/**
* Test data to see if it could be a valid JPEG image.
*
* The function will only look at the first few bytes of the data,
* and try to determine if it could be a valid JPEG image based on
* those bytes. This means that the check is more like a heuristic
* than a rigorous check.
*
* @param PelDataWindow the bytes that will be checked.
*
* @return boolean true if the bytes look like the beginning of a
* JPEG image, false otherwise.
*
* @see PelTiff::isValid()
*/
static function isValid(PelDataWindow $d)
{
/* JPEG data is stored in big-endian format. */
$d->setByteOrder(PelConvert::BIG_ENDIAN);
for ($i = 0; $i < 7; $i++) {
if ($d->getByte($i) != 0xff) {
break;
}
}
return $d->getByte($i) == PelJpegMarker::SOI;
}
/**
* Check if data is valid TIFF data.
*
* This will read just enough data from the data window to determine
* if the data could be a valid TIFF data. This means that the
* check is more like a heuristic than a rigorous check.
*
* @param PelDataWindow $d
* the bytes that will be examined.
*
* @return boolean true if the data looks like valid TIFF data,
* false otherwise.
*
* @see PelJpeg::isValid()
*/
public static function isValid(PelDataWindow $d)
{
/* First check that we have enough data. */
if ($d->getSize() < 8) {
return false;
}
/* Byte order */
if ($d->strcmp(0, 'II')) {
$d->setByteOrder(PelConvert::LITTLE_ENDIAN);
} elseif ($d->strcmp(0, 'MM')) {
Pel::debug('Found Motorola byte order');
$d->setByteOrder(PelConvert::BIG_ENDIAN);
} else {
return false;
}
/* Verify the TIFF header */
return $d->getShort(2) == self::TIFF_HEADER;
}
function testReadBigIntegers()
{
$window = new PelDataWindow("‰«Íï", PelConvert::BIG_ENDIAN);
$this->assertEqual($window->getSize(), 4);
$this->assertEqual($window->getBytes(), "‰«Íï");
$this->assertEqual($window->getByte(0), 0x89);
$this->assertEqual($window->getByte(1), 0xab);
$this->assertEqual($window->getByte(2), 0xcd);
$this->assertEqual($window->getByte(3), 0xef);
$this->assertEqual($window->getShort(0), 0x89ab);
$this->assertEqual($window->getShort(1), 0xabcd);
$this->assertEqual($window->getShort(2), 0xcdef);
$this->assertEqual($window->getLong(0), 0x89abcdef);
$window->setByteOrder(PelConvert::LITTLE_ENDIAN);
$this->assertEqual($window->getSize(), 4);
$this->assertEqual($window->getBytes(), "‰«Íï");
$this->assertEqual($window->getByte(0), 0x89);
$this->assertEqual($window->getByte(1), 0xab);
$this->assertEqual($window->getByte(2), 0xcd);
$this->assertEqual($window->getByte(3), 0xef);
$this->assertEqual($window->getShort(0), 0xab89);
$this->assertEqual($window->getShort(1), 0xcdab);
$this->assertEqual($window->getShort(2), 0xefcd);
$this->assertEqual($window->getLong(0), 0xefcdab89);
}
