mirror of
https://github.com/zxing/zxing.git
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e2e8794d64
git-svn-id: https://zxing.googlecode.com/svn/trunk@1881 59b500cc-1b3d-0410-9834-0bbf25fbcc57
438 lines
15 KiB
C#
Executable file
438 lines
15 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 BitSource = com.google.zxing.common.BitSource;
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using CharacterSetECI = com.google.zxing.common.CharacterSetECI;
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using DecoderResult = com.google.zxing.common.DecoderResult;
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namespace com.google.zxing.qrcode.decoder
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{
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/// <summary> <p>QR Codes can encode text as bits in one of several modes, and can use multiple modes
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/// in one QR Code. This class decodes the bits back into text.</p>
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///
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/// <p>See ISO 18004:2006, 6.4.3 - 6.4.7</p>
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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 DecodedBitStreamParser
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{
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/// <summary> See ISO 18004:2006, 6.4.4 Table 5</summary>
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//UPGRADE_NOTE: Final was removed from the declaration of 'ALPHANUMERIC_CHARS'. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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private static readonly char[] ALPHANUMERIC_CHARS = new char[]{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', ' ', '$', '%', '*', '+', '-', '.', '/', ':'};
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private const System.String SHIFT_JIS = "SJIS";
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private const System.String EUC_JP = "EUC_JP";
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private static bool ASSUME_SHIFT_JIS;
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private const System.String UTF8 = "UTF-8";
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// Redivivus.in Java to c# Porting update
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// 30/01/2010
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// Commented & Added
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private const System.String ISO88591 = "ISO-8859-1";
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private DecodedBitStreamParser()
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{
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}
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internal static DecoderResult decode(sbyte[] bytes, Version version, ErrorCorrectionLevel ecLevel)
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{
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BitSource bits = new BitSource(bytes);
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System.Text.StringBuilder result = new System.Text.StringBuilder(50);
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CharacterSetECI currentCharacterSetECI = null;
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bool fc1InEffect = false;
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System.Collections.ArrayList byteSegments = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(1));
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Mode mode;
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do
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{
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// While still another segment to read...
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if (bits.available() < 4)
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{
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// OK, assume we're done. Really, a TERMINATOR mode should have been recorded here
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mode = Mode.TERMINATOR;
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}
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else
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{
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try
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{
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mode = Mode.forBits(bits.readBits(4)); // mode is encoded by 4 bits
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}
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catch (System.ArgumentException iae)
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{
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throw ReaderException.Instance;
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}
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}
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if (!mode.Equals(Mode.TERMINATOR))
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{
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if (mode.Equals(Mode.FNC1_FIRST_POSITION) || mode.Equals(Mode.FNC1_SECOND_POSITION))
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{
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// We do little with FNC1 except alter the parsed result a bit according to the spec
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fc1InEffect = true;
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}
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else if (mode.Equals(Mode.STRUCTURED_APPEND))
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{
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// not really supported; all we do is ignore it
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// Read next 8 bits (symbol sequence #) and 8 bits (parity data), then continue
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bits.readBits(16);
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}
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else if (mode.Equals(Mode.ECI))
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{
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// Count doesn't apply to ECI
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int value_Renamed = parseECIValue(bits);
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currentCharacterSetECI = CharacterSetECI.getCharacterSetECIByValue(value_Renamed);
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if (currentCharacterSetECI == null)
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{
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throw ReaderException.Instance;
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}
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}
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else
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{
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// How many characters will follow, encoded in this mode?
