[Qgis-developer] closestSegmentWithContext

Worth Lutz wal3 at mindspring.com
Thu May 5 09:25:21 PDT 2016


I'm trying to use "closestSegmentWithContext" method of QgsGeometry in a 
plugin. I don't seem to be getting what I'm expecting.

Comparing 
http://qgis.org/api/classQgsGeometry.html#ac09505a6a8a29f244a37c6f336cd98e7

with the following from: 
https://github.com/qgis/QGIS/blob/master/python/core/geometry/qgsgeometry.sip

     /**
      * Searches for the closest segment of geometry to the given point
      * @param point Specifies the point for search
      * @param minDistPoint Receives the nearest point on the segment
      * @param afterVertex Receives index of the vertex after the 
closest segment. The vertex
      * before the closest segment is always afterVertex - 1
      * @param leftOf Out: Returns if the point lies on the left of 
right side of the segment ( < 0 means left, > 0 means right )
      * @param epsilon epsilon for segment snapping (added in 1.8)
      * @return The squared cartesian distance is also returned in 
sqrDist, negative number on error
      */
     double closestSegmentWithContext( const QgsPoint& point, QgsPoint& 
minDistPoint /Out/, int& afterVertex /Out/ ) const;


When I try:

    results =
    self.selectedStreetSegment.geometry().closestSegmentWithContext(point)


I get a results as:

    (2560.365846544, (2106395, 746610), 1)

I take this to be (sqrDist, minDistPoint, afterVertex ).  It does not 
seem to be returning "leftOf" which is the value I'm looking for.

Is something missing in that "sip" definition?  I do not know what I'm 
looking at so I may be looking at the wrong thing. In any case, I cannot 
seem to find the results I need.

Thanks,
--
*Worth Lutz*


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