You can download the source to JTS here:
http://jts-topo-suite.svn.sourceforge.net/viewvc/jts-topo-suite/trunk/
Look for: com.vividsolutions.jts.algorithm.CGAlgorithms.java
/**
* Returns the signed area for a ring. The area is positive if
* the ring is oriented CW.
*/
public static double signedArea(Coordinate[] ring)
{
if (ring.length < 3) return 0.0;
double sum = 0.0;
for (int i = 0; i < ring.length - 1; i++) {
double bx = ring[i].x;
double by = ring[i].y;
double cx = ring[i + 1].x;
double cy = ring[i + 1].y;
sum += (bx + cx) * (cy - by);
}
return -sum / 2.0;
}
Larry
On Tue, Dec 15, 2009 at 4:49 PM, karthik shravanam <
karthikshrava...@gmail.com> wrote:
> Hi All,
>
> Since this is topic of distance, i had a question about the are that shows
> up in the toolbar at the bottom along with the distance on the open jump
> application,I was wondering if anyone has the code for it so that i can know
> how the tool is calculating the area.
>
> Can you please let me know.
>
> Thanks for the help in advance.
>
>
>
> Thanks
>
> On Mon, Dec 14, 2009 at 6:46 AM, Larry Becker <becker.la...@gmail.com>wrote:
>
>> Sorry, it should have been:
>>
>> {
>> import com.vividsolutions.jts.geom.*;
>> import com.vividsolutions.jump.feature.*;
>> import com.vividsolutions.jump.workbench.model.*;
>>
>> features=
>> wc.getLayerViewPanel().getSelectionManager().getFeaturesWithSelectedItems();
>> Iterator i = features.iterator();
>> if (features.size() == 2){
>> feature = (Feature) i.next();
>> geoOne = feature.getGeometry();
>> feature = (Feature) i.next();
>> geoTwo= feature.getGeometry();
>> htmlFrame = wc.workbench.frame.outputFrame;
>> htmlFrame.createNewDocument();
>> htmlFrame.addText("Distance = "+geoOne.distance(geoTwo));
>> wc.workbench.frame.flash(htmlFrame);
>> htmlFrame.surface();
>> }
>> }
>>
>> The former script got the distance between the first two features on the
>> selected layer. This one uses the two selected items.
>>
>> Larry
>>
>> On Mon, Dec 14, 2009 at 8:33 AM, Larry Becker <becker.la...@gmail.com>wrote:
>>
>>> Hi Jukka,
>>>
>>> Here is a script that leverages the JTS distance function:
>>>
>>> {
>>> import com.vividsolutions.jts.geom.*;
>>> import com.vividsolutions.jump.feature.*;
>>> import com.vividsolutions.jump.workbench.model.*;
>>>
>>> fc =
>>> wc.getLayerNamePanel().getSelectedLayers()[0].getFeatureCollectionWrapper();
>>> Iterator i = fc.getFeatures().iterator();
>>> if (i.hasNext()) {
>>> feature = (Feature) i.next();
>>> geoOne = feature.getGeometry();
>>> feature = (Feature) i.next();
>>> geoTwo= feature.getGeometry();
>>> htmlFrame = wc.workbench.frame.outputFrame;
>>> htmlFrame.createNewDocument();
>>> htmlFrame.addText("Distance = "+geoOne.distance(geoTwo));
>>> wc.workbench.frame.flash(htmlFrame);
>>> htmlFrame.surface();
>>> }
>>> }
>>>
>>> regards,
>>> Larry
>>>
>>>
>>> On Sun, Dec 13, 2009 at 8:00 AM, Rahkonen Jukka <
>>> jukka.rahko...@mmmtike.fi> wrote:
>>>
>>>> Hi,
>>>>
>>>> I agree totally with Larry. OpenJump is already a very productive
>>>> editing tool. Connecting routines which are used hundreds of times per day
>>>> to menu shortcut or toolbar button does not only speed up the work but it
>>>> also cuts down the number of errors, and perhaps most important, it makes
>>>> the work much less irritating. And it seems to be that a very useful
>>>> features can be added by writing a lines of scripting code. I think that we
>>>> should have a script library somewhere in OpenJump wiki. As an example I
>>>> must create some screen captures about how to use a fine script made by
>>>> Larry for assisting in generating Web Coverage Service requests. I also
>>>> notised a Jython script for measuring distance between two selected
>>>> features
>>>> from GvSIG mailing list. Perhaps it could be modified to work with
>>>> OpenJump
>>>> as well because the real work is done by JTS. Link to this sript is here:
>>>>
>>>> http://n2.nabble.com/Distance-using-Jython-td4139275.html#a4139275
>>>>
>>>> What I am missing most in OpenJump is the ability to write edited data
>>>> back to the database.
>>>>
>>>> -Jukka Rahkonen-
>>>>
>>>>
>>>> Larry Becker wrote:
>>>>
>>>>
>>>> > Thanks for the feedback Michaël and Stefan. In case anyone out there
>>>> is
>>>> > wondering what is the use of a toolbox that can only reuse existing
>>>> menu
>>>> > features, it is all about optimizing work flow. I believe we have an
>>>> > opportunity to position OpenJump as being the best tool for data
>>>> creation
>>>> > and editing. The EZ Buttons function furthers that aim by allowing
>>>> users to
>>>> > optimize repetitive tasks. EZ Buttons can be used in conjunction with
>>>> > BeanTools scripting for the creation of custom tools. However, I do
>>>> intend
>>>> > to eventually revisit Jukka's idea of a quick-and-easy custom data
>>>> entry
>>>> > tool for ad hoc field digitizing.
>>>>
>>>> > regards,
>>>> > Larry
>>>>
>>>>
>>>>
>>>> ------------------------------------------------------------------------------
>>>> Return on Information:
>>>> Google Enterprise Search pays you back
>>>> Get the facts.
>>>> http://p.sf.net/sfu/google-dev2dev
>>>> _______________________________________________
>>>> Jump-pilot-devel mailing list
>>>> Jump-pilot-devel@lists.sourceforge.net
>>>> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
>>>>
>>>
>>>
>>>
>>> --
>>> Larry Becker
>>> Integrated Systems Analysts, Inc.
>>>
>>
>>
>>
>> --
>> Larry Becker
>> Integrated Systems Analysts, Inc.
>>
>>
>> ------------------------------------------------------------------------------
>> Return on Information:
>> Google Enterprise Search pays you back
>> Get the facts.
>> http://p.sf.net/sfu/google-dev2dev
>>
>> _______________________________________________
>> Jump-pilot-devel mailing list
>> Jump-pilot-devel@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
>>
>>
>
>
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--
Larry Becker
Integrated Systems Analysts, Inc.
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