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279 lines
7.1 KiB
279 lines
7.1 KiB
/*
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Ported to JavaScript by Lazar Laszlo 2011
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lazarsoft@gmail.com, www.lazarsoft.info
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*/
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/*
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*
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* Copyright 2007 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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function AlignmentPattern(posX, posY, estimatedModuleSize)
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{
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this.x=posX;
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this.y=posY;
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this.count = 1;
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this.estimatedModuleSize = estimatedModuleSize;
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this.__defineGetter__("EstimatedModuleSize", function()
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{
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return this.estimatedModuleSize;
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});
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this.__defineGetter__("Count", function()
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{
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return this.count;
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});
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this.__defineGetter__("X", function()
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{
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return Math.floor(this.x);
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});
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this.__defineGetter__("Y", function()
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{
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return Math.floor(this.y);
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});
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this.incrementCount = function()
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{
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this.count++;
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}
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this.aboutEquals=function( moduleSize, i, j)
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{
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if (Math.abs(i - this.y) <= moduleSize && Math.abs(j - this.x) <= moduleSize)
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{
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var moduleSizeDiff = Math.abs(moduleSize - this.estimatedModuleSize);
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return moduleSizeDiff <= 1.0 || moduleSizeDiff / this.estimatedModuleSize <= 1.0;
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}
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return false;
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}
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}
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function AlignmentPatternFinder( image, startX, startY, width, height, moduleSize, resultPointCallback)
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{
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this.image = image;
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this.possibleCenters = new Array();
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this.startX = startX;
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this.startY = startY;
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this.width = width;
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this.height = height;
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this.moduleSize = moduleSize;
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this.crossCheckStateCount = new Array(0,0,0);
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this.resultPointCallback = resultPointCallback;
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this.centerFromEnd=function(stateCount, end)
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{
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return (end - stateCount[2]) - stateCount[1] / 2.0;
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}
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this.foundPatternCross = function(stateCount)
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{
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var moduleSize = this.moduleSize;
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var maxVariance = moduleSize / 2.0;
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for (var i = 0; i < 3; i++)
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{
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if (Math.abs(moduleSize - stateCount[i]) >= maxVariance)
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{
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return false;
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}
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}
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return true;
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}
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this.crossCheckVertical=function( startI, centerJ, maxCount, originalStateCountTotal)
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{
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var image = this.image;
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var maxI = qrcode.height;
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var stateCount = this.crossCheckStateCount;
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stateCount[0] = 0;
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stateCount[1] = 0;
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stateCount[2] = 0;
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// Start counting up from center
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var i = startI;
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while (i >= 0 && image[centerJ + i*qrcode.width] && stateCount[1] <= maxCount)
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{
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stateCount[1]++;
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i--;
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}
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// If already too many modules in this state or ran off the edge:
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if (i < 0 || stateCount[1] > maxCount)
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{
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return NaN;
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}
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while (i >= 0 && !image[centerJ + i*qrcode.width] && stateCount[0] <= maxCount)
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{
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stateCount[0]++;
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i--;
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}
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if (stateCount[0] > maxCount)
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{
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return NaN;
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}
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// Now also count down from center
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i = startI + 1;
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while (i < maxI && image[centerJ + i*qrcode.width] && stateCount[1] <= maxCount)
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{
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stateCount[1]++;
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i++;
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}
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if (i == maxI || stateCount[1] > maxCount)
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{
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return NaN;
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}
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while (i < maxI && !image[centerJ + i*qrcode.width] && stateCount[2] <= maxCount)
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{
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stateCount[2]++;
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i++;
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}
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if (stateCount[2] > maxCount)
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{
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return NaN;
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}
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var stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
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if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal)
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{
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return NaN;
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}
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return this.foundPatternCross(stateCount)?this.centerFromEnd(stateCount, i):NaN;
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}
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this.handlePossibleCenter=function( stateCount, i, j)
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{
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var stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
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var centerJ = this.centerFromEnd(stateCount, j);
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var centerI = this.crossCheckVertical(i, Math.floor (centerJ), 2 * stateCount[1], stateCountTotal);
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if (!isNaN(centerI))
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{
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var estimatedModuleSize = (stateCount[0] + stateCount[1] + stateCount[2]) / 3.0;
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var max = this.possibleCenters.length;
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for (var index = 0; index < max; index++)
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{
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var center = this.possibleCenters[index];
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// Look for about the same center and module size:
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if (center.aboutEquals(estimatedModuleSize, centerI, centerJ))
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{
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return new AlignmentPattern(centerJ, centerI, estimatedModuleSize);
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}
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}
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// Hadn't found this before; save it
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var point = new AlignmentPattern(centerJ, centerI, estimatedModuleSize);
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this.possibleCenters.push(point);
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if (this.resultPointCallback != null)
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{
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this.resultPointCallback.foundPossibleResultPoint(point);
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}
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}
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return null;
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}
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this.find = function()
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{
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var startX = this.startX;
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var height = this.height;
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var maxJ = startX + width;
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var middleI = startY + (height >> 1);
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// We are looking for black/white/black modules in 1:1:1 ratio;
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// this tracks the number of black/white/black modules seen so far
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var stateCount = new Array(0,0,0);
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for (var iGen = 0; iGen < height; iGen++)
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{
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// Search from middle outwards
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var i = middleI + ((iGen & 0x01) == 0?((iGen + 1) >> 1):- ((iGen + 1) >> 1));
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stateCount[0] = 0;
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stateCount[1] = 0;
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stateCount[2] = 0;
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var j = startX;
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// Burn off leading white pixels before anything else; if we start in the middle of
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// a white run, it doesn't make sense to count its length, since we don't know if the
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// white run continued to the left of the start point
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while (j < maxJ && !image[j + qrcode.width* i])
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{
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j++;
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}
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var currentState = 0;
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while (j < maxJ)
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{
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if (image[j + i*qrcode.width])
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{
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// Black pixel
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if (currentState == 1)
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{
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// Counting black pixels
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stateCount[currentState]++;
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}
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else
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{
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// Counting white pixels
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if (currentState == 2)
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{
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// A winner?
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if (this.foundPatternCross(stateCount))
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{
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// Yes
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var confirmed = this.handlePossibleCenter(stateCount, i, j);
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if (confirmed != null)
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{
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return confirmed;
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}
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}
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stateCount[0] = stateCount[2];
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stateCount[1] = 1;
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stateCount[2] = 0;
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currentState = 1;
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}
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else
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{
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stateCount[++currentState]++;
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}
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}
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}
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else
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{
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// White pixel
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if (currentState == 1)
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{
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// Counting black pixels
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currentState++;
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}
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stateCount[currentState]++;
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}
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j++;
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}
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if (this.foundPatternCross(stateCount))
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{
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var confirmed = this.handlePossibleCenter(stateCount, i, maxJ);
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if (confirmed != null)
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{
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return confirmed;
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}
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}
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}
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// Hmm, nothing we saw was observed and confirmed twice. If we had
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// any guess at all, return it.
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if (!(this.possibleCenters.length == 0))
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{
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return this.possibleCenters[0];
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}
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throw "Couldn't find enough alignment patterns";
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}
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}
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