The Flash Ani(mation)S applet

Page 3 - Using overlays

3a. Simple overlays. In order to use overlays, you must provide four pieces of information:

The filename of the background image
The labels for the overlaid fields
The filename(s) for the overlay(s)
The value of the color to use as transparent

In our example, we will use the previously shown images as the overlays, and will put a satellite image up as the background. The HTML for the applet looks like this: controls = overlay overlay_labels = map, temperature, streamlines filenames = TIR1.GIF overlay_filenames = TMAP.GIF, TSFC1.GIF, TSTR1.GIF transparency = x000000 no_enh=true

3b. Now let's animate the background. You need only add more filenames. You also need more filenames for the overlays, but in this case, we will also specify that the first overlay is an animation, but the second and third are not. This is done by using an ampersand between filenames that are to appear on each frame. Of course, we also should add some controls for the animation (although this is not necessary):

Also, to illustrate it's use -- the "debug" window is enabled, using the "debug=true" option. You can just close it after viewing it's contents, but it can be useful for debugging problems.

controls = startstop, overlay, zoom, enhance overlay_labels = temperature, streamlines, map filenames = TIR1.GIF, TIR2.GIF, TIR3.GIF, TIR4.GIF overlay_filenames = TSFC1.GIF & TSFC2.GIF & TSFC3.GIF & TSFC4.GIF, TSTR1.GIF, TMAP.GIF transparency = x000000 debug=true

3c. Using image window scaling. When your images are too large, you can cause them to be rescaled. As the user zooms in, then, more data are revealed. To the above example's configuration file, we will add just one line (and omit the "enhance" control):

image_window_size = 160 , 120

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If you would like more information, or have questions or suggestions, please contact Tom Whittaker