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int count = bits.readBits(mode.getCharacterCountBits(version));
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if (mode.Equals(Mode.NUMERIC))
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{
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decodeNumericSegment(bits, result, count);
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}
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else if (mode.Equals(Mode.ALPHANUMERIC))
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{
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decodeAlphanumericSegment(bits, result, count, fc1InEffect);
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}
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else if (mode.Equals(Mode.BYTE))
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{
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decodeByteSegment(bits, result, count, currentCharacterSetECI, byteSegments);
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}
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else if (mode.Equals(Mode.KANJI))
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{
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decodeKanjiSegment(bits, result, count);
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}
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else
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{
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throw ReaderException.Instance;
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}
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}
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}
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}
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while (!mode.Equals(Mode.TERMINATOR));
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return new DecoderResult(bytes, result.ToString(), (byteSegments.Count == 0)?null:byteSegments, ecLevel);
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}
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private static void decodeKanjiSegment(BitSource bits, System.Text.StringBuilder result, int count)
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{
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// Each character will require 2 bytes. Read the characters as 2-byte pairs
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// and decode as Shift_JIS afterwards
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sbyte[] buffer = new sbyte[2 * count];
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int offset = 0;
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while (count > 0)
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{
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// Each 13 bits encodes a 2-byte character
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int twoBytes = bits.readBits(13);
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int assembledTwoBytes = ((twoBytes / 0x0C0) << 8) | (twoBytes % 0x0C0);
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if (assembledTwoBytes < 0x01F00)
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{
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// In the 0x8140 to 0x9FFC range
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assembledTwoBytes += 0x08140;
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}
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else
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{
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// In the 0xE040 to 0xEBBF range
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assembledTwoBytes += 0x0C140;
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}
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buffer[offset] = (sbyte) (assembledTwoBytes >> 8);
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buffer[offset + 1] = (sbyte) assembledTwoBytes;
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offset += 2;
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count--;
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}
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// Shift_JIS may not be supported in some environments:
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try
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{
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//UPGRADE_TODO: The differences in the Format of parameters for constructor 'java.lang.String.String' may cause compilation errors. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1092'"
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result.Append(System.Text.Encoding.GetEncoding(SHIFT_JIS).GetString(SupportClass.ToByteArray(buffer)));
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}
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catch (System.IO.IOException uee)
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{
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throw ReaderException.Instance;
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}
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}
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private static void decodeByteSegment(BitSource bits, System.Text.StringBuilder result, int count, CharacterSetECI currentCharacterSetECI, System.Collections.ArrayList byteSegments)
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{
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sbyte[] readBytes = new sbyte[count];
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if (count << 3 > bits.available())
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{
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throw ReaderException.Instance;
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}
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for (int i = 0; i < count; i++)
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{
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readBytes[i] = (sbyte) bits.readBits(8);
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}
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System.String encoding;
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if (currentCharacterSetECI == null)
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{
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// The spec isn't clear on this mode; see
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// section 6.4.5: t does not say which encoding to assuming
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// upon decoding. I have seen ISO-8859-1 used as well as
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// Shift_JIS -- without anything like an ECI designator to
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// give a hint.
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encoding = guessEncoding(readBytes);
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}
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else
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{
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encoding = currentCharacterSetECI.EncodingName;
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}
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try
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{
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//UPGRADE_TODO: The differences in the Format of parameters for constructor 'java.lang.String.String' may cause compilation errors. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1092'"
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result.Append(System.Text.Encoding.GetEncoding(encoding).GetString(SupportClass.ToByteArray(readBytes)));
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}
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catch (System.IO.IOException uce)
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{
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throw ReaderException.Instance;
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}
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byteSegments.Add(SupportClass.ToByteArray(readBytes));
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}
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private static void decodeAlphanumericSegment(BitSource bits, System.Text.StringBuilder result, int count, bool fc1InEffect)
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{
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// Read two characters at a time
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int start = result.Length;
