GIF89a Animation

Beginning with version 2b05, Netscape browsers support GIF89a animations as does Microsoft Internet Explorer version 3 and above. If your readers are using one of these browsers, you can use this feature to add animation to your pages. If you are viewing this document with a browser that supports GIF89a animation, the little globe should be spinning.

The banner at the top of the index to the HTML CD Treasure Chest is a GIF animation. If you see the spinning globes, you should have seen the banner scroll in. Note that the first frame of the animation is the entire banner. This is to accomodate browsers that do not support GIF animation, and only show the first frame.

Advantages of GIF89a Animation

There are many advantages to using GIF89a animations over server-push or client-pull. Some of them include:

• Everything is in one file. Once the image file is loaded, no further network connections are needed (vs multiple connections for client pull, or a lengthy connection for server push).
• Small file size. The spinning globe only takes 11kb.
• No need for multiple HTML files (as with client pull). It's all contained in a single image file.
• No need for access to CGI. These are just images and can be used like any other image. If the viewing browser doesn't support animation, only the first "frame" will be displayed.
• No additional overhead if you reuse the image in a document. Once the image is loaded, you can use it over and over in the same document, and it doesn't need to be reloaded over the network.

If your browser supports loop control for GIF animation, you can specify the number of times the animation should repeat in the LOOP block of your image file. You can also set the delay between each frame.

For more information about animated GIFs, check out Royal E. Frazier's GIF89a document.