@zxing/library
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TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
302 lines (301 loc) • 11.5 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.
*/
/*namespace com.google.zxing.common.detector {*/
import ResultPoint from '../../ResultPoint';
import MathUtils from './MathUtils';
import NotFoundException from '../../NotFoundException';
/**
* <p>
* Detects a candidate barcode-like rectangular region within an image. It
* starts around the center of the image, increases the size of the candidate
* region until it finds a white rectangular region. By keeping track of the
* last black points it encountered, it determines the corners of the barcode.
* </p>
*
* @author David Olivier
*/
export default class WhiteRectangleDetector {
// public constructor(private image: BitMatrix) /*throws NotFoundException*/ {
// this(image, INIT_SIZE, image.getWidth() / 2, image.getHeight() / 2)
// }
/**
* @param image barcode image to find a rectangle in
* @param initSize initial size of search area around center
* @param x x position of search center
* @param y y position of search center
* @throws NotFoundException if image is too small to accommodate {@code initSize}
*/
constructor(image, initSize /*int*/, x /*int*/, y /*int*/) {
this.image = image;
this.height = image.getHeight();
this.width = image.getWidth();
if (undefined === initSize || null === initSize) {
initSize = WhiteRectangleDetector.INIT_SIZE;
}
if (undefined === x || null === x) {
x = image.getWidth() / 2 | 0;
}
if (undefined === y || null === y) {
y = image.getHeight() / 2 | 0;
}
const halfsize = initSize / 2 | 0;
this.leftInit = x - halfsize;
this.rightInit = x + halfsize;
this.upInit = y - halfsize;
this.downInit = y + halfsize;
if (this.upInit < 0 || this.leftInit < 0 || this.downInit >= this.height || this.rightInit >= this.width) {
throw new NotFoundException();
}
}
/**
* <p>
* Detects a candidate barcode-like rectangular region within an image. It
* starts around the center of the image, increases the size of the candidate
* region until it finds a white rectangular region.
* </p>
*
* @return {@link ResultPoint}[] describing the corners of the rectangular
* region. The first and last points are opposed on the diagonal, as
* are the second and third. The first point will be the topmost
* point and the last, the bottommost. The second point will be
* leftmost and the third, the rightmost
* @throws NotFoundException if no Data Matrix Code can be found
*/
detect() {
let left = this.leftInit;
let right = this.rightInit;
let up = this.upInit;
let down = this.downInit;
let sizeExceeded = false;
let aBlackPointFoundOnBorder = true;
let atLeastOneBlackPointFoundOnBorder = false;
let atLeastOneBlackPointFoundOnRight = false;
let atLeastOneBlackPointFoundOnBottom = false;
let atLeastOneBlackPointFoundOnLeft = false;
let atLeastOneBlackPointFoundOnTop = false;
const width = this.width;
const height = this.height;
while (aBlackPointFoundOnBorder) {
aBlackPointFoundOnBorder = false;
// .....
// . |
// .....
let rightBorderNotWhite = true;
while ((rightBorderNotWhite || !atLeastOneBlackPointFoundOnRight) && right < width) {
rightBorderNotWhite = this.containsBlackPoint(up, down, right, false);
if (rightBorderNotWhite) {
right++;
aBlackPointFoundOnBorder = true;
atLeastOneBlackPointFoundOnRight = true;
}
else if (!atLeastOneBlackPointFoundOnRight) {
right++;
}
}
if (right >= width) {
sizeExceeded = true;
break;
}
// .....
// . .
// .___.
let bottomBorderNotWhite = true;
while ((bottomBorderNotWhite || !atLeastOneBlackPointFoundOnBottom) && down < height) {
bottomBorderNotWhite = this.containsBlackPoint(left, right, down, true);
if (bottomBorderNotWhite) {
down++;
aBlackPointFoundOnBorder = true;
atLeastOneBlackPointFoundOnBottom = true;
}
else if (!atLeastOneBlackPointFoundOnBottom) {
down++;
}
}
if (down >= height) {
sizeExceeded = true;
break;
}
// .....
// | .
// .....
let leftBorderNotWhite = true;
while ((leftBorderNotWhite || !atLeastOneBlackPointFoundOnLeft) && left >= 0) {
leftBorderNotWhite = this.containsBlackPoint(up, down, left, false);
if (leftBorderNotWhite) {
left--;
aBlackPointFoundOnBorder = true;
atLeastOneBlackPointFoundOnLeft = true;
}
else if (!atLeastOneBlackPointFoundOnLeft) {
left--;
}
}
if (left < 0) {
sizeExceeded = true;
break;
}
// .___.
