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https://gitee.com/akwkevin/aistudio.-wpf.-diagram
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433 lines
17 KiB
C#
433 lines
17 KiB
C#
/*
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* Copyright 2008 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 System.Text;
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using ZXing.Common;
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namespace ZXing.OneD
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{
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/// <summary>
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/// <p>Encapsulates functionality and implementation that is common to UPC and EAN families
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/// of one-dimensional barcodes.</p>
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/// <author>dswitkin@google.com (Daniel Switkin)</author>
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/// <author>Sean Owen</author>
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/// <author>alasdair@google.com (Alasdair Mackintosh)</author>
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/// </summary>
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public abstract class UPCEANReader : OneDReader
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{
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// These two values are critical for determining how permissive the decoding will be.
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// We've arrived at these values through a lot of trial and error. Setting them any higher
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// lets false positives creep in quickly.
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private static readonly int MAX_AVG_VARIANCE = (int)(PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.48f);
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private static readonly int MAX_INDIVIDUAL_VARIANCE = (int)(PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.7f);
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/// <summary>
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/// Start/end guard pattern.
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/// </summary>
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internal static int[] START_END_PATTERN = { 1, 1, 1, };
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/// <summary>
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/// Pattern marking the middle of a UPC/EAN pattern, separating the two halves.
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/// </summary>
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internal static int[] MIDDLE_PATTERN = { 1, 1, 1, 1, 1 };
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/// <summary>
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/// "Odd", or "L" patterns used to encode UPC/EAN digits.
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/// </summary>
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internal static int[][] L_PATTERNS = {
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new[] {3, 2, 1, 1}, // 0
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new[] {2, 2, 2, 1}, // 1
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new[] {2, 1, 2, 2}, // 2
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new[] {1, 4, 1, 1}, // 3
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new[] {1, 1, 3, 2}, // 4
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new[] {1, 2, 3, 1}, // 5
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new[] {1, 1, 1, 4}, // 6
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new[] {1, 3, 1, 2}, // 7
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new[] {1, 2, 1, 3}, // 8
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new[] {3, 1, 1, 2} // 9
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};
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/// <summary>
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/// As above but also including the "even", or "G" patterns used to encode UPC/EAN digits.
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/// </summary>
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internal static int[][] L_AND_G_PATTERNS;
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static UPCEANReader()
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{
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L_AND_G_PATTERNS = new int[20][];
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Array.Copy(L_PATTERNS, 0, L_AND_G_PATTERNS, 0, 10);
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for (int i = 10; i < 20; i++)
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{
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int[] widths = L_PATTERNS[i - 10];
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int[] reversedWidths = new int[widths.Length];
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for (int j = 0; j < widths.Length; j++)
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{
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reversedWidths[j] = widths[widths.Length - j - 1];
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}
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L_AND_G_PATTERNS[i] = reversedWidths;
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}
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}
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private readonly StringBuilder decodeRowStringBuffer;
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private readonly UPCEANExtensionSupport extensionReader;
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private readonly EANManufacturerOrgSupport eanManSupport;
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/// <summary>
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/// Initializes a new instance of the <see cref="UPCEANReader"/> class.
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/// </summary>
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protected UPCEANReader()
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{
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decodeRowStringBuffer = new StringBuilder(20);
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extensionReader = new UPCEANExtensionSupport();
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eanManSupport = new EANManufacturerOrgSupport();
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}
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internal static int[] findStartGuardPattern(BitArray row)
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{
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bool foundStart = false;
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int[] startRange = null;
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int nextStart = 0;
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int[] counters = new int[START_END_PATTERN.Length];
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while (!foundStart)
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{
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for (int idx = 0; idx < START_END_PATTERN.Length; idx++)
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counters[idx] = 0;
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startRange = findGuardPattern(row, nextStart, false, START_END_PATTERN, counters);
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if (startRange == null)
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return null;
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int start = startRange[0];
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nextStart = startRange[1];
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// Make sure there is a quiet zone at least as big as the start pattern before the barcode.
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// If this check would run off the left edge of the image, do not accept this barcode,
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// as it is very likely to be a false positive.
