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d4efd44fb0
git-svn-id: https://zxing.googlecode.com/svn/trunk@1202 59b500cc-1b3d-0410-9834-0bbf25fbcc57
339 lines
13 KiB
C#
Executable file
339 lines
13 KiB
C#
Executable file
/*
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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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using System;
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using ReaderException = com.google.zxing.ReaderException;
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using ResultPoint = com.google.zxing.ResultPoint;
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using ResultPointCallback = com.google.zxing.ResultPointCallback;
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using BitMatrix = com.google.zxing.common.BitMatrix;
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namespace com.google.zxing.qrcode.detector
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{
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/// <summary> <p>This class attempts to find alignment patterns in a QR Code. Alignment patterns look like finder
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/// patterns but are smaller and appear at regular intervals throughout the image.</p>
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///
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/// <p>At the moment this only looks for the bottom-right alignment pattern.</p>
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///
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/// <p>This is mostly a simplified copy of {@link FinderPatternFinder}. It is copied,
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/// pasted and stripped down here for maximum performance but does unfortunately duplicate
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/// some code.</p>
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///
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/// <p>This class is thread-safe but not reentrant. Each thread must allocate its own object.
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///
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/// </summary>
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/// <author> Sean Owen
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/// </author>
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/// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source
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/// </author>
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sealed class AlignmentPatternFinder
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{
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//UPGRADE_NOTE: Final was removed from the declaration of 'image '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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private BitMatrix image;
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//UPGRADE_NOTE: Final was removed from the declaration of 'possibleCenters '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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private System.Collections.ArrayList possibleCenters;
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//UPGRADE_NOTE: Final was removed from the declaration of 'startX '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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private int startX;
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//UPGRADE_NOTE: Final was removed from the declaration of 'startY '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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private int startY;
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//UPGRADE_NOTE: Final was removed from the declaration of 'width '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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private int width;
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//UPGRADE_NOTE: Final was removed from the declaration of 'height '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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private int height;
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//UPGRADE_NOTE: Final was removed from the declaration of 'moduleSize '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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private float moduleSize;
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//UPGRADE_NOTE: Final was removed from the declaration of 'crossCheckStateCount '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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private int[] crossCheckStateCount;
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//UPGRADE_NOTE: Final was removed from the declaration of 'resultPointCallback '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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private ResultPointCallback resultPointCallback;
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/// <summary> <p>Creates a finder that will look in a portion of the whole image.</p>
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///
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/// </summary>
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/// <param name="image">image to search
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/// </param>
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/// <param name="startX">left column from which to start searching
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/// </param>
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/// <param name="startY">top row from which to start searching
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/// </param>
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/// <param name="width">width of region to search
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/// </param>
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/// <param name="height">height of region to search
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/// </param>
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/// <param name="moduleSize">estimated module size so far
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/// </param>
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internal AlignmentPatternFinder(BitMatrix image, int startX, int startY, int width, int height, float moduleSize, ResultPointCallback resultPointCallback)
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{
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this.image = image;
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this.possibleCenters = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(5));
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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 int[3];
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this.resultPointCallback = resultPointCallback;
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}
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/// <summary> <p>This method attempts to find the bottom-right alignment pattern in the image. It is a bit messy since
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/// it's pretty performance-critical and so is written to be fast foremost.</p>
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///
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/// </summary>
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/// <returns> {@link AlignmentPattern} if found
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/// </returns>
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/// <throws> ReaderException if not found </throws>
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internal AlignmentPattern find()
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{
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int startX = this.startX;
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int height = this.height;
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int maxJ = startX + width;
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int 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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int[] stateCount = new int[3];
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for (int iGen = 0; iGen < height; iGen++)
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{
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// Search from middle outwards
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int 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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int 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.get_Renamed(j, i))
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{
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j++;
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}
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int currentState = 0;
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while (j < maxJ)
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{
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if (image.get_Renamed(j, i))
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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 (foundPatternCross(stateCount))
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{
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// Yes
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AlignmentPattern confirmed = 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 (foundPatternCross(stateCount))
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{
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AlignmentPattern confirmed = 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 (!(possibleCenters.Count == 0))
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{
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return (AlignmentPattern) possibleCenters[0];
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}
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throw ReaderException.Instance;
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}
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/// <summary> Given a count of black/white/black pixels just seen and an end position,
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/// figures the location of the center of this black/white/black run.
