Merge pull request #5791 from nyalldawson/geom_snapper_vertices

Fix geometry snapper sometimes creates unwanted overlapping segments when snapping line layers

Author: nyalldawson

python/analysis/vector/qgsgeometrysnapper.sip

@@ -28,6 +28,8 @@ class QgsGeometrySnapper : QObject
     {
       PreferNodes,
       PreferClosest,
+      PreferNodesNoExtraVertices,
+      PreferClosestNoExtraVertices,
       EndPointPreferNodes,
       EndPointPreferClosest,
       EndPointToEndPoint,

python/core/geometry/qgsabstractgeometry.sip

@@ -436,6 +436,29 @@ Returns the centroid of the geometry
  :rtype: QgsAbstractGeometry
 %End
 
+    virtual bool removeDuplicateNodes( double epsilon = 4 * DBL_EPSILON, bool useZValues = false ) = 0;
+%Docstring
+ Removes duplicate nodes from the geometry, wherever removing the nodes does not result in a
+ degenerate geometry.
+
+ The ``epsilon`` parameter specifies the tolerance for coordinates when determining that
+ vertices are identical.
+
+ By default, z values are not considered when detecting duplicate nodes. E.g. two nodes
+ with the same x and y coordinate but different z values will still be considered
+ duplicate and one will be removed. If ``useZValues`` is true, then the z values are
+ also tested and nodes with the same x and y but different z will be maintained.
+
+ Note that duplicate nodes are not tested between different parts of a multipart geometry. E.g.
+ a multipoint geometry with overlapping points will not be changed by this method.
+
+ The function will return true if nodes were removed, or false if no duplicate nodes
+ were found.
+
+.. versionadded:: 3.0
+ :rtype: bool
+%End
+
     virtual double vertexAngle( QgsVertexId vertex ) const = 0;
 %Docstring
  Returns approximate angle at a vertex. This is usually the average angle between adjacent

python/core/geometry/qgscircularstring.sip

@@ -83,6 +83,9 @@ class QgsCircularString: QgsCurve
 
     virtual QgsCircularString *snappedToGrid( double hSpacing, double vSpacing, double dSpacing = 0, double mSpacing = 0 ) const /Factory/;
 
+    virtual bool removeDuplicateNodes( double epsilon = 4 * DBL_EPSILON, bool useZValues = false );
+
+
     virtual void draw( QPainter &p ) const;
 
      virtual void transform( const QgsCoordinateTransform &ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,

python/core/geometry/qgscompoundcurve.sip

@@ -79,6 +79,8 @@ class QgsCompoundCurve: QgsCurve
 
     virtual QgsCompoundCurve *snappedToGrid( double hSpacing, double vSpacing, double dSpacing = 0, double mSpacing = 0 ) const /Factory/;
 
+    virtual bool removeDuplicateNodes( double epsilon = 4 * DBL_EPSILON, bool useZValues = false );
+
 
     int nCurves() const;
 %Docstring

python/core/geometry/qgscurvepolygon.sip

@@ -67,6 +67,8 @@ class QgsCurvePolygon: QgsSurface
 
     virtual QgsCurvePolygon *snappedToGrid( double hSpacing, double vSpacing, double dSpacing = 0, double mSpacing = 0 ) const /Factory/;
 
+    virtual bool removeDuplicateNodes( double epsilon = 4 * DBL_EPSILON, bool useZValues = false );
+
 
     int numInteriorRings() const;
 %Docstring

python/core/geometry/qgsgeometry.sip

@@ -501,7 +501,7 @@ Returns true if WKB of the geometry is of WKBMulti* type
  \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 left side of the geometry ( < 0 means left, > 0 means right, 0 indicates
- that the test was unsuccesful, e.g. for a point exactly on the line)
+ that the test was unsuccessful, e.g. for a point exactly on the line)
  \param epsilon epsilon for segment snapping
  :return: The squared Cartesian distance is also returned in sqrDist, negative number on error
  :rtype: float
@@ -688,6 +688,29 @@ Returns true if WKB of the geometry is of WKBMulti* type
  :rtype: QgsGeometry
 %End
 
