/*
|
Ported to JavaScript by Lazar Laszlo 2011
|
|
lazarsoft@gmail.com, www.lazarsoft.info
|
|
*/
|
|
/*
|
*
|
* 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.
|
*/
|
|
|
export default function AlignmentPattern(posX, posY, estimatedModuleSize) {
|
this.x = posX;
|
this.y = posY;
|
this.count = 1;
|
this.estimatedModuleSize = estimatedModuleSize;
|
}
|
|
Object.defineProperty(AlignmentPattern.prototype, "X", {
|
get: function() {
|
return Math.floor(this.x);
|
}
|
});
|
|
Object.defineProperty(AlignmentPattern.prototype, "Y", {
|
get: function() {
|
return Math.floor(this.y);
|
}
|
});
|
|
AlignmentPattern.prototype.incrementCount = function() {
|
this.count++;
|
};
|
|
AlignmentPattern.prototype.aboutEquals = function(moduleSize, i, j) {
|
if (Math.abs(i - this.y) <= moduleSize && Math.abs(j - this.x) <= moduleSize) {
|
var moduleSizeDiff = Math.abs(moduleSize - this.estimatedModuleSize);
|
return moduleSizeDiff <= 1.0 || moduleSizeDiff / this.estimatedModuleSize <= 1.0;
|
}
|
return false;
|
};
|
|
export function AlignmentPatternFinder(image, startX, startY, width, height, moduleSize, resultPointCallback) {
|
this.image = image;
|
this.possibleCenters = [];
|
this.startX = startX;
|
this.startY = startY;
|
this.width = width;
|
this.height = height;
|
this.moduleSize = moduleSize;
|
this.crossCheckStateCount = [0, 0, 0];
|
this.resultPointCallback = resultPointCallback;
|
}
|
|
AlignmentPatternFinder.prototype.centerFromEnd = function(stateCount, end) {
|
return (end - stateCount[2]) - stateCount[1] / 2.0;
|
};
|
|
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;
|
};
|
|
AlignmentPatternFinder.prototype.crossCheckVertical = function(startI, centerJ, maxCount, originalStateCountTotal) {
|
var image = this.image;
|
|
var maxI = image.height;
|
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.data[centerJ + i * image.width] && 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.data[centerJ + i * image.width] && 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.data[centerJ + i * image.width] && stateCount[1] <= maxCount) {
|
stateCount[1]++;
|
i++;
|
}
|
if (i == maxI || stateCount[1] > maxCount) {
|
return NaN;
|
}
|
while (i < maxI && !image.data[centerJ + i * image.width] && 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) ? this.centerFromEnd(stateCount, i) : NaN;
|
};
|
|
AlignmentPatternFinder.prototype.handlePossibleCenter = function(stateCount, i, j) {
|
var stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
|
var centerJ = this.centerFromEnd(stateCount, j);
|
var centerI = this.crossCheckVertical(i, Math.floor(centerJ), 2 * stateCount[1], stateCountTotal);
|
if (!isNaN(centerI)) {
|
var estimatedModuleSize = (stateCount[0] + stateCount[1] + stateCount[2]) / 3.0;
|
var max = this.possibleCenters.length;
|
for (var index = 0; index < max; index++) {
|
var center = this.possibleCenters[index];
|
// Look for about the same center and module size:
|
if (center.aboutEquals(estimatedModuleSize, centerI, centerJ)) {
|
return new AlignmentPattern(centerJ, centerI, estimatedModuleSize);
|
}
|
}
|
// Hadn't found this before; save it
|
var point = new AlignmentPattern(centerJ, centerI, estimatedModuleSize);
|
this.possibleCenters.push(point);
|
if (this.resultPointCallback != null) {
|
this.resultPointCallback.foundPossibleResultPoint(point);
|
}
|
}
|
return null;
|
};
|
|
AlignmentPatternFinder.prototype.find = function() {
|
var image = this.image;
|
var startX = this.startX;
|
var height = this.height;
|
var maxJ = startX + this.width;
|
var middleI = this.startY + (height >> 1);
|
// 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 = [0, 0, 0];
|
for (var iGen = 0; iGen < height; iGen++) {
|
// Search from middle outwards
|
var i = middleI + ((iGen & 0x01) == 0 ? ((iGen + 1) >> 1) : -((iGen + 1) >> 1));
|
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.data[j + image.width * i]) {
|
j++;
|
}
|
var currentState = 0;
|
while (j < maxJ) {
|
if (image.data[j + i * image.width]) {
|
// Black pixel
|
if (currentState == 1) {
|
// Counting black pixels
|
stateCount[currentState]++;
|
} 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 "Couldn't find enough alignment patterns";
|
};
|
