On-line Snapshot Generators

Two classes of snapshot generators are available on the web. BrowserCam and NetRenderer support web site developers who need to verify their web designs on multiple platforms and browser versions. These snapshots are full-size and present exactly what would appear on a user’s screen. NetRenderer describes their solution as follows: “we use a proprietary C# application to control parallel rendering and to generate the virtual screenshot images.” BrowserCam allows you to connect to their rendering machine using VNC.

The second class of web-available snapshot generators offer their service to website authors as a way of enriching their site’s graphics. These are typically thumbnail images, in terms of size, detail, and function. This class of generator is more in line with my possible use for snapshots.

Wordpress offers Snap’s snapshot generator on all links within these blogs (to go to their site, hover on any link then click on the SnapShot logo in the lower-right footer). New snapshots are generated relatively quickly (i.e. minutes, not hours).

A similar offering comes from ShrinkTheWeb. Let’s try it on the New York Public Library web site:

Although NYPL might be cached, I tried it on an unlisted site and the thumbnail appeared within 10 seconds. The engine is usually available and offers parameters to control the size and quality of the snapshot. The image is directly embeddable in my web page, unlike Snap.

If you compare the actual web site to the various thumbnail engines, notice that Java, Flash, and JavaScript generated graphics may not appear. I would expect that BrowserCam would be most faithful in this regard, since one actually connects to a real browser.

Currently I can’t easily gain possession of the image file. I could capture the image with wget or Curl, but that’s not the same as directly generating the image. And Snap displays the image only in a pop-up.

Command Line Snapshot Generation

Ideally, I’d like to replicate snapshot functionality on a local workstation. In Linux, I would hope to generate a thumbnail by providing a URL and a view-port size to Firefox or Konqueror, then requesting that it save the image to a file in my preferred format. Something like this:

   browser --background --size 800x600 --jpeg www.yahoo.com > yh.jpg

Alas, man pages and user documentation gave no evidence that Firefox, Opera, or Konqueror support a background mode of operation. Others have succeeded, however. In his Planet-PHP Website Thumbnails entry from 2005, J Eichorn describes using Mozilla in just such a fashion. Update: This functionality is available online at Bluga.net Webthumbs.

Things have evolved from 2005 — now I guess SeaMonkey is the suite offering. If one wants access to the rendering engine, the Mozilla web site suggests embedding the Gecko engine directly using the Toolkit API.

openSUSE 10.2

• Apache2, PHP 5.2, mod_php, mod_rewrite.
• PHP magic_quotes_gpc is set to off in openSUSE (the proper choice, but not the PHP default as I painfully learned when installing at the ISPs).
• PEAR supported in the Apache PHP include path.
• Subdirectories written into by the application (e.g. Smarty template compilation area) need world-write privilege.

GoDaddy Hosting

• Apache1.3, PHP4 (5.1.4 optional), CGI/fastCGI, mod_rewrite.
• Cannot use php_flag because using CGI, must use php5.ini instead.
• Switch from PHP 4 to 5 in .htaccess:
  AddHandler x-httpd-php5 .php
  AddHandler x-httpd-php .php4
• PHP magic_quotes_gpc on by default, turn off with local php5.ini file.
• AllowOverride Options disabled, can’t use in .htaccess.
• Files created by web site users (i.e. by the httpd user) have the same uid/gid as my ftp login user. An excellent configuration approach, as I don’t need to give world write privileges to local data subdirectories.
• ini_set(’session.cache_limiter’, ‘private’) causes server 500 error.

A2 Hosting

• Apache 1.x (server_signature empty), PHP 5.2, mod_php, mod_rewrite.
• PHP magic_quotes_gpc is on by default, turn off using php_flag (here is the Running PHP as an Apache Module PHP man page describing how to use php.ini directives within .htaccess).
• Subdirectories written to by the application need world-write privilege. My ftp area is a public_html directory, so A2 uses mod_userdir. The home directory looks similar to my local workstation.
• ini_set(’session.cache_limiter’, ‘private’) works fine. Moved this parameter to a php_flag directive.
• A2 mentions PEAR support on their web page, but they don’t add the directory to the PHP include path and only offer a handful of modules. Will add modules per customer request, but what will happen if they move my account to a different server?

Web Hosting Requirements

• PHP Extensions: CURL, XMLWriter.
• Apache Modules: rewrite.