zxing/csharp/qrcode/decoder/DecodedBitStreamParser.cs
2013-01-18 20:14:03 +00:00

442 lines
14 KiB
C#
Executable file

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;
/*
* Copyright 2007 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
namespace com.google.zxing.qrcode.decoder
{
using DecodeHintType = com.google.zxing.DecodeHintType;
using FormatException = com.google.zxing.FormatException;
using BitSource = com.google.zxing.common.BitSource;
using CharacterSetECI = com.google.zxing.common.CharacterSetECI;
using DecoderResult = com.google.zxing.common.DecoderResult;
using StringUtils = com.google.zxing.common.StringUtils;
using com.google.zxing.common;
/// <summary>
/// <p>QR Codes can encode text as bits in one of several modes, and can use multiple modes
/// in one QR Code. This class decodes the bits back into text.</p>
///
/// <p>See ISO 18004:2006, 6.4.3 - 6.4.7</p>
///
/// @author Sean Owen
/// </summary>
internal sealed class DecodedBitStreamParser
{
/// <summary>
/// See ISO 18004:2006, 6.4.4 Table 5
/// </summary>
private static readonly char[] ALPHANUMERIC_CHARS = {'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', ' ', '$', '%', '*', '+', '-', '.', '/', ':'};
private const int GB2312_SUBSET = 1;
private DecodedBitStreamParser()
{
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: static com.google.zxing.common.DecoderResult decode(byte[] bytes, Version version, ErrorCorrectionLevel ecLevel, java.util.Map<com.google.zxing.DecodeHintType,?> hints) throws com.google.zxing.FormatException
internal static DecoderResult decode(sbyte[] bytes, Version version, ErrorCorrectionLevel ecLevel, IDictionary<DecodeHintType, object> hints)
{
BitSource bits = new BitSource(bytes);
StringBuilder result = new StringBuilder(50);
IList<sbyte[]> byteSegments = new List<sbyte[]>(1);
try
{
CharacterSetECI currentCharacterSetECI = null;
bool fc1InEffect = false;
Mode mode;
do
{
// While still another segment to read...
if (bits.available() < 4)
{
// OK, assume we're done. Really, a TERMINATOR mode should have been recorded here
mode = Mode.TERMINATOR;
}
else
{
mode = Mode.forBits(bits.readBits(4)); // mode is encoded by 4 bits
}
if (mode != Mode.TERMINATOR)
{
if (mode == Mode.FNC1_FIRST_POSITION || mode == Mode.FNC1_SECOND_POSITION)
{
// We do little with FNC1 except alter the parsed result a bit according to the spec
fc1InEffect = true;
}
else if (mode == Mode.STRUCTURED_APPEND)
{
if (bits.available() < 16)
{
throw FormatException.FormatInstance;
}
// not really supported; all we do is ignore it
// Read next 8 bits (symbol sequence #) and 8 bits (parity data), then continue
bits.readBits(16);
}
else if (mode == Mode.ECI)
{
// Count doesn't apply to ECI
int value = parseECIValue(bits);
currentCharacterSetECI = CharacterSetECI.getCharacterSetECIByValue(value);
if (currentCharacterSetECI == null)
{
throw FormatException.FormatInstance;
}
}
else
{
// First handle Hanzi mode which does not start with character count
if (mode == Mode.HANZI)
{
//chinese mode contains a sub set indicator right after mode indicator
int subset = bits.readBits(4);
int countHanzi = bits.readBits(mode.getCharacterCountBits(version));
if (subset == GB2312_SUBSET)
{
decodeHanziSegment(bits, result, countHanzi);
}
}
else
{
// "Normal" QR code modes:
// How many characters will follow, encoded in this mode?
int count = bits.readBits(mode.getCharacterCountBits(version));
if (mode == Mode.NUMERIC)
{
decodeNumericSegment(bits, result, count);
}
else if (mode == Mode.ALPHANUMERIC)
{
decodeAlphanumericSegment(bits, result, count, fc1InEffect);
}
else if (mode == Mode.BYTE)
{
decodeByteSegment(bits, result, count, currentCharacterSetECI, byteSegments, hints);
}
else if (mode == Mode.KANJI)
{
decodeKanjiSegment(bits, result, count);
}
else
{
throw FormatException.FormatInstance;
}
}
}
}
} while (mode != Mode.TERMINATOR);
}
catch (System.ArgumentException iae)
{
// from readBits() calls
throw FormatException.FormatInstance;
}
return new DecoderResult(bytes, result.ToString(), byteSegments.Count == 0 ? null : byteSegments, ecLevel == null ? null : ecLevel.ToString());
}
/// <summary>
/// See specification GBT 18284-2000
/// </summary>
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: private static void decodeHanziSegment(com.google.zxing.common.BitSource bits, StringBuilder result, int count) throws com.google.zxing.FormatException
private static void decodeHanziSegment(BitSource bits, StringBuilder result, int count)
{
// Don't crash trying to read more bits than we have available.
