Download file_get_contents response - php

Question

I have the following jquery:
$(".download").click(function(){
$.post('get_bot.php', "url_code="+url_code, function (response) {
alert(response);
});
});
url_code is a variable that has the url for a json structure, here is a live example of the return:
https://services.sapo.pt/Codebits/botmake/01,02,03,04,05,06,07,08,I%20Rule!
Those numbers are parameters to generate different images.
On my get_bot.php page I'm doing:
$urlc=$_POST['url_code'];
$bot = file_get_contents($urlc);
header("content-type: image/png");
echo $bot;
I'm looking into ways on how to get a response as a .png file download, so when the user clicks .download there is a download window prompt with the .png file.
Passing in a correct url and echoing the file_get_content results seems to work fine (although if I try to right click and save the image, it actually saves the php file...)
Any help with this would be great, I'm not very experienced with json structures, so far I've only dealt with array structures, never an image output.
I'm aware I'm probably way off here on getting an actual result, but any pointers would be appreciated.

Answer 1

RFC2616 describes what you need to do. Basically, you need to add
Content-Disposition: attachment; filename="fname.ext"
To the header if I'm not mistaken.
EDIT
Here is a sample script. I've confirmed that this works on two of my servers with different setups.
<?php
header("content-type: image/jpg");
header("Content-Disposition: attachment; filename='pic.jpg'");
readfile('http://lorempixel.com/400/200/');
?>

Answer 2

Just use this function on your get_bot.php to start a download of a file instead of showing it in the browser (should work cross-browser):
function download($file, $path)
{
$size = filesize($path.$file);
#ob_end_clean();
if(ini_get('zlib.output_compression'))
ini_set('zlib.output_compression', 'Off');
header('Content-Type: application/force-download');
header('Content-Disposition: attachment; filename="'.basename($file).'"');
header("Content-Transfer-Encoding: binary");
header('Accept-Ranges: bytes');
header("Cache-control: no-cache, pre-check=0, post-check=0");
header("Cache-control: private");
header('Pragma: private');
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
if(isset($_SERVER['HTTP_RANGE']))
{
list($a, $range) = explode("=",$_SERVER['HTTP_RANGE'],2);
list($range) = explode(",",$range,2);
list($range, $range_end) = explode("-", $range);
$range=intval($range);
if(!$range_end) {
$range_end=$size-1;
} else {
$range_end=intval($range_end);
}
$new_length = $range_end-$range+1;
header("HTTP/1.1 206 Partial Content");
header("Content-Length: $new_length");
header("Content-Range: bytes $range-$range_end/$size");
} else {
$new_length=$size;
header("Content-Length: ".$size);
}
$chunksize = 1*(1024*1024);
$bytes_send = 0;
if ($file = fopen($path.$file, 'rb'))
{
if(isset($_SERVER['HTTP_RANGE']))
fseek($file, $range);
while
(!feof($file) &&
(!connection_aborted()) &&
($bytes_send<$new_length) )
{
$buffer = fread($file, $chunksize);
print($buffer);
flush();
$bytes_send += strlen($buffer);
}
fclose($file);
} else die('Error - can not open file.');
die();
}