Re: zooming with polylines: slow, memory hogged

Wasn't it benft who wrote:
>
>My map has a few dozen markers and polylines - see
>http://bentom.com/gm/carsmap.html
>when you zoom in such that lines ar clipped at the map edges, memofy
>use goes into the hundreds of MB and it slows way down. Happens even if
>all listeners are removed. A Google script BUG? Workaround, anyone?

I see that you've not got it to work at all in IE yet. My guess is that
when you do get it to work, it will run fast in IE. The polylines will
be drawn almost instantaneously.

In browsers that don't use VML, those 74 polylines are delivered as
images. When you zoom, or pan further than one map tile, new images have
to be fetched from the server. When you're zoomed into the middle of the
map, some of the lines span the whole of the graphics area which is one
or two tiles wider than the viewport.

For example, this polyline
<http://mt.google.com/mld?width=1753&height=892&path=mlBCvnDov@}oR&color
=153,153,255,0&weight=2>
is served as a rectangular image that's 1753*892 pixels - mainly
transparent with one thin blue stripe - which has a file size of 34330
bytes.

In some zoomed-in regions you might have a dozen polyline image files
that are close to that size, and some shorter ones, so expect something
on the order of half a megabyte of polyline images. That's a minimum of
10 seconds of file transfer time on a 512kb/s broadband connection if
everything is working at maximum efficiency.

[One odd thing is that the Google server seems to make the filesize
larger than it needs to be. When I re-save such images from a graphics
editor, the file sizes are somewhat smaller. That 34330 byte image
reduces to 20321 bytes]

--
The Blackpool Community Church Google Map API Tutorial
http://www.econym.demon.co.uk/googlemaps/