@zxing/library
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TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
486 lines (485 loc) • 20.7 kB
JavaScript
/*
* Copyright 2010 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.
*/
import ResultPoint from '../../ResultPoint';
import AztecDetectorResult from '../AztecDetectorResult';
import MathUtils from '../../common/detector/MathUtils';
import WhiteRectangleDetector from '../../common/detector/WhiteRectangleDetector';
import GenericGF from '../../common/reedsolomon/GenericGF';
import ReedSolomonDecoder from '../../common/reedsolomon/ReedSolomonDecoder';
import NotFoundException from '../../NotFoundException';
import GridSamplerInstance from '../../common/GridSamplerInstance';
import Integer from '../../util/Integer';
export class Point {
constructor(x, y) {
this.x = x;
this.y = y;
}
toResultPoint() {
return new ResultPoint(this.getX(), this.getY());
}
getX() {
return this.x;
}
getY() {
return this.y;
}
}
/**
* Encapsulates logic that can detect an Aztec Code in an image, even if the Aztec Code
* is rotated or skewed, or partially obscured.
*
* @author David Olivier
* @author Frank Yellin
*/
export default class Detector {
constructor(image) {
this.EXPECTED_CORNER_BITS = new Int32Array([
0xee0,
0x1dc,
0x83b,
0x707,
]);
this.image = image;
}
detect() {
return this.detectMirror(false);
}
/**
* Detects an Aztec Code in an image.
*
* @param isMirror if true, image is a mirror-image of original
* @return {@link AztecDetectorResult} encapsulating results of detecting an Aztec Code
* @throws NotFoundException if no Aztec Code can be found
*/
detectMirror(isMirror) {
// 1. Get the center of the aztec matrix
let pCenter = this.getMatrixCenter();
// 2. Get the center points of the four diagonal points just outside the bull's eye
// [topRight, bottomRight, bottomLeft, topLeft]
let bullsEyeCorners = this.getBullsEyeCorners(pCenter);
if (isMirror) {
let temp = bullsEyeCorners[0];
bullsEyeCorners[0] = bullsEyeCorners[2];
bullsEyeCorners[2] = temp;
}
// 3. Get the size of the matrix and other parameters from the bull's eye
this.extractParameters(bullsEyeCorners);
// 4. Sample the grid
let bits = this.sampleGrid(this.image, bullsEyeCorners[this.shift % 4], bullsEyeCorners[(this.shift + 1) % 4], bullsEyeCorners[(this.shift + 2) % 4], bullsEyeCorners[(this.shift + 3) % 4]);
// 5. Get the corners of the matrix.
let corners = this.getMatrixCornerPoints(bullsEyeCorners);
return new AztecDetectorResult(bits, corners, this.compact, this.nbDataBlocks, this.nbLayers);
}
/**
* Extracts the number of data layers and data blocks from the layer around the bull's eye.
*
* @param bullsEyeCorners the array of bull's eye corners
* @throws NotFoundException in case of too many errors or invalid parameters
*/
extractParameters(bullsEyeCorners) {
if (!this.isValidPoint(bullsEyeCorners[0]) || !this.isValidPoint(bullsEyeCorners[1]) ||
!this.isValidPoint(bullsEyeCorners[2]) || !this.isValidPoint(bullsEyeCorners[3])) {
throw new NotFoundException();
}
let length = 2 * this.nbCenterLayers;
// Get the bits around the bull's eye
let sides = new Int32Array([
this.sampleLine(bullsEyeCorners[0], bullsEyeCorners[1], length),
this.sampleLine(bullsEyeCorners[1], bullsEyeCorners[2], length),
this.sampleLine(bullsEyeCorners[2], bullsEyeCorners[3], length),
this.sampleLine(bullsEyeCorners[3], bullsEyeCorners[0], length) // Top
]);
// bullsEyeCorners[shift] is the corner of the bulls'eye that has three
// orientation marks.
// sides[shift] is the row/column that goes from the corner with three
// orientation marks to the corner with two.
this.shift = this.getRotation(sides, length);
// Flatten the parameter bits into a single 28- or 40-bit long
let parameterData = 0;
for (let i = 0; i < 4; i++) {
let side = sides[(this.shift + i) % 4];
if (this.compact) {
// Each side of the form ..XXXXXXX. where Xs are parameter data
parameterData <<= 7;
parameterData += (side >> 1) & 0x7F;
}
else {
// Each side of the form ..XXXXX.XXXXX. where Xs are parameter data
parameterData <<= 10;
parameterData += ((side >> 2) & (0x1f << 5)) + ((side >> 1) & 0x1F);
}
}
// Corrects parameter data using RS. Returns just the data portion
// without the error correction.