+    bool removeDuplicateNodes( double epsilon = 4 * DBL_EPSILON, bool useZValues = false );
+%Docstring
+ Removes duplicate nodes from the geometry, wherever removing the nodes does not result in a
+ degenerate geometry.
+
+ The ``epsilon`` parameter specifies the tolerance for coordinates when determining that
+ vertices are identical.
+
+ By default, z values are not considered when detecting duplicate nodes. E.g. two nodes
+ with the same x and y coordinate but different z values will still be considered
+ duplicate and one will be removed. If ``useZValues`` is true, then the z values are
+ also tested and nodes with the same x and y but different z will be maintained.
+
+ Note that duplicate nodes are not tested between different parts of a multipart geometry. E.g.
+ a multipoint geometry with overlapping points will not be changed by this method.
+
+ The function will return true if nodes were removed, or false if no duplicate nodes
+ were found.
+
+.. versionadded:: 3.0
+ :rtype: bool
+%End
+
     bool intersects( const QgsRectangle &r ) const;
 %Docstring
 Tests for intersection with a rectangle (uses GEOS)

python/core/geometry/qgsgeometrycollection.sip

@@ -52,6 +52,9 @@ class QgsGeometryCollection: QgsAbstractGeometry
     virtual void clear();
 
     virtual QgsGeometryCollection *snappedToGrid( double hSpacing, double vSpacing, double dSpacing = 0, double mSpacing = 0 ) const /Factory/;
+
+    virtual bool removeDuplicateNodes( double epsilon = 4 * DBL_EPSILON, bool useZValues = false );
+
     virtual QgsAbstractGeometry *boundary() const /Factory/;
 
     virtual void adjacentVertices( QgsVertexId vertex, QgsVertexId &previousVertex /Out/, QgsVertexId &nextVertex /Out/ ) const;

python/core/geometry/qgslinestring.sip

@@ -179,6 +179,8 @@ Closes the line string by appending the first point to the end of the line, if i
 
     virtual QgsLineString *snappedToGrid( double hSpacing, double vSpacing, double dSpacing = 0, double mSpacing = 0 ) const /Factory/;
 
+    virtual bool removeDuplicateNodes( double epsilon = 4 * DBL_EPSILON, bool useZValues = false );
+
 
     virtual bool fromWkb( QgsConstWkbPtr &wkb );
 

python/core/geometry/qgspoint.sip

@@ -339,6 +339,9 @@ class QgsPoint: QgsAbstractGeometry
     virtual QgsPoint *clone() const /Factory/;
 
     virtual QgsPoint *snappedToGrid( double hSpacing, double vSpacing, double dSpacing = 0, double mSpacing = 0 ) const /Factory/;
+
+    virtual bool removeDuplicateNodes( double epsilon = 4 * DBL_EPSILON, bool useZValues = false );
+
     virtual void clear();
 
     virtual bool fromWkb( QgsConstWkbPtr &wkb );

python/plugins/processing/algs/qgis/CheckValidity.py

@@ -68,6 +68,9 @@ def icon(self):
     def group(self):
         return self.tr('Vector geometry')
 
+    def tags(self):
+        return self.tr('valid,invalid,detect').split(',')
+
     def __init__(self):
         super().__init__()
 
@@ -79,7 +82,7 @@ def initAlgorithm(self, config=None):
         self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT_LAYER,
                                                               self.tr('Input layer')))
         self.addParameter(QgsProcessingParameterEnum(self.METHOD,
-                                                     self.tr('Method'), self.methods))
+                                                     self.tr('Method'), self.methods, defaultValue=2))
         self.parameterDefinition(self.METHOD).setMetadata({
             'widget_wrapper': {
                 'class': 'processing.gui.wrappers.EnumWidgetWrapper',