[processing][FEATURE] multiring buffer algorithm

qgis · Mar 2, 2018 · 04ce435 · 04ce435
1 parent b61882f
commit 04ce435
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diff --git a/src/analysis/CMakeLists.txt b/src/analysis/CMakeLists.txt
@@ -47,6 +47,7 @@ SET(QGIS_ANALYSIS_SRCS
   processing/qgsalgorithmmergevector.cpp
   processing/qgsalgorithmminimumenclosingcircle.cpp
   processing/qgsalgorithmmultiparttosinglepart.cpp
+  processing/qgsalgorithmmultiringbuffer.cpp
   processing/qgsalgorithmorderbyexpression.cpp
   processing/qgsalgorithmorientedminimumboundingbox.cpp
   processing/qgsalgorithmpackage.cpp

diff --git a/src/analysis/processing/qgsalgorithmmultiringbuffer.cpp b/src/analysis/processing/qgsalgorithmmultiringbuffer.cpp
@@ -0,0 +1,129 @@
+/***************************************************************************
+                         qgsalgorithmnultitingbuffer.cpp
+                         --------------------------
+    begin                : February 2018
+    copyright            : (C) 2018 by Alexander Bruy
+    email                : alexander dot bruy 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 "qgsalgorithmmultiringbuffer.h"
+
+///@cond PRIVATE
+
+QString QgsMultiRingBufferAlgorithm::name() const
+{
+  return QStringLiteral( "multiringbuffer" );
+}
+
+QString QgsMultiRingBufferAlgorithm::displayName() const
+{
+  return QObject::tr( "Multi-ring buffer" );
+}
+
+QStringList QgsMultiRingBufferAlgorithm::tags() const
+{
+  return QObject::tr( "buffer,grow,multiple,rings,distance,donut" ).split( ',' );
+}
+
+QString QgsMultiRingBufferAlgorithm::group() const
+{
+  return QObject::tr( "Vector geometry" );
+}
+
+QString QgsMultiRingBufferAlgorithm::groupId() const
+{
+  return QStringLiteral( "vectorgeometry" );
+}
+
+QString QgsMultiRingBufferAlgorithm::outputName() const
+{
+  return QObject::tr( "Multi-ring buffer" );
+}
+
+QString QgsMultiRingBufferAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm computes multi-ring ('donuts') buffer for all the features in an input layer, using a fixed or dynamic distance and rings number." );
+}
+
+QgsMultiRingBufferAlgorithm *QgsMultiRingBufferAