@zxing/library
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TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
257 lines (256 loc) • 10.9 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 NotFoundException from '../../NotFoundException';
/**
* @author Mariusz Dąbrowski
*/
export default class CornerDetector {
/**
* @throws NotFoundException if image is too small to accommodate {@code initSize}
*/
constructor(image, initSize, x, y, targetMatrixSize) {
this.image = image;
this.height = image.getHeight();
this.width = image.getWidth();
const halfsize = initSize / 2;
this.leftInit = x - halfsize;
this.rightInit = x + halfsize;
this.upInit = y - halfsize;
this.downInit = y + halfsize;
this.targetMatrixSize = targetMatrixSize * 2;
if (this.upInit < 0 || this.leftInit < 0 || this.downInit >= this.height || this.rightInit >= this.width) {
throw new NotFoundException();
}
}
/**
* @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;
while (aBlackPointFoundOnBorder) {
aBlackPointFoundOnBorder = false;
// .....
// . |
// .....
let rightBorderNotWhite = true;
while ((rightBorderNotWhite || !atLeastOneBlackPointFoundOnRight) && right < this.width) {
rightBorderNotWhite = this.containsBlackPoint(up, down, right, false);
if (rightBorderNotWhite) {
right++;
aBlackPointFoundOnBorder = true;
atLeastOneBlackPointFoundOnRight = true;
}
else if (!atLeastOneBlackPointFoundOnRight) {
right++;
}
}
if (right >= this.width) {
sizeExceeded = true;
break;
}
// .....
// . .
// .___.
let bottomBorderNotWhite = true;
while ((bottomBorderNotWhite || !atLeastOneBlackPointFoundOnBottom) && down < this.height) {
bottomBorderNotWhite = this.containsBlackPoint(left, right, down, true);
if (bottomBorderNotWhite) {
down++;
aBlackPointFoundOnBorder = true;
atLeastOneBlackPointFoundOnBottom = true;
}
else if (!atLeastOneBlackPointFoundOnBottom) {
down++;
}
}
if (down >= this.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) {
return this.findCorners(right, left, down, up);
}
else {
throw new NotFoundException();
}
}
findCorners(right, left, down, up) {
//
// A------------ ------------B
// | | up | |
// | -------|--------------|------- |
// | | | | | |
// | | | | | |
// ------------AP BP------------
// | |
// | |
// left | | right
// | |
// | |
// ------------DP CP------------
// | | | | | |
// | | | down | | |
// | -------|-------------|-------- |
// | | | |
// D-----------| |------------C
//
const width = right - left;
const height = down - up;
const sampler = 16 / this.targetMatrixSize;
const sampler2 = 4 / this.targetMatrixSize;
const deltaX = width * sampler2;
const deltaY = height * sampler2;
const areaWidth = deltaX + (right - left) * sampler;
const areaHeight = deltaY + (down - up) * sampler;
const a = new ResultPoint(left - deltaX, up - deltaY);
const b = new ResultPoint(right + deltaX, up - deltaY);
const c = new ResultPoint(right + deltaX, down + deltaY);
const d = new ResultPoint(left - deltaX, down + deltaY);
const ap = new ResultPoint(a.getX() + areaWidth, a.getY() + areaHeight);
const bp = new ResultPoint(b.getX() - areaWidth, b.getY() + areaHeight);
const cp = new ResultPoint(c.getX() - areaWidth, c.getY() - areaHeight);
const dp = new ResultPoint(d.getX() + areaWidth, d.getY() - areaHeight);
const topLeftCorner = this.getCornerFromArea(a.getX(), ap.getX(), a.getY(), ap.getY(), false, false);
const topRightCorner = this.getCornerFromArea(bp.getX(), b.getX(), b.getY(), bp.getY(), true, false);
const bottomRightCorner = this.getCornerFromArea(cp.getX(), c.getX(), cp.getY(), c.getY(), true, true);
const bottomLeftCorner = this.getCornerFromArea(d.getX(), dp.getX(), dp.getY(), d.getY(), false, true);
const xCorrection = (topRightCorner.getX() - topLeftCorner.getX()) / this.targetMatrixSize;
const yCorrection = (bottomRightCorner.getY() - topRightCorner.getY()) / this.targetMatrixSize;
const topLeftCornerCenter = new ResultPoint(topLeftCorner.getX() + xCorrection, topLeftCorner.getY() + yCorrection);
const topRightCornerCenter = new ResultPoint(topRightCorner.getX() - xCorrection, topRightCorner.getY() + yCorrection);
const bottomRightCornerCenter = new ResultPoint(bottomRightCorner.getX() - xCorrection, bottomRightCorner.getY() - yCorrection);
const bottomLeftCornerCenter = new ResultPoint(bottomLeftCorner.getX() + xCorrection, bottomLeftCorner.getY() - yCorrection);
const result = [topLeftCornerCenter, topRightCornerCenter, bottomRightCornerCenter, bottomLeftCornerCenter];
return result;
}
getCornerFromArea(left, right, top, bottom, maximizeX, maximizeY) {
let resX = maximizeX ? 0 : Number.MAX_VALUE;
let resY = maximizeY ? 0 : Number.MAX_VALUE;
for (let x = left; x < right; x++) {
for (let y = top; y < bottom; y++) {
if (x > 0 && y > 0 && x < this.image.getWidth() && y < this.image.getHeight()) {
if (this.image.get(x, y)) {
if (maximizeX) {
if (x > resX) {
resX = x;
}
}
else {
if (x < resX) {
resX = x;
}
}
if (maximizeY) {
if (y > resY) {
resY = y;
}
}
else {
if (y < resY) {
resY = y;
}
}
}
}
}
}
if (resX === 0 || resY === 0) {
throw new NotFoundException();
}
else {
return new ResultPoint(resX, resY);
}
}
/**
* 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, b, fixed, horizontal) {
if (horizontal) {
for (let x = a; x <= b; x++) {
if (this.image.get(x, fixed)) {
return true;
}
}
}
else {
for (let y = a; y <= b; y++) {
if (this.image.get(fixed, y)) {
return true;
}
}
}
return false;
}
}