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int quietStart = start - (nextStart - start);
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if (quietStart >= 0)
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{
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foundStart = row.isRange(quietStart, start, false);
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}
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}
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return startRange;
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}
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/// <summary>
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/// <p>Attempts to decode a one-dimensional barcode format given a single row of
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/// an image.</p>
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/// </summary>
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/// <param name="rowNumber">row number from top of the row</param>
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/// <param name="row">the black/white pixel data of the row</param>
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/// <param name="hints">decode hints</param>
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/// <returns>
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/// <see cref="Result"/>containing encoded string and start/end of barcode or null, if an error occurs or barcode cannot be found
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/// </returns>
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override public Result decodeRow(int rowNumber, BitArray row, IDictionary<DecodeHintType, object> hints)
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{
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return decodeRow(rowNumber, row, findStartGuardPattern(row), hints);
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}
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/// <summary>
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/// <p>Like decodeRow(int, BitArray, java.util.Map), but
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/// allows caller to inform method about where the UPC/EAN start pattern is
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/// found. This allows this to be computed once and reused across many implementations.</p>
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/// </summary>
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/// <param name="rowNumber">row index into the image</param>
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/// <param name="row">encoding of the row of the barcode image</param>
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/// <param name="startGuardRange">start/end column where the opening start pattern was found</param>
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/// <param name="hints">optional hints that influence decoding</param>
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/// <returns><see cref="Result"/> encapsulating the result of decoding a barcode in the row</returns>
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virtual public Result decodeRow(int rowNumber,
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BitArray row,
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int[] startGuardRange,
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IDictionary<DecodeHintType, object> hints)
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{
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var resultPointCallback = hints == null || !hints.ContainsKey(DecodeHintType.NEED_RESULT_POINT_CALLBACK) ? null :
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(ResultPointCallback)hints[DecodeHintType.NEED_RESULT_POINT_CALLBACK];
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if (resultPointCallback != null)
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{
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resultPointCallback(new ResultPoint(
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(startGuardRange[0] + startGuardRange[1]) / 2.0f, rowNumber
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));
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}
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var result = decodeRowStringBuffer;
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result.Length = 0;
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var endStart = decodeMiddle(row, startGuardRange, result);
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if (endStart < 0)
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return null;
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if (resultPointCallback != null)
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{
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resultPointCallback(new ResultPoint(
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endStart, rowNumber
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));
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}
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var endRange = decodeEnd(row, endStart);
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if (endRange == null)
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return null;
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if (resultPointCallback != null)
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{
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resultPointCallback(new ResultPoint(
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(endRange[0] + endRange[1]) / 2.0f, rowNumber
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));
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}
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// Make sure there is a quiet zone at least as big as the end pattern after the barcode. The
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// spec might want more whitespace, but in practice this is the maximum we can count on.
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var end = endRange[1];
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var quietEnd = end + (end - endRange[0]);
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if (quietEnd >= row.Size || !row.isRange(end, quietEnd, false))
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{
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return null;
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}
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var resultString = result.ToString();
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// UPC/EAN should never be less than 8 chars anyway
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if (resultString.Length < 8)
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{
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return null;
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}
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if (!checkChecksum(resultString))
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{
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return null;
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}
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var left = (startGuardRange[1] + startGuardRange[0]) / 2.0f;
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var right = (endRange[1] + endRange[0]) / 2.0f;
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var format = BarcodeFormat;
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var decodeResult = new Result(resultString,
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null, // no natural byte representation for these barcodes
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new ResultPoint[]
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{
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new ResultPoint(left, rowNumber),
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new ResultPoint(right, rowNumber)
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},
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format);
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var extensionResult = extensionReader.decodeRow(rowNumber, row, endRange[1]);
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if (extensionResult != null)
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{
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decodeResult.putMetadata(ResultMetadataType.UPC_EAN_EXTENSION, extensionResult.Text);
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decodeResult.putAllMetadata(extensionResult.ResultMetadata);
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decodeResult.addResultPoints(extensionResult.ResultPoints);
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int extensionLength = extensionResult.Text.Length;
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int[] allowedExtensions = hints != null && hints.ContainsKey(DecodeHintType.ALLOWED_EAN_EXTENSIONS) ?
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(int[]) hints[DecodeHintType.ALLOWED_EAN_EXTENSIONS] : null;
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if (allowedExtensions != null)
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{
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bool valid = false;
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foreach (int length in allowedExtensions)
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{
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if (extensionLength == length)
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{
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valid = true;
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break;
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}
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}
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if (!valid)
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{
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return null;
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}
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}
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}
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if (format == BarcodeFormat.EAN_13 || format == BarcodeFormat.UPC_A)
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{
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String countryID = eanManSupport.lookupCountryIdentifier(resultString);
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if (countryID != null)
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{
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decodeResult.putMetadata(ResultMetadataType.POSSIBLE_COUNTRY, countryID);
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}
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}
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return decodeResult;
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}
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/// <summary>
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/// </summary>
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/// <param name="s">string of digits to check</param>
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/// <returns>see <see cref="checkStandardUPCEANChecksum(String)"/></returns>
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virtual protected bool checkChecksum(String s)
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{
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return checkStandardUPCEANChecksum(s);
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}
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/// <summary>
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/// Computes the UPC/EAN checksum on a string of digits, and reports
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/// whether the checksum is correct or not.
