[OpenLayers-Dev] [Dev] Re: Vectors in OpenLayers?

[Paul Spencer]

Hi Pierre,

I haven't looked at the code but I think that this will be needed in  
some sort of factory object that can create Geometry (and associated  
Shape) objects from WKT.  We are a bit early for implementation  
details right now (despite the fact that I've already done a bunch of  
implementation), but when the design is finalized, we'll need this  
piece.

This reminds me that Geometry objects need to be able to serialize  
themselves as WKT.

Cheers

Paul

On 13-Oct-06, at 12:46 PM, Pierre GIRAUD wrote:

> I wanna propose you some peace of code for this.
> Hope you'll be able to have a quick look and check if I'm the good  
> way.
>
> I tried to follow the "factory" pattern, but I'm not sure I
> implemented it right considering the rest of the architecture.
>
> Regards and nice week-end
>
> Pierre
>
> ps : this code might be useable in the current vector sandbox
>
> On 10/13/06, Pierre GIRAUD <bluecarto at gmail.com> wrote:
>> I don't know if this is a needed functionnality, but it can probably
>> help. I was trying to think about and implement a way to add a  
>> feature
>> by its WKT string writing.
>>
>> Something like :
>>
>> OpenLayers.Vector.WKT
>>
>> p4 = new OpenLayers.Vector.WKT('POINT(-40 30)');
>>
>> Regards
>>
>> Pierre
>>
>> On 10/13/06, Paul Spencer <pspencer at dmsolutions.ca> wrote:
>> > Thanks Chris :)
>> >
>> > Performance really sucks if you add a lot of features.  I wrote a
>> > quick loop to add a 1 degree box every 10 degrees and brought my
>> > firefox to a halt.  Profiling reveals a number of problematic  
>> areas,
>> > the biggest of which is getPx (of course).
>> >
>> > I've done some optimization that improves performance in this case:
>> >
>> > * remove the call to Pixel.add(x,y) and directly modify the pixel
>> > position - this was a big savings ...
>> >
>> > * cached px location in the Point object based on the bounds of the
>> > containing vectorLayer so getPx is only called when the bounds have
>> > actually changed.
>> >
>> > attached is a patch against the sandbox to incorporate these  
>> changes.
>> >
>> > Next steps for me are:
>> >
>> > * fix rendering in IE and Safari (that was the whole point of using
>> > excanvas)
>> >
>> > * further optimizations, including:
>> >
>> >    o try caching the bounds of each vector and test for  
>> intersection
>> > with layer bounds before rendering
>> >
>> >    o tighten inner loops and remove deep call chains (possibly
>> > putting some of the pixel conversion stuff right into convertToPx)
>> >
>> >   o anything else you can think of
>> >
>> > * convenience functions for constructing polygons and lines from
>> > points without having to construct intermediate objects
>> >
>> > Other things that need to be done at some point, but not  
>> necessarily
>> > for 2.3:
>> >
>> > * refactor the code (what, already?) so that the Vector  
>> architecture
>> > can support multiple rendering types (Canvas, SVG, VML, possibly
>> > others in the future) by introducing Layer.Vector subclasses and a
>> > new Rendering class that knows how to render into the sub-classed
>> > layer types
>> >
>> > * refactor styling support to make it less specific to Canvas
>> > rendering stuff
>> >
>> > * add some Controls for digitizing and possibly editing
>> >
>> > Cheers
>> >
>> > Paul
>> >
>> > On 12-Oct-06, at 7:55 PM, Christopher Schmidt wrote:
>> >
>> > > On Thu, Oct 12, 2006 at 05:02:00PM -0400, Paul Spencer wrote:
>> > >> Schuyler, et al
>> > >>
>> > >> attached is a first cut at the vector stuff.  It extracts  
>> over an
>> > >> existing openlayers folder and contains only the new files  
>> I've added
>> > >> plus a change to OpenLayers.js to load the extra files by  
>> default
>> > >> (except for excanvas for some reason ;)).
>> > >>
>> > >> There is a vector.html in the examples folder.
>> > >
>> > > This code, with some improvements from Schuyler and I, is now  
>> in place
>> > > in a sandbox in the OpenLayers SVN. You can check out with:
>> > >
>> > > svn co http://svn.openlayers.org/sandbox/sderle/vector/
>> > >
>> > > You can try it out at:
>> > >
>> > > http://openlayers.org/~crschmidt/vector/examples/vector.html
>> > >
>> > > Click once to start drawing a line -- click again to end it.
>> > >
>> > > FF only at the moment.
>> > >
>> > > Cool stuff, Paul, thanks for getting the ball rolling on this.
>> > > --
>> > > Christopher Schmidt
>> > > Web Developer
>> >
>> > +-----------------------------------------------------------------+
>> > |Paul Spencer                          pspencer at dmsolutions.ca    |
>> > +-----------------------------------------------------------------+
>> > |Chief Technology Officer                                         |
>> > |DM Solutions Group Inc                http://www.dmsolutions.ca/ |
>> > +-----------------------------------------------------------------+
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > _______________________________________________
>> > Dev mailing list
>> > Dev at openlayers.org
>> > http://openlayers.org/mailman/listinfo/dev
>> >
>> >
>> >
>> >
>>
>> <wkt.html>
>> <WKT.js>
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+-----------------------------------------------------------------+
|Paul Spencer                          pspencer at dmsolutions.ca    |
+-----------------------------------------------------------------+
|Chief Technology Officer                                         |
|DM Solutions Group Inc                http://www.dmsolutions.ca/ |
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