Add method to filter vertices for geometries in place, by providing a custom filter function

python/core/auto_generated/geometry/qgscircularstring.sip.in

@@ -158,6 +158,7 @@ Sets the circular string's points
     virtual double yAt( int index ) const;
 
 
+
     virtual QgsCircularString *createEmptyWithSameType() const /Factory/;
 
 

python/core/auto_generated/geometry/qgscompoundcurve.sip.in

@@ -162,6 +162,7 @@ Appends first point if not already closed.
     virtual double yAt( int index ) const;
 
 
+
     virtual QgsCompoundCurve *createEmptyWithSameType() const /Factory/;
 
 

python/core/auto_generated/geometry/qgscurvepolygon.sip.in

@@ -201,6 +201,7 @@ Returns approximate rotation angle for a vertex. Usually average angle between a
     virtual QgsCurvePolygon *toCurveType() const /Factory/;
 
 
+
     virtual QgsCurvePolygon *createEmptyWithSameType() const /Factory/;
 
 

python/core/auto_generated/geometry/qgsgeometry.sip.in

@@ -1588,6 +1588,7 @@ was performed on the geometry.
 .. versionadded:: 3.0
 %End
 
+
     static QgsGeometry fromQPointF( QPointF point );
 %Docstring
 Construct geometry from a QPointF

python/core/auto_generated/symbology/qgsfillsymbollayer.sip.in

@@ -345,6 +345,8 @@ class QgsShapeburstFillSymbolLayer : QgsFillSymbolLayer
     ~QgsShapeburstFillSymbolLayer();
 
 
+
+
     static QgsSymbolLayer *create( const QgsStringMap &properties = QgsStringMap() ) /Factory/;
 
 

src/core/geometry/qgsabstractgeometry.cpp

@@ -246,6 +246,11 @@ bool QgsAbstractGeometry::convertTo( QgsWkbTypes::Type type )
   return true;
 }
 
+void QgsAbstractGeometry::filterVertices( const std::function<bool ( const QgsPoint & )> & )
+{
+  // Ideally this would be pure virtual, but SIP has issues with that
+}
+
 QgsVertexIterator QgsAbstractGeometry::vertices() const
 {
   return QgsVertexIterator( this );

src/core/geometry/qgsabstractgeometry.h

@@ -569,6 +569,18 @@ class CORE_EXPORT QgsAbstractGeometry
 
 #ifndef SIP_RUN
 
+    /**
+     * Filters the vertices from the geometry in place, removing any which do not return true for the \a filter function
+     * check. Has no meaning when called on a single point geometry.
+     *
+     * Depending on the \a filter used, this may result in an invalid geometry. However, CurvePolygon rings which are no longer
+     * valid rings will be automatically removed after filtering.
+     *
+     * \since QGIS 3.2
+     * \note Not available in Python bindings
+     */
+    virtual void filterVertices( const std::function< bool( const QgsPoint & ) > &filter );
+
     /**
      * \ingroup core
      * The vertex_iterator class provides STL-style iterator for vertices.

src/core/geometry/qgscircularstring.cpp

@@ -546,6 +546,52 @@ double QgsCircularString::yAt( int index ) const
     return 0.0;
 }
 
+void QgsCircularString::filterVertices( const std::function<bool ( const QgsPoint & )> &filter )
+{
+  bool hasZ = is3D();
+  bool hasM = isMeasure();
+  int size = mX.size();
+
+  double *srcX = mX.data(); // clazy:exclude=detaching-member
+  double *srcY = mY.data(); // clazy:exclude=detaching-member
+  double *srcM = hasM ? mM.data() : nullptr; // clazy:exclude=detaching-member
+  double *srcZ = hasZ ? mZ.data() : nullptr; // clazy:exclude=detaching-member
+
+  double *destX = srcX;
+  double *destY = srcY;
+  double *destM = srcM;
+  double *destZ = srcZ;
+
+  int filteredPoints = 0;
+  for ( int i = 0; i < size; ++i )
+  {
+    double x = *srcX++;
+    double y = *srcY++;
+    double z = hasZ ? *srcZ++ : std::numeric_limits<double>::quiet_NaN();
+    double m = hasM ? *srcM++ : std::numeric_limits<double>::quiet_NaN();
+
+    if ( filter( QgsPoint( x, y, z, m ) ) )
+    {
+      filteredPoints++;
+      *destX++ = x;
+      *destY++ = y;
+      if ( hasM )
+        *destM++ = m;
+      if ( hasZ )
+        *destZ++ = z;
+    }
+  }
+
+  mX.resize( filteredPoints );
+  mY.resize( filteredPoints );
+  if ( hasZ )
+    mZ.resize( filteredPoints );
+  if ( hasM )
+    mM.resize( filteredPoints );
+
+  clearCache();
+}
+
 void QgsCircularString::points( QgsPointSequence &pts ) const
 {
   pts.clear();

