@zxing/library
Version:
TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
272 lines (271 loc) • 12 kB
JavaScript
"use strict";
/*
* 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.
*/
var __values = (this && this.__values) || function(o) {
var s = typeof Symbol === "function" && Symbol.iterator, m = s && o[s], i = 0;
if (m) return m.call(o);
if (o && typeof o.length === "number") return {
next: function () {
if (o && i >= o.length) o = void 0;
return { value: o && o[i++], done: !o };
}
};
throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
};
Object.defineProperty(exports, "__esModule", { value: true });
var AlignmentPattern_1 = require("./AlignmentPattern");
var NotFoundException_1 = require("../../NotFoundException");
/*import java.util.ArrayList;*/
/*import java.util.List;*/
/**
* <p>This class attempts to find alignment patterns in a QR Code. Alignment patterns look like finder
* patterns but are smaller and appear at regular intervals throughout the image.</p>
*
* <p>At the moment this only looks for the bottom-right alignment pattern.</p>
*
* <p>This is mostly a simplified copy of {@link FinderPatternFinder}. It is copied,
* pasted and stripped down here for maximum performance but does unfortunately duplicate
* some code.</p>
*
* <p>This class is thread-safe but not reentrant. Each thread must allocate its own object.</p>
*
* @author Sean Owen
*/
var AlignmentPatternFinder = /** @class */ (function () {
/**
* <p>Creates a finder that will look in a portion of the whole image.</p>
*
* @param image image to search
* @param startX left column from which to start searching
* @param startY top row from which to start searching
* @param width width of region to search
* @param height height of region to search
* @param moduleSize estimated module size so far
*/
function AlignmentPatternFinder(image, startX /*int*/, startY /*int*/, width /*int*/, height /*int*/, moduleSize /*float*/, resultPointCallback) {
this.image = image;
this.startX = startX;
this.startY = startY;
this.width = width;
this.height = height;
this.moduleSize = moduleSize;
this.resultPointCallback = resultPointCallback;
this.possibleCenters = []; // new Array<any>(5))
// TYPESCRIPTPORT: array initialization without size as the length is checked below
this.crossCheckStateCount = new Int32Array(3);
}
/**
* <p>This method attempts to find the bottom-right alignment pattern in the image. It is a bit messy since
* it's pretty performance-critical and so is written to be fast foremost.</p>
*
* @return {@link AlignmentPattern} if found
* @throws NotFoundException if not found
*/
AlignmentPatternFinder.prototype.find = function () {
var startX = this.startX;
var height = this.height;
var width = this.width;
var maxJ = startX + width;
var middleI = this.startY + (height / 2);
// We are looking for black/white/black modules in 1:1:1 ratio
// this tracks the number of black/white/black modules seen so far
var stateCount = new Int32Array(3);
var image = this.image;
for (var iGen = 0; iGen < height; iGen++) {
// Search from middle outwards
var i = middleI + ((iGen & 0x01) === 0 ? Math.floor((iGen + 1) / 2) : -Math.floor((iGen + 1) / 2));
stateCount[0] = 0;
stateCount[1] = 0;
stateCount[2] = 0;
var j = startX;
// Burn off leading white pixels before anything else; if we start in the middle of
// a white run, it doesn't make sense to count its length, since we don't know if the
// white run continued to the left of the start point
while (j < maxJ && !image.get(j, i)) {
j++;
}
var currentState = 0;
while (j < maxJ) {
if (image.get(j, i)) {
// Black pixel
if (currentState === 1) { // Counting black pixels
stateCount[1]++;
}
else { // Counting white pixels
if (currentState === 2) { // A winner?
if (this.foundPatternCross(stateCount)) { // Yes
var confirmed = this.handlePossibleCenter(stateCount, i, j);
if (confirmed !== null) {
return confirmed;
}
}
stateCount[0] = stateCount[2];
stateCount[1] = 1;
stateCount[2] = 0;
currentState = 1;
}
else {
stateCount[++currentState]++;
}
}
}
else { // White pixel
if (currentState === 1) { // Counting black pixels
currentState++;
}
stateCount[currentState]++;
}
j++;
}
if (this.foundPatternCross(stateCount)) {
var confirmed = this.handlePossibleCenter(stateCount, i, maxJ);
if (confirmed !== null) {
return confirmed;
}
}
}
// Hmm, nothing we saw was observed and confirmed twice. If we had
// any guess at all, return it.
if (this.possibleCenters.length !== 0) {
return this.possibleCenters[0];
}
throw new NotFoundException_1.default();
};
/**
* Given a count of black/white/black pixels just seen and an end position,
* figures the location of the center of this black/white/black run.
