src/core/qrcode/detector/Detector.ts
/*
* Copyright 2007 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.qrcode.detector {*/
import BitMatrix from '../../common/BitMatrix';
import MathUtils from '../../common/detector/MathUtils';
import DetectorResult from '../../common/DetectorResult';
// import GridSampler from '../../common/GridSampler';
import GridSamplerInstance from '../../common/GridSamplerInstance';
import PerspectiveTransform from '../../common/PerspectiveTransform';
import DecodeHintType from '../../DecodeHintType';
import NotFoundException from '../../NotFoundException';
import ResultPoint from '../../ResultPoint';
import ResultPointCallback from '../../ResultPointCallback';
import Version from '../decoder/Version';
import AlignmentPattern from './AlignmentPattern';
import AlignmentPatternFinder from './AlignmentPatternFinder';
import FinderPattern from './FinderPattern';
import FinderPatternFinder from './FinderPatternFinder';
import FinderPatternInfo from './FinderPatternInfo';
/*import java.util.Map;*/
/**
* <p>Encapsulates logic that can detect a QR Code in an image, even if the QR Code
* is rotated or skewed, or partially obscured.</p>
*
* @author Sean Owen
*/
export default class Detector {
private resultPointCallback: ResultPointCallback;
public constructor(private image: BitMatrix) { }
protected getImage(): BitMatrix {
return this.image;
}
protected getResultPointCallback(): ResultPointCallback {
return this.resultPointCallback;
}
/**
* <p>Detects a QR Code in an image.</p>
*
* @return {@link DetectorResult} encapsulating results of detecting a QR Code
* @throws NotFoundException if QR Code cannot be found
* @throws FormatException if a QR Code cannot be decoded
*/
// public detect(): DetectorResult /*throws NotFoundException, FormatException*/ {
// return detect(null)
// }
/**
* <p>Detects a QR Code in an image.</p>
*
* @param hints optional hints to detector
* @return {@link DetectorResult} encapsulating results of detecting a QR Code
* @throws NotFoundException if QR Code cannot be found
* @throws FormatException if a QR Code cannot be decoded
*/
public detect(hints: Map<DecodeHintType, any>): DetectorResult /*throws NotFoundException, FormatException*/ {
this.resultPointCallback = (hints === null || hints === undefined) ? null :
/*(ResultPointCallback) */hints.get(DecodeHintType.NEED_RESULT_POINT_CALLBACK);
const finder = new FinderPatternFinder(this.image, this.resultPointCallback);
const info = finder.find(hints);
return this.processFinderPatternInfo(info);
}
protected processFinderPatternInfo(info: FinderPatternInfo): DetectorResult {
const topLeft: FinderPattern = info.getTopLeft();
const topRight: FinderPattern = info.getTopRight();
const bottomLeft: FinderPattern = info.getBottomLeft();
const moduleSize: number /*float*/ = this.calculateModuleSize(topLeft, topRight, bottomLeft);
if (moduleSize < 1.0) {
throw new NotFoundException('No pattern found in proccess finder.');
}
const dimension = Detector.computeDimension(topLeft, topRight, bottomLeft, moduleSize);
const provisionalVersion: Version = Version.getProvisionalVersionForDimension(dimension);
const modulesBetweenFPCenters = provisionalVersion.getDimensionForVersion() - 7;
let alignmentPattern: AlignmentPattern = null;
// Anything above version 1 has an alignment pattern
if (provisionalVersion.getAlignmentPatternCenters().length > 0) {
// Guess where a "bottom right" finder pattern would have been
const bottomRightX: number /*float*/ = topRight.getX() - topLeft.getX() + bottomLeft.getX();
