[FEATURE][processing] Line substring algorithm

This algorithm returns the portion of a line (or curve) which falls between the specified start and end distances (measured from the beginning of the line). Z and M values are linearly interpolated from existing values.
qgis · Aug 15, 2018 · 7ef5631 · 7ef5631
1 parent a4386d6
commit 7ef5631
Show file tree

Hide file tree

Showing 10 changed files with 406 additions and 0 deletions.
diff --git a/python/plugins/processing/tests/testdata/airports.gfs b/python/plugins/processing/tests/testdata/airports.gfs
@@ -0,0 +1,43 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>airports</Name>
+    <ElementPath>airports</ElementPath>
+    <!--POINT-->
+    <GeometryType>1</GeometryType>
+    <SRSName>EPSG:2964</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>76</FeatureCount>
+      <ExtentXMin>-4480198.52221</ExtentXMin>
+      <ExtentXMax>4615124.97899</ExtentXMax>
+      <ExtentYMin>1433525.79887</ExtentYMin>
+      <ExtentYMax>6502586.83035</ExtentYMax>
+    </DatasetSpecificInfo>
+    <PropertyDefn>
+      <Name>ID</Name>
+      <ElementPath>ID</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>fk_region</Name>
+      <ElementPath>fk_region</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>ELEV</Name>
+      <ElementPath>ELEV</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>NAME</Name>
+      <ElementPath>NAME</ElementPath>
+      <Type>String</Type>
+      <Width>26</Width>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>USE</Name>
+      <ElementPath>USE</ElementPath>
+      <Type>String</Type>
+      <Width>23</Width>
+    </PropertyDefn>
+  </GMLFeatureClass>
+</GMLFeatureClassList>
diff --git a/python/plugins/processing/tests/testdata/custom/circular_strings.gpkg b/python/plugins/processing/tests/testdata/custom/circular_strings.gpkg
diff --git a/python/plugins/processing/tests/testdata/expected/airportsvoronoidiagram.gfs b/python/plugins/processing/tests/testdata/expected/airportsvoronoidiagram.gfs
@@ -0,0 +1,43 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>airportsvoronoidiagram</Name>
+    <ElementPath>airportsvoronoidiagram</ElementPath>
+    <!--POLYGON-->
+    <GeometryType>3</GeometryType>
+    <SRSName>EPSG:2964</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>76</FeatureCount>
+      <ExtentXMin>-4480198.52221</ExtentXMin>
+      <ExtentXMax>4615124.97899</ExtentXMax>
+      <ExtentYMin>1433525.79887</ExtentYMin>
+      <ExtentYMax>6502586.83035</ExtentYMax>
+    </DatasetSpecificInfo>
+    <PropertyDefn>
+      <Name>ID</Name>
+      <ElementPath>ID</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>fk_region</Name>
+      <ElementPath>fk_region</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>ELEV</Name>
+      <ElementPath>ELEV</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>NAME</Name>
+      <ElementPath>NAME</ElementPath>
+      <Type>String</Type>
+      <Width>26</Width>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>USE</Name>
+      <ElementPath>USE</ElementPath>
+      <Type>String</Type>
+      <Width>23</Width>
+    </PropertyDefn>
+  </GMLFeatureClass>
+</GMLFeatureClassList>
diff --git a/python/plugins/processing/tests/testdata/expected/line_substring.gml b/python/plugins/processing/tests/testdata/expected/line_substring.gml
@@ -0,0 +1,48 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation="http://ogr.maptools.org/ line_substring.xsd"
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>-0.8</gml:X><gml:Y>-3</gml:Y></gml:coord>
+      <gml:coord><gml:X>7.8</gml:X><gml:Y>2</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:line_substring fid="lines.0">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>6.2,2.0 6.8,2.0</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:line_substring>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:line_substring fid="lines.1">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>-0.8,-1.0 -0.2,-1.0</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:line_substring>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:line_substring fid="lines.2">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>2.0,0.2 2.0,0.8</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:line_substring>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:line_substring fid="lines.3">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>3.2,1.0 3.8,1.0</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:line_substring>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:line_substring fid="lines.4">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>7.2,-3.0 7.8,-3.0</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:line_substring>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:line_substring fid="lines.5">
+      <ogr:geometryProperty><gml:LineString srsName="EPSG:4326"><gml:coordinates>6.14142135623731,-2.85857864376269 6.56568542494924,-2.43431457505076</gml:coordinates></gml:LineString></ogr:geometryProperty>
+    </ogr:line_substring>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:line_substring fid="lines.6">
+    </ogr:line_substring>
+  </gml:featureMember>
+</ogr:FeatureCollection>
diff --git a/python/plugins/processing/tests/testdata/expected/line_substring.xsd b/python/plugins/processing/tests/testdata/expected/line_substring.xsd
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xs:schema targetNamespace="http://ogr.maptools.org/" xmlns:ogr="http://ogr.maptools.org/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:gml="http://www.opengis.net/gml" elementFormDefault="qualified" version="1.0">
+<xs:import namespace="http://www.opengis.net/gml" schemaLocation="http://schemas.opengis.net/gml/2.1.2/feature.xsd"/>
+<xs:element name="FeatureCollection" type="ogr:FeatureCollectionType" substitutionGroup="gml:_FeatureCollection"/>
+<xs:complexType name="FeatureCollectionType">
+  <xs:complexContent>
+    <xs:extension base="gml:AbstractFeatureCollectionType">
+      <xs:attribute name="lockId" type="xs:string" use="optional"/>
+      <xs:attribute name="scope" type="xs:string" use="optional"/>
+    </xs:extension>
+  </xs:complexContent>
+</xs:complexType>
+<xs:element name="line_substring" type="ogr:line_substring_Type" substitutionGroup="gml:_Feature"/>
+<xs:complexType name="line_substring_Type">
+  <xs:complexContent>
+    <xs:extension base="gml:AbstractFeatureType">
+      <xs:sequence>
+        <xs:element name="geometryProperty" type="gml:LineStringPropertyType" nillable="true" minOccurs="0" maxOccurs="1"/>
+      </xs:sequence>
+    </xs:extension>
+  </xs:complexContent>
+</xs:complexType>
+</xs:schema>
diff --git a/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml b/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml
@@ -6043,6 +6043,18 @@ tests:
         name: expected/drape_lines_m.shp
         type: vector
 
