Port simplify geometries to c++

nyalldawson · nyalldawson · commit d96a3f4dd483 · 2017-09-14T09:57:15.000+10:00
diff --git a/python/plugins/processing/algs/help/qgis.yaml b/python/plugins/processing/algs/help/qgis.yaml
@@ -528,11 +528,6 @@ qgis:setzvalue: >
 
   If Z values already exist in the layer, they will be overwritten with the new value. If no Z values exist, the geometry will be upgraded to include Z values and the specified value used as the initial Z value for all geometries.
 
-qgis:simplifygeometries: >
-  This algorithm simplifies the geometries in a line or polygon layer. It creates a new layer with the same features as the ones in the input layer, but with geometries containing a lower number of vertices.
-
-  The algorithm gives a choice of simplification methods, including distance based (the "Douglas-Peucker" algorithm), area based ("Visvalingam" algorithm) and snapping geometries to grid.
-
 qgis:singlesidedbuffer: >
   This algorithm buffers lines by a specified distance on one side of the line only.
 
diff --git a/python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py b/python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py
@@ -141,7 +141,6 @@
 from .ShortestPathLayerToPoint import ShortestPathLayerToPoint
 from .ShortestPathPointToLayer import ShortestPathPointToLayer
 from .ShortestPathPointToPoint import ShortestPathPointToPoint
-from .SimplifyGeometries import SimplifyGeometries
 from .SingleSidedBuffer import SingleSidedBuffer
 from .Slope import Slope
 from .SnapGeometries import SnapGeometriesToLayer
@@ -279,7 +278,6 @@ def getAlgs(self):
                 ShortestPathLayerToPoint(),
                 ShortestPathPointToLayer(),
                 ShortestPathPointToPoint(),
-                SimplifyGeometries(),
                 SingleSidedBuffer(),
                 Slope(),
                 SnapGeometriesToLayer(),
diff --git a/python/plugins/processing/algs/qgis/SimplifyGeometries.py b/python/plugins/processing/algs/qgis/SimplifyGeometries.py
diff --git a/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml b/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml
@@ -1209,7 +1209,7 @@ tests:
         name: expected/extract_nodes_lines.gml
         type: vector
 
-  - algorithm: qgis:simplifygeometries
+  - algorithm: native:simplifygeometries
     name: Simplify (lines)
     params:
       INPUT:
@@ -1221,7 +1221,7 @@ tests:
         name: expected/simplify_lines.gml
         type: vector
 
-  - algorithm: qgis:simplifygeometries
+  - algorithm: native:simplifygeometries
     name: Simplify (multilines)
     params:
       INPUT:
@@ -1233,7 +1233,7 @@ tests:
         name: expected/simplify_multilines.gml
         type: vector
 
-  - algorithm: qgis:simplifygeometries
+  - algorithm: native:simplifygeometries
     name: Simplify (visval)
     params:
       INPUT:
@@ -1249,7 +1249,7 @@ tests:
           geometry:
             precision: 7
 
-  - algorithm: qgis:simplifygeometries
+  - algorithm: native:simplifygeometries
     name: Simplify (grid)
     params:
       INPUT:
diff --git a/src/core/processing/qgsnativealgorithms.cpp b/src/core/processing/qgsnativealgorithms.cpp
@@ -81,6 +81,7 @@ void QgsNativeAlgorithms::loadAlgorithms()
   addAlgorithm( new QgsFixGeometriesAlgorithm() );
   addAlgorithm( new QgsMergeLinesAlgorithm() );
   addAlgorithm( new QgsSmoothAlgorithm() );
+  addAlgorithm( new QgsSimplifyAlgorithm() );
 }
 
 void QgsCentroidAlgorithm::initAlgorithm( const QVariantMap & )
@@ -1751,5 +1752,66 @@ QgsFeature QgsSmoothAlgorithm::processFeature( const QgsFeature &feature, QgsPro
   return f;
 }
 