*/
AlignmentPatternFinder.centerFromEnd = function (stateCount, end /*int*/) {
return (end - stateCount[2]) - stateCount[1] / 2.0;
};
/**
* @param stateCount count of black/white/black pixels just read
* @return true iff the proportions of the counts is close enough to the 1/1/1 ratios
* used by alignment patterns to be considered a match
*/
AlignmentPatternFinder.prototype.foundPatternCross = function (stateCount) {
var moduleSize = this.moduleSize;
var maxVariance = moduleSize / 2.0;
for (var i = 0; i < 3; i++) {
if (Math.abs(moduleSize - stateCount[i]) >= maxVariance) {
return false;
}
}
return true;
};
/**
* <p>After a horizontal scan finds a potential alignment pattern, this method
* "cross-checks" by scanning down vertically through the center of the possible
* alignment pattern to see if the same proportion is detected.</p>
*
* @param startI row where an alignment pattern was detected
* @param centerJ center of the section that appears to cross an alignment pattern
* @param maxCount maximum reasonable number of modules that should be
* observed in any reading state, based on the results of the horizontal scan
* @return vertical center of alignment pattern, or {@link Float#NaN} if not found
*/
AlignmentPatternFinder.prototype.crossCheckVertical = function (startI /*int*/, centerJ /*int*/, maxCount /*int*/, originalStateCountTotal /*int*/) {
var image = this.image;
var maxI = image.getHeight();
var stateCount = this.crossCheckStateCount;
stateCount[0] = 0;
stateCount[1] = 0;
stateCount[2] = 0;
// Start counting up from center
var i = startI;
while (i >= 0 && image.get(centerJ, i) && stateCount[1] <= maxCount) {
stateCount[1]++;
i--;
}
// If already too many modules in this state or ran off the edge:
if (i < 0 || stateCount[1] > maxCount) {
return NaN;
}
while (i >= 0 && !image.get(centerJ, i) && stateCount[0] <= maxCount) {
stateCount[0]++;
i--;
}
if (stateCount[0] > maxCount) {
return NaN;
}
// Now also count down from center
i = startI + 1;
while (i < maxI && image.get(centerJ, i) && stateCount[1] <= maxCount) {
stateCount[1]++;
i++;
}
if (i === maxI || stateCount[1] > maxCount) {
return NaN;
}
while (i < maxI && !image.get(centerJ, i) && stateCount[2] <= maxCount) {
stateCount[2]++;
i++;
}
if (stateCount[2] > maxCount) {
return NaN;
}
var stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal) {
return NaN;
}
return this.foundPatternCross(stateCount) ? AlignmentPatternFinder.centerFromEnd(stateCount, i) : NaN;
};
/**
* <p>This is called when a horizontal scan finds a possible alignment pattern. It will
* cross check with a vertical scan, and if successful, will see if this pattern had been
* found on a previous horizontal scan. If so, we consider it confirmed and conclude we have
* found the alignment pattern.</p>
*
* @param stateCount reading state module counts from horizontal scan
* @param i row where alignment pattern may be found
* @param j end of possible alignment pattern in row
* @return {@link AlignmentPattern} if we have found the same pattern twice, or null if not
*/
AlignmentPatternFinder.prototype.handlePossibleCenter = function (stateCount, i /*int*/, j /*int*/) {
var e_1, _a;
var stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
var centerJ = AlignmentPatternFinder.centerFromEnd(stateCount, j);
var centerI = this.crossCheckVertical(i, /*(int) */ centerJ, 2 * stateCount[1], stateCountTotal);
if (!isNaN(centerI)) {
var estimatedModuleSize = (stateCount[0] + stateCount[1] + stateCount[2]) / 3.0;
try {
for (var _b = __values(this.possibleCenters), _c = _b.next(); !_c.done; _c = _b.next()) {
var center = _c.value;
// Look for about the same center and module size:
if (center.aboutEquals(estimatedModuleSize, centerI, centerJ)) {
return center.combineEstimate(centerI, centerJ, estimatedModuleSize);
}
}
}
catch (e_1_1) { e_1 = { error: e_1_1 }; }
finally {
try {
if (_c && !_c.done && (_a = _b.return)) _a.call(_b);
}
finally { if (e_1) throw e_1.error; }
}
// Hadn't found this before; save it
var point = new AlignmentPattern_1.default(centerJ, centerI, estimatedModuleSize);
this.possibleCenters.push(point);
if (this.resultPointCallback !== null && this.resultPointCallback !== undefined) {
this.resultPointCallback.foundPossibleResultPoint(point);
}
}
return null;
};
return AlignmentPatternFinder;
}());
exports.default = AlignmentPatternFinder;