incomplete port of decoded bit stream parser

src/qrcode/decoder/decoded_bit_stream_parser.rs

@@ -0,0 +1,368 @@
+/*
+ * 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.
+ */
+
+use crate::{Exceptions, common::{BitSource, StringUtils, DecoderRXingResult, CharacterSetECI}, DecodingHintDictionary};
+
+use super::{VersionRef, Mode, ErrorCorrectionLevel};
+
+
+/**
+ * <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
+ */
+
+  /**
+   * See ISO 18004:2006, 6.4.4 Table 5
+   */
+  const ALPHANUMERIC_CHARS : &str=
+      "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:";
+  const GB2312_SUBSET :u8 = 1;
+
+
+  pub fn decode(bytes : &[u8],
+                               version:VersionRef,
+                               ecLevel:ErrorCorrectionLevel,
+                              hints:DecodingHintDictionary) -> Result<DecoderRXingResult,Exceptions> {
+    let bits =  BitSource::new(bytes);
+    let result = String::with_capacity(50);
+    let byteSegments = vec![vec![0u8;0];0];
+    let symbolSequence = -1;
+    let parityData = -1;
+    let symbologyModifier;
+
+    // try {
+      let currentCharacterSetECI = None;
+      let fc1InEffect = false;
+      let hasFNC1first = false;
+      let hasFNC1second = false;
+      let mode;
+      loop {
+        // 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
+        }
+        match mode {
+          Mode::TERMINATOR => {},
+            Mode::FNC1_FIRST_POSITION=> {
+            hasFNC1first = true; // symbology detection
+            // We do little with FNC1 except alter the parsed result a bit according to the spec
+            fc1InEffect = true;},
+            Mode::FNC1_SECOND_POSITION=> {
+            hasFNC1second = true; // symbology detection
+            // We do little with FNC1 except alter the parsed result a bit according to the spec
+            fc1InEffect = true;},
+            Mode::STRUCTURED_APPEND=> {
+            if (bits.available() < 16) {
+              return Err(Exceptions::FormatException(format!("Mode::Structured append expected bits.available() < 16, found bits of {}", bits.available())))
+            }
+            // sequence number and parity is added later to the result metadata
+            // Read next 8 bits (symbol sequence #) and 8 bits (parity data), then continue
+            symbolSequence = bits.readBits(8);
+            parityData = bits.readBits(8);},
+            Mode::ECI=> {
+            // Count doesn't apply to ECI
+            let value = parseECIValue(&bits)?;
+            currentCharacterSetECI = CharacterSetECI::getCharacterSetECIByValue(value);
+            if (currentCharacterSetECI.is_none()) {
+              return Err(Exceptions::FormatException(format!("Value of {} not valid", value)))
+
+            }},
+            Mode::HANZI=> {
+            // First handle Hanzi mode which does not start with character count
+            // Chinese mode contains a sub set indicator right after mode indicator
+            let subset = bits.readBits(4);
+            let countHanzi = bits.readBits(mode.getCharacterCountBits(version));
+            if (subset == GB2312_SUBSET) {
+              decodeHanziSegment(&bits, &result, countHanzi)?;
+            }},
+          _=>{
+            // "Normal" QR code modes:
+            // How many characters will follow, encoded in this mode?