+  - algorithm: native:linesubstring
+    name: Line substrings
+    params:
+      END_DISTANCE: 0.8
+      INPUT:
+        name: lines.gml
+        type: vector
+      START_DISTANCE: 0.2
+    results:
+      OUTPUT:
+        name: expected/line_substring.gml
+        type: vector
 
 
 # See ../README.md for a description of the file format
diff --git a/src/analysis/CMakeLists.txt b/src/analysis/CMakeLists.txt
@@ -52,6 +52,7 @@ SET(QGIS_ANALYSIS_SRCS
   processing/qgsalgorithmjoinwithlines.cpp
   processing/qgsalgorithmkmeansclustering.cpp
   processing/qgsalgorithmlineintersection.cpp
+  processing/qgsalgorithmlinesubstring.cpp
   processing/qgsalgorithmloadlayer.cpp
   processing/qgsalgorithmmeancoordinates.cpp
   processing/qgsalgorithmmergelines.cpp

diff --git a/src/analysis/processing/qgsalgorithmlinesubstring.cpp b/src/analysis/processing/qgsalgorithmlinesubstring.cpp
@@ -0,0 +1,163 @@
+/***************************************************************************
+                         qgsalgorithmlinesubstring.cpp
+                         ---------------------
+    begin                : August 2018
+    copyright            : (C) 2018 by Nyall Dawson
+    email                : nyall dot dawson at gmail dot com
+ ***************************************************************************/
+
+/***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgsalgorithmlinesubstring.h"
+#include "qgsgeometrycollection.h"
+#include "qgscurve.h"
+
+///@cond PRIVATE
+
+QString QgsLineSubstringAlgorithm::name() const
+{
+  return QStringLiteral( "linesubstring" );
+}
+
+QString QgsLineSubstringAlgorithm::displayName() const
+{
+  return QObject::tr( "Line substring" );
+}
+
+QStringList QgsLineSubstringAlgorithm::tags() const
+{
+  return QObject::tr( "linestring,curve,split,portion,reference,referencing,distance,interpolate" ).split( ',' );
+}
+
+QString QgsLineSubstringAlgorithm::group() const
+{
+  return QObject::tr( "Vector geometry" );
+}
+
+QString QgsLineSubstringAlgorithm::groupId() const
+{
+  return QStringLiteral( "vectorgeometry" );
+}
+
+QString QgsLineSubstringAlgorithm::outputName() const
+{
+  return QObject::tr( "Substring" );
+}
+
+QString QgsLineSubstringAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm returns the portion of a line (or curve) which falls "
+                      "between the specified start and end distances (measured from the "
+                      "beginning of the line).\n\n"
+                      "Z and M values are linearly interpolated from existing values." );
+}
+
+QString QgsLineSubstringAlgorithm::shortDescription() const
+{
+  return QObject::tr( "Returns the substring of lines which fall between start and end distances." );
+}
+
+QList<int> QgsLineSubstringAlgorithm::inputLayerTypes() const
+{
+  return QList<int>() << QgsProcessing::TypeVectorLine;
+}
+
+QgsProcessing::SourceType QgsLineSubstringAlgorithm::outputLayerType() const
+{
+  return QgsProcessing::TypeVectorLine;
+}
+
+QgsLineSubstringAlgorithm *QgsLineSubstringAlgorithm::createInstance() const
+{
+  return new QgsLineSubstringAlgorithm();
+}
+
+void QgsLineSubstringAlgorithm::initParameters( const QVariantMap & )
+{
+  std::unique_ptr< QgsProcessingParameterDistance> startDistance = qgis::make_unique< QgsProcessingParameterDistance >( QStringLiteral( "START_DISTANCE" ),