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/// </summary>
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private static float centerFromEnd(int[] stateCount, int end)
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{
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//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
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return (float) (end - stateCount[2]) - stateCount[1] / 2.0f;
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}
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/// <param name="stateCount">count of black/white/black pixels just read
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/// </param>
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/// <returns> true iff the proportions of the counts is close enough to the 1/1/1 ratios
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/// used by alignment patterns to be considered a match
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/// </returns>
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private bool foundPatternCross(int[] stateCount)
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{
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float moduleSize = this.moduleSize;
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float maxVariance = moduleSize / 2.0f;
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for (int i = 0; i < 3; i++)
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{
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if (System.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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/// <summary> <p>After a horizontal scan finds a potential alignment pattern, this method
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/// "cross-checks" by scanning down vertically through the center of the possible
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/// alignment pattern to see if the same proportion is detected.</p>
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///
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/// </summary>
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/// <param name="startI">row where an alignment pattern was detected
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/// </param>
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/// <param name="centerJ">center of the section that appears to cross an alignment pattern
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/// </param>
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/// <param name="maxCount">maximum reasonable number of modules that should be
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/// observed in any reading state, based on the results of the horizontal scan
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/// </param>
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/// <returns> vertical center of alignment pattern, or {@link Float#NaN} if not found
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/// </returns>
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private float crossCheckVertical(int startI, int centerJ, int maxCount, int originalStateCountTotal)
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{
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BitMatrix image = this.image;
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int maxI = image.Height;
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int[] stateCount = 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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int i = startI;
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while (i >= 0 && image.get_Renamed(centerJ, i) && 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 System.Single.NaN;
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}
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while (i >= 0 && !image.get_Renamed(centerJ, i) && 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 System.Single.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.get_Renamed(centerJ, i) && 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 System.Single.NaN;
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}
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while (i < maxI && !image.get_Renamed(centerJ, i) && 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 System.Single.NaN;
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}
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int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
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if (5 * System.Math.Abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal)
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{
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return System.Single.NaN;
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}
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return foundPatternCross(stateCount)?centerFromEnd(stateCount, i):System.Single.NaN;
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}
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/// <summary> <p>This is called when a horizontal scan finds a possible alignment pattern. It will
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/// cross check with a vertical scan, and if successful, will see if this pattern had been
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/// found on a previous horizontal scan. If so, we consider it confirmed and conclude we have
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/// found the alignment pattern.</p>
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///
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/// </summary>
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/// <param name="stateCount">reading state module counts from horizontal scan
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/// </param>
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/// <param name="i">row where alignment pattern may be found
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/// </param>
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/// <param name="j">end of possible alignment pattern in row
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/// </param>
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/// <returns> {@link AlignmentPattern} if we have found the same pattern twice, or null if not
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/// </returns>
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private AlignmentPattern handlePossibleCenter(int[] stateCount, int i, int j)
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{
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int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
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float centerJ = centerFromEnd(stateCount, j);
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//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
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float centerI = crossCheckVertical(i, (int) centerJ, 2 * stateCount[1], stateCountTotal);
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if (!System.Single.IsNaN(centerI))
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{
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//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
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float estimatedModuleSize = (float) (stateCount[0] + stateCount[1] + stateCount[2]) / 3.0f;
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int max = possibleCenters.Count;
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for (int index = 0; index < max; index++)
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{
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AlignmentPattern center = (AlignmentPattern) 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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ResultPoint point = new AlignmentPattern(centerJ, centerI, estimatedModuleSize);
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possibleCenters.Add(point);
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if (resultPointCallback != null)
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{
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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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}
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} |