[OpenLayers-Dev] Geometry editing

[Jeff Dege]

On Thursday, June 14, 2007 12:49 PM,
Jeff Yutzler wrote:
> 
> About a month ago, Christopher Schmidt, Tim Schaub, and a few others 
> talked to me about the emerging geometry editing tools in OL.  I am 
> currently using the point/line/polygon stuff from 2.4 in my own 
> application.  It is quite nice, but falls short of what we developed 
> outside of OL a year ago.  Here are the two main 
> functionality gaps that 
> we are interested in:
> 
>     * complex geometry support (multi-point, multi-line, 
> multi-polygon,
>       and inner ring).  I see that this is supported in the geometry
>       model itself, but not the editing tools.  In my own work, I
>       implemented this through a set of toolbars.
>     * geometry editing.  The move vertex stuff in
>       
> http://dev.openlayers.org/sandbox/tschaub/feature/examples/mod
> ify-feature.html
>       is nice, but to be complete, it needs to also be able to delete
>       vertices, insert vertices before/after another vertex, and
>       add/remove geometry parts.  In my own work, I implemented this
>       through popups on vertices.

I've found that the move-vertex model of geometry editing isn't always a
very good fit for what our customers are doing.  What we've been doing
is doing unions and differences of polygons - we display polygon A, let
the user draw a second polygon B, then we display A union B or A
difference B, depending upon whether the user was in add or subtract
mode.

We've also found it necessary to clip the polygons that the user is
editing against the polygons the user is not editing, since in our
customers' problem domain, polygons cannot be allowed to overlap.