Question

My application sends urlencoded or base64encoded string via http get request, the string contain image data, that most be download from the php file, but i dont know how php would download image from my string that is either urlencoded or base64encoded, please help me out guys… im lost

Answer 1

Serve image to a user

// we assume $imageData is PNG
$image = urldecode($imageData);
// or
$image = base64_decode($imageData);

// in case of force download change Content-Type: image/png to
// application/octet-stream and Content-Disposition: inline to attachment
header('Content-type: image/png');
header('Content-Disposition: inline; filename=' . md5($image) . '.png');
header('Content-Length: ' . strlen($image));

echo $image;
exit;

The problem si to detect correct Content-Type if you don’t know it. But browsers should be able to autodetect it on its own.

Some notes about caching
PHP implicitly sends headers which prevents browser caching of retrieved data. I suggest you to set these headers manually (Cache-Control, Expires, Pragma). To work properly, every single image must be served by an unique URL. Also try to avoid of starting sessions. On heavily accessed website with public access you can easily flood webserver with redundant session files.

Save image to a file

$image = urlencode($imageData);
// or
$image = base64_decode($imageData);

if (!file_put_contents('abs/path/to/save/file.png', $image)) {
    throw new Exception('Image could not be saved');
}