429 lines
19 KiB
C#
Executable File
429 lines
19 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 System.Collections.Generic;
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using ZXing.Common;
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using ZXing.Common.Detector;
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namespace ZXing.QrCode.Internal
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{
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/// <summary>
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/// <p>Encapsulates logic that can detect a QR Code in an image, even if the QR Code
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/// is rotated or skewed, or partially obscured.</p>
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/// </summary>
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/// <author>Sean Owen</author>
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public class Detector
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{
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private readonly BitMatrix image;
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private ResultPointCallback resultPointCallback;
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/// <summary>
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/// Initializes a new instance of the <see cref="Detector"/> class.
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/// </summary>
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/// <param name="image">The image.</param>
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public Detector(BitMatrix image)
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{
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this.image = image;
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}
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/// <summary>
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/// Gets the image.
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/// </summary>
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virtual protected internal BitMatrix Image
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{
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get
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{
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return image;
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}
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}
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/// <summary>
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/// Gets the result point callback.
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/// </summary>
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virtual protected internal ResultPointCallback ResultPointCallback
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{
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get
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{
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return resultPointCallback;
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}
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}
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/// <summary>
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/// <p>Detects a QR Code in an image, simply.</p>
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/// </summary>
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/// <returns>
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/// <see cref="DetectorResult"/> encapsulating results of detecting a QR Code
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/// </returns>
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public virtual DetectorResult detect()
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{
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return detect(null);
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}
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/// <summary>
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/// <p>Detects a QR Code in an image, simply.</p>
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/// </summary>
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/// <param name="hints">optional hints to detector</param>
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/// <returns>
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/// <see cref="DetectorResult"/> encapsulating results of detecting a QR Code
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/// </returns>
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public virtual DetectorResult detect(IDictionary<DecodeHintType, object> hints)
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{
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resultPointCallback = hints == null || !hints.ContainsKey(DecodeHintType.NEED_RESULT_POINT_CALLBACK) ? null : (ResultPointCallback)hints[DecodeHintType.NEED_RESULT_POINT_CALLBACK];
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FinderPatternFinder finder = new FinderPatternFinder(image, resultPointCallback);
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FinderPatternInfo info = finder.find(hints);
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if (info == null)
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return null;
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return processFinderPatternInfo(info);
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}
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/// <summary>
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/// Processes the finder pattern info.
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/// </summary>
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/// <param name="info">The info.</param>
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/// <returns></returns>
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protected internal virtual DetectorResult processFinderPatternInfo(FinderPatternInfo info)
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{
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FinderPattern topLeft = info.TopLeft;
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FinderPattern topRight = info.TopRight;
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FinderPattern bottomLeft = info.BottomLeft;
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float moduleSize = calculateModuleSize(topLeft, topRight, bottomLeft);
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if (moduleSize < 1.0f)
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{
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return null;
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}
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int dimension;
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if (!computeDimension(topLeft, topRight, bottomLeft, moduleSize, out dimension))
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return null;
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Internal.Version provisionalVersion = Internal.Version.getProvisionalVersionForDimension(dimension);
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if (provisionalVersion == null)
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return null;
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int modulesBetweenFPCenters = provisionalVersion.DimensionForVersion - 7;
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AlignmentPattern alignmentPattern = null;
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// Anything above version 1 has an alignment pattern
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if (provisionalVersion.AlignmentPatternCenters.Length > 0)
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{
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// Guess where a "bottom right" finder pattern would have been
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float bottomRightX = topRight.X - topLeft.X + bottomLeft.X;
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float bottomRightY = topRight.Y - topLeft.Y + bottomLeft.Y;
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// Estimate that alignment pattern is closer by 3 modules
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// from "bottom right" to known top left location
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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 correctionToTopLeft = 1.0f - 3.0f / (float)modulesBetweenFPCenters;
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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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int estAlignmentX = (int)(topLeft.X + correctionToTopLeft * (bottomRightX - topLeft.X));
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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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int estAlignmentY = (int)(topLeft.Y + correctionToTopLeft * (bottomRightY - topLeft.Y));
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// Kind of arbitrary -- expand search radius before giving up
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for (int i = 4; i <= 16; i <<= 1)
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{
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alignmentPattern = findAlignmentInRegion(moduleSize, estAlignmentX, estAlignmentY, (float)i);
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if (alignmentPattern == null)
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continue;
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break;
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}
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// If we didn't find alignment pattern... well try anyway without it
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}