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/// </summary>
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/// <param name="s">string of digits to check</param>
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/// <returns>true iff string of digits passes the UPC/EAN checksum algorithm</returns>
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internal static bool checkStandardUPCEANChecksum(String s)
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{
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int length = s.Length;
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if (length == 0)
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{
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return false;
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}
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int sum = 0;
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for (int i = length - 2; i >= 0; i -= 2)
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{
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int digit = (int)s[i] - (int)'0';
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if (digit < 0 || digit > 9)
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{
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return false;
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}
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sum += digit;
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}
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sum *= 3;
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for (int i = length - 1; i >= 0; i -= 2)
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{
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int digit = (int)s[i] - (int)'0';
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if (digit < 0 || digit > 9)
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{
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return false;
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}
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sum += digit;
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}
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return sum % 10 == 0;
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}
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/// <summary>
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/// Decodes the end.
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/// </summary>
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/// <param name="row">The row.</param>
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/// <param name="endStart">The end start.</param>
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/// <returns></returns>
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virtual protected int[] decodeEnd(BitArray row, int endStart)
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{
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return findGuardPattern(row, endStart, false, START_END_PATTERN);
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}
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internal static int[] findGuardPattern(BitArray row,
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int rowOffset,
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bool whiteFirst,
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int[] pattern)
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{
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return findGuardPattern(row, rowOffset, whiteFirst, pattern, new int[pattern.Length]);
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}
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/// <summary>
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/// </summary>
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/// <param name="row">row of black/white values to search</param>
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/// <param name="rowOffset">position to start search</param>
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/// <param name="whiteFirst">if true, indicates that the pattern specifies white/black/white/...</param>
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/// pixel counts, otherwise, it is interpreted as black/white/black/...
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/// <param name="pattern">pattern of counts of number of black and white pixels that are being</param>
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/// searched for as a pattern
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/// <param name="counters">array of counters, as long as pattern, to re-use</param>
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/// <returns>start/end horizontal offset of guard pattern, as an array of two ints</returns>
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internal static int[] findGuardPattern(BitArray row,
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int rowOffset,
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bool whiteFirst,
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int[] pattern,
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int[] counters)
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{
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int patternLength = pattern.Length;
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int width = row.Size;
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bool isWhite = whiteFirst;
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rowOffset = whiteFirst ? row.getNextUnset(rowOffset) : row.getNextSet(rowOffset);
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int counterPosition = 0;
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int patternStart = rowOffset;
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for (int x = rowOffset; x < width; x++)
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{
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if (row[x] ^ isWhite)
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{
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counters[counterPosition]++;
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}
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else
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{
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if (counterPosition == patternLength - 1)
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{
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if (patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE) < MAX_AVG_VARIANCE)
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{
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return new int[] { patternStart, x };
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}
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patternStart += counters[0] + counters[1];
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Array.Copy(counters, 2, counters, 0, patternLength - 2);
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counters[patternLength - 2] = 0;
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counters[patternLength - 1] = 0;
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counterPosition--;
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}
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else
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{
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counterPosition++;
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}
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counters[counterPosition] = 1;
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isWhite = !isWhite;
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}
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}
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return null;
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}
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/// <summary>
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/// Attempts to decode a single UPC/EAN-encoded digit.
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/// </summary>
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/// <param name="row">row of black/white values to decode</param>
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/// <param name="counters">the counts of runs of observed black/white/black/... values</param>
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/// <param name="rowOffset">horizontal offset to start decoding from</param>
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/// <param name="patterns">the set of patterns to use to decode -- sometimes different encodings</param>
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/// for the digits 0-9 are used, and this indicates the encodings for 0 to 9 that should
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/// be used
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/// <returns>horizontal offset of first pixel beyond the decoded digit</returns>
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internal static bool decodeDigit(BitArray row, int[] counters, int rowOffset, int[][] patterns, out int digit)
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{
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digit = -1;
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if (!recordPattern(row, rowOffset, counters))
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return false;
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int bestVariance = MAX_AVG_VARIANCE; // worst variance we'll accept
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int max = patterns.Length;
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for (int i = 0; i < max; i++)
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{
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int[] pattern = patterns[i];
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int variance = patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE);
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if (variance < bestVariance)
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{
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bestVariance = variance;
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digit = i;
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}
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}
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return digit >= 0;
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}
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/// <summary>
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/// Get the format of this decoder.
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/// </summary>
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/// <returns>The 1D format.</returns>
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internal abstract BarcodeFormat BarcodeFormat { get; }
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/// <summary>
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/// Subclasses override this to decode the portion of a barcode between the start
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/// and end guard patterns.
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/// </summary>
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/// <param name="row">row of black/white values to search</param>
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/// <param name="startRange">start/end offset of start guard pattern</param>
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/// <param name="resultString"><see cref="StringBuilder" />to append decoded chars to</param>
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/// <returns>horizontal offset of first pixel after the "middle" that was decoded or -1 if decoding could not complete successfully</returns>
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protected internal abstract int decodeMiddle(BitArray row,
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int[] startRange,
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StringBuilder resultString);
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}
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} |
