {
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if (ctx) {
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ImageDebug.drawPath(extendedLine, {x: 'x', y: 'y'}, ctx, {color: 'red', lineWidth: 1});
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}
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}
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Bresenham.toBinaryLine(barcodeLine);
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const match = findPattern(barcodeLine.line, START_PATTERN, {modulo: MODULO});
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console.log(match);
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return [
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vec2.clone([199, 84]),
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vec2.clone([210, 303]),
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vec2.clone([634, 88]),
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vec2.clone([660, 271]),
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vec2.clone([295, 83]),
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vec2.clone([310, 295]),
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vec2.clone([554, 83]),
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vec2.clone([580, 277])
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]
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};
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@ -0,0 +1,126 @@
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export function nextSet(line, offset) {
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var i;
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offset = offset || 0;
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for (i = offset; i < line.length; i++) {
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if (line[i]) {
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return i;
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}
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}
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return line.length;
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};
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export function normalize(counter, modulo) {
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var i,
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sum = 0,
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ratio,
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numOnes = 0,
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normalized = [],
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norm = 0;
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for (i = 0; i < counter.length; i++) {
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if (counter[i] === 1) {
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numOnes++;
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} else {
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sum += counter[i];
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}
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}
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ratio = sum / (modulo - numOnes);
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if (ratio > 1.0) {
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for (i = 0; i < counter.length; i++) {
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norm = counter[i] === 1 ? counter[i] : counter[i] / ratio;
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normalized.push(norm);
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}
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} else {
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ratio = (sum + numOnes) / modulo;
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for (i = 0; i < counter.length; i++) {
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norm = counter[i] / ratio;
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normalized.push(norm);
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}
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}
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return normalized;
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}
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export function matchPattern(counter, code, modulo, maxSingleError=1) {
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var i,
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error = 0,
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singleError = 0;
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for (i = 0; i < counter.length; i++) {
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singleError = Math.abs(code[i] - counter[i]);
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if (singleError > maxSingleError) {
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return Number.MAX_VALUE;
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}
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error += singleError;
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}
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return error / modulo;
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}
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export function findPattern(row, pattern, {
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offset,
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isWhite=false,
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tryHarder=true,
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epsilon=0.5,
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maxSingleError=0.5,
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modulo}) {
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var counter = [],
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i,
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counterPos = 0,
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bestMatch = {
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error: Number.MAX_VALUE,
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code: -1,
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start: 0,
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end: 0
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},
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error,
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j,
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sum,
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normalized;
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if (!offset) {
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offset = nextSet(row);
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}
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for ( i = 0; i < pattern.length; i++) {
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counter[i] = 0;
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}
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for ( i = offset; i < row.length; i++) {
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if (row[i] ^ isWhite) {
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counter[counterPos]++;
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} else {
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if (counterPos === counter.length - 1) {
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sum = 0;
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for ( j = 0; j < counter.length; j++) {
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sum += counter[j];
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}
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normalized = normalize(counter, modulo);
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if (normalized) {
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error = matchPattern(normalized, pattern, modulo, maxSingleError);
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if (error < epsilon) {
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bestMatch.error = error;
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bestMatch.start = i - sum;
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bestMatch.end = i;
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return bestMatch;
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}
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}
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if (tryHarder) {
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for ( j = 0; j < counter.length - 2; j++) {
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counter[j] = counter[j + 2];
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}
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counter[counter.length - 2] = 0;
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counter[counter.length - 1] = 0;
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counterPos--;
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} else {
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return null;
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}
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} else {
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counterPos++;
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}
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counter[counterPos] = 1;
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isWhite = !isWhite;
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}
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}
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return null;
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}
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@ -0,0 +1,30 @@
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import BarcodeReader from './barcode_reader';
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import detect from '../detector/pdf_147_detector';
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import ImageDebug from '../common/image_debug';
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function Pdf147Reader() {
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BarcodeReader.call(this);
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}
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const properties = {
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SINGLE_CODE_ERROR: {value: 1},
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AVG_CODE_ERROR: {value: 0.5},
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FORMAT: {value: "pdf147", writeable: false}
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};
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Pdf147Reader.prototype = Object.create(BarcodeReader.prototype, properties);
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Pdf147Reader.prototype.constructor = Pdf147Reader;
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Pdf147Reader.prototype.decode = function(inputImageWrapper, box, ctx) {
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console.log("Pdf147Reader...");
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const detectionInfo = detect(inputImageWrapper, box, ctx);
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console.log(detectionInfo);
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if (ENV.development) {
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if (ctx) {
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ImageDebug.drawVertices(detectionInfo, {x: 0, y: 1}, ctx, {color: "red", lineWidth: 1});
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}
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}
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console.log("Pdf147Reader... END")
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};
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export default Pdf147Reader;
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