如何使用cURL将图像资源从URL加载到PHP脚本？

Question

I'm using the Google Charts service to generate some QR codes that I afterward need to manipulate (e.g. rotate, scale) in a PHP script and merge with other images to generate one final image.

How do I correctly load such a resource (from a URL) into a PHP script, in a way that will allow me to manipulate it?

An example URL is: https://chart.googleapis.com/chart?cht=qr&chs=500x500&chl=xghsdfgsdfg&choe=UTF-8&chld=L|0

I currently have the following code to retrieve the image using cURL:

function getImage($url){
        $ch = curl_init ($url);
        curl_setopt($ch, CURLOPT_HEADER, 0);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_BINARYTRANSFER,1);
        $resource = curl_exec($ch);
        curl_close ($ch);

        return $resource;
}

But when I use it like this:

$image = imagecreatefrompng(getImage("https://chart.googleapis.com/chart?cht=qr&chs=500x500&chl=xghsdfgsdfg&choe=UTF-8&chld=L|0"));

The following error is returned:

Warning: imagecreatefrompng(‰PNG  ) [function.imagecreatefrompng]: failed to open stream: No such file or directory in /home/picselbc/public_html/projects/cakemyface/preview.php on line 383
https://chart.googleapis.com/chart?cht=qr&chs=500x500&chl=xghsdfgsdfg&choe=UTF-8&chld=L|0

Answer 1

What you need instead of imagecreatefrompng() is imagecreatefromstring(), because the former expects a filename instead of the file contents itself.