+      QObject::tr( "Start distance" ), 0.0, QStringLiteral( "INPUT" ), false, 0 );
+  startDistance->setIsDynamic( true );
+  startDistance->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "Start Distance" ), QObject::tr( "Start distance" ), QgsPropertyDefinition::DoublePositive ) );
+  startDistance->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );
+  addParameter( startDistance.release() );
+
+  std::unique_ptr< QgsProcessingParameterDistance> endDistance = qgis::make_unique< QgsProcessingParameterDistance >( QStringLiteral( "END_DISTANCE" ),
+      QObject::tr( "End distance" ), 1.0, QStringLiteral( "INPUT" ), false, 0 );
+  endDistance->setIsDynamic( true );
+  endDistance->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "End Distance" ), QObject::tr( "End distance" ), QgsPropertyDefinition::DoublePositive ) );
+  endDistance->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );
+  addParameter( endDistance.release() );
+}
+
+QgsProcessingFeatureSource::Flag QgsLineSubstringAlgorithm::sourceFlags() const
+{
+  // skip geometry checks - this algorithm doesn't care about invalid geometries
+  return QgsProcessingFeatureSource::FlagSkipGeometryValidityChecks;
+}
+
+bool QgsLineSubstringAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
+{
+  mStartDistance = parameterAsDouble( parameters, QStringLiteral( "START_DISTANCE" ), context );
+  mDynamicStartDistance = QgsProcessingParameters::isDynamic( parameters, QStringLiteral( "START_DISTANCE" ) );
+  if ( mDynamicStartDistance )
+    mStartDistanceProperty = parameters.value( QStringLiteral( "START_DISTANCE" ) ).value< QgsProperty >();
+
+  mEndDistance = parameterAsDouble( parameters, QStringLiteral( "END_DISTANCE" ), context );
+  mDynamicEndDistance = QgsProcessingParameters::isDynamic( parameters, QStringLiteral( "END_DISTANCE" ) );
+  if ( mDynamicEndDistance )
+    mEndDistanceProperty = parameters.value( QStringLiteral( "END_DISTANCE" ) ).value< QgsProperty >();
+
+  return true;
+}
+
+QgsFeatureList QgsLineSubstringAlgorithm::processFeature( const QgsFeature &feature, QgsProcessingContext &context, QgsProcessingFeedback * )
+{
+  QgsFeature f = feature;
+  if ( f.hasGeometry() )
+  {
+    const QgsGeometry geometry = f.geometry();
+    double startDistance = mStartDistance;
+    if ( mDynamicStartDistance )
+      startDistance = mStartDistanceProperty.valueAsDouble( context.expressionContext(), startDistance );
+
+    double endDistance = mEndDistance;
+    if ( mDynamicEndDistance )
+      endDistance = mEndDistanceProperty.valueAsDouble( context.expressionContext(), endDistance );
+
+    const QgsCurve *curve = nullptr;
+    if ( !geometry.isMultipart() )
+      curve = qgsgeometry_cast< const QgsCurve * >( geometry.constGet() );
+    else
+    {
+      if ( const QgsGeometryCollection *collection = qgsgeometry_cast< const QgsGeometryCollection * >( geometry.constGet() ) )
+      {
+        if ( collection->numGeometries() > 0 )
+        {
+          curve = qgsgeometry_cast< const QgsCurve * >( collection->geometryN( 0 ) );
+        }
+      }
+    }
+    if ( curve )
+    {
+      std::unique_ptr< QgsCurve > substring( curve->curveSubstring( startDistance, endDistance ) );
+      QgsGeometry result( std::move( substring ) );
+      f.setGeometry( result );
+    }
+    else
+    {
+      f.clearGeometry();
+    }
+  }
+  return QgsFeatureList() << f;
+}
+
+///@endcond
+
+