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PerspectiveTransform transform = createTransform(topLeft, topRight, bottomLeft, alignmentPattern, dimension);
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BitMatrix bits = sampleGrid(image, transform, dimension);
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if (bits == null)
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return null;
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ResultPoint[] points;
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if (alignmentPattern == null)
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{
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points = new ResultPoint[] { bottomLeft, topLeft, topRight };
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}
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else
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{
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points = new ResultPoint[] { bottomLeft, topLeft, topRight, alignmentPattern };
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}
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return new DetectorResult(bits, points);
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}
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private static PerspectiveTransform createTransform(ResultPoint topLeft, ResultPoint topRight, ResultPoint bottomLeft, ResultPoint alignmentPattern, int dimension)
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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 dimMinusThree = (float)dimension - 3.5f;
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float bottomRightX;
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float bottomRightY;
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float sourceBottomRightX;
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float sourceBottomRightY;
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if (alignmentPattern != null)
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{
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bottomRightX = alignmentPattern.X;
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bottomRightY = alignmentPattern.Y;
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sourceBottomRightX = sourceBottomRightY = dimMinusThree - 3.0f;
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}
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else
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{
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// Don't have an alignment pattern, just make up the bottom-right point
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bottomRightX = (topRight.X - topLeft.X) + bottomLeft.X;
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bottomRightY = (topRight.Y - topLeft.Y) + bottomLeft.Y;
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sourceBottomRightX = sourceBottomRightY = dimMinusThree;
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}
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return PerspectiveTransform.quadrilateralToQuadrilateral(
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3.5f,
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3.5f,
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dimMinusThree,
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3.5f,
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sourceBottomRightX,
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sourceBottomRightY,
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3.5f,
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dimMinusThree,
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topLeft.X,
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topLeft.Y,
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topRight.X,
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topRight.Y,
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bottomRightX,
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bottomRightY,
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bottomLeft.X,
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bottomLeft.Y);
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}
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private static BitMatrix sampleGrid(BitMatrix image, PerspectiveTransform transform, int dimension)
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{
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GridSampler sampler = GridSampler.Instance;
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return sampler.sampleGrid(image, dimension, dimension, transform);
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}
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/// <summary> <p>Computes the dimension (number of modules on a size) of the QR Code based on the position
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/// of the finder patterns and estimated module size.</p>
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/// </summary>
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private static bool computeDimension(ResultPoint topLeft, ResultPoint topRight, ResultPoint bottomLeft, float moduleSize, out int dimension)
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{
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int tltrCentersDimension = MathUtils.round(ResultPoint.distance(topLeft, topRight) / moduleSize);
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int tlblCentersDimension = MathUtils.round(ResultPoint.distance(topLeft, bottomLeft) / moduleSize);
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dimension = ((tltrCentersDimension + tlblCentersDimension) >> 1) + 7;
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switch (dimension & 0x03)
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{
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// mod 4
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case 0:
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dimension++;
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break;
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// 1? do nothing
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case 2:
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dimension--;
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break;
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case 3:
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return true;
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}
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return true;
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}
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/// <summary> <p>Computes an average estimated module size based on estimated derived from the positions
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/// of the three finder patterns.</p>
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/// </summary>
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protected internal virtual float calculateModuleSize(ResultPoint topLeft, ResultPoint topRight, ResultPoint bottomLeft)
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{
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// Take the average
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return (calculateModuleSizeOneWay(topLeft, topRight) + calculateModuleSizeOneWay(topLeft, bottomLeft)) / 2.0f;
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}
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/// <summary> <p>Estimates module size based on two finder patterns -- it uses
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/// {@link #sizeOfBlackWhiteBlackRunBothWays(int, int, int, int)} to figure the
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/// width of each, measuring along the axis between their centers.</p>
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/// </summary>
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private float calculateModuleSizeOneWay(ResultPoint pattern, ResultPoint otherPattern)
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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 moduleSizeEst1 = sizeOfBlackWhiteBlackRunBothWays((int)pattern.X, (int)pattern.Y, (int)otherPattern.X, (int)otherPattern.Y);
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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 moduleSizeEst2 = sizeOfBlackWhiteBlackRunBothWays((int)otherPattern.X, (int)otherPattern.Y, (int)pattern.X, (int)pattern.Y);
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if (Single.IsNaN(moduleSizeEst1))
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{
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return moduleSizeEst2 / 7.0f;
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}
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if (Single.IsNaN(moduleSizeEst2))
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{
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return moduleSizeEst1 / 7.0f;
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}
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// Average them, and divide by 7 since we've counted the width of 3 black modules,
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// and 1 white and 1 black module on either side. Ergo, divide sum by 14.
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return (moduleSizeEst1 + moduleSizeEst2) / 14.0f;
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}
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/// <summary> See {@link #sizeOfBlackWhiteBlackRun(int, int, int, int)}; computes the total width of
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/// a finder pattern by looking for a black-white-black run from the center in the direction
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/// of another point (another finder pattern center), and in the opposite direction too.