const bottomRightY: number /*float*/ = topRight.getY() - topLeft.getY() + bottomLeft.getY();
// Estimate that alignment pattern is closer by 3 modules
// from "bottom right" to known top left location
const correctionToTopLeft: number /*float*/ = 1.0 - 3.0 / modulesBetweenFPCenters;
const estAlignmentX = /*(int) */Math.floor(topLeft.getX() + correctionToTopLeft * (bottomRightX - topLeft.getX()));
const estAlignmentY = /*(int) */Math.floor(topLeft.getY() + correctionToTopLeft * (bottomRightY - topLeft.getY()));
// Kind of arbitrary -- expand search radius before giving up
for (let i = 4; i <= 16; i <<= 1) {
try {
alignmentPattern = this.findAlignmentInRegion(moduleSize,
estAlignmentX,
estAlignmentY,
i);
break;
} catch (re/*NotFoundException*/) {
if (!(re instanceof NotFoundException)) {
throw re;
}
// try next round
}
}
// If we didn't find alignment pattern... well try anyway without it
}
const transform: PerspectiveTransform =
Detector.createTransform(topLeft, topRight, bottomLeft, alignmentPattern, dimension);
const bits: BitMatrix = Detector.sampleGrid(this.image, transform, dimension);
let points: ResultPoint[];
if (alignmentPattern === null) {
points = [bottomLeft, topLeft, topRight];
} else {
points = [bottomLeft, topLeft, topRight, alignmentPattern];
}
return new DetectorResult(bits, points);
}
private static createTransform(topLeft: ResultPoint,
topRight: ResultPoint,
bottomLeft: ResultPoint,
alignmentPattern: ResultPoint,
dimension: number /*int*/): PerspectiveTransform {
const dimMinusThree: number /*float*/ = dimension - 3.5;
let bottomRightX: number; /*float*/
let bottomRightY: number; /*float*/
let sourceBottomRightX: number; /*float*/
let sourceBottomRightY: number; /*float*/
if (alignmentPattern !== null) {
bottomRightX = alignmentPattern.getX();
bottomRightY = alignmentPattern.getY();
sourceBottomRightX = dimMinusThree - 3.0;
sourceBottomRightY = sourceBottomRightX;
} else {
// Don't have an alignment pattern, just make up the bottom-right point
bottomRightX = (topRight.getX() - topLeft.getX()) + bottomLeft.getX();
bottomRightY = (topRight.getY() - topLeft.getY()) + bottomLeft.getY();
sourceBottomRightX = dimMinusThree;
sourceBottomRightY = dimMinusThree;
}
return PerspectiveTransform.quadrilateralToQuadrilateral(
3.5,
3.5,
dimMinusThree,
3.5,
sourceBottomRightX,
sourceBottomRightY,
3.5,
dimMinusThree,
topLeft.getX(),
topLeft.getY(),
topRight.getX(),
topRight.getY(),
bottomRightX,
bottomRightY,
bottomLeft.getX(),
bottomLeft.getY());
}
private static sampleGrid(image: BitMatrix,
transform: PerspectiveTransform,
dimension: number /*int*/): BitMatrix /*throws NotFoundException*/ {
const sampler = GridSamplerInstance.getInstance();
return sampler.sampleGridWithTransform(image, dimension, dimension, transform);
}
/**
* <p>Computes the dimension (number of modules on a size) of the QR Code based on the position
* of the finder patterns and estimated module size.</p>
*/
private static computeDimension(topLeft: ResultPoint,
topRight: ResultPoint,
bottomLeft: ResultPoint,
moduleSize: number/*float*/): number /*int*/ /*throws NotFoundException*/ {
const tltrCentersDimension = MathUtils.round(ResultPoint.distance(topLeft, topRight) / moduleSize);
const tlblCentersDimension = MathUtils.round(ResultPoint.distance(topLeft, bottomLeft) / moduleSize);
let dimension = Math.floor((tltrCentersDimension + tlblCentersDimension) / 2) + 7;
switch (dimension & 0x03) { // mod 4
case 0:
dimension++;
break;
// 1? do nothing
