[OpenLayers-Users] First try with html5 canvas for layers

[Eric Lemoine]

On Thursday, November 19, 2009, Kris Geusebroek <kgeusebroek at xebia.com> wrote:
> Hi Eric,

Hi Kris. Thanks for response.

>
> Indeed it's cool, thanks.
> My goal was to write an application with open source technologies to
> track cars driving around.
> I wrote a prototype with geoserver and openlayers and this was
> succesfull. The big problem was the memory consumption (especially in
> IE) because of the large amount of DOM manipulation that is done when
> panning and zooming

do you manage to actually lower memory consumption with your
Canvas-based tiles? IIRC an image tile is two DOM elements (a div and
an img). How many elements is a Canvas tile? One?

> and drawing vector's (the cars, with fills, stroke,
> label etc.)
>
> Since using a plugin is out of the question here I began investigating
> the html5 canvas.
> I know it's not supported in IE, but for me that was a good thing
> because it gave me the opportunity to have the client choose a different
> browser then IE.
>
> My plans for the future of the app is to also use workers and the
> browser database (to be able to store historical responses clientside to
> draw a route the car has followed for the last 10 minutes or so)

This could be written as a OpenLayers.Protocol. Chris Schmidt started
an HTML5 Protocol a while back if I recall correctly. You may want to
check this with him.

Thanks,

-- 
Eric Lemoine

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