/**
* <p>Reads format information from one of its two locations within the QR Code.</p>
*
* @return {@link FormatInformation} encapsulating the QR Code's format info
* @throws FormatException if both format information locations cannot be parsed as
* the valid encoding of format information
*/
function readFormatInformation()
{
if ($this->parsedFormatInfo != null) {
return $this->parsedFormatInfo;
}
// Read top-left format info bits
$formatInfoBits1 = 0;
for ($i = 0; $i < 6; $i++) {
$formatInfoBits1 = $this->copyBit($i, 8, $formatInfoBits1);
}
// .. and skip a bit in the timing pattern ...
$formatInfoBits1 = $this->copyBit(7, 8, $formatInfoBits1);
$formatInfoBits1 = $this->copyBit(8, 8, $formatInfoBits1);
$formatInfoBits1 = $this->copyBit(8, 7, $formatInfoBits1);
// .. and skip a bit in the timing pattern ...
for ($j = 5; $j >= 0; $j--) {
$formatInfoBits1 = $this->copyBit(8, $j, $formatInfoBits1);
}
// Read the top-right/bottom-left pattern too
$dimension = $this->bitMatrix->getHeight();
$formatInfoBits2 = 0;
$jMin = $dimension - 7;
for ($j = $dimension - 1; $j >= $jMin; $j--) {
$formatInfoBits2 = $this->copyBit(8, $j, $formatInfoBits2);
}
for ($i = $dimension - 8; $i < $dimension; $i++) {
$formatInfoBits2 = $this->copyBit($i, 8, $formatInfoBits2);
}
$parsedFormatInfo = FormatInformation::decodeFormatInformation($formatInfoBits1, $formatInfoBits2);
if ($parsedFormatInfo != null) {
return $parsedFormatInfo;
}
throw FormatException::getFormatInstance();
}
static function decodeVersionInformation($versionBits)
{
$bestDifference = PHP_INT_MAX;
$bestVersion = 0;
for ($i = 0; $i < count(self::$VERSION_DECODE_INFO); $i++) {
$targetVersion = self::$VERSION_DECODE_INFO[$i];
// Do the version info bits match exactly? done.
if ($targetVersion == $versionBits) {
return self::getVersionForNumber($i + 7);
}
// Otherwise see if this is the closest to a real version info bit string
// we have seen so far
$bitsDifference = FormatInformation::numBitsDiffering($versionBits, $targetVersion);
if ($bitsDifference < $bestDifference) {
$bestVersion = $i + 7;
$bestDifference = $bitsDifference;
}
}
// We can tolerate up to 3 bits of error since no two version info codewords will
// differ in less than 8 bits.
if ($bestDifference <= 3) {
return self::getVersionForNumber($bestVersion);
}
// If we didn't find a close enough match, fail
return null;
}