if (count * 13 > bits.available())
{
throw FormatException.FormatInstance;
}
// Each character will require 2 bytes. Read the characters as 2-byte pairs
// and decode as GB2312 afterwards
sbyte[] buffer = new sbyte[2 * count];
int offset = 0;
while (count > 0)
{
// Each 13 bits encodes a 2-byte character
int twoBytes = bits.readBits(13);
int assembledTwoBytes = ((twoBytes / 0x060) << 8) | (twoBytes % 0x060);
if (assembledTwoBytes < 0x003BF)
{
// In the 0xA1A1 to 0xAAFE range
assembledTwoBytes += 0x0A1A1;
}
else
{
// In the 0xB0A1 to 0xFAFE range
assembledTwoBytes += 0x0A6A1;
}
buffer[offset] = (sbyte)((assembledTwoBytes >> 8) & 0xFF);
buffer[offset + 1] = (sbyte)(assembledTwoBytes & 0xFF);
offset += 2;
count--;
}
try
{
//result.Append(new string(buffer, StringUtils.GB2312));
result.Append(GetEncodedStringFromBuffer(buffer, StringUtils.GB2312));
}
catch (System.IO.IOException)
{
throw FormatException.FormatInstance;
}
}
private static string GetEncodedStringFromBuffer(sbyte[] buffer, string encoding)
{
byte[] bytes = buffer.ToBytes();
Encoding en = Encoding.GetEncoding(encoding);
return en.GetString(bytes);
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: private static void decodeKanjiSegment(com.google.zxing.common.BitSource bits, StringBuilder result, int count) throws com.google.zxing.FormatException
private static void decodeKanjiSegment(BitSource bits, StringBuilder result, int count)
{
// Don't crash trying to read more bits than we have available.
if (count * 13 > bits.available())
{
throw FormatException.FormatInstance;
}
// Each character will require 2 bytes. Read the characters as 2-byte pairs
// and decode as Shift_JIS afterwards
sbyte[] buffer = new sbyte[2 * count];
int offset = 0;
while (count > 0)
{
// Each 13 bits encodes a 2-byte character
int twoBytes = bits.readBits(13);
int assembledTwoBytes = ((twoBytes / 0x0C0) << 8) | (twoBytes % 0x0C0);
if (assembledTwoBytes < 0x01F00)
{
// In the 0x8140 to 0x9FFC range
assembledTwoBytes += 0x08140;
}
else
{
// In the 0xE040 to 0xEBBF range
assembledTwoBytes += 0x0C140;
}
buffer[offset] = (sbyte)(assembledTwoBytes >> 8);
buffer[offset + 1] = (sbyte) assembledTwoBytes;
offset += 2;
count--;
}
// Shift_JIS may not be supported in some environments:
try
{
//result.Append(new string(buffer, StringUtils.SHIFT_JIS));
result.Append(GetEncodedStringFromBuffer(buffer, StringUtils.SHIFT_JIS));
}
catch (System.IO.IOException)
{
throw FormatException.FormatInstance;
}
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: private static void decodeByteSegment(com.google.zxing.common.BitSource bits, StringBuilder result, int count, com.google.zxing.common.CharacterSetECI currentCharacterSetECI, java.util.Collection<byte[]> byteSegments, java.util.Map<com.google.zxing.DecodeHintType,?> hints) throws com.google.zxing.FormatException
private static void decodeByteSegment(BitSource bits, StringBuilder result, int count, CharacterSetECI currentCharacterSetECI, ICollection<sbyte[]> byteSegments, IDictionary<DecodeHintType, object> hints)
{
// Don't crash trying to read more bits than we have available.
if (count << 3 > bits.available())
{
throw FormatException.FormatInstance;
}
sbyte[] readBytes = new sbyte[count];
for (int i = 0; i < count; i++)
{
readBytes[i] = (sbyte) bits.readBits(8);
}
string encoding;
if (currentCharacterSetECI == null)
{
// The spec isn't clear on this mode; see
// section 6.4.5: t does not say which encoding to assuming
// upon decoding. I have seen ISO-8859-1 used as well as
// Shift_JIS -- without anything like an ECI designator to
// give a hint.