case 2:
dimension--;
break;
case 3:
throw new NotFoundException('Dimensions could be not found.');
}
return dimension;
}
/**
* <p>Computes an average estimated module size based on estimated derived from the positions
* of the three finder patterns.</p>
*
* @param topLeft detected top-left finder pattern center
* @param topRight detected top-right finder pattern center
* @param bottomLeft detected bottom-left finder pattern center
* @return estimated module size
*/
protected calculateModuleSize(topLeft: ResultPoint,
topRight: ResultPoint,
bottomLeft: ResultPoint): number/*float*/ {
// Take the average
return (this.calculateModuleSizeOneWay(topLeft, topRight) +
this.calculateModuleSizeOneWay(topLeft, bottomLeft)) / 2.0;
}
/**
* <p>Estimates module size based on two finder patterns -- it uses
* {@link #sizeOfBlackWhiteBlackRunBothWays(int, int, int, int)} to figure the
* width of each, measuring along the axis between their centers.</p>
*/
private calculateModuleSizeOneWay(pattern: ResultPoint, otherPattern: ResultPoint): number/*float*/ {
const moduleSizeEst1: number /*float*/ = this.sizeOfBlackWhiteBlackRunBothWays(/*(int) */Math.floor(pattern.getX()),
/*(int) */Math.floor(pattern.getY()),
/*(int) */Math.floor(otherPattern.getX()),
/*(int) */Math.floor(otherPattern.getY()));
const moduleSizeEst2: number /*float*/ = this.sizeOfBlackWhiteBlackRunBothWays(/*(int) */Math.floor(otherPattern.getX()),
/*(int) */Math.floor(otherPattern.getY()),
/*(int) */Math.floor(pattern.getX()),
/*(int) */Math.floor(pattern.getY()));
if (isNaN(moduleSizeEst1)) {
return moduleSizeEst2 / 7.0;
}
if (isNaN(moduleSizeEst2)) {
return moduleSizeEst1 / 7.0;
}
// Average them, and divide by 7 since we've counted the width of 3 black modules,
// and 1 white and 1 black module on either side. Ergo, divide sum by 14.
return (moduleSizeEst1 + moduleSizeEst2) / 14.0;
}
/**
* See {@link #sizeOfBlackWhiteBlackRun(int, int, int, int)}; computes the total width of
* a finder pattern by looking for a black-white-black run from the center in the direction
* of another point (another finder pattern center), and in the opposite direction too.
*/
private sizeOfBlackWhiteBlackRunBothWays(fromX: number /*int*/, fromY: number /*int*/, toX: number /*int*/, toY: number /*int*/): number/*float*/ {
let result: number /*float*/ = this.sizeOfBlackWhiteBlackRun(fromX, fromY, toX, toY);
// Now count other way -- don't run off image though of course
let scale: number /*float*/ = 1.0;
let otherToX = fromX - (toX - fromX);
if (otherToX < 0) {
scale = fromX / /*(float) */(fromX - otherToX);
otherToX = 0;
} else if (otherToX >= this.image.getWidth()) {
scale = (this.image.getWidth() - 1 - fromX) / /*(float) */(otherToX - fromX);
otherToX = this.image.getWidth() - 1;
}
let otherToY = /*(int) */Math.floor(fromY - (toY - fromY) * scale);
scale = 1.0;
if (otherToY < 0) {
scale = fromY / /*(float) */(fromY - otherToY);
otherToY = 0;
} else if (otherToY >= this.image.getHeight()) {
scale = (this.image.getHeight() - 1 - fromY) / /*(float) */(otherToY - fromY);
otherToY = this.image.getHeight() - 1;
}
otherToX = /*(int) */Math.floor(fromX + (otherToX - fromX) * scale);
result += this.sizeOfBlackWhiteBlackRun(fromX, fromY, otherToX, otherToY);
// Middle pixel is double-counted this way; subtract 1
return result - 1.0;
}
/**
* <p>This method traces a line from a point in the image, in the direction towards another point.
* It begins in a black region, and keeps going until it finds white, then black, then white again.
