Question

Possible Duplicate:
Thumbnails in php generated gallery loading slow

Code link can be found on the bottom of the page.

The site is running from 1and1.co.uk linux based system, good enough to load the gallery much faster than it currently does.

The php generated thumbnails are loading a bit slow, can you tell me why?

http://site-perf.com/cgi-bin/show.cgi?id=vz5le19Fp5E

code:
http://satinaweb.com/tmp/functions.txt

Here is crop.php:

$sourceimage = $_GET['a'];

function crop($sourceimage) {
    // Draw & resize
    header('Content-Type: $imsz[\'mime\']');

    list($width, $height) = getimagesize($sourceimage);

    if($width > $height){
        $new_width = 100;
        $new_height = 75;
    } else {
        $new_width = 75;
        $new_height = 100;
    }

    $image = imagecreatefromjpeg($sourceimage);
    $image_p = imagecreatetruecolor($new_width, $new_height);

    imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
    imagejpeg($image_p);
    imagedestroy($image_p);
    imagedestroy($image);
} 

crop($sourceimage);

If you have questions, please ask!

Answer 1

What you should have noticed from your site-perf graph most is that,

I’m not going to look through all your code, but you have a file called crop.php. This is going to be slow because it (presumably) crops the images on every page load, which takes a relatively long time (made apparent from the site-perf data); for each request, the browser spends most of it’s time waiting for the server to respond.

You should consider using a cache folder to store cropped images and serve them up as-is to reduce loading time.

In crop.php, you could do something like this (pseudo code):

IF original image newer than cropped OR cropped doesn't exist
    Load original image
    Crop original image
    Save cropped image to cache folder
ELSE
    Serve already-cropped image from cache
ENDIF

---

Every time you call crop(), you read the image, modify it and spit it out to the client. This is incredibly wasteful, because you need to re-process the image for every request. You’re even destroying the image afterwards (not that this makes much difference). Instead, use is_file() with a cache directory, and save the image to disk as well as sending it to the client.

Now, your script might look like this:

$sourceimage = $_GET['a'];

$cache_dir = dirname(__FILE__) . "/cache";        // Cache directory
$cache_file = $cache_dir . '/' . $source_image; // Path to cached image

function crop($sourceimage) {
    header('Content-Type: $imsz[\'mime\']');

    // If cached version of cropped image doesn't exist, create it
    if(!is_file($cache_file)) {     
        list($width, $height) = getimagesize($sourceimage);

        if($width > $height) {
            $new_width = 100;
            $new_height = 75;
        } else {
            $new_width = 75;
            $new_height = 100;
        }

        $image = imagecreatefromjpeg($sourceimage);
        $image_p = imagecreatetruecolor($new_width, $new_height);

        imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

        imagejpeg($image_p, $cache_file);   // Save image file to disk
    } else {    // If cached file exists, output to browser without processing
        echo file_get_contents($cache_file);
    }
} 

crop($sourceimage);

This is untested, but should work. Please don’t just copy and paste the above code; read through it and make sure you understand how and why it does what it does.