Compress & save base64 image - php

Question

My app is receiving base64-encoded image-files from the webbrowser. I need to save them on the client. So I did:
$data = base64_decode($base64img);
$fileName = uniqid() . '.jpg';
file_put_contents($uploadPath . $fileName, $data);
return $fileName;
Which works fine.
Now I need to compress & resize the image to max. 800 width & height, maintaining the aspect-ratio.
So I tried:
$data = base64_decode($base64img);
$fileName = uniqid() . '.jpg';
file_put_contents($uploadPath . $fileName, $data);
return $fileName;
which does not work (error: "imagejpeg() expects parameter 1 to be resource, string given").
And of course, this does compress, but not resize.
Would it be best to save the file in /tmp, read it and resize/move via GD?
Thanks.
2nd part
Thanks to #ontrack I know now that
$data = imagejpeg(imagecreatefromstring($data),$uploadPath . $fileName,80);
works.
But now I need to resize the image to max 800 width and height. I have this function:
function resizeAndCompressImagefunction($file, $w, $h, $crop=FALSE) {
list($width, $height) = getimagesize($file);
$r = $width / $height;
if ($crop) {
if ($width > $height) {
$width = ceil($width-($width*($r-$w/$h)));
} else {
$height = ceil($height-($height*($r-$w/$h)));
}
$newwidth = $w;
$newheight = $h;
} else {
if ($w/$h > $r) {
$newwidth = $h*$r;
$newheight = $h;
} else {
$newheight = $w/$r;
$newwidth = $w;
}
}
$src = imagecreatefromjpeg($file);
$dst = imagecreatetruecolor($newwidth, $newheight);
imagecopyresampled($dst, $src, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
return $dst;
}
So I thought I could do:
$data = imagejpeg(resizeAndCompressImagefunction(imagecreatefromstring($data),800,800),$uploadPath . $fileName,80);
which does not work.

Answer 1

You can use imagecreatefromstring
To answer the second part:
$data = imagejpeg(resizeAndCompressImagefunction(imagecreatefromstring($data),800,800),$uploadPath . $fileName,80);
$data will only contain either true or false to indicate wether the operation of imagejpeg was a success. The bytes are in $uploadPath . $fileName. If you want the actual bytes back in $data you have to use a temporary output buffer:
$img = imagecreatefromstring($data);
$img = resizeAndCompressImagefunction($img, 800, 800);
ob_start();
imagejpeg($img, null, 80);
$data = ob_get_clean();