DecodedBitStreamParser.cs

/silverlight/qrcode/decoder/DecodedBitStreamParser.cs

https://bitbucket.org/jrasanen/silverlightzxing
C# | 447 lines | 331 code | 14 blank | 102 comment | 100 complexity | 4c7863b1cc346cf88bbece4a8e096532 MD5 | raw file

/*

* 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.

*/

using System;

using ReaderException = com.google.zxing.ReaderException;

using BitSource = com.google.zxing.common.BitSource;

using CharacterSetECI = com.google.zxing.common.CharacterSetECI;

using DecoderResult = com.google.zxing.common.DecoderResult;

namespace com.google.zxing.qrcode.decoder

{

	

	/// <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>

	/// 

	/// </summary>

	/// <author>  Sean Owen

	/// </author>

	/// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source 

	/// </author>

	sealed class DecodedBitStreamParser

	{

		

		/// <summary> See ISO 18004:2006, 6.4.4 Table 5</summary>

		//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'"

		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', ' ', '$', '%', '*', '+', '-', '.', '/', ':'};

		private const System.String SHIFT_JIS = "SJIS";

		private const System.String EUC_JP = "EUC_JP";

		private static bool ASSUME_SHIFT_JIS;

		private const System.String UTF8 = "UTF8";

        // Redivivus.in Java to c# Porting update

        // 30/01/2010 

        // Commented & Added        

        private const System.String ISO88591 = "ISO-8859-1";

		

		private DecodedBitStreamParser()

		{

		}

		

		internal static DecoderResult decode(sbyte[] bytes, Version version, ErrorCorrectionLevel ecLevel)

		{

			BitSource bits = new BitSource(bytes);

			System.Text.StringBuilder result = new System.Text.StringBuilder(50);

			CharacterSetECI currentCharacterSetECI = null;

			bool fc1InEffect = false;

            System.Collections.Generic.List<Object> byteSegments = new System.Collections.Generic.List<Object>(1);

			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

				{

					try

					{

						mode = Mode.forBits(bits.readBits(4)); // mode is encoded by 4 bits

					}

					catch (System.ArgumentException iae)

					{

						throw ReaderException.Instance;

					}

				}

				if (!mode.Equals(Mode.TERMINATOR))

				{

					if (mode.Equals(Mode.FNC1_FIRST_POSITION) || mode.Equals(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.Equals(Mode.STRUCTURED_APPEND))

					{

						// 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.Equals(Mode.ECI))

					{

						// Count doesn't apply to ECI

						int value_Renamed = parseECIValue(bits);

						currentCharacterSetECI = CharacterSetECI.getCharacterSetECIByValue(value_Renamed);

						if (currentCharacterSetECI == null)

						{

							throw ReaderException.Instance;

						}

					}

					else

					{

						// How many characters will follow, encoded in this mode?

						int count = bits.readBits(mode.getCharacterCountBits(version));

						if (mode.Equals(Mode.NUMERIC))

						{

							decodeNumericSegment(bits, result, count);

						}

						else if (mode.Equals(Mode.ALPHANUMERIC))

						{

							decodeAlphanumericSegment(bits, result, count, fc1InEffect);

						}

						else if (mode.Equals(Mode.BYTE))

						{

							decodeByteSegment(bits, result, count, currentCharacterSetECI, byteSegments);

						}

						else if (mode.Equals(Mode.KANJI))

						{

							decodeKanjiSegment(bits, result, count);

						}

						else

						{

							throw ReaderException.Instance;

						}

					}

				}

			}

			while (!mode.Equals(Mode.TERMINATOR));

			

			return new DecoderResult(bytes, result.ToString(), (byteSegments.Count == 0)?null:byteSegments, ecLevel);

		}

		

		private static void  decodeKanjiSegment(BitSource bits, System.Text.StringBuilder result, int count)

		{

			// 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

			{

				//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'"

				//result.Append(System.Text.Encoding.GetEncoding(SHIFT_JIS).GetString(SupportClass.ToByteArray(buffer)));



                  byte[] inputBytes =SupportClass.ToByteArray(buffer);

                //Marauderz : Errrr... what if this thing isn't Null terminated?

                result.Append(System.Text.Encoding.UTF8.GetString(inputBytes,0,inputBytes.Length));



			}

			catch (System.IO.IOException uee)

			{

				throw ReaderException.Instance;

			}

		}

		

		private static void  decodeByteSegment(BitSource bits, System.Text.StringBuilder result, int count, CharacterSetECI currentCharacterSetECI, System.Collections.Generic.List<Object> byteSegments)

		{

			sbyte[] readBytes = new sbyte[count];

			if (count << 3 > bits.available())

