How to check if a $byte_array contains data?

[JeremyCanada26]

I have two questions regarding $byte_array.

 

1. Is there a general way to check if a $byte_array contains any data?

 

2. Is there a way to confirm if the $byte_array contains an actual PNG image?

[fugix]

to check if a variable contains data you can use the empty() function

[JeremyCanada26]

to check if a variable contains data you can use the empty() function

Thanks fugix, yes that empty() function is awesome. I wonder if it's possible to check if the $byte_array contains valid PNG data?

[fugix]

yeah you can check if the variable contains the mime type "image/png"

[JeremyCanada26]

function checkIfSuppliedImageDataIsValid()
{
//first, check that the byte_array isset, then make sure it's not empty, then make sure it contains valid image data
if(isset($this->byte_array) && !empty($this->byte_array) && imagecreatefromstring($this->byte_array))
{
	//passed in byte array is good
	return true;
} else
{
	//missing or invalid
	return false;
}
}

 

The above function is what i'm settling for, although I also see there might be another way to do it manually but I'm not technical enough to know how.

 

The first eight bytes of a PNG file always contain the following (decimal) values: 137 80 78 71 13 10 26 10

 

Taken from the png RFC page, http://www.faqs.org/rfcs/rfc2083.html, section, 3.1. PNG file signature

 

[fugix]

okay