generate thumbnail on fly

imagick.php

<?php
/*
Author: tzangms
Email: tzangms@gmail.com

Apache Rewrite rules
=========================================================================================
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_URI} !=/imagick.php
RewriteRule ^([^.]+).(\d+)x(\d+).([^.]+)$ imagick.php?path=$1.$4&width=$2&height=$3 [L]
RewriteCond %{REQUEST_URI} !=/imagick.php
RewriteRule ^(.*)$ imagick.php?path=$1 [L]
=========================================================================================
*/

$domain = 'http://tzangms.com/';

# Arguments
$path = array_key_exists('path', $_GET) ? $_GET['path'] : null;
$width = array_key_exists('width', $_GET) ? $_GET['width'] : null;
$height = array_key_exists('height', $_GET) ? $_GET['height'] : null;
$if_modified_since = array_key_exists('HTTP_IF_MODIFIED_SINCE', $_SERVER)?$_SERVER['HTTP_IF_MODIFIED_SINCE']:false;

if ($if_modified_since) {
     header('HTTP/1.1 304 Not Modified');
     exit;
}

# Required Arguments
if (!$path) {
    print "Please provide path";
    exit;
}

$url = $domain . $path;

# Fetch
$curl = curl_init($url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
$return = curl_exec($curl);
$content_type = curl_getinfo($curl, CURLINFO_CONTENT_TYPE);
$status_code = curl_getinfo($curl, CURLINFO_HTTP_CODE);
curl_close($curl);

# 404 Not Found
if ($status_code != 200) {
    header("HTTP/1.0 404 Not Found");
    exit;
}

# Original
if (!$width and !$height) {
    header("Content-Type: " . $content_type);
    print $return;
}

# Thumbnail
$im = new Imagick();
$im->readImageBlob($return);

# flatten GIF image
if ($im->getImageFormat() == 'GIF') {
    $im->flattenImages();
}

if ($width and !$height) {
    $geo = $im->getImageGeometry();
    $ratio = $geo['width'] / $width;
    $height = $geo['height'] / $ratio;
} elseif ($height and !$width) {
    $geo = $im->getImageGeometry();
    $ratio = $geo['height'] / $height;
    $width = $geo['width'] / $ratio;
}

# Output
$im->stripImage();
$im->setImageCompressionQuality(88);
$im->cropThumbnailImage($width, $height);

header("Content-Type: " . $content_type);
header("Content-Length: " . strlen($im));
header("Cache-Control: max-age=31536000");
header("Expires: Sat, 26 Jul 2022 05:00:00 GMT");
header("Last-Modified: Sat, 26 Jul 2001 05:00:00 GMT");
print $im;