/**
* Determines if we can read the content of the file and returns a file pointer resource
*
* We can't use something like $node->isReadable() as it's too unreliable
* Some storage classes just check for the presence of the file
*
* @param File $file
*
* @return resource
* @throws InternalServerErrorServiceException
*/
private function isFileReadable($file)
{
try {
$fileHandle = $file->fopen('rb');
if (!$fileHandle) {
throw new \Exception();
}
} catch (\Exception $exception) {
throw new InternalServerErrorServiceException('Something went wrong when trying to read' . $file->getPath());
}
return $fileHandle;
}
/**
* Tests if a GIF is animated
*
* An animated gif contains multiple "frames", with each frame having a
* header made up of:
* * a static 4-byte sequence (\x00\x21\xF9\x04)
* * 4 variable bytes
* * a static 2-byte sequence (\x00\x2C) (Photoshop uses \x00\x21)
*
* We read through the file until we reach the end of the file, or we've
* found at least 2 frame headers
*
* @link http://php.net/manual/en/function.imagecreatefromgif.php#104473
*
* @param File $file
*
* @return bool
* @throws InternalServerErrorServiceException
*/
private function isGifAnimated($file)
{
$count = 0;
try {
$fileHandle = $file->fopen('rb');
while (!feof($fileHandle) && $count < 2) {
$chunk = fread($fileHandle, 1024 * 100);
//read 100kb at a time
$count += preg_match_all('#\\x00\\x21\\xF9\\x04.{4}\\x00(\\x2C|\\x21)#s', $chunk, $matches);
}
fclose($fileHandle);
} catch (\Exception $exception) {
throw new InternalServerErrorServiceException('Something went wrong when trying to read a GIF file');
}
return $count > 1;
}
/**
* Tests if a GIF is animated
*
* An animated gif contains multiple "frames", with each frame having a
* header made up of:
* * a static 4-byte sequence (\x00\x21\xF9\x04)
* * 4 variable bytes
* * a static 2-byte sequence (\x00\x2C) (Photoshop uses \x00\x21)
*
* We read through the file until we reach the end of the file, or we've
* found at least 2 frame headers
*
* @link http://php.net/manual/en/function.imagecreatefromgif.php#104473
*
* @param File $file
*
* @return bool
*/
private function isGifAnimated($file)
{
$fileHandle = $file->fopen('rb');
$count = 0;
while (!feof($fileHandle) && $count < 2) {
$chunk = fread($fileHandle, 1024 * 100);
//read 100kb at a time
$count += preg_match_all('#\\x00\\x21\\xF9\\x04.{4}\\x00(\\x2C|\\x21)#s', $chunk, $matches);
}
fclose($fileHandle);
return $count > 1;
}