			{

				throw ReaderException.Instance;

			}

			for (int i = 0; i < count; i++)

			{

				readBytes[i] = (sbyte) bits.readBits(8);

			}

			System.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 = guessEncoding(readBytes);

			}

			else

			{

				encoding = currentCharacterSetECI.EncodingName;

			}

			try

			{

				//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'"

                //Marauderz : Switching to UTF 8 encoding

				//result.Append(System.Text.Encoding.GetEncoding(encoding).GetString(SupportClass.ToByteArray(readBytes)));

               byte[] inputBytes =SupportClass.ToByteArray(readBytes);

                //Marauderz : Errrr... what if this thing isn't Null terminated?

                result.Append(System.Text.Encoding.UTF8.GetString(inputBytes,0,inputBytes.Length));



			}

			catch (System.IO.IOException uce)

			{

				throw ReaderException.Instance;

			}

			byteSegments.Add(SupportClass.ToByteArray(readBytes));

		}

		

		private static void  decodeAlphanumericSegment(BitSource bits, System.Text.StringBuilder result, int count, bool fc1InEffect)

		{

			// Read two characters at a time

			int start = result.Length;

			while (count > 1)

			{

				int nextTwoCharsBits = bits.readBits(11);

				result.Append(ALPHANUMERIC_CHARS[nextTwoCharsBits / 45]);

				result.Append(ALPHANUMERIC_CHARS[nextTwoCharsBits % 45]);

				count -= 2;

			}

			if (count == 1)

			{

				// special case: one character left

				result.Append(ALPHANUMERIC_CHARS[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;

						}

					}

				}

			}

		}

		

		private static void  decodeNumericSegment(BitSource bits, System.Text.StringBuilder result, int count)

		{

			// Read three digits at a time

			while (count >= 3)

			{

				// Each 10 bits encodes three digits

				int threeDigitsBits = bits.readBits(10);

				if (threeDigitsBits >= 1000)

				{

					throw ReaderException.Instance;

				}

				result.Append(ALPHANUMERIC_CHARS[threeDigitsBits / 100]);

				result.Append(ALPHANUMERIC_CHARS[(threeDigitsBits / 10) % 10]);

				result.Append(ALPHANUMERIC_CHARS[threeDigitsBits % 10]);

				count -= 3;

			}

			if (count == 2)

			{

				// Two digits left over to read, encoded in 7 bits

				int twoDigitsBits = bits.readBits(7);

				if (twoDigitsBits >= 100)

				{

					throw ReaderException.Instance;

				}

				result.Append(ALPHANUMERIC_CHARS[twoDigitsBits / 10]);

				result.Append(ALPHANUMERIC_CHARS[twoDigitsBits % 10]);

			}

			else if (count == 1)

			{

				// One digit left over to read

				int digitBits = bits.readBits(4);

				if (digitBits >= 10)

				{

					throw ReaderException.Instance;

				}

				result.Append(ALPHANUMERIC_CHARS[digitBits]);

			}

		}

		

		private static System.String guessEncoding(sbyte[] bytes)

		{

			if (ASSUME_SHIFT_JIS)

			{

				return SHIFT_JIS;

			}

			// Does it start with the UTF-8 byte order mark? then guess it's UTF-8

			if (bytes.Length > 3 && bytes[0] == (sbyte) SupportClass.Identity(0xEF) && bytes[1] == (sbyte) SupportClass.Identity(0xBB) && bytes[2] == (sbyte) SupportClass.Identity(0xBF))

			{

				return UTF8;

			}

			// For now, merely tries to distinguish ISO-8859-1, UTF-8 and Shift_JIS,

			// which should be by far the most common encodings. ISO-8859-1

			// should not have bytes in the 0x80 - 0x9F range, while Shift_JIS

			// uses this as a first byte of a two-byte character. If we see this

			// followed by a valid second byte in Shift_JIS, assume it is Shift_JIS.

			// If we see something else in that second byte, we'll make the risky guess

			// that it's UTF-8.

			int length = bytes.Length;

			bool canBeISO88591 = true;

			bool canBeShiftJIS = true;

			int maybeDoubleByteCount = 0;

			int maybeSingleByteKatakanaCount = 0;

			bool sawLatin1Supplement = false;

			bool lastWasPossibleDoubleByteStart = false;

			for (int i = 0; i < length && (canBeISO88591 || canBeShiftJIS); i++)

			{

				int value_Renamed = bytes[i] & 0xFF;

				if ((value_Renamed == 0xC2 || value_Renamed == 0xC3) && i < length - 1)

				{

					// This is really a poor hack. The slightly more exotic characters people might want to put in

