I'm using a third party API that allows me to upload an image via a POST request and the parameter is required to be in binary format e.g. [137,80,78,71,13,10,26,10,0,0,0,13,73,72,68,82,0,0,3,...]
I tried using the unpack() function and got the binary data to upload but when I try to view it on the upload server I only got a blank image BUT the image size is correct. So I think the data is there I'm just doing something wrong when unpacking.
if(!$fp = fopen ($image_url, 'rb')) return 0;
/* Read bytes from the top of the file */
if(!$data = fread ($fp, filesize($image_path))) return 0;
/* Unpack data */
$data = unpack ('C*', $data);
//$data value: Array ( [1] => 137 [2] => 80 [3] => 78 [4] => 71 [5] => 13....
To test if it will convert back to the image correctly I use the pack() function like so:
$bin = pack('C*', ...$data);
header('Content-type: image/png');
header('Content-Disposition: inline; filename="test_image"');
header('Content-Transfer-Encoding: binary');
echo $bin;
exit();
So this will output a png file that is blank but has the same exact size as the original image. Is there are a way to fix the unpack function so that it will convert back correctly? I have no control on how to display it since it's in the third party API, so I can only correct it on the first code block.
I've tinkered a bit with what you're doing and this works for me:
$data = file_get_contents('test.png');
$u = unpack('C*', $data);
$bin = pack('C*', ...$u);
header('Content-type: image/png');
echo $bin;
exit();
My assumption would be that your fopen and fread isn't returning what you're expecting.