diff --git a/AUTHORS b/AUTHORS index c21c443cd..aa3e6c25a 100644 --- a/AUTHORS +++ b/AUTHORS @@ -4,6 +4,7 @@ in alphabetical order. Agustín Delgado (Servinform S.A.) Aitor Almeida (University of Deusto) Alasdair Mackintosh (Google) +Alex Dupre Alexander Martin (Haase & Martin GmbH) Andreas Pillath Andrew Walbran (Google) @@ -20,6 +21,7 @@ Dave MacLachlan (Google) David Phillip Oster (Google) David Albert (Bug Labs) David Olivier +dawalker (Google) Diego Pierotto drejc83 Eduardo Castillejo (University of Deusto) diff --git a/core/src/com/google/zxing/common/StringUtils.java b/core/src/com/google/zxing/common/StringUtils.java index 331d55813..5861b30f3 100644 --- a/core/src/com/google/zxing/common/StringUtils.java +++ b/core/src/com/google/zxing/common/StringUtils.java @@ -24,6 +24,7 @@ import com.google.zxing.DecodeHintType; * Common string-related functions. * * @author Sean Owen + * @author Alex Dupre */ public final class StringUtils { @@ -54,30 +55,33 @@ public final class StringUtils { return characterSet; } } - // Does it start with the UTF-8 byte order mark? then guess it's UTF-8 - if (bytes.length > 3 && - bytes[0] == (byte) 0xEF && - bytes[1] == (byte) 0xBB && - bytes[2] == (byte) 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. + // which should be by far the most common encodings. int length = bytes.length; boolean canBeISO88591 = true; boolean canBeShiftJIS = true; boolean canBeUTF8 = true; int utf8BytesLeft = 0; - int maybeDoubleByteCount = 0; - int maybeSingleByteKatakanaCount = 0; - boolean sawLatin1Supplement = false; - boolean sawUTF8Start = false; - boolean lastWasPossibleDoubleByteStart = false; + //int utf8LowChars = 0; + int utf2BytesChars = 0; + int utf3BytesChars = 0; + int utf4BytesChars = 0; + int sjisBytesLeft = 0; + //int sjisLowChars = 0; + int sjisKatakanaChars = 0; + //int sjisDoubleBytesChars = 0; + int sjisCurKatakanaWordLength = 0; + int sjisCurDoubleBytesWordLength = 0; + int sjisMaxKatakanaWordLength = 0; + int sjisMaxDoubleBytesWordLength = 0; + //int isoLowChars = 0; + //int isoHighChars = 0; + int isoHighOther = 0; + + boolean utf8bom = bytes.length > 3 && + bytes[0] == (byte) 0xEF && + bytes[1] == (byte) 0xBB && + bytes[2] == (byte) 0xBF; for (int i = 0; i < length && (canBeISO88591 || canBeShiftJIS || canBeUTF8); @@ -86,105 +90,122 @@ public final class StringUtils { int value = bytes[i] & 0xFF; // UTF-8 stuff - if (value >= 0x80 && value <= 0xBF) { + if (canBeUTF8) { if (utf8BytesLeft > 0) { - utf8BytesLeft--; - } - } else { - if (utf8BytesLeft > 0) { - canBeUTF8 = false; - } - if (value >= 0xC0 && value <= 0xFD) { - sawUTF8Start = true; - int valueCopy = value; - while ((valueCopy & 0x40) != 0) { - utf8BytesLeft++; - valueCopy <<= 1; + if ((value & 0x80) == 0) { + canBeUTF8 = false; + } else { + utf8BytesLeft--; } - } + } else if ((value & 0x80) != 0) { + if ((value & 0x40) == 0) { + canBeUTF8 = false; + } else { + utf8BytesLeft++; + if ((value & 0x20) == 0) { + utf2BytesChars++; + } else { + utf8BytesLeft++; + if ((value & 0x10) == 0) { + utf3BytesChars++; + } else { + utf8BytesLeft++; + if ((value & 0x08) == 0) { + utf4BytesChars++; + } else { + canBeUTF8 = false; + } + } + } + } + } //else { + //utf8LowChars++; + //} } // ISO-8859-1 stuff - - if ((value == 0xC2 || value == 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 == 0xC2 && nextValue >= 0xA0) || (value == 0xC3 && nextValue >= 0x80))) { - sawLatin1Supplement = true; - } - } - if (value >= 0x7F && value <= 0x9F) { - canBeISO88591 = false; + if (canBeISO88591) { + if (value > 0x7F && value < 0xA0) { + canBeISO88591 = false; + } else if (value > 0x9F) { + if (value < 0xC0 || value == 0xD7 || value == 0xF7) { + isoHighOther++; + } //else { + //isoHighChars++; + //} + } //else { + //isoLowChars++; + //} } // Shift_JIS stuff - - if (value >= 0xA1 && value <= 0xDF) { - // count the number of characters that might be a Shift_JIS single-byte Katakana character - if (!lastWasPossibleDoubleByteStart) { - maybeSingleByteKatakanaCount++; - } - } - if (!lastWasPossibleDoubleByteStart && - ((value >= 0xF0 && value <= 0xFF) || value == 0x80 || value == 0xA0)) { - canBeShiftJIS = false; - } - if ((value >= 0x81 && value <= 0x9F) || (value >= 0xE0 && value <= 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) { + if (canBeShiftJIS) { + if (sjisBytesLeft > 0) { + if (value < 0x40 || value == 0x7F || value > 0xFC) { 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. + sjisBytesLeft--; } + } else if (value == 0x80 || value == 0xA0 || value > 0xEF) { + canBeShiftJIS = false; + } else if (value > 0xA0 && value < 0xE0) { + sjisKatakanaChars++; + sjisCurDoubleBytesWordLength = 0; + sjisCurKatakanaWordLength++; + if (sjisCurKatakanaWordLength > sjisMaxKatakanaWordLength) { + sjisMaxKatakanaWordLength = sjisCurKatakanaWordLength; + } + } else if (value > 0x7F) { + sjisBytesLeft++; + //sjisDoubleBytesChars++; + sjisCurKatakanaWordLength = 0; + sjisCurDoubleBytesWordLength++; + if (sjisCurDoubleBytesWordLength > sjisMaxDoubleBytesWordLength) { + sjisMaxDoubleBytesWordLength = sjisCurDoubleBytesWordLength; + } + } else { + //sjisLowChars++; + sjisCurKatakanaWordLength = 0; + sjisCurDoubleBytesWordLength = 0; } - } else { - lastWasPossibleDoubleByteStart = false; } } - if (utf8BytesLeft > 0) { + + if (canBeUTF8 && utf8BytesLeft > 0) { canBeUTF8 = false; } - - // Easy -- if assuming Shift_JIS and no evidence it can't be, done - if (canBeShiftJIS && ASSUME_SHIFT_JIS) { - return SHIFT_JIS; + if (canBeShiftJIS && sjisBytesLeft > 0) { + canBeShiftJIS = false; } - if (canBeUTF8 && sawUTF8Start) { + + // Easy -- if there is BOM or at least 1 valid not-single byte character (and no evidence it can't be UTF-8), done + if (canBeUTF8 && (utf8bom || utf2BytesChars + utf3BytesChars + utf4BytesChars > 0)) { return UTF8; } - // Distinguishing Shift_JIS and ISO-8859-1 can be a little tough. The crude heuristic is: - // - If we saw - // - at least 3 bytes that starts a double-byte value (bytes that are rare in ISO-8859-1), or - // - over 5% of bytes 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)) { + // Easy -- if assuming Shift_JIS or at least 3 valid consecutive not-ascii characters (and no evidence it can't be), done + if (canBeShiftJIS && (ASSUME_SHIFT_JIS || sjisMaxKatakanaWordLength >= 3 || sjisMaxDoubleBytesWordLength >= 3)) { return SHIFT_JIS; } - // Otherwise, we default to ISO-8859-1 unless we know it can't be - if (!sawLatin1Supplement && canBeISO88591) { + // Distinguishing Shift_JIS and ISO-8859-1 can be a little tough for short words. The crude heuristic is: + // - If we saw + // - only two consecutive katakana chars in the whole text, or + // - at least 10% of bytes that could be "upper" not-alphanumeric Latin1, + // - then we conclude Shift_JIS, else ISO-8859-1 + if (canBeISO88591 && canBeShiftJIS) { + return (sjisMaxKatakanaWordLength == 2 && sjisKatakanaChars == 2) || isoHighOther * 10 >= length + ? SHIFT_JIS : ISO88591; + } + + // Otherwise, try in order ISO-8859-1, Shift JIS, UTF-8 and fall back to default platform encoding + if (canBeISO88591) { return ISO88591; } + if (canBeShiftJIS) { + return SHIFT_JIS; + } + if (canBeUTF8) { + return UTF8; + } // Otherwise, we take a wild guess with platform encoding return PLATFORM_DEFAULT_ENCODING; } diff --git a/core/test/src/com/google/zxing/common/StringUtilsTestCase.java b/core/test/src/com/google/zxing/common/StringUtilsTestCase.java new file mode 100644 index 000000000..944490f5a --- /dev/null +++ b/core/test/src/com/google/zxing/common/StringUtilsTestCase.java @@ -0,0 +1,72 @@ +/* + * Copyright 2012 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. + */ + +package com.google.zxing.common; + +import org.junit.Assert; +import org.junit.Test; + +import java.nio.charset.Charset; + +public final class StringUtilsTestCase extends Assert { + + @Test + public void testShortShiftJIS_1() { + // ÈáëÈ≠ö + doTest(new byte[] { (byte) 0x8b, (byte) 0xe0, (byte) 0x8b, (byte) 0x9b, }, "SJIS"); + } + + @Test + public void testShortISO88591_1() { + // b√•d + doTest(new byte[] { (byte) 0x62, (byte) 0xe5, (byte) 0x64, }, "ISO-8859-1"); + } + + @Test + public void testMixedShiftJIS_1() { + // Hello Èáë! + doTest(new byte[] { (byte) 0x48, (byte) 0x65, (byte) 0x6c, (byte) 0x6c, (byte) 0x6f, + (byte) 0x20, (byte) 0x8b, (byte) 0xe0, (byte) 0x21, }, + "SJIS"); + } + + private static void doTest(byte[] bytes, String charsetName) { + Charset charset = Charset.forName(charsetName); + String guessedName = StringUtils.guessEncoding(bytes, null); + Charset guessedEncoding = Charset.forName(guessedName); + assertEquals(charset, guessedEncoding); + } + + /** + * Utility for printing out a string in given encoding as a Java statement, since it's better + * to write that into the Java source file rather than risk character encoding issues in the + * source file itself + */ + public static void main(String[] args) { + String text = args[0]; + Charset charset = Charset.forName(args[1]); + StringBuilder declaration = new StringBuilder(); + declaration.append("new byte[] { "); + for (byte b : text.getBytes(charset)) { + declaration.append("(byte) 0x"); + declaration.append(Integer.toHexString(b & 0xFF)); + declaration.append(", "); + } + declaration.append('}'); + System.out.println(declaration); + } + +}