Re: data.xml, info windows and separating functions

Wasn't it Darius who wrote:
>
>Hello Mike,
>
>you are right as always,
>but to my understanding, client side graphics, so called web based
>games, don't run really fast vs. non-web based games.

Yes, it's the web communications that slow things down. The client side
graphics computations are fast.

>Polylines are generated client-side.

Only when using the IE browser.

>I don't have an authorization to cache my own transparent PNG files on
>Google server.
>I can cache my own off-line generated, transparent PNG files on my own
>server - acting as Google Maps overlay, representing off-line generated
>polylines.

I would have thought that it would be easier to get Google to generate
them in the first place, rather than draw them yourself. The problem is
that you have to determine in advance what zoom levels you're going to
use. If you were to cache all possible zoom levels, then that would
require a huge amount of data, much of which might never be used.

>What do you mean by saying :
>The Google polyline image server

Polylines use two completely different technologies in different
browsers. In IE, the graphics are generated in the client. In other
browsers, such as Firefox, the graphics are generated in a Google server
that serves the polyline images over the Internet to the client.

>In the above discussed example
>http://www.vta.org/news/vtacmp/gmaps/index.html
>polylines are generated from data included in a source code of a web
>page, so polylines are generated client-side.

Only in IE. In other browsers the client code sends a request like this

<http://mt.google.com/mld?width=27&height=50&path=m@GDGHK@A?ABA@A@A@A@AD
E?C@ACGQ]}oR&color=131,22,154,0&weight=4>

(Use http://tinyurl.com/d335l if your newsreader doesn't join the
lines for you)

That request goes to a server program at mt.google.com/mld which
calculates the graphics in a manner that's probably similar to how it
happens in the IE browser. The server sends back a transparent PNG file

>Having opened this page on my laptop powered by Intel Celeron 2.5GHz I
>can see progress of polylines generated, so such code and source data,
>executed client-side
>can not be compared to server-side generated transparent PNG file
>representing polylines, as download times for overlays can be keep much
>lowe than client-side code Javascript code execution.

I can see that you're using Firefox for your posting, so I assume that
you're looking at Firefox polylines on your laptop. They're not being
generated in your laptop, they're being fetched one-by-one from the
Google polyline image server.

If you run that same page in IE, you'll see that the polylines appear
instantaneously. In particular, try changing the zoom level in IE and
notice that the recalculated polylines are displayed instantaneously,
and then the map tiles appear one by one as they're fetched from the
server.

--
Mike Williams
Gentleman of Leisure