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<?php
/*
* 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.
*/
namespace Zxing\Qrcode\Decoder;
use Zxing\FormatException;
use Zxing\Common\BitMatrix;
/**
* @author Sean Owen
*/
final class BitMatrixParser
{
private $bitMatrix;
private $parsedVersion;
private $parsedFormatInfo;
private $mirror;
/**
* @param bitMatrix {@link BitMatrix} to parse
*
* @throws FormatException if dimension is not >= 21 and 1 mod 4
*/
public function __construct($bitMatrix)
{
$dimension = $bitMatrix->getHeight();
if ($dimension < 21 || ($dimension & 0x03) != 1) {
throw FormatException::getFormatInstance();
}
$this->bitMatrix = $bitMatrix;
}
/**
* <p>Reads the bits in the {@link BitMatrix} representing the finder pattern in the
* correct order in order to reconstruct the codewords bytes contained within the
* QR Code.</p>
*
* @return bytes encoded within the QR Code
* @throws FormatException if the exact number of bytes expected is not read
*/
public function readCodewords()
{
$formatInfo = $this->readFormatInformation();
$version = $this->readVersion();
// Get the data mask for the format used in this QR Code. This will exclude
// some bits from reading as we wind through the bit matrix.
$dataMask = DataMask::forReference($formatInfo->getDataMask());
$dimension = $this->bitMatrix->getHeight();
$dataMask->unmaskBitMatrix($this->bitMatrix, $dimension);
$functionPattern = $version->buildFunctionPattern();
$readingUp = true;
if ($version->getTotalCodewords()) {
$result = fill_array(0, $version->getTotalCodewords(), 0);
} else {
$result = [];
}
$resultOffset = 0;
$currentByte = 0;
$bitsRead = 0;
// Read columns in pairs, from right to left
for ($j = $dimension - 1; $j > 0; $j -= 2) {
if ($j == 6) {
// Skip whole column with vertical alignment pattern;
// saves time and makes the other code proceed more cleanly
$j--;
}
// Read alternatingly from bottom to top then top to bottom
for ($count = 0; $count < $dimension; $count++) {
$i = $readingUp ? $dimension - 1 - $count : $count;
for ($col = 0; $col < 2; $col++) {
// Ignore bits covered by the function pattern
if (!$functionPattern->get($j - $col, $i)) {
// Read a bit
$bitsRead++;
$currentByte <<= 1;
if ($this->bitMatrix->get($j - $col, $i)) {
$currentByte |= 1;
}
// If we've made a whole byte, save it off
if ($bitsRead == 8) {
$result[$resultOffset++] = $currentByte; //(byte)
$bitsRead = 0;
$currentByte = 0;
}
}
}
}
$readingUp ^= true; // readingUp = !readingUp; // switch directions
}
if ($resultOffset != $version->getTotalCodewords()) {
throw FormatException::getFormatInstance();
}
return $result;
}
/**
* <p>Reads format information from one of its two locations within the QR Code.</p>
*
* @return {@link FormatInformation} encapsulating the QR Code's format info
* @throws FormatException if both format information locations cannot be parsed as
* the valid encoding of format information
*/
public function readFormatInformation()
{
if ($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 $parsedFormatInfo;
}
throw FormatException::getFormatInstance();
}
private function copyBit($i, $j, $versionBits)
{
$bit = $this->mirror ? $this->bitMatrix->get($j, $i) : $this->bitMatrix->get($i, $j);
return $bit ? ($versionBits << 1) | 0x1 : $versionBits << 1;
}
/**
* <p>Reads version information from one of its two locations within the QR Code.</p>
*
* @return {@link Version} encapsulating the QR Code's version
* @throws FormatException if both version information locations cannot be parsed as
* the valid encoding of version information
*/
public function readVersion()
{
if ($this->parsedVersion != null) {
return $this->parsedVersion;
}
$dimension = $this->bitMatrix->getHeight();
$provisionalVersion = ($dimension - 17) / 4;
if ($provisionalVersion <= 6) {
return Version::getVersionForNumber($provisionalVersion);
}
// Read top-right version info: 3 wide by 6 tall
$versionBits = 0;
$ijMin = $dimension - 11;
for ($j = 5; $j >= 0; $j--) {
for ($i = $dimension - 9; $i >= $ijMin; $i--) {
$versionBits = $this->copyBit($i, $j, $versionBits);
}
}
$theParsedVersion = Version::decodeVersionInformation($versionBits);
if ($theParsedVersion != null && $theParsedVersion->getDimensionForVersion() == $dimension) {
$this->parsedVersion = $theParsedVersion;
return $theParsedVersion;
}
// Hmm, failed. Try bottom left: 6 wide by 3 tall
$versionBits = 0;
for ($i = 5; $i >= 0; $i--) {
for ($j = $dimension - 9; $j >= $ijMin; $j--) {
$versionBits = $this->copyBit($i, $j, $versionBits);
}
}
$theParsedVersion = Version::decodeVersionInformation($versionBits);
if ($theParsedVersion != null && $theParsedVersion->getDimensionForVersion() == $dimension) {
$this->parsedVersion = $theParsedVersion;
return $theParsedVersion;
}
throw FormatException::getFormatInstance();
}
/**
* Revert the mask removal done while reading the code words. The bit matrix should revert to its original state.
*/
public function remask()
{
if ($this->parsedFormatInfo == null) {
return; // We have no format information, and have no data mask
}
$dataMask = DataMask::forReference($this->parsedFormatInfo->getDataMask());
$dimension = $this->bitMatrix->getHeight();
$dataMask->unmaskBitMatrix($this->bitMatrix, $dimension);
}
/**
* Prepare the parser for a mirrored operation.
* This flag has effect only on the {@link #readFormatInformation()} and the
* {@link #readVersion()}. Before proceeding with {@link #readCodewords()} the
* {@link #mirror()} method should be called.
*
* @param mirror Whether to read version and format information mirrored.
*/
public function setMirror($mirror)
{
$parsedVersion = null;
$parsedFormatInfo = null;
$this->mirror = $mirror;
}
/** Mirror the bit matrix in order to attempt a second reading. */
public function mirror()
{
for ($x = 0; $x < $this->bitMatrix->getWidth(); $x++) {
for ($y = $x + 1; $y < $this->bitMatrix->getHeight(); $y++) {
if ($this->bitMatrix->get($x, $y) != $this->bitMatrix->get($y, $x)) {
$this->bitMatrix->flip($y, $x);
$this->bitMatrix->flip($x, $y);
}
}
}
}
}
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