let correctedData = this.getCorrectedParameterData(parameterData, this.compact);
if (this.compact) {
// 8 bits: 2 bits layers and 6 bits data blocks
this.nbLayers = (correctedData >> 6) + 1;
this.nbDataBlocks = (correctedData & 0x3F) + 1;
}
else {
// 16 bits: 5 bits layers and 11 bits data blocks
this.nbLayers = (correctedData >> 11) + 1;
this.nbDataBlocks = (correctedData & 0x7FF) + 1;
}
}
getRotation(sides, length) {
// In a normal pattern, we expect to See
// ** .* D A
// * *
//
// . *
// .. .. C B
//
// Grab the 3 bits from each of the sides the form the locator pattern and concatenate
// into a 12-bit integer. Start with the bit at A
let cornerBits = 0;
sides.forEach((side, idx, arr) => {
// XX......X where X's are orientation marks
let t = ((side >> (length - 2)) << 1) + (side & 1);
cornerBits = (cornerBits << 3) + t;
});
// for (var side in sides) {
// // XX......X where X's are orientation marks
// var t = ((side >> (length - 2)) << 1) + (side & 1);
// cornerBits = (cornerBits << 3) + t;
// }
// Mov the bottom bit to the top, so that the three bits of the locator pattern at A are
// together. cornerBits is now:
// 3 orientation bits at A || 3 orientation bits at B || ... || 3 orientation bits at D
cornerBits = ((cornerBits & 1) << 11) + (cornerBits >> 1);
// The result shift indicates which element of BullsEyeCorners[] goes into the top-left
// corner. Since the four rotation values have a Hamming distance of 8, we
// can easily tolerate two errors.
for (let shift = 0; shift < 4; shift++) {
if (Integer.bitCount(cornerBits ^ this.EXPECTED_CORNER_BITS[shift]) <= 2) {
return shift;
}
}
throw new NotFoundException();
}
/**
* Corrects the parameter bits using Reed-Solomon algorithm.
*
* @param parameterData parameter bits
* @param compact true if this is a compact Aztec code
* @throws NotFoundException if the array contains too many errors
*/
getCorrectedParameterData(parameterData, compact) {
let numCodewords;
let numDataCodewords;
if (compact) {
numCodewords = 7;
numDataCodewords = 2;
}
else {
numCodewords = 10;
numDataCodewords = 4;
}
let numECCodewords = numCodewords - numDataCodewords;
let parameterWords = new Int32Array(numCodewords);
for (let i = numCodewords - 1; i >= 0; --i) {
parameterWords[i] = parameterData & 0xF;
parameterData >>= 4;
}
try {
let rsDecoder = new ReedSolomonDecoder(GenericGF.AZTEC_PARAM);
rsDecoder.decode(parameterWords, numECCodewords);
}
catch (ignored) {
throw new NotFoundException();
}
// Toss the error correction. Just return the data as an integer
let result = 0;
for (let i = 0; i < numDataCodewords; i++) {
result = (result << 4) + parameterWords[i];
}
return result;
}
/**
* Finds the corners of a bull-eye centered on the passed point.
* This returns the centers of the diagonal points just outside the bull's eye
* Returns [topRight, bottomRight, bottomLeft, topLeft]
*
* @param pCenter Center point
* @return The corners of the bull-eye
* @throws NotFoundException If no valid bull-eye can be found
*/
getBullsEyeCorners(pCenter) {
let pina = pCenter;
let pinb = pCenter;
let pinc = pCenter;
let pind = pCenter;
let color = true;
for (this.nbCenterLayers = 1; this.nbCenterLayers < 9; this.nbCenterLayers++) {
let pouta = this.getFirstDifferent(pina, color, 1, -1);
let poutb = this.getFirstDifferent(pinb, color, 1, 1);
let poutc = this.getFirstDifferent(pinc, color, -1, 1);
let poutd = this.getFirstDifferent(pind, color, -1, -1);
// d a
//
// c b
if (this.nbCenterLayers > 2) {
let q = (this.distancePoint(poutd, pouta) * this.nbCenterLayers) / (this.distancePoint(pind, pina) * (this.nbCenterLayers + 2));
if (q < 0.75 || q > 1.25 || !this.isWhiteOrBlackRectangle(pouta, poutb, poutc, poutd)) {
break;
}
}
pina = pouta;
pinb = poutb;
pinc = poutc;
pind = poutd;
color = !color;
}
if (this.nbCenterLayers !== 5 && this.nbCenterLayers !== 7) {
throw new NotFoundException();
}
this.compact = this.nbCenterLayers === 5;
// Expand the square by .5 pixel in each direction so that we're on the border
// between the white square and the black square
let pinax = new ResultPoint(pina.getX() + 0.5, pina.getY() - 0.5);
let pinbx = new ResultPoint(pinb.getX() + 0.5, pinb.getY() + 0.5);
let pincx = new ResultPoint(pinc.getX() - 0.5, pinc.getY() + 0.5);
let pindx = new ResultPoint(pind.getX() - 0.5, pind.getY() - 0.5);
// Expand the square so that its corners are the centers of the points
// just outside the bull's eye.