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while (count > 1)
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{
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int nextTwoCharsBits = bits.readBits(11);
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result.Append(ALPHANUMERIC_CHARS[nextTwoCharsBits / 45]);
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result.Append(ALPHANUMERIC_CHARS[nextTwoCharsBits % 45]);
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count -= 2;
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}
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if (count == 1)
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{
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// special case: one character left
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result.Append(ALPHANUMERIC_CHARS[bits.readBits(6)]);
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}
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// See section 6.4.8.1, 6.4.8.2
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if (fc1InEffect)
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{
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// We need to massage the result a bit if in an FNC1 mode:
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for (int i = start; i < result.Length; i++)
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{
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if (result[i] == '%')
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{
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if (i < result.Length - 1 && result[i + 1] == '%')
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{
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// %% is rendered as %
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result.Remove(i + 1, 1);
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}
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else
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{
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// In alpha mode, % should be converted to FNC1 separator 0x1D
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result[i] = (char) 0x1D;
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}
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}
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}
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}
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}
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private static void decodeNumericSegment(BitSource bits, System.Text.StringBuilder result, int count)
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{
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// Read three digits at a time
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while (count >= 3)
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{
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// Each 10 bits encodes three digits
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int threeDigitsBits = bits.readBits(10);
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if (threeDigitsBits >= 1000)
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{
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throw ReaderException.Instance;
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}
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result.Append(ALPHANUMERIC_CHARS[threeDigitsBits / 100]);
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result.Append(ALPHANUMERIC_CHARS[(threeDigitsBits / 10) % 10]);
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result.Append(ALPHANUMERIC_CHARS[threeDigitsBits % 10]);
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count -= 3;
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}
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if (count == 2)
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{
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// Two digits left over to read, encoded in 7 bits
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int twoDigitsBits = bits.readBits(7);
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if (twoDigitsBits >= 100)
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{
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throw ReaderException.Instance;
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}
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result.Append(ALPHANUMERIC_CHARS[twoDigitsBits / 10]);
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result.Append(ALPHANUMERIC_CHARS[twoDigitsBits % 10]);
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}
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else if (count == 1)
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{
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// One digit left over to read
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int digitBits = bits.readBits(4);
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if (digitBits >= 10)
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{
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throw ReaderException.Instance;
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}
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result.Append(ALPHANUMERIC_CHARS[digitBits]);
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}
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}
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private static System.String guessEncoding(sbyte[] bytes)
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{
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if (ASSUME_SHIFT_JIS)
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{
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return SHIFT_JIS;
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}
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// Does it start with the UTF-8 byte order mark? then guess it's UTF-8
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if (bytes.Length > 3 && bytes[0] == (sbyte) SupportClass.Identity(0xEF) && bytes[1] == (sbyte) SupportClass.Identity(0xBB) && bytes[2] == (sbyte) SupportClass.Identity(0xBF))
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{
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return UTF8;
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}
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// For now, merely tries to distinguish ISO-8859-1, UTF-8 and Shift_JIS,
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// which should be by far the most common encodings. ISO-8859-1
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// should not have bytes in the 0x80 - 0x9F range, while Shift_JIS
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// uses this as a first byte of a two-byte character. If we see this
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// followed by a valid second byte in Shift_JIS, assume it is Shift_JIS.
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// If we see something else in that second byte, we'll make the risky guess
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// that it's UTF-8.
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int length = bytes.Length;
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bool canBeISO88591 = true;
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bool canBeShiftJIS = true;
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int maybeDoubleByteCount = 0;
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int maybeSingleByteKatakanaCount = 0;
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bool sawLatin1Supplement = false;
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bool lastWasPossibleDoubleByteStart = false;
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for (int i = 0; i < length && (canBeISO88591 || canBeShiftJIS); i++)
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{
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int value_Renamed = bytes[i] & 0xFF;
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if ((value_Renamed == 0xC2 || value_Renamed == 0xC3) && i < length - 1)
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{
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// This is really a poor hack. The slightly more exotic characters people might want to put in
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// a QR Code, by which I mean the Latin-1 supplement characters (e.g. u-umlaut) have encodings
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// that start with 0xC2 followed by [0xA0,0xBF], or start with 0xC3 followed by [0x80,0xBF].