encoding = StringUtils.guessEncoding(readBytes, hints);
}
else
{
encoding = currentCharacterSetECI.name();
}
try
{
//result.Append(new string(readBytes, encoding));
result.Append(GetEncodedStringFromBuffer(readBytes, encoding));
}
catch (System.IO.IOException)
{
throw FormatException.FormatInstance;
}
byteSegments.Add(readBytes);
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: private static char toAlphaNumericChar(int value) throws com.google.zxing.FormatException
private static char toAlphaNumericChar(int value)
{
if (value >= ALPHANUMERIC_CHARS.Length)
{
throw FormatException.FormatInstance;
}
return ALPHANUMERIC_CHARS[value];
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: private static void decodeAlphanumericSegment(com.google.zxing.common.BitSource bits, StringBuilder result, int count, boolean fc1InEffect) throws com.google.zxing.FormatException
private static void decodeAlphanumericSegment(BitSource bits, StringBuilder result, int count, bool fc1InEffect)
{
// Read two characters at a time
int start = result.Length;
while (count > 1)
{
if (bits.available() < 11)
{
throw FormatException.FormatInstance;
}
int nextTwoCharsBits = bits.readBits(11);
result.Append(toAlphaNumericChar(nextTwoCharsBits / 45));
result.Append(toAlphaNumericChar(nextTwoCharsBits % 45));
count -= 2;
}
if (count == 1)
{
// special case: one character left
if (bits.available() < 6)
{
throw FormatException.FormatInstance;
}
result.Append(toAlphaNumericChar(bits.readBits(6)));
}
// See section 6.4.8.1, 6.4.8.2
if (fc1InEffect)
{
// We need to massage the result a bit if in an FNC1 mode:
for (int i = start; i < result.Length; i++)
{
if (result[i] == '%')
{
if (i < result.Length - 1 && result[i + 1] == '%')
{
// %% is rendered as %
result.Remove(i + 1, 1);
}
else
{
// In alpha mode, % should be converted to FNC1 separator 0x1D
result[i] = (char) 0x1D;
}
}
}
}
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: private static void decodeNumericSegment(com.google.zxing.common.BitSource bits, StringBuilder result, int count) throws com.google.zxing.FormatException
private static void decodeNumericSegment(BitSource bits, StringBuilder result, int count)
{
// Read three digits at a time
while (count >= 3)
{
// Each 10 bits encodes three digits
if (bits.available() < 10)
{
throw FormatException.FormatInstance;
}
int threeDigitsBits = bits.readBits(10);
if (threeDigitsBits >= 1000)
{
throw FormatException.FormatInstance;
}
result.Append(toAlphaNumericChar(threeDigitsBits / 100));
result.Append(toAlphaNumericChar((threeDigitsBits / 10) % 10));
result.Append(toAlphaNumericChar(threeDigitsBits % 10));
count -= 3;
}
if (count == 2)
{
// Two digits left over to read, encoded in 7 bits
if (bits.available() < 7)
{
throw FormatException.FormatInstance;
}
int twoDigitsBits = bits.readBits(7);
if (twoDigitsBits >= 100)
{
throw FormatException.FormatInstance;
}
result.Append(toAlphaNumericChar(twoDigitsBits / 10));
result.Append(toAlphaNumericChar(twoDigitsBits % 10));
}
else if (count == 1)
{
// One digit left over to read
if (bits.available() < 4)
{
throw FormatException.FormatInstance;
}
int digitBits = bits.readBits(4);
if (digitBits >= 10)
{
throw FormatException.FormatInstance;
}
result.Append(toAlphaNumericChar(digitBits));
}
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: private static int parseECIValue(com.google.zxing.common.BitSource bits) throws com.google.zxing.FormatException
private static int parseECIValue(BitSource bits)
{
int firstByte = bits.readBits(8);
if ((firstByte & 0x80) == 0)
{
// just one byte
return firstByte & 0x7F;
}
if ((firstByte & 0xC0) == 0x80)
{
// two bytes
int secondByte = bits.readBits(8);
return ((firstByte & 0x3F) << 8) | secondByte;
}
if ((firstByte & 0xE0) == 0xC0)
{
// three bytes
int secondThirdBytes = bits.readBits(16);
return ((firstByte & 0x1F) << 16) | secondThirdBytes;
}
throw FormatException.FormatInstance;
}
}
}