Today's example was requested by a user called Devo. This example illustrates making an animated GIF image by creating the frames from scratch. It's been so long since I've really drawn anything so I decided to use text as the base for this animation.

His example ends up as a string ("Hello World") that's animated to show one more letter at a time as each frame loads.

As I stated at the end of the previous article of this series, the GD extension comes packaged with many other useful functions, which indeed deserve a close and detailed look. Thus, in this second tutorial I'll show you how to create different types of image streams from existing graphics, but in this case limiting the process to building GIF, JPG and PNG images.

They work through each of the types (GIF, JPG and PNG) creating an new one from a previous "clouds" image of the same type (a GIF out of a GIF, a JPG from a JPG, etc).

The exploit code slipped through the site's defenses with the aid of a legitimate image at the beginning of the file, according to a blog post on the Sans Institutes's Internet Storm Center. [...] Malicious attackers planted PHP coded exploit script within an image file. PHP is often used as a programming language to create dynamic Web sites.

The article reports that, while this exploit hasn't happened much, the occurrences of it's use are growing with victims in a wide range of classifications - from small personal sites out to a certain major image hosting site. This same issue was discussed here on the PHPClasses.org website as well.

Manuel Lemos writes:

The problem that was discovered is that you can insert PHP code in the middle of a GIF image. That would not be a problem if it was not for the insecure ways some developers use to serve images upload by their users. Usually, uploaded files are moved to a given directory. If the site then serves the images directly from that directory and preserve the original file name, the site may be open for security exploits.

The problem comes when a user decides to upload an "image" file that's actually a PHP script (ending in PHP even) to the remote system. When this is outputted, it's placed inside the image tag and executed with each page load. Manuel offers a suggestion to prevent the issue - protecting the images directory and using readfile to grab the contents of the file to output rather than just a straight echo.

Laszlo Zsidi is a PHP Web developer that has written an harder to break CAPTCHA solution. It consists in generating animated GIF images that exhibit the validation text.

Since the text never appears all at once in each of the animated frames, this solution certainly raises the bar in terms of difficulty for the robots to guess the validation text, making it very hard to defeat, if possible at all.

You can check out the class here, including a sample animated gif file and a download of everything you'll need to get started.

He has developed several pure PHP components that implement impressive 3D animated graphics, like a 3D objects rendering engine, emulate a waving flag or the reflex of an image near a lake. The generated frames are combined into a single animated GIF with another pure PHP component also written by László. All these components were nominated to the PHP Programming Innovation Award for the evident creativity, demonstrating that PHP can be used for non-trivial software applications.

Some of the libraries in the listing include:

• Animated GIF into images
• Image Flag Effect
• Text 3D
• FXLake effect
• Convex 3D

You can use it to give your site that 'iTunes / Apple' look if you so desire. I created it to make image uploads to a site I run look that little bit nicer, so figured I would share it with you all.

The script, Easy Reflections, can be grabbed from here along with the installation and use instructions (including the values for the six parameters to change the image).

I used the great mobile site from the NWS, but it still didn't give me the effect I wanted. And hey, I'm already filling a database with weather observations and radar images! So I decided to see what it would take to make a custom radar loop that I could get to at any given moment. The Treo can display animated gif files, so that seemed like the most efficient solution. The question is, how do we create an animated gif using PHP?

To answer the question, he found this script ("GIF images into animated GIF with native PHP class") and used it to create a simple script to grab the GIF images and combine them into a single animated image suitable for viewing in any browser. He includes the script used to generate it as well as an example of the result and how it looks on the phone.

I've seen a lot of implementations of thumb nail functionality in PHP, I've even written a couple of my own. I like this class thought. In looking over the code the first thing you notice is that it's clean code. I don't mean they use the latest whiz-bang method to cshave a few keystrokes.

This code is simple, nicely formatted and easy to read through. My only real problem with the code itself is that it is not terribly well documented. That can be forgiven since easy to read.

Cal talks about some of the other features of the class, including that it works with gif/jpeg/png images, makes it easy to set the quality of the jpgs, and makes it easy to display the dynamic images directly to the browser. Check out the demo for more.