[Chameleon] Query by rectangle

Paul Spencer
Wed, 10 Mar 2004 09:17:48 -0500

we have added a couple of new widgets that may be of interest to you:

ROICircleTool - allows the user to draw a circular regions of interest
ROIPolygonTool - allows the user to draw arbitrary polygonal regions of 

This adds to the existing ROIRectangleTool (no points for guessing what 
it does ;)).

There are also the following widgets:

ROIManager - no UI, just put in page to make other ROI widgets cooperate
ROIManagerMode - can have one of three modes:

normal - puts the ROIManager into normal mode, only a single ROI can be 
active at a time and drawing a new ROI replaces the existing one
add - puts the ROIManager into add mode, ROIs accumulate so you can 
define mutliple regions
subtract - puts the ROIManager into subtract mode, new ROIs are removed 
from the existing (cumulative) ROI allowing for the creation of holes.

So as things stand, you would put one each of the Tool widgets, an 
ROIManager widget and optionally three ROIManagerMode widgets into a 
template to activate the full functionality.

There will be (shortly) an ROIFeatureTool which will create an ROI from 
a feature in the selected layer when the user clicks in the feature 
(with the tool selected) ... needs SelectLayers widget to select layer 
unless widget is configured to work on a fixed layer name ... this could 
be useful for you?

As you know, the ROI widgets define a Region of Interest separately from 
the current view region and other widgets can use this Region of 
Interest as they wish.

Currently only the expression builder and extraction widgets use the 
ROI.  Both work with remote WFS data sources.  I would imagine that the 
ROIs can also be used with query widgets ... so I would expect that the 
'third' mode of the query widget would be query by ROI.

Most of this is in CVS and appears to work ... only the ROIFeatureTool 
is not there yet.



Hans Verlouw wrote:

> Sounds good !
> Currently I'm working on a project where we would like to have a third 
> mode, mode="polygon".
> Not a user drawn polygon, but a selected polygon from another layer.
> Are there any plans on making this at MD Solutions, or should I try to 
> make it myself?
> t       k
>   Han    s
> At 3/10/2004 02:23 PM, Paul Spencer wrote:
>> I would expect that the current query widget will be modified at some 
>> point to include two modes of operation: mode="point" and 
>> mode="rectangle".  The intention would be to allow the application 
>> designer to decide if the query widget can do only point or both point 
>> and rectangle queries.  I suspect that we will be developing this in 
>> the near future as this is a common feature needed by most applications.
> Hans Verlouw
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|Paul Spencer                     |
|Applications & Software Development                              |
|DM Solutions Group Inc       |

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