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int nextValue = bytes[i + 1] & 0xFF;
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if (nextValue <= 0xBF && ((value_Renamed == 0xC2 && nextValue >= 0xA0) || (value_Renamed == 0xC3 && nextValue >= 0x80)))
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{
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sawLatin1Supplement = true;
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}
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}
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if (value_Renamed >= 0x7F && value_Renamed <= 0x9F)
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{
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canBeISO88591 = false;
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}
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if (value_Renamed >= 0xA1 && value_Renamed <= 0xDF)
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{
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// count the number of characters that might be a Shift_JIS single-byte Katakana character
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if (!lastWasPossibleDoubleByteStart)
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{
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maybeSingleByteKatakanaCount++;
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}
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}
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if (!lastWasPossibleDoubleByteStart && ((value_Renamed >= 0xF0 && value_Renamed <= 0xFF) || value_Renamed == 0x80 || value_Renamed == 0xA0))
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{
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canBeShiftJIS = false;
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}
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if (((value_Renamed >= 0x81 && value_Renamed <= 0x9F) || (value_Renamed >= 0xE0 && value_Renamed <= 0xEF)))
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{
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// These start double-byte characters in Shift_JIS. Let's see if it's followed by a valid
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// second byte.
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if (lastWasPossibleDoubleByteStart)
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{
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// If we just checked this and the last byte for being a valid double-byte
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// char, don't check starting on this byte. If this and the last byte
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// formed a valid pair, then this shouldn't be checked to see if it starts
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// a double byte pair of course.
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lastWasPossibleDoubleByteStart = false;
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}
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else
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{
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// ... otherwise do check to see if this plus the next byte form a valid
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// double byte pair encoding a character.
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lastWasPossibleDoubleByteStart = true;
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if (i >= bytes.Length - 1)
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{
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canBeShiftJIS = false;
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}
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else
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{
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int nextValue = bytes[i + 1] & 0xFF;
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if (nextValue < 0x40 || nextValue > 0xFC)
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{
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canBeShiftJIS = false;
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}
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else
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{
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maybeDoubleByteCount++;
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}
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// There is some conflicting information out there about which bytes can follow which in
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// double-byte Shift_JIS characters. The rule above seems to be the one that matches practice.
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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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lastWasPossibleDoubleByteStart = false;
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}
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}
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// Distinguishing Shift_JIS and ISO-8859-1 can be a little tough. The crude heuristic is:
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// - If we saw
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// - at least three byte that starts a double-byte value (bytes that are rare in ISO-8859-1), or
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// - over 5% of bytes that could be single-byte Katakana (also rare in ISO-8859-1),
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// - and, saw no sequences that are invalid in Shift_JIS, then we conclude Shift_JIS
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if (canBeShiftJIS && (maybeDoubleByteCount >= 3 || 20 * maybeSingleByteKatakanaCount > length))
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{
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return SHIFT_JIS;
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}
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// Otherwise, we default to ISO-8859-1 unless we know it can't be
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if (!sawLatin1Supplement && canBeISO88591)
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{
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return ISO88591;
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}
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// Otherwise, we take a wild guess with UTF-8
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return UTF8;
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}
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private static int parseECIValue(BitSource bits)
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{
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int firstByte = bits.readBits(8);
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if ((firstByte & 0x80) == 0)
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{
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// just one byte
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return firstByte & 0x7F;
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}
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else if ((firstByte & 0xC0) == 0x80)
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{
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// two bytes
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int secondByte = bits.readBits(8);
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return ((firstByte & 0x3F) << 8) | secondByte;
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}
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else if ((firstByte & 0xE0) == 0xC0)
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{
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// three bytes
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int secondThirdBytes = bits.readBits(16);
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return ((firstByte & 0x1F) << 16) | secondThirdBytes;
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}
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throw new System.ArgumentException("Bad ECI bits starting with byte " + firstByte);
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}
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static DecodedBitStreamParser()
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{
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{
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// Redivivus.in Java to c# Porting update
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// 30/01/2010
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// Commented & Added
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//System.String platformDefault = System_Renamed.getProperty("file.encoding");
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//ASSUME_SHIFT_JIS = SHIFT_JIS.ToUpper().Equals(platformDefault.ToUpper()) || EUC_JP.ToUpper().Equals(platformDefault.ToUpper());
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ASSUME_SHIFT_JIS = false;
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}
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}
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}
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}
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