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Roger L. Costello wrote:
> I have a few general questions about SVG:
>
> 1. Suppose that I render an SVG document in a browser (using the Adobe SVG
> plugin). My experiments show that I can right-mouse-click on the image and
> select Zoom in. However, my experiments also show that I can only Zoom in 3
> or 4 times, at which time the Zoom in menu pick gets grayed-out. Does SVG
> limit the level of Zooming in, or is that a limitation of the Adobe
> renderer?
SVG as a vector graphics system has no resolution limits. In addition
to the practical issues that others have already answered, bear in mind
that you can display a bitmapped image in svg, and that image would be
subject to the same problems as all bitmapped images.
> 2. Continuing with the last question ... Suppose that I have a map of a
> country. How much detail can be put into the map? Can I put details down
> to the level of a building, on a street, in a city, in a state in the
> country? Can I then Zoom in from the country level down to see the
> building?
>
You have three approaches that i know about for zooming in with svg -
1) Plain magnification.
2) Progressively disclose more detail for each stage of the zoom using
javascript.
3) Progressively disclose more detail for each stage of the zoom by
changing a css stylesheet. I don't know which, if any, implementations
let you manipulate the css using javascript, though.
You could also accomplish progressive disclosure by loading new pages
for each step - the pages might only differ by the magnification and the
stylesheet.
> 3. Can I associate textual information with parts of the SVG graphic? For
> example, if I have a graphic of a country, I might like to associate some
> textual information for each city. Is it possible to hide the textual
> information until the user, for example, right-mouse-clicks on the city?
>
Scripting is your friend.
> 5. Suppose that I want to create an SVG image of a country. I cannot
> imagine handcrafting an XML SVG document. How do you suggest that I create
> the SVG document?
A couple of years ago, when Microsoft was adding xml support to sql
server, they published an article on their web site that took publicly
available street map data for Manhattan, stored it in the database, then
extracted it as an svg street map with the help of some xslt
transformations. It seemed to work very nicely. If you are lucky,
maybe the page is still squirreled away on their site somewhere that
Google knows about.
You do want to remember that different svg implementations use
non-compatible ways to specify the use of javascript and css (different
MIME types). This is a real nuisance if you want to get something
working across several implementations, and have it use javascript, css,
or both. Mozilla is the most annoying in this respect (I consider the
top three implementations for experimenting with to be the Adobe plugin,
Batik, and Mozilla). Mozilla also has not yet implemented the "use"
element, which I think is a real weakness since it is one of the most
features you can use whenever you have repetitive groups you want to
place at different places on the diagram. I filed a bug against this,
so maybe at some point it will be implemented.
Overall, I have been happiest with Batik, but the Adobe plugin is
certainly convenient if you are willing to use IE.
Cheers,
Tom P
--
Thomas B. Passin
Explorer's Guide to the Semantic Web (Manning Books)
http://www.manning.com/catalog/view.php?book=passin
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