Simple PHP Image Upload Form

This little chunk of PHP allows a user to upload a JPEG image and then resizes that image to generate a thumbnail automatically. With a little work, you can change the file types allowed, formula for resizing the thumbnails, etc. but I wanted to keep this simple so only JPEGs are allowed and everything is resized based on height.

<?php

$allowedfiletypes = array("jpeg","jpg");
$uploadfolder = "uploads/" ;
$thumbnailheight = 100; //in pixels
$thumbnailfolder = $uploadfolder."thumbs/" ;

$action = $_POST['action'];
if ($action == "upload") {
    echo "<p>Uploading image... " ;
    if(empty($_FILES['uploadimage']['name'])){
        echo "<strong>Error: File not uploaded!</strong></p>\n\n" ;
    } else {
        $uploadfilename = $_FILES['uploadimage']['name'];
        $fileext = strtolower(substr($uploadfilename,strrpos($uploadfilename,".")+1));
        if (!in_array($fileext,$allowedfiletypes)) { echo "<strong>Error: Invalid file extension!</strong></p>\n\n" ; }
        else {
            $fulluploadfilename = $uploadfolder.$uploadfilename ;
            if (move_uploaded_file($_FILES['uploadimage']['tmp_name'], $fulluploadfilename)) {
                echo "$uploadfilename has been uploaded succesfully.</p>\n\n";
                $im = imagecreatefromjpeg($fulluploadfilename);
                if (!$im) { echo "<p><strong>Error: Couldn't open image to create thumbnail!</strong></p>\n\n" ; }
                else {
                    $imw = imagesx($im); // uploaded image width
                    $imh = imagesy($im); // uploaded image height
                    $nh = $thumbnailheight; // thumbnail height
                    $nw = round(($nh / $imh) * $imw); //thumnail width
                    $newim = imagecreatetruecolor ($nw, $nh);
                    imagecopyresampled ($newim,$im, 0, 0, 0, 0, $nw, $nh, $imw, $imh) ;
                    $thumbfilename = $thumbnailfolder.$uploadfilename ;
                    imagejpeg($newim, $thumbfilename) or die("<p><strong>Error: Couldn't save thumnbail!</strong></p>");
                    echo "<p><img src=\"$thumbfilename\"></p>\n\n" ;
                }
            } else { echo "<strong>Error: Couldn't save file ($fulluploadfilename)!</strong></p>\n\n"; }
        }
    }
}

echo "<form action=\"".$_SERVER['PHP_SELF']."\" method=\"post\" enctype=\"multipart/form-data\">\n" ;
echo "<input type=\"hidden\" name=\"action\" value=\"upload\" />\n" ;
echo "JPEG Image File: <br />\n" ;
echo "<input type=\"file\" name=\"uploadimage\" /><br /><br />\n" ;
echo "<input type=\"submit\" value=\"Upload Image\" />\n" ;
echo "</form>\n\n";

?>

After you've uploaded it, here's how you can easily resize your image on the fly.

This post was published on Saturday, January 17th, 2009 by Robert James Reese in the following categories: HTML, Images, PHP. Before using any of the code or other content in this post, you must read and agree to our Terms & Conditions.

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