mirror of
https://github.com/zxing/zxing.git
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7854d30103
git-svn-id: https://zxing.googlecode.com/svn/trunk@817 59b500cc-1b3d-0410-9834-0bbf25fbcc57
266 lines
12 KiB
C#
Executable file
266 lines
12 KiB
C#
Executable file
/*
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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 com.google.zxing.common;
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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> srowen@google.com (Sean Owen)
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/// </author>
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public 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 = "Shift_JIS";
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private static bool ASSUME_SHIFT_JIS;
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private DecodedBitStreamParser()
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{
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}
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internal static System.String decode(sbyte[] bytes, Version version)
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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();
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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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mode = Mode.forBits(bits.readBits(4)); // mode is encoded by 4 bits
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if (!mode.Equals(Mode.TERMINATOR))
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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);
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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);
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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 new ReaderException("Unsupported mode indicator");
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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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// I thought it wasn't allowed to leave extra bytes after the terminator but it happens
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/*
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int bitsLeft = bits.available();
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if (bitsLeft > 0) {
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if (bitsLeft > 6 || bits.readBits(bitsLeft) != 0) {
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throw new ReaderException("Excess bits or non-zero bits after terminator mode indicator");
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}
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}
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*/
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return result.ToString();
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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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byte[] bytes = SupportClass.ToByteArray(buffer);
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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(bytes, 0, bytes.Length));
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}
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catch (System.IO.IOException uee)
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{
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throw new ReaderException("SHIFT_JIS encoding is not supported on this device");
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}
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}
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private static void decodeByteSegment(BitSource bits, System.Text.StringBuilder result, int count)
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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 new ReaderException("Count too large: " + count);
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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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// 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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System.String encoding = guessEncoding(readBytes);
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try
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{
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byte[] bytes = SupportClass.ToByteArray(readBytes);
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//System.Windows.Forms.MessageBox.Show("encodings: "+ System.Text.Encoding.());
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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(bytes, 0, bytes.Length));
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}
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catch (System.IO.IOException uce)
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{
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//UPGRADE_TODO: The equivalent in .NET for method 'java.lang.Throwable.toString' may return a different value. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1043'"
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throw new ReaderException(uce.ToString());
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}
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}
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private static void decodeAlphanumericSegment(BitSource bits, System.Text.StringBuilder result, int count)
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{
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// Read two characters at a time
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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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}
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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 new ReaderException("Illegal value for 3-digit unit: " + threeDigitsBits);
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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 new ReaderException("Illegal value for 2-digit unit: " + twoDigitsBits);
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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 new ReaderException("Illegal value for digit unit: " + digitBits);
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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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// For now, merely tries to distinguish ISO-8859-1 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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int length = bytes.Length;
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for (int i = 0; i < length; i++)
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{
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int value_Renamed = bytes[i] & 0xFF;
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if (value_Renamed >= 0x80 && value_Renamed <= 0x9F && i < length - 1)
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{
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// ISO-8859-1 shouldn't use this, but before we decide it is Shift_JIS,
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// just double check that it is followed by a byte that's valid in
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// the Shift_JIS encoding
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int nextValue = bytes[i + 1] & 0xFF;
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if ((value_Renamed & 0x1) == 0)
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{
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// if even,
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if (nextValue >= 0x40 && nextValue <= 0x9E)
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{
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return SHIFT_JIS;
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}
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}
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else
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{
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if (nextValue >= 0x9F && nextValue <= 0x7C)
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{
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return SHIFT_JIS;
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}
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}
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}
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}
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return "ASCII";
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}
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//static DecodedBitStreamParser()
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//{
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// {
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// //UPGRADE_ISSUE: Method 'java.lang.System.getProperty' was not converted. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1000_javalangSystem'"
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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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// }
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//}
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}
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} |