// . .
// .....
let topBorderNotWhite = true;
while ((topBorderNotWhite || !atLeastOneBlackPointFoundOnTop) && up >= 0) {
topBorderNotWhite = this.containsBlackPoint(left, right, up, true);
if (topBorderNotWhite) {
up--;
aBlackPointFoundOnBorder = true;
atLeastOneBlackPointFoundOnTop = true;
}
else if (!atLeastOneBlackPointFoundOnTop) {
up--;
}
}
if (up < 0) {
sizeExceeded = true;
break;
}
if (aBlackPointFoundOnBorder) {
atLeastOneBlackPointFoundOnBorder = true;
}
}
if (!sizeExceeded && atLeastOneBlackPointFoundOnBorder) {
const maxSize = right - left;
let z = null;
for (let i = 1; z === null && i < maxSize; i++) {
z = this.getBlackPointOnSegment(left, down - i, left + i, down);
}
if (z == null) {
throw new NotFoundException();
}
let t = null;
// go down right
for (let i = 1; t === null && i < maxSize; i++) {
t = this.getBlackPointOnSegment(left, up + i, left + i, up);
}
if (t == null) {
throw new NotFoundException();
}
let x = null;
// go down left
for (let i = 1; x === null && i < maxSize; i++) {
x = this.getBlackPointOnSegment(right, up + i, right - i, up);
}
if (x == null) {
throw new NotFoundException();
}
let y = null;
// go up left
for (let i = 1; y === null && i < maxSize; i++) {
y = this.getBlackPointOnSegment(right, down - i, right - i, down);
}
if (y == null) {
throw new NotFoundException();
}
return this.centerEdges(y, z, x, t);
}
else {
throw new NotFoundException();
}
}
getBlackPointOnSegment(aX /*float*/, aY /*float*/, bX /*float*/, bY /*float*/) {
const dist = MathUtils.round(MathUtils.distance(aX, aY, bX, bY));
const xStep = (bX - aX) / dist;
const yStep = (bY - aY) / dist;
const image = this.image;
for (let i = 0; i < dist; i++) {
const x = MathUtils.round(aX + i * xStep);
const y = MathUtils.round(aY + i * yStep);
if (image.get(x, y)) {
return new ResultPoint(x, y);
}
}
return null;
}
/**
* recenters the points of a constant distance towards the center
*
* @param y bottom most point
* @param z left most point
* @param x right most point
* @param t top most point
* @return {@link ResultPoint}[] describing the corners of the rectangular
* region. The first and last points are opposed on the diagonal, as
* are the second and third. The first point will be the topmost
* point and the last, the bottommost. The second point will be
* leftmost and the third, the rightmost
*/
centerEdges(y, z, x, t) {
//
// t t
// z x
// x OR z
// y y
//
const yi = y.getX();
const yj = y.getY();
const zi = z.getX();
const zj = z.getY();
const xi = x.getX();
const xj = x.getY();
const ti = t.getX();
const tj = t.getY();
const CORR = WhiteRectangleDetector.CORR;
if (yi < this.width / 2.0) {
return [
new ResultPoint(ti - CORR, tj + CORR),
new ResultPoint(zi + CORR, zj + CORR),
new ResultPoint(xi - CORR, xj - CORR),
new ResultPoint(yi + CORR, yj - CORR)
];
}
else {
return [
new ResultPoint(ti + CORR, tj + CORR),
new ResultPoint(zi + CORR, zj - CORR),
new ResultPoint(xi - CORR, xj + CORR),
new ResultPoint(yi - CORR, yj - CORR)
];
}
}
/**
* Determines whether a segment contains a black point
*
* @param a min value of the scanned coordinate
* @param b max value of the scanned coordinate
* @param fixed value of fixed coordinate
* @param horizontal set to true if scan must be horizontal, false if vertical
* @return true if a black point has been found, else false.
*/
containsBlackPoint(a /*int*/, b /*int*/, fixed /*int*/, horizontal) {
const image = this.image;
if (horizontal) {
for (let x = a; x <= b; x++) {
if (image.get(x, fixed)) {
return true;
}
}
}
else {
for (let y = a; y <= b; y++) {
if (image.get(fixed, y)) {
return true;
}
}
}
return false;
}
}
WhiteRectangleDetector.INIT_SIZE = 10;
WhiteRectangleDetector.CORR = 1;