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Add a bit of a hack to better detect UTF-8 in the wild, versus ISO88591

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git-svn-id: https://zxing.googlecode.com/svn/trunk@712 59b500cc-1b3d-0410-9834-0bbf25fbcc57
This commit is contained in:
srowen 2008-11-16 12:46:18 +00:00
parent 4fcdac3ae7
commit be59e299dc
1 changed files with 12 additions and 2 deletions
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14
core/src/com/google/zxing/qrcode/decoder/DecodedBitStreamParser.java
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@ -253,9 +253,19 @@ final class DecodedBitStreamParser {
boolean canBeShiftJIS = true;
boolean sawDoubleByteStart = false;
int maybeSingleByteKatakanaCount = 0;
boolean sawLatin1Supplement = false;
boolean lastWasPossibleDoubleByteStart = false;
for (int i = 0; i < length && (canBeISO88591 || canBeShiftJIS); i++) {
int value = bytes[i] & 0xFF;
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;
}
@ -298,11 +308,11 @@ final class DecodedBitStreamParser {
// - at least one 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 ((sawDoubleByteStart || 20 * maybeSingleByteKatakanaCount > length) && canBeShiftJIS) {
if (canBeShiftJIS && (sawDoubleByteStart || 20 * maybeSingleByteKatakanaCount > length)) {
return SHIFT_JIS;
}
// Otherwise, we default to ISO-8859-1 unless we know it can't be
if (canBeISO88591) {
if (!sawLatin1Supplement && canBeISO88591) {
return ISO88591;
}
// Otherwise, we take a wild guess with UTF-8