public function emit(array $chunkInfo, $callback)
{
if (!isset($chunkInfo['crcBytes'])) {
$chunkInfo['crc'] = TOGoS_PNGChunks_Util::calculateChunkCrcBytes($chunkInfo);
}
$chunkInfo['lengthBytes'] = pack('N', strlen($chunkInfo['data']));
call_user_func($callback, $chunkInfo['lengthBytes'] . $chunkInfo['typeBytes']);
call_user_func($callback, $chunkInfo['data']);
call_user_func($callback, $chunkInfo['crcBytes']);
}
protected function _update()
{
switch ($this->state) {
case self::STATE_BEGIN:
if (strlen($this->buffer) >= 8) {
if ($this->validating) {
$header = substr($this->buffer, 0, 8);
if ($header !== TOGoS_PNGChunks_Util::PNG_HEADER) {
throw new TOGoS_PNGChunks_MalformedDataException("Bad PNG header.");
}
}
$this->buffer = substr($this->buffer, 8);
$this->state = self::STATE_HEADER_READ;
return true;
}
return false;
case self::STATE_HEADER_READ:
if (strlen($this->buffer) >= 12) {
// 12 being the minimum chunk length
$unpacked = unpack('Nlen', $this->buffer);
$length = $unpacked['len'];
$chunkLen = $length + 12;
if (strlen($this->buffer) >= $chunkLen) {
$typeBytes = substr($this->buffer, 4, 4);
$data = substr($this->buffer, 8, $length);
$crcBytes = substr($this->buffer, $chunkLen - 4, 4);
$chunkInfo = array('data' => $data, 'typeBytes' => $typeBytes, 'crcBytes' => $crcBytes);
if ($this->validating) {
TOGoS_PNGChunks_Util::verifyChunkCrc($chunkInfo);
}
call_user_func($this->chunkCallback, $chunkInfo);
$this->buffer = substr($this->buffer, $chunkLen);
return true;
}
}
return false;
default:
throw new Exception("Invalid state: " . $this->state);
}
}