return this.expandSquare([pinax, pinbx, pincx, pindx], 2 * this.nbCenterLayers - 3, 2 * this.nbCenterLayers);
}
/**
* Finds a candidate center point of an Aztec code from an image
*
* @return the center point
*/
getMatrixCenter() {
let pointA;
let pointB;
let pointC;
let pointD;
// Get a white rectangle that can be the border of the matrix in center bull's eye or
try {
let cornerPoints = new WhiteRectangleDetector(this.image).detect();
pointA = cornerPoints[0];
pointB = cornerPoints[1];
pointC = cornerPoints[2];
pointD = cornerPoints[3];
}
catch (e) {
// This exception can be in case the initial rectangle is white
// In that case, surely in the bull's eye, we try to expand the rectangle.
let cx = this.image.getWidth() / 2;
let cy = this.image.getHeight() / 2;
pointA = this.getFirstDifferent(new Point(cx + 7, cy - 7), false, 1, -1).toResultPoint();
pointB = this.getFirstDifferent(new Point(cx + 7, cy + 7), false, 1, 1).toResultPoint();
pointC = this.getFirstDifferent(new Point(cx - 7, cy + 7), false, -1, 1).toResultPoint();
pointD = this.getFirstDifferent(new Point(cx - 7, cy - 7), false, -1, -1).toResultPoint();
}
// Compute the center of the rectangle
let cx = MathUtils.round((pointA.getX() + pointD.getX() + pointB.getX() + pointC.getX()) / 4.0);
let cy = MathUtils.round((pointA.getY() + pointD.getY() + pointB.getY() + pointC.getY()) / 4.0);
// Redetermine the white rectangle starting from previously computed center.
// This will ensure that we end up with a white rectangle in center bull's eye
// in order to compute a more accurate center.
try {
let cornerPoints = new WhiteRectangleDetector(this.image, 15, cx, cy).detect();
pointA = cornerPoints[0];
pointB = cornerPoints[1];
pointC = cornerPoints[2];
pointD = cornerPoints[3];
}
catch (e) {
// This exception can be in case the initial rectangle is white
// In that case we try to expand the rectangle.
pointA = this.getFirstDifferent(new Point(cx + 7, cy - 7), false, 1, -1).toResultPoint();
pointB = this.getFirstDifferent(new Point(cx + 7, cy + 7), false, 1, 1).toResultPoint();
pointC = this.getFirstDifferent(new Point(cx - 7, cy + 7), false, -1, 1).toResultPoint();
pointD = this.getFirstDifferent(new Point(cx - 7, cy - 7), false, -1, -1).toResultPoint();
}
// Recompute the center of the rectangle
cx = MathUtils.round((pointA.getX() + pointD.getX() + pointB.getX() + pointC.getX()) / 4.0);
cy = MathUtils.round((pointA.getY() + pointD.getY() + pointB.getY() + pointC.getY()) / 4.0);
return new Point(cx, cy);
}
/**
* Gets the Aztec code corners from the bull's eye corners and the parameters.
*
* @param bullsEyeCorners the array of bull's eye corners
* @return the array of aztec code corners
*/
getMatrixCornerPoints(bullsEyeCorners) {
return this.expandSquare(bullsEyeCorners, 2 * this.nbCenterLayers, this.getDimension());
}
/**
* Creates a BitMatrix by sampling the provided image.
* topLeft, topRight, bottomRight, and bottomLeft are the centers of the squares on the
* diagonal just outside the bull's eye.
*/
sampleGrid(image, topLeft, topRight, bottomRight, bottomLeft) {
let sampler = GridSamplerInstance.getInstance();
let dimension = this.getDimension();
let low = dimension / 2 - this.nbCenterLayers;
let high = dimension / 2 + this.nbCenterLayers;
return sampler.sampleGrid(image, dimension, dimension, low, low, // topleft
high, low, // topright
high, high, // bottomright
low, high, // bottomleft
topLeft.getX(), topLeft.getY(), topRight.getX(), topRight.getY(), bottomRight.getX(), bottomRight.getY(), bottomLeft.getX(), bottomLeft.getY());
}
/**
* Samples a line.