src/core/geometry/qgscircularstring.h

@@ -125,7 +125,9 @@ class CORE_EXPORT QgsCircularString: public QgsCurve
     void swapXy() override;
     double xAt( int index ) const override;
     double yAt( int index ) const override;
+
 #ifndef SIP_RUN
+    void filterVertices( const std::function< bool( const QgsPoint & ) > &filter ) override;
 
     /**
      * Cast the \a geom to a QgsCircularString.

src/core/geometry/qgscompoundcurve.cpp

@@ -773,6 +773,15 @@ double QgsCompoundCurve::yAt( int index ) const
   return 0.0;
 }
 
+void QgsCompoundCurve::filterVertices( const std::function<bool ( const QgsPoint & )> &filter )
+{
+  for ( QgsCurve *curve : qgis::as_const( mCurves ) )
+  {
+    curve->filterVertices( filter );
+  }
+  clearCache();
+}
+
 void QgsCompoundCurve::sumUpArea( double &sum ) const
 {
   for ( const QgsCurve *curve : mCurves )

src/core/geometry/qgscompoundcurve.h

@@ -125,7 +125,9 @@ class CORE_EXPORT QgsCompoundCurve: public QgsCurve
 
     double xAt( int index ) const override;
     double yAt( int index ) const override;
+
 #ifndef SIP_RUN
+    void filterVertices( const std::function< bool( const QgsPoint & ) > &filter ) override;
 
     /**
      * Cast the \a geom to a QgsCompoundCurve.

src/core/geometry/qgscurvepolygon.cpp

@@ -1174,6 +1174,31 @@ QgsCurvePolygon *QgsCurvePolygon::toCurveType() const
   return clone();
 }
 
+void QgsCurvePolygon::filterVertices( const std::function<bool ( const QgsPoint & )> &filter )
+{
+  if ( mExteriorRing )
+    mExteriorRing->filterVertices( filter );
+
+  QVector<QgsCurve *> filteredRings;
+  filteredRings.reserve( mInteriorRings.size() );
+  for ( QgsCurve *curve : qgis::as_const( mInteriorRings ) )
+  {
+    curve->filterVertices( filter );
+
+    if ( !curve->isRing() )
+    {
+      // remove invalid rings
+      delete curve;
+    }
+    else
+    {
+      filteredRings << curve;
+    }
+  }
+  mInteriorRings = filteredRings;
+  clearCache();
+}
+
 int QgsCurvePolygon::childCount() const
 {
   return 1 + mInteriorRings.count();

src/core/geometry/qgscurvepolygon.h

@@ -153,7 +153,9 @@ class CORE_EXPORT QgsCurvePolygon: public QgsSurface
     void swapXy() override;
 
     QgsCurvePolygon *toCurveType() const override SIP_FACTORY;
+
 #ifndef SIP_RUN
+    void filterVertices( const std::function< bool( const QgsPoint & ) > &filter ) override;
 
     /**
      * Cast the \a geom to a QgsCurvePolygon.

src/core/geometry/qgsgeometry.cpp

@@ -2574,6 +2574,16 @@ QString QgsGeometry::lastError() const
   return mLastError;
 }
 
+void QgsGeometry::filterVertices( const std::function<bool ( const QgsPoint & )> &filter )
+{
+  if ( !d->geometry )
+    return;
+
+  detach();
+
+  d->geometry->filterVertices( filter );
+}
+
 void QgsGeometry::convertPointList( const QVector<QgsPointXY> &input, QgsPointSequence &output )
 {
   output.clear();

src/core/geometry/qgsgeometry.h

@@ -1529,6 +1529,18 @@ class CORE_EXPORT QgsGeometry
      */
     QString lastError() const;
 
