将映像文件从服务器复制到PHP中的磁盘

Question

I have a js script that saves an image as .jpg in a specific folder on the server:

$data = substr($_POST['imageData'], strpos($_POST['imageData'], ",") + 1);
$decodedData = base64_decode($data);
$fp = fopen("imgdownload/cc.jpg", 'wb');
fwrite($fp, $decodedData);
fclose($fp);

The next step would be for the user to save it on his/her disk, the best would be to open a dialog box "save as" and choose the name and location, but just forcing download to a set location would be a dream.

I've tried:

$file = 'imgdownload/cc.jpg';

if (file_exists($file)) {
    header('Content-Description: File Transfer');
    header('Content-Type: image/jpg');
    header('Content-Disposition: attachment; filename='.basename($file));
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Length: ' . filesize($file));
    readfile($file);
    exit;
}

And other things without success. What am I doing wrong and how to do it right?

EDIT - this is my JS:

savePicture: function() {
    $(this.el).find('canvas').attr('id', 'myCanvas');
    var data = document.getElementById("myCanvas").toDataURL();
    $.post("api/process.php", {
        imageData: data
    }, function(data) {
        //window.location = data;
    });
},

Answer 1

You cannot trigger a download in response to a background AJAX request. You'll have to direct the main browser to the URL where the download occurs. Eg, in your AJAX callback:

window.location = '/download.php';

That means you'll need to store the file server-side in the AJAX upload request to then have it available for download in the separate following request to download.php somewhere.