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For lots of gif89a animation examples, and some how-to tips, see the
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Animation Gallery.
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What the heck is a gif89a animation?
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- Gif89a is an image-file format that has been around for a while,
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and is used extensively on the web: whenever you see a transparent
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gif, you are seeing an aspect of the gif89a spec. However, there are other
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aspects of the gif89a format that are only now being supported, namely,
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the multiple-block option, which allows users to build an animation
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by stacking many image 'blocks' together in one image file. It LOOKS like
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a plain-old binary image, but when you view it with Netscape 2.0 or other
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compatible browser, it 'plays' as an animation.
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Gif89a animations are great for a lot of reasons: they
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are server-independent and portable; they do not add big burden to the server's processing
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power in the way that CGI does; the software to create them is cheap to free;
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they are easy to make; they are usually small; there are no plugins or special
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settings required to view them, since they will be recognized by
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graphical browsers as a gif, if not an animated gif.
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But will the final product be as cool as, say, a shockwave animation?
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More to the point, are there bugs?
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- Fortunately, many of the implementation issues that you might notice
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when you look at a gif89a animation -- that annoying 'disk whir' noise,
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the 'downloading image' message that Netscape 2 displays, the suspicion
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that Macintosh users may crash -- are browser-related and not the fault of
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the gif89a format. For example, that disk-whirring sound and the constant
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'downloading image' message are fixed in Netscape 3 beta/Atlas.
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Moreover, you can use currently-supported (or partly-supported)
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features of gif89a to 'work around' current annoyances; I add significant
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time lags both to insure against Macintosh 'crashes' and to minimize
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the 'noise'. (See some examples of how
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to use time to improve the animation/reduce the need for high bandwidth.)
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Browsers that recognize animated gifs may incorrectly interpret the
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frame-rate assigned to the frames of an animated gif, slowing it down too
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much; this is why you could insert a time lag of a tenth of a second per
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frame and the browser plays it back at a half second or so per frame.
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Although these drawbacks are annoying as hell to people like me, who
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see gif89a animations as a superb, open-platform, bandwidth-friendly
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way to spice up a website, most of the drawbacks are temporary.
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There are other features of gif89a that will allow interactivity once
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the browsers work out the bugs in implementation.
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Many browsers recognize some but not all aspects of
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the gif89a spec; Netscape
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and Microsoft Internet Explorer recognize most of the gif89a
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features, including animation. Most browsers will show transparent gifs,
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but old browsers will not recognize the additional 'blocks' of an animated
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gif and will just display the first image. Similarly, other aspects of
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gif89a are not recognized by any but the newest browser: Netscape 3 (Atlas)
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beta will recognize the 'loop iteration' feature of gif89a animations, but
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most browsers will not. When browsers recognize the 'wait for user input'
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gif89a feature, then true interactivity will be accessible to
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non-programmers and those who can't afford expensive multimedia software.
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How do I make the images that will become the frames of my animation?
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Gif89a employs the use of multiple 'blocks'.
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A block is an individual component of the gif89a image, and may be
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of several types: a control block, an image block, a loop block,
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a comment block, and a plain text block. The part of the animation
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that everyone sees is the image block, and you need to use whatever
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graphics application you normally use to create these images.
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Since most graphics applications do not support the
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'block' property of gif89a yet, you should make the
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'frames' of your animation as separate images
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and save them individually as gifs.
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Now that I have these gifs sitting around, how do I put them together?
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- A growing number of
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utilities for both Mac and Windows
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will do the trick in a
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fairly user-friendly manner. I used
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Gif Construction Set for Windows to make the above
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swirling swirl.
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A list of utilities
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that you can download is available at
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REI world. Most of the utilities for making
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gif89a animations allow
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you to place multiple gifs in the one file (using
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menus or drag and drop). Using the utility, you stack these blocks
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in 'chronological' order. Most utilities have a graphical interface which makes this fairly easy,
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and if you misplace a block you can also remove it. For example, if
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you want a looping animation of transparent gifs, you would do the following:
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1) Open a gif image using the animation utility.
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2) Insert a 'control' block before this image, and use the menu options
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provided by the control block to set the transparency.
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3) Insert the second image. You will be presented with a menu option
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which takes you to a standard file-finding menu for selecting the image.
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4) Insert a control block before this image.
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5) Insert a 'loop' block. You can only insert one of these.
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The 'blocks' will be displayed in the order in which you placed them.
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Now can I save the file and impress my friends?
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- Using the utility, save the file as a new gif (in 89a format) under a new
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name. Voila!
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A portable, programming-free gif file that won't break
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most browsers and will actually animate on many of them.
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Be careful not to edit the file in your usual graphics
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application, which probably won't recognize the gif89a
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properties and will drop the extra blocks.
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