How to measure areas and lengths of geometry drawn on sketchlayer?

AnoopMohandas

Hi all,

I'm new to ArcGis SDK, lately I have been trying to find the x-y coordinate, length and area of AGSPoint, AGSPolyline and AGSPolygon drawn on a sketchlayer.

The steps I did
1. Created an instance of AGSGeometryTaskService, initialized with server and set delegate.
2. Extraced the AGSGeometry information from sketchlayer.geometry.
3. Created an instance of AGSAreasAndLengthsParameters, set the units, assigned an array of Geometry objects and passed these parameters to areasAndLengthsWithParameters
4. The response obtained was not in the units specified in the parameters.

self.gst = [[[AGSGeometryServiceTask alloc]initWithURL:[NSURL URLWithString:kGeometryServerURL]]autorelease];
    
    self.gst.delegate = self;
    
    AGSGeometry* sketchGeometry = [[_sketchLayer.geometry copy] autorelease];
    
    //NSLog(@%@",sketchGeometry);
    
    AGSAreasAndLengthsParameters *areaAndLengthParams = [[AGSAreasAndLengthsParameters alloc]init];
    
    areaAndLengthParams.areaUnit = AGSAreaUnitsSquareMeters;
    areaAndLengthParams.lengthUnit = AGSSRUnitMeter;
    areaAndLengthParams.polygons = [NSArray arrayWithObject:sketchGeometry];
    
    [self.gst areasAndLengthsWithParameters:areaAndLengthParams];
    
    [areaAndLengthParams release];

Any information on where I'm doing wrong is much appreciated .

RickJones

Take a look at SketchLayer example code.

I modified the respondToGeomChanged event for my app:

//Get the sketch geometry
AGSGeometryEngine *geo = [AGSGeometryEngine defaultGeometryEngine];
AGSGeometry* sketchGeometry = [[_sketchLayer.geometry copy] autorelease];
double length = 0;
double area = 0;

        // there are only line and poly buttons in my version
switch (_sketchTools.selectedSegmentIndex) {
  case 0: // line
   length = [geo lengthOfGeometry:sketchGeometry];
   _measureText.text = [NSString stringWithFormat:@Length: %f, length];
   break;
  case 1: // poly
   area = [geo areaOfGeometry:sketchGeometry];
   _measureText.text = [NSString stringWithFormat:@Area: %f, area];
   break;
  default:
   _measureText.text = @"";
   break;
}


For some reason, the poly area shows negative if the points are drawn counter-clockwise.