使用PHP从URL创建缩略图

Question

I want to generate thumbnails of websites. I found a few sites that handle it with an API, such as http://www.websnapr.com/

How can this be done with PHP so I can handle all of the requests on my server?

Answer 1

PHP can't do this on it's own as it does not include an HTML rendering library.

You can find an external method of capturing the screenshots and communicate with that method using PHP, though.

First you'll need a system set up to take screenshots. Look into IECapt (http://iecapt.sourceforge.net/), CutyCapt (http://cutycapt.sourceforge.net/) or khtml2png (http://khtml2png.sourceforge.net/) and configure one of those on a system.

Then set up a PHP script that will exec() the screenshot taking application and return the data to the browser.

For example:

<?php
$in_url = 'http://' . $_REQUEST['url']; // !!INSECURE!! In production, make sure to sanitize this input!
$filename = '/var/cutycapt/images/' . $_REQUEST['url'] . '.png'; // Will probably need to normalize filename too, this is just an illustration

// First check the file does not exist, if it does exist skip generation and reuse the file
// This is a super simple caching system that will help to reduce the resource requirements
if(!file_exists($filename)) {
  exec('/usr/local/bin/CutyCapt --url="' . $_REQUEST['url'] . '" --out="' . $filename . '"');
}

// Second check if the file exists, either from a previous run or from the above generation routine
if(file_exists($filename)) {
  header('Content-type: image/png');
  print file_get_contents($filename);
} else {
  header('Status: 500 Internal Server Error');
}
?>

You can then call the script in the following way:

http://localhost/screenshot.php?url=www.google.com

Building the screenshots is going to be CPU intensive so I'd strongly recommend building in some kind of file caching (ie. save the results of the output and check to see if you already have a screenshot somewhere), perhaps even a queuing system so your screenshot server does not get overwhelmed.