*
* @param p1 start point (inclusive)
* @param p2 end point (exclusive)
* @param size number of bits
* @return the array of bits as an int (first bit is high-order bit of result)
*/
sampleLine(p1, p2, size) {
let result = 0;
let d = this.distanceResultPoint(p1, p2);
let moduleSize = d / size;
let px = p1.getX();
let py = p1.getY();
let dx = moduleSize * (p2.getX() - p1.getX()) / d;
let dy = moduleSize * (p2.getY() - p1.getY()) / d;
for (let i = 0; i < size; i++) {
if (this.image.get(MathUtils.round(px + i * dx), MathUtils.round(py + i * dy))) {
result |= 1 << (size - i - 1);
}
}
return result;
}
/**
* @return true if the border of the rectangle passed in parameter is compound of white points only
* or black points only
*/
isWhiteOrBlackRectangle(p1, p2, p3, p4) {
let corr = 3;
p1 = new Point(p1.getX() - corr, p1.getY() + corr);
p2 = new Point(p2.getX() - corr, p2.getY() - corr);
p3 = new Point(p3.getX() + corr, p3.getY() - corr);
p4 = new Point(p4.getX() + corr, p4.getY() + corr);
let cInit = this.getColor(p4, p1);
if (cInit === 0) {
return false;
}
let c = this.getColor(p1, p2);
if (c !== cInit) {
return false;
}
c = this.getColor(p2, p3);
if (c !== cInit) {
return false;
}
c = this.getColor(p3, p4);
return c === cInit;
}
/**
* Gets the color of a segment
*
* @return 1 if segment more than 90% black, -1 if segment is more than 90% white, 0 else
*/
getColor(p1, p2) {
let d = this.distancePoint(p1, p2);
let dx = (p2.getX() - p1.getX()) / d;
let dy = (p2.getY() - p1.getY()) / d;
let error = 0;
let px = p1.getX();
let py = p1.getY();
let colorModel = this.image.get(p1.getX(), p1.getY());
let iMax = Math.ceil(d);
for (let i = 0; i < iMax; i++) {
px += dx;
py += dy;
if (this.image.get(MathUtils.round(px), MathUtils.round(py)) !== colorModel) {
error++;
}
}
let errRatio = error / d;
if (errRatio > 0.1 && errRatio < 0.9) {
return 0;
}
return (errRatio <= 0.1) === colorModel ? 1 : -1;
}
/**
* Gets the coordinate of the first point with a different color in the given direction
*/
getFirstDifferent(init, color, dx, dy) {
let x = init.getX() + dx;
let y = init.getY() + dy;
while (this.isValid(x, y) && this.image.get(x, y) === color) {
x += dx;
y += dy;
}
x -= dx;
y -= dy;
while (this.isValid(x, y) && this.image.get(x, y) === color) {
x += dx;
}
x -= dx;
while (this.isValid(x, y) && this.image.get(x, y) === color) {
y += dy;
}
y -= dy;
return new Point(x, y);
}
/**
* Expand the square represented by the corner points by pushing out equally in all directions
*
* @param cornerPoints the corners of the square, which has the bull's eye at its center
* @param oldSide the original length of the side of the square in the target bit matrix
* @param newSide the new length of the size of the square in the target bit matrix
* @return the corners of the expanded square
*/
expandSquare(cornerPoints, oldSide, newSide) {
let ratio = newSide / (2.0 * oldSide);
let dx = cornerPoints[0].getX() - cornerPoints[2].getX();
let dy = cornerPoints[0].getY() - cornerPoints[2].getY();
let centerx = (cornerPoints[0].getX() + cornerPoints[2].getX()) / 2.0;
let centery = (cornerPoints[0].getY() + cornerPoints[2].getY()) / 2.0;
let result0 = new ResultPoint(centerx + ratio * dx, centery + ratio * dy);
let result2 = new ResultPoint(centerx - ratio * dx, centery - ratio * dy);
dx = cornerPoints[1].getX() - cornerPoints[3].getX();
dy = cornerPoints[1].getY() - cornerPoints[3].getY();
centerx = (cornerPoints[1].getX() + cornerPoints[3].getX()) / 2.0;
centery = (cornerPoints[1].getY() + cornerPoints[3].getY()) / 2.0;
let result1 = new ResultPoint(centerx + ratio * dx, centery + ratio * dy);
let result3 = new ResultPoint(centerx - ratio * dx, centery - ratio * dy);
let results = [result0, result1, result2, result3];
return results;
}
isValid(x, y) {
return x >= 0 && x < this.image.getWidth() && y > 0 && y < this.image.getHeight();
}
isValidPoint(point) {
let x = MathUtils.round(point.getX());
let y = MathUtils.round(point.getY());
return this.isValid(x, y);
}
distancePoint(a, b) {
return MathUtils.distance(a.getX(), a.getY(), b.getX(), b.getY());
}
distanceResultPoint(a, b) {
return MathUtils.distance(a.getX(), a.getY(), b.getX(), b.getY());
}
getDimension() {
if (this.compact) {
return 4 * this.nbLayers + 11;
}
if (this.nbLayers <= 4) {
return 4 * this.nbLayers + 15;
}
return 4 * this.nbLayers + 2 * (Integer.truncDivision((this.nbLayers - 4), 8) + 1) + 15;
}
}