+            let count = bits.readBits(mode.getCharacterCountBits(version));
+            match mode {
+              Mode::NUMERIC=>
+                decodeNumericSegment(&bits, &result, count)?,
+                Mode::ALPHANUMERIC=>decodeAlphanumericSegment(&bits, &result, count, fc1InEffect)?,
+                Mode::BYTE=>decodeByteSegment(&bits, &result, count, currentCharacterSetECI, &byteSegments, hints)?,
+                Mode::KANJI=>decodeKanjiSegment(&bits, &result, count)?,
+              _=>
+                return Err(Exceptions::FormatException("".to_owned()))
+            }},
+        }
+
+        if mode != Mode::TERMINATOR {break}
+      } 
+
+      if (currentCharacterSetECI != null) {
+        if (hasFNC1first) {
+          symbologyModifier = 4;
+        } else if (hasFNC1second) {
+          symbologyModifier = 6;
+        } else {
+          symbologyModifier = 2;
+        }
+      } else {
+        if (hasFNC1first) {
+          symbologyModifier = 3;
+        } else if (hasFNC1second) {
+          symbologyModifier = 5;
+        } else {
+          symbologyModifier = 1;
+        }
+      }
+
+    // } catch (IllegalArgumentException iae) {
+    //   // from readBits() calls
+    //   throw FormatException.getFormatInstance();
+    // }
+
+    return  DecoderRXingResult::new(bytes,
+                             result.toString(),
+                             if byteSegments.isEmpty()  {None} else  {byteSegments},
+                             if ecLevel.is_none()  {None} else {ecLevel.toString()},
+                             symbolSequence,
+                             parityData,
+                             symbologyModifier);
+  }
+
+  /**
+   * See specification GBT 18284-2000
+   */
+  fn decodeHanziSegment( bits:&BitSource,
+                                          result:&String,
+                                          count:u32) -> Result<(),Exceptions> {
+    // Don't crash trying to read more bits than we have available.
+    if (count * 13 > bits.available()) {
+      return Err(Exceptions::FormatException("".to_owned()))
+    }
+
+    // Each character will require 2 bytes. Read the characters as 2-byte pairs
+    // and decode as GB2312 afterwards
+    let buffer = vec![0u8;2 * count];
+    let offset = 0;
+    while (count > 0) {
+      // Each 13 bits encodes a 2-byte character
+      let twoBytes = bits.readBits(13)?;
+      let assembledTwoBytes = ((twoBytes / 0x060) << 8) | (twoBytes % 0x060);
+      if (assembledTwoBytes < 0x00A00) {
+        // In the 0xA1A1 to 0xAAFE range
+        assembledTwoBytes += 0x0A1A1;
+      } else {
+        // In the 0xB0A1 to 0xFAFE range
+        assembledTwoBytes += 0x0A6A1;
+      }
+      buffer[offset] =  ((assembledTwoBytes >> 8) & 0xFF);
+      buffer[offset + 1] =  (assembledTwoBytes & 0xFF);
+      offset += 2;
+      count-=1;
+    }
+
+    let gb_encoder = encoding::label::encoding_from_whatwg_label("GB2312").unwrap();
+    let encode_string = gb_encoder.decode(&buffer, encoding::DecoderTrap::Strict).unwrap();
+    result.append(encode_string);
+    Ok(())
+  }
+
+  fn decodeKanjiSegment( bits:&BitSource,
+                                          result:&String,
+                                         count:u32) -> Result<(),Exceptions> {
+    // Don't crash trying to read more bits than we have available.
+    if (count * 13 > bits.available()) {
+      return Err(Exceptions::FormatException("".to_owned()))
+    }
+
+    // Each character will require 2 bytes. Read the characters as 2-byte pairs
+    // and decode as Shift_JIS afterwards
+    let buffer = vec![0u8;2 * count];
+    let offset = 0;
+    while (count > 0) {
+      // Each 13 bits encodes a 2-byte character
+      let twoBytes = bits.readBits(13);
+      let 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] = (assembledTwoBytes >> 8);
+      buffer[offset + 1] = assembledTwoBytes;
+      offset += 2;
+      count-=1;
+    }
+    
+    let sjs_encoder = encoding::label::encoding_from_whatwg_label("SJIS").unwrap();
+    let encode_string = sjs_encoder.decode(&buffer, encoding::DecoderTrap::Strict).unwrap();
+    result.append(encode_string);
+
+    Ok(())
+  }
+
+  fn decodeByteSegment( bits:&BitSource,
+                                         result:&String,
+                                         count:u32,
+                                         currentCharacterSetECI:Option<&CharacterSetECI>,
+                                         byteSegments:&Vec<Vec<u8>>,
+                                         hints:DecodingHintDictionary) -> Result<(),Exceptions> {
+    // Don't crash trying to read more bits than we have available.