+    /**
+     * Filters the vertices from the geometry in place, removing any which do not return true for the \a filter function
+     * check. Has no effect when called on a single point geometry.
+     *
+     * Depending on the \a filter used, this may result in an invalid geometry. However, CurvePolygon rings which are no longer
+     * valid rings will be automatically removed after filtering.
+     *
+     * \since QGIS 3.2
+     * \note Not available in Python bindings
+     */
+    void filterVertices( const std::function< bool( const QgsPoint & ) > &filter ) SIP_SKIP;
+
     /**
      * Construct geometry from a QPointF
      * \param point source QPointF

src/core/geometry/qgsgeometrycollection.cpp

@@ -830,6 +830,16 @@ bool QgsGeometryCollection::dropMValue()
   return true;
 }
 
+void QgsGeometryCollection::filterVertices( const std::function<bool ( const QgsPoint & )> &filter )
+{
+  for ( QgsAbstractGeometry *geom : qgis::as_const( mGeometries ) )
+  {
+    if ( geom )
+      geom->filterVertices( filter );
+  }
+  clearCache();
+}
+
 void QgsGeometryCollection::swapXy()
 {
   for ( QgsAbstractGeometry *geom : qgis::as_const( mGeometries ) )

src/core/geometry/qgsgeometrycollection.h

@@ -143,6 +143,7 @@ class CORE_EXPORT QgsGeometryCollection: public QgsAbstractGeometry
     QgsGeometryCollection *toCurveType() const override SIP_FACTORY;
 
 #ifndef SIP_RUN
+    void filterVertices( const std::function< bool( const QgsPoint & ) > &filter ) override;
 
     /**
      * Cast the \a geom to a QgsGeometryCollection.

src/core/geometry/qgslinestring.cpp

@@ -1329,3 +1329,49 @@ bool QgsLineString::convertTo( QgsWkbTypes::Type type )
     return QgsCurve::convertTo( type );
   }
 }
+
+void QgsLineString::filterVertices( const std::function<bool ( const QgsPoint & )> &filter )
+{
+  bool hasZ = is3D();
+  bool hasM = isMeasure();
+  int size = mX.size();
+
+  double *srcX = mX.data();
+  double *srcY = mY.data();
+  double *srcM = hasM ? mM.data() : nullptr;
+  double *srcZ = hasZ ? mZ.data() : nullptr;
+
+  double *destX = srcX;
+  double *destY = srcY;
+  double *destM = srcM;
+  double *destZ = srcZ;
+
+  int filteredPoints = 0;
+  for ( int i = 0; i < size; ++i )
+  {
+    double x = *srcX++;
+    double y = *srcY++;
+    double z = hasZ ? *srcZ++ : std::numeric_limits<double>::quiet_NaN();
+    double m = hasM ? *srcM++ : std::numeric_limits<double>::quiet_NaN();
+
+    if ( filter( QgsPoint( x, y, z, m ) ) )
+    {
+      filteredPoints++;
+      *destX++ = x;
+      *destY++ = y;
+      if ( hasM )
+        *destM++ = m;
+      if ( hasZ )
+        *destZ++ = z;
+    }
+  }
+
+  mX.resize( filteredPoints );
+  mY.resize( filteredPoints );
+  if ( hasZ )
+    mZ.resize( filteredPoints );
+  if ( hasM )
+    mM.resize( filteredPoints );
+
+  clearCache();
+}

src/core/geometry/qgslinestring.h

@@ -268,6 +268,7 @@ class CORE_EXPORT QgsLineString: public QgsCurve
     bool convertTo( QgsWkbTypes::Type type ) override;
 
 #ifndef SIP_RUN
+    void filterVertices( const std::function< bool( const QgsPoint & ) > &filter ) override;
 
     /**
      * Cast the \a geom to a QgsLineString.

src/core/geometry/qgspoint.cpp

@@ -592,6 +592,10 @@ bool QgsPoint::convertTo( QgsWkbTypes::Type type )
   return false;
 }
 
+void QgsPoint::filterVertices( const std::function<bool ( const QgsPoint & )> & )
+{
+  // no meaning for points
+}
 
 QPointF QgsPoint::toQPointF() const
 {

src/core/geometry/qgspoint.h

@@ -440,6 +440,8 @@ class CORE_EXPORT QgsPoint: public QgsAbstractGeometry
 
 #ifndef SIP_RUN
 
+    void filterVertices( const std::function< bool( const QgsPoint & ) > &filter ) override;
+
     /**
      * Cast the \a geom to a QgsPoint.
      * Should be used by qgsgeometry_cast<QgsPoint *>( geometry ).