VISITview Access to Remote Image Files

Note: This capability will only work in non-browser (that is, pre-loaded) mode because of Java security.

Here are the details:

1. Pages defined with URL-based image filenames (defined as any "filename" that starts with "http://") will be loaded over the web during the lesson/collaboration, and whenever the lesson is loaded in the Lesson Builder.
2. A page defined with a URL-based image can be used:
   • for all pre-loaded lessons (be careful when using these for recorded lessons, however, as the load time may throw off the timing) -- the page will be loaded over the web during the lesson, so be careful about long loops!
   • for browser-based lessons ONLY if the images are loaded from the same host machine as the HTML (and the VISITview server).
3. If a page is defined using a URL-based image, no other images should be put onto that page; there is no protection against this in the Lesson Builder yet, however.
4. If you want more than one frame for the page, you must either use the wildcard (*) form of the URL. e.g.,
       http://www.ssec.wisc.edu/visit/lessons/ev/ev_mar29_*
   defines a series of filenames like "ev_mar29_0", "ev_mar29_1", etc., (note - the first number must always be zero)...
   or...you can use embedded string substitution to imply more than one image. e.g.,
       http://www.ssec.wisc.edu/visit/lessons/ev/ev_mar29_[00;01;32;56;02].jpg
   which specifies 5 frames (ev_map29_00.jpg, ev_mar29_01.jpg, ev_mar29_32.jpg, etc.). This form is also useful if your image names are in a sequence that does not begin with zero.
5. The URL format has some restrictions:
   • All URLs must start with "http://" (case sensitive!)
   • No spaces!
   • No "substitution characters" (for example, %20 for "space")
   • Only image files should be pointed at (no cgi-bin generated stuff)
6. You may move a URL-based page around, as usual. You cannot remove frames, etc., from the page. In otherwords, once you import a URL-based page, you're stuck with its characteristics. You can, of course, delete it and re-import something different if you like.
7. In the Lesson Builder, a new Menu Item, "Image from URL" will be added. When you click on this, a modal dialog will appear. There will be two text fields for you to type into:
   • the URL:
     • the URL itself for a single image.
     • the URL for more than one image, using the wildcard (*) to substitute for the sequence of numbers starting at 0 (e.g., 0,1,2,3...)
     • the URL with embedded string substitutions to imply multiple frames. Enclose the substitution strings in square brackets, and separate the strings with semi-colons. For example,
           http://www.my.gov/images/img[0;1;4;3;2].jpg
       implies a 5 frame animation (img0.jpg, img1.jpg, etc).
   • The number of frames (will always default to 1) which can only be > 1 if the wildcard (*) is used. For the "embedded string substitutions", above, this should remain = 1.
   You should type in the appropriate info, and then click "Close" button (there is also a "Cancel" button).

   After that, the first image will be browsed into the usual thumbnail view, and the "Append" and "Insert" buttons will be enabled. Note that when you click either of these, the total number of frames you specified will be inserted into the lesson on a _single page_ (see Item #2 above).

   If the thumbnail does not appear, there is an access problem (like an invalid URL or filename). Bring the dialog up again and correct the problem.

   The thumbnails will exist only during the Lesson Builder session; when you Save the lesson, only the URLs are written into the lesson file -- no images will be saved for those pages. When you re-start the Lesson Builders, any pages defined with URLs will be reloaded from the web.

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