Merge pull request #7626 from rudivs/kneighbour

[feature] Adapted k-neighbour concave hull plugin as QGIS 3 algorithm

Author: luipir

images/images.qrc

@@ -92,6 +92,7 @@
         <file>themes/default/algorithms/mAlgorithmExtractVertices.svg</file>
         <file>themes/default/algorithms/mAlgorithmExtractLayerExtent.svg</file>
         <file>themes/default/algorithms/mAlgorithmIntersect.svg</file>
+        <file>themes/default/algorithms/mAlgorithmConcaveHull.svg</file>
         <file>themes/default/algorithms/mAlgorithmLineIntersections.svg</file>
         <file>themes/default/algorithms/mAlgorithmLineToPolygon.svg</file>
         <file>themes/default/algorithms/mAlgorithmMeanCoordinates.svg</file>

images/themes/default/algorithms/mAlgorithmConcaveHull.svg

@@ -233,6 +233,13 @@ qgis:joinbylocationsummary: >
 qgis:keepnbiggestparts: >
   This algorithm takes a polygon layer and creates a new polygon layer in which multipart geometries have been removed, leaving only the n largest (in terms of area) parts.
 
+qgis:knearestconcavehull: >
+  This algorithm generates a concave hull polygon from a set of points. If the input layer is a line or polygon layer, it will use the nodes.
+
+  The number of neighbours to consider determines the concaveness of the output polygon. A lower number will result in a concave hull that follows the points very closely, while a higher number will have a smoother shape. The minimum number of neighbour points to consider is 3. A value equal to or greater than the number of points will result in a convex hull.
+
+  If a field is selected, the algorithm will group the features in the input layer using unique values in that field and generate individual polygons in the output layer for each group.
+
 qgis:lineintersections: >
   This algorithm creates point features where the lines in the Intersect layer intersect the lines in the Input layer.
 

python/plugins/processing/algs/help/qgis.yaml

@@ -28,7 +28,8 @@
 from qgis.PyQt.QtCore import QCoreApplication
 from math import sqrt
 
-from qgis.core import (QgsFeature,
+from qgis.core import (QgsApplication,
+                       QgsFeature,
                        QgsFeatureSink,
                        QgsWkbTypes,
                        QgsProcessing,
@@ -75,7 +76,16 @@ def name(self):
         return 'concavehull'
 
     def displayName(self):
-        return self.tr('Concave hull')
+        return self.tr('Concave hull (alpha shapes)')
+
+    def shortDescription(self):
+        return self.tr('Creates a concave hull using the alpha shapes algorithm.')
+
+    def icon(self):
+        return QgsApplication.getThemeIcon("/algorithms/mAlgorithmConcaveHull.svg")
+
+    def svgIconPath(self):
+        return QgsApplication.iconPath("/algorithms/mAlgorithmConcaveHull.svg")
 
     def processAlgorithm(self, parameters, context, feedback):
         layer = self.parameterAsSource(parameters, ConcaveHull.INPUT, context)