How can I add a download button? - php

Question

I have this code which outputs a QR code:
<?php
include(JPATH_LIBRARIES . '/phpqrcode/qrlib.php');
$db = JFactory::getDbo();
$user = JFactory::getUser();
$query = $db->getQuery(true);
$query->select($db->quoteName(array('Soci', 'Nom', 'Cognoms', 'eCorreu')))
->from($db->quoteName('#__rsform_socis'))
->where($db->quoteName('username') . ' = '. $db->quote($user->username));
$db->setQuery($query);
$codeContents = $db->loadObjectList();
$data .= "Soci Nº: {$codeContents[0]->Soci}\n ";
$data .= "Nom: {$codeContents[0]->Nom} ";
$data .= "{$codeContents[0]->Cognoms}\n";
$data .= "e-correu: {$codeContents[0]->eCorreu}";
$tempDir = JPATH_SITE . '/images/';
$fileName = 'qr_'.md5($data).'.png';
$pngAbsoluteFilePath = $tempDir.$fileName;
$urlRelativeFilePath = JUri::root() .'images/' . $fileName;
if (!file_exists($pngAbsoluteFilePath)) {
QRcode::png($data, $pngAbsoluteFilePath);
}
echo '<img src="'.$urlRelativeFilePath.'" />';
?>
How can I add a download button so the user can download the code to the computer?
Thanks,
Dani

Answer 1

This is more of a HTML question, so lets get started: There is an attribute called "download" and you can use it like this:
echo 'Download QR';
It downloads the file as the name you supply here. So if the image url on your server is: wadAHEybwdYRfaedBFD22324Dsefmsf.png it would download the file as "qrcode.png". Unfortunately this is not supported in all browsers. Another easy fix is to make a form that has your filename as an action like so:
echo '<form method="get" action="'.$urlRelativeFilePath.'"><button type="submit">Download QR Code!</button></form>';
Another way (little more code) to do this is using PHP with some specific headers like this:
<?php
// place this code inside a php file and call it f.e. "download.php"
$path = $_SERVER['DOCUMENT_ROOT']."/path2file/"; // change the path to fit your websites document structure
$fullPath = $path.$_GET['download_file'];
if ($fd = fopen ($fullPath, "r")) {
$fsize = filesize($fullPath);
$path_parts = pathinfo($fullPath);
$ext = strtolower($path_parts["extension"]);
switch ($ext) {
case "pdf":
header("Content-type: application/pdf"); // add here more headers for diff. extensions
header("Content-Disposition: attachment; filename=\"".$path_parts["basename"]."\""); // use 'attachment' to force a download
break;
default;
header("Content-type: application/octet-stream");
header("Content-Disposition: filename=\"".$path_parts["basename"]."\"");
}
header("Content-length: $fsize");
header("Cache-control: private"); //use this to open files directly
while(!feof($fd)) {
$buffer = fread($fd, 2048);
echo $buffer;
}
}
fclose ($fd);
exit;
// example: place this kind of link into the document where the file download is offered:
// Download here
?>
It works for large and small files and also for many different filetypes. Info found here: http://www.finalwebsites.com/forums/topic/php-file-download

Answer 2

Well, you are obviously creating a .png picture file of the QR code with your script. So simply add a link to the location of the picture:
echo "Download";
This will however just redirect the user to the picture in his browser.
If you want to force a download you will need to use PHP headers to send the file to the visitors browser.
For example make a script and call it download_code.php.
Then add:
echo "Download";
And in the download_code.php:
$handle = fopen("/var/www/yourdomain.com/images/" . $filename, "r");
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.$filename);
header('Content-Transfer-Encoding: binary');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Expires: 0');
header('Pragma: public');
header('Content-Length: ' . filesize("/var/www/yourdomain.com/images" . $filename));
flush();
readfile("/var/www/yourdomain.com/images" . $filename);
fclose($handle);