+    if (8 * count > bits.available()) {
+      return Err(Exceptions::FormatException("".to_owned()))
+    }
+
+    let readBytes = vec![0u8;count];
+    for i in 0..count {
+    // for (int i = 0; i < count; i++) {
+      readBytes[i] = bits.readBits(8);
+    }
+    let encoding;
+    if (currentCharacterSetECI.is_none()) {
+      // 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::guessCharset(&readBytes, hints);
+    } else {
+      encoding = currentCharacterSetECI.getCharset();
+    }
+    let encode_string = encoding.decode(&readBytes, encoding::DecoderTrap::Strict).unwrap();
+    result.append(encode_string);
+    byteSegments.add(readBytes);
+
+    Ok(())
+  }
+
+  fn toAlphaNumericChar( value:u32) -> Result<char,Exceptions> {
+    if (value >= ALPHANUMERIC_CHARS.len()) {
+      return Err(Exceptions::FormatException("".to_owned()))
+    }
+    Ok( ALPHANUMERIC_CHARS[value])
+  }
+
+  fn decodeAlphanumericSegment( bits:&BitSource,
+                                                 result:&String,
+                                                 count:u32,
+                                                 fc1InEffect:bool) -> Result<(),Exceptions> {
+    // Read two characters at a time
+    let start = result.len();
+    while count > 1 {
+      if bits.available() < 11 {
+        return Err(Exceptions::FormatException("".to_owned()))
+      }
+      let 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) {
+        return Err(Exceptions::FormatException("".to_owned()))
+      }
+      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 i in start..result.len() {
+      // for (int i = start; i < result.length(); i++) {
+        if (result.charAt(i) == '%') {
+          if (i < result.length() - 1 && result.charAt(i + 1) == '%') {
+            // %% is rendered as %
+            result.deleteCharAt(i + 1);
+          } else {
+            // In alpha mode, % should be converted to FNC1 separator 0x1D
+            result.setCharAt(i,  0x1D);
+          }
+        }
+      }
+    }
+
+    Ok(())
+  }
+
+  fn decodeNumericSegment( bits:&BitSource,
+                                            result:&String,
+                                            count:u32) -> Result<(),Exceptions> {
+    // Read three digits at a time
+    while count >= 3 {
+      // Each 10 bits encodes three digits
+      if bits.available() < 10 {
+        return Err(Exceptions::FormatException("".to_owned()))
+      }
+      let threeDigitsBits = bits.readBits(10)?;
+      if threeDigitsBits >= 1000 {
+        return Err(Exceptions::FormatException("".to_owned()))
+      }
+      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 {
+        return Err(Exceptions::FormatException("".to_owned()))
+      }
+      let twoDigitsBits = bits.readBits(7)?;
+      if twoDigitsBits >= 100 {
+        return Err(Exceptions::FormatException("".to_owned()))
+      }
+      result.append(toAlphaNumericChar(twoDigitsBits / 10));
+      result.append(toAlphaNumericChar(twoDigitsBits % 10));
+    } else if count == 1 {
+      // One digit left over to read
+      if bits.available() < 4 {
+        return Err(Exceptions::FormatException("".to_owned()))
+      }
+      let digitBits = bits.readBits(4)?;
+      if digitBits >= 10 {
+        return Err(Exceptions::FormatException("".to_owned()))
+      }
+      result.append(toAlphaNumericChar(digitBits));
+    }
+
+    Ok(())
+  }
+
+  fn parseECIValue( bits:&BitSource) -> Result<u32,Exceptions> {
+    let firstByte = bits.readBits(8)?;
+    if (firstByte & 0x80) == 0 {
+      // just one byte
+      return Ok(firstByte & 0x7F);
+    }
+    if (firstByte & 0xC0) == 0x80 {
+      // two bytes
+      let secondByte = bits.readBits(8);
+      return Ok(((firstByte & 0x3F) << 8) | secondByte);
+    }
+    if (firstByte & 0xE0) == 0xC0 {
+      // three bytes
+      let secondThirdBytes = bits.readBits(16);
+      return Ok(((firstByte & 0x1F) << 16) | secondThirdBytes);
+    }
+    
+    Err(Exceptions::FormatException("".to_owned()))
+  }
+