					// a QR Code, by which I mean the Latin-1 supplement characters (e.g. u-umlaut) have encodings

					// that start with 0xC2 followed by [0xA0,0xBF], or start with 0xC3 followed by [0x80,0xBF].

					int nextValue = bytes[i + 1] & 0xFF;

					if (nextValue <= 0xBF && ((value_Renamed == 0xC2 && nextValue >= 0xA0) || (value_Renamed == 0xC3 && nextValue >= 0x80)))

					{

						sawLatin1Supplement = true;

					}

				}

				if (value_Renamed >= 0x7F && value_Renamed <= 0x9F)

				{

					canBeISO88591 = false;

				}

				if (value_Renamed >= 0xA1 && value_Renamed <= 0xDF)

				{

					// count the number of characters that might be a Shift_JIS single-byte Katakana character

					if (!lastWasPossibleDoubleByteStart)

					{

						maybeSingleByteKatakanaCount++;

					}

				}

				if (!lastWasPossibleDoubleByteStart && ((value_Renamed >= 0xF0 && value_Renamed <= 0xFF) || value_Renamed == 0x80 || value_Renamed == 0xA0))

				{

					canBeShiftJIS = false;

				}

				if (((value_Renamed >= 0x81 && value_Renamed <= 0x9F) || (value_Renamed >= 0xE0 && value_Renamed <= 0xEF)))

				{

					// These start double-byte characters in Shift_JIS. Let's see if it's followed by a valid

					// second byte.

					if (lastWasPossibleDoubleByteStart)

					{

						// If we just checked this and the last byte for being a valid double-byte

						// char, don't check starting on this byte. If this and the last byte

						// formed a valid pair, then this shouldn't be checked to see if it starts

						// a double byte pair of course.

						lastWasPossibleDoubleByteStart = false;

					}

					else

					{

						// ... otherwise do check to see if this plus the next byte form a valid

						// double byte pair encoding a character.

						lastWasPossibleDoubleByteStart = true;

						if (i >= bytes.Length - 1)

						{

							canBeShiftJIS = false;

						}

						else

						{

							int nextValue = bytes[i + 1] & 0xFF;

							if (nextValue < 0x40 || nextValue > 0xFC)

							{

								canBeShiftJIS = false;

							}

							else

							{

								maybeDoubleByteCount++;

							}

							// There is some conflicting information out there about which bytes can follow which in

							// double-byte Shift_JIS characters. The rule above seems to be the one that matches practice.

						}

					}

				}

				else

				{

					lastWasPossibleDoubleByteStart = false;

				}

			}

			// Distinguishing Shift_JIS and ISO-8859-1 can be a little tough. The crude heuristic is:

			// - If we saw

			//   - at least three byte that starts a double-byte value (bytes that are rare in ISO-8859-1), or

			//   - over 5% of bytes that could be single-byte Katakana (also rare in ISO-8859-1),

			// - and, saw no sequences that are invalid in Shift_JIS, then we conclude Shift_JIS

			if (canBeShiftJIS && (maybeDoubleByteCount >= 3 || 20 * maybeSingleByteKatakanaCount > length))

			{

				return SHIFT_JIS;

			}

			// Otherwise, we default to ISO-8859-1 unless we know it can't be

			if (!sawLatin1Supplement && canBeISO88591)

			{

				return ISO88591;

			}

			// Otherwise, we take a wild guess with UTF-8

			return UTF8;

		}

		

		private static int parseECIValue(BitSource bits)

		{

			int firstByte = bits.readBits(8);

			if ((firstByte & 0x80) == 0)

			{

				// just one byte

				return firstByte & 0x7F;

			}

			else if ((firstByte & 0xC0) == 0x80)

			{

				// two bytes

				int secondByte = bits.readBits(8);

				return ((firstByte & 0x3F) << 8) | secondByte;

			}

			else if ((firstByte & 0xE0) == 0xC0)

			{

				// three bytes

				int secondThirdBytes = bits.readBits(16);

				return ((firstByte & 0x1F) << 16) | secondThirdBytes;

			}

			throw new System.ArgumentException("Bad ECI bits starting with byte " + firstByte);

		}

		static DecodedBitStreamParser()

		{

			{

                // Redivivus.in Java to c# Porting update

                // 30/01/2010 

                // Commented & Added

				//System.String platformDefault = System_Renamed.getProperty("file.encoding");

				//ASSUME_SHIFT_JIS = SHIFT_JIS.ToUpper().Equals(platformDefault.ToUpper()) || EUC_JP.ToUpper().Equals(platformDefault.ToUpper());

                ASSUME_SHIFT_JIS = false;

			}

		}

	}

}