A Complete Guide to Web Design

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Animated GIFs

Web Design in a Nutshell, eMatter Edition

Chapter 18Animated GIFs

CHAPTER 18

Animated GIFs

These days, it’s just about impossible to browse the Web without seeing the
flashing, bouncing, and wiggling of GIF animation. The animated GIF is ubiqui-
tous, and there are many good reasons fueling its popularity.

• Users need no special software or plug-in.All they need is a browser that sup-
  ports animation—which is fortunately the overwhelming majority of browsers
  in use as of this writing.


• GIF is the standard file format for the Web.Animated GIFs are not a unique
  file format in themselves, but merely take advantage of the full capabilities of
  the original GIF89a specification. Even if a browser cannot display all of its
  frames, the GIF will still be visible as a static image.


• They’re easy to create.There are scores of GIF animation tools available
  (some are built into larger web graphics applications), and they’re simple to
  learn and use.


• They require no server configurations.Because they are standard GIF files,
  you do not need to define a new file type on the server.


• They use streaming technology.Users don’t need to wait for the entire file to
  download to see something. Each frame displays as soon as it downloads.

The only drawbacks to animated GIFs are that they can contain no sound, no
interactivity (you can’t make different parts respond to mouse actions), and they
may cause some extra work for your hard disk to keep refreshing the images.

How They Work

Animated GIFs work a lot like traditional cell animation. The file contains a
number of frames layered on top of each other. In simple animations, each frame
is a complete scene. In more sophisticated animations, the first frame provides the
background and subsequent frames just provide the changing portion of the
image.