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/// </summary>
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private float sizeOfBlackWhiteBlackRunBothWays(int fromX, int fromY, int toX, int toY)
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{
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float result = sizeOfBlackWhiteBlackRun(fromX, fromY, toX, toY);
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// Now count other way -- don't run off image though of course
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float scale = 1.0f;
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int otherToX = fromX - (toX - fromX);
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if (otherToX < 0)
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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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scale = (float)fromX / (float)(fromX - otherToX);
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otherToX = 0;
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}
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else if (otherToX >= image.Width)
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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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scale = (float)(image.Width - 1 - fromX) / (float)(otherToX - fromX);
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otherToX = image.Width - 1;
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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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int otherToY = (int)(fromY - (toY - fromY) * scale);
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scale = 1.0f;
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if (otherToY < 0)
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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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scale = (float)fromY / (float)(fromY - otherToY);
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otherToY = 0;
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}
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else if (otherToY >= image.Height)
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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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scale = (float)(image.Height - 1 - fromY) / (float)(otherToY - fromY);
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otherToY = image.Height - 1;
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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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otherToX = (int)(fromX + (otherToX - fromX) * scale);
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result += sizeOfBlackWhiteBlackRun(fromX, fromY, otherToX, otherToY);
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return result - 1.0f; // -1 because we counted the middle pixel twice
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}
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/// <summary> <p>This method traces a line from a point in the image, in the direction towards another point.
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/// It begins in a black region, and keeps going until it finds white, then black, then white again.
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/// It reports the distance from the start to this point.</p>
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///
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/// <p>This is used when figuring out how wide a finder pattern is, when the finder pattern
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/// may be skewed or rotated.</p>
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/// </summary>
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private float sizeOfBlackWhiteBlackRun(int fromX, int fromY, int toX, int toY)
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{
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// Mild variant of Bresenham's algorithm;
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// see http://en.wikipedia.org/wiki/Bresenham's_line_algorithm
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bool steep = Math.Abs(toY - fromY) > Math.Abs(toX - fromX);
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if (steep)
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{
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int temp = fromX;
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fromX = fromY;
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fromY = temp;
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temp = toX;
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toX = toY;
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toY = temp;
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}
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int dx = Math.Abs(toX - fromX);
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int dy = Math.Abs(toY - fromY);
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int error = -dx >> 1;
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int xstep = fromX < toX ? 1 : -1;
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int ystep = fromY < toY ? 1 : -1;
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// In black pixels, looking for white, first or second time.
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int state = 0;
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// Loop up until x == toX, but not beyond
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int xLimit = toX + xstep;
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for (int x = fromX, y = fromY; x != xLimit; x += xstep)
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{
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int realX = steep ? y : x;
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int realY = steep ? x : y;
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// Does current pixel mean we have moved white to black or vice versa?
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// Scanning black in state 0,2 and white in state 1, so if we find the wrong
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// color, advance to next state or end if we are in state 2 already
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if ((state == 1) == image[realX, realY])
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{
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if (state == 2)
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{
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return MathUtils.distance(x, y, fromX, fromY);
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}
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state++;
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}
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error += dy;
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if (error > 0)
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{
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if (y == toY)
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{
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break;
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}
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y += ystep;
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error -= dx;
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}
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}
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// Found black-white-black; give the benefit of the doubt that the next pixel outside the image
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// is "white" so this last point at (toX+xStep,toY) is the right ending. This is really a
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// small approximation; (toX+xStep,toY+yStep) might be really correct. Ignore this.
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if (state == 2)
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{
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return MathUtils.distance(toX + xstep, toY, fromX, fromY);
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}
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// else we didn't find even black-white-black; no estimate is really possible
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return Single.NaN;
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}
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/// <summary>
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/// <p>Attempts to locate an alignment pattern in a limited region of the image, which is
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/// guessed to contain it. This method uses {@link AlignmentPattern}.</p>
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/// </summary>
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/// <param name="overallEstModuleSize">estimated module size so far</param>
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/// <param name="estAlignmentX">x coordinate of center of area probably containing alignment pattern</param>
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/// <param name="estAlignmentY">y coordinate of above</param>
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/// <param name="allowanceFactor">number of pixels in all directions to search from the center</param>
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/// <returns>
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/// <see cref="AlignmentPattern"/> if found, or null otherwise
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/// </returns>
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protected AlignmentPattern findAlignmentInRegion(float overallEstModuleSize, int estAlignmentX, int estAlignmentY, float allowanceFactor)
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{
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// Look for an alignment pattern (3 modules in size) around where it
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// should be
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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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int allowance = (int)(allowanceFactor * overallEstModuleSize);
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int alignmentAreaLeftX = Math.Max(0, estAlignmentX - allowance);
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int alignmentAreaRightX = Math.Min(image.Width - 1, estAlignmentX + allowance);
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if (alignmentAreaRightX - alignmentAreaLeftX < overallEstModuleSize * 3)
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{
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return null;
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}
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int alignmentAreaTopY = Math.Max(0, estAlignmentY - allowance);
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int alignmentAreaBottomY = Math.Min(image.Height - 1, estAlignmentY + allowance);
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var alignmentFinder = new AlignmentPatternFinder(
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image,
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alignmentAreaLeftX,
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alignmentAreaTopY,
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alignmentAreaRightX - alignmentAreaLeftX,
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alignmentAreaBottomY - alignmentAreaTopY,
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overallEstModuleSize,
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resultPointCallback);
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return alignmentFinder.find();
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}
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}
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} |