+QString QgsSimplifyAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm simplifies the geometries in a line or polygon layer. It creates a new layer "
+                      "with the same features as the ones in the input layer, but with geometries containing a lower number of vertices.\n\n"
+                      "The algorithm gives a choice of simplification methods, including distance based "
+                      "(the \"Douglas-Peucker\" algorithm), area based (\"Visvalingam\" algorithm) and snapping geometries to a grid." );
+}
+
+QgsSimplifyAlgorithm *QgsSimplifyAlgorithm::createInstance() const
+{
+  return new QgsSimplifyAlgorithm();
+}
+
+void QgsSimplifyAlgorithm::initParameters( const QVariantMap & )
+{
+  QStringList methods;
+  methods << QObject::tr( "Distance (Douglas-Peucker)" )
+          << QObject::tr( "Snap to grid" )
+          << QObject::tr( "Area (Visvalingam)" );
+
+  addParameter( new QgsProcessingParameterEnum(
+                  QStringLiteral( "METHOD" ),
+                  QObject::tr( "Simplification method" ),
+                  methods, false, 0 ) );
+  addParameter( new QgsProcessingParameterNumber( QStringLiteral( "TOLERANCE" ),
+                QObject::tr( "Tolerance" ), QgsProcessingParameterNumber::Double,
+                1.0, false, 0, 10000000.0 ) );
+}
+
+bool QgsSimplifyAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
+{
+  mTolerance = parameterAsDouble( parameters, QStringLiteral( "TOLERANCE" ), context );
+  mMethod = static_cast< QgsMapToPixelSimplifier::SimplifyAlgorithm >( parameterAsEnum( parameters, QStringLiteral( "METHOD" ), context ) );
+  if ( mMethod != QgsMapToPixelSimplifier::Distance )
+    mSimplifier.reset( new QgsMapToPixelSimplifier( QgsMapToPixelSimplifier::SimplifyGeometry, mTolerance, mMethod ) );
+
+  return true;
+}
+
+QgsFeature QgsSimplifyAlgorithm::processFeature( const QgsFeature &feature, QgsProcessingFeedback * )
+{
+  QgsFeature f = feature;
+  if ( f.hasGeometry() )
+  {
+    QgsGeometry inputGeometry = f.geometry();
+    QgsGeometry outputGeometry;
+    if ( mMethod == QgsMapToPixelSimplifier::Distance )
+    {
+      outputGeometry = inputGeometry.simplify( mTolerance );
+    }
+    else
+    {
+      outputGeometry = mSimplifier->simplify( inputGeometry );
+    }
+    f.setGeometry( outputGeometry );
+  }
+  return f;
+}
+
 ///@endcond
 
+
+
diff --git a/src/core/processing/qgsnativealgorithms.h b/src/core/processing/qgsnativealgorithms.h
@@ -24,6 +24,7 @@
 #include "qgis.h"
 #include "qgsprocessingalgorithm.h"
 #include "qgsprocessingprovider.h"
+#include "qgsmaptopixelgeometrysimplifier.h"
 
 ///@cond PRIVATE
 
@@ -632,6 +633,35 @@ class QgsSmoothAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     double mMaxAngle = 0;
 };
 
+/**
+ * Native simplify algorithm.
+ */
+class QgsSimplifyAlgorithm : public QgsProcessingFeatureBasedAlgorithm
+{
+
+  public:
+
+    QgsSimplifyAlgorithm() = default;
+    QString name() const override { return QStringLiteral( "simplifygeometries" ); }
+    QString displayName() const override { return QObject::tr( "Simplify geometries" ); }
+    virtual QStringList tags() const override { return QObject::tr( "simplify,generalize,douglas,peucker,visvalingam" ).split( ',' ); }
+    QString group() const override { return QObject::tr( "Vector geometry" ); }
+    QString shortHelpString() const override;
+    QgsSimplifyAlgorithm *createInstance() const override SIP_FACTORY;
+    void initParameters( const QVariantMap &configuration = QVariantMap() ) override;
+
+  protected:
+    QString outputName() const override { return QObject::tr( "Simplified" ); }
+    bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+    QgsFeature processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback ) override;
+
+  private:
+
+    double mTolerance = 1.0;
+    QgsMapToPixelSimplifier::SimplifyAlgorithm mMethod = QgsMapToPixelSimplifier::Distance;
+    std::unique_ptr< QgsMapToPixelSimplifier > mSimplifier;
+
+};
 ///@endcond PRIVATE
 
 #endif // QGSNATIVEALGORITHMS_H