* It reports the distance from the start to this point.</p>
*
* <p>This is used when figuring out how wide a finder pattern is, when the finder pattern
* may be skewed or rotated.</p>
*/
private sizeOfBlackWhiteBlackRun(fromX: number /*int*/, fromY: number /*int*/, toX: number /*int*/, toY: number /*int*/): number/*float*/ {
// Mild variant of Bresenham's algorithm
// see http://en.wikipedia.org/wiki/Bresenham's_line_algorithm
const steep: boolean = Math.abs(toY - fromY) > Math.abs(toX - fromX);
if (steep) {
let temp = fromX;
fromX = fromY;
fromY = temp;
temp = toX;
toX = toY;
toY = temp;
}
const dx = Math.abs(toX - fromX);
const dy = Math.abs(toY - fromY);
let error = -dx / 2;
const xstep = fromX < toX ? 1 : -1;
const ystep = fromY < toY ? 1 : -1;
// In black pixels, looking for white, first or second time.
let state = 0;
// Loop up until x == toX, but not beyond
const xLimit = toX + xstep;
for (let x = fromX, y = fromY; x !== xLimit; x += xstep) {
const realX = steep ? y : x;
const realY = steep ? x : y;
// Does current pixel mean we have moved white to black or vice versa?
// Scanning black in state 0,2 and white in state 1, so if we find the wrong
// color, advance to next state or end if we are in state 2 already
if ((state === 1) === this.image.get(realX, realY)) {
if (state === 2) {
return MathUtils.distance(x, y, fromX, fromY);
}
state++;
}
error += dy;
if (error > 0) {
if (y === toY) {
break;
}
y += ystep;
error -= dx;
}
}
// Found black-white-black; give the benefit of the doubt that the next pixel outside the image
// is "white" so this last point at (toX+xStep,toY) is the right ending. This is really a
// small approximation; (toX+xStep,toY+yStep) might be really correct. Ignore this.
if (state === 2) {
return MathUtils.distance(toX + xstep, toY, fromX, fromY);
}
// else we didn't find even black-white-black; no estimate is really possible
return NaN;
}
/**
* <p>Attempts to locate an alignment pattern in a limited region of the image, which is
* guessed to contain it. This method uses {@link AlignmentPattern}.</p>
*
* @param overallEstModuleSize estimated module size so far
* @param estAlignmentX x coordinate of center of area probably containing alignment pattern
* @param estAlignmentY y coordinate of above
* @param allowanceFactor number of pixels in all directions to search from the center
* @return {@link AlignmentPattern} if found, or null otherwise
* @throws NotFoundException if an unexpected error occurs during detection
*/
protected findAlignmentInRegion(overallEstModuleSize: number/*float*/,
estAlignmentX: number /*int*/,
estAlignmentY: number /*int*/,
allowanceFactor: number/*float*/): AlignmentPattern {
// Look for an alignment pattern (3 modules in size) around where it
// should be
const allowance = /*(int) */Math.floor(allowanceFactor * overallEstModuleSize);
const alignmentAreaLeftX = Math.max(0, estAlignmentX - allowance);
const alignmentAreaRightX = Math.min(this.image.getWidth() - 1, estAlignmentX + allowance);
if (alignmentAreaRightX - alignmentAreaLeftX < overallEstModuleSize * 3) {
throw new NotFoundException('Alignment top exceeds estimated module size.');
}
const alignmentAreaTopY = Math.max(0, estAlignmentY - allowance);
const alignmentAreaBottomY = Math.min(this.image.getHeight() - 1, estAlignmentY + allowance);
if (alignmentAreaBottomY - alignmentAreaTopY < overallEstModuleSize * 3) {
throw new NotFoundException('Alignment bottom exceeds estimated module size.');
}
const alignmentFinder = new AlignmentPatternFinder(
this.image,
alignmentAreaLeftX,
alignmentAreaTopY,
alignmentAreaRightX - alignmentAreaLeftX,
alignmentAreaBottomY - alignmentAreaTopY,
overallEstModuleSize,
this.resultPointCallback
);
return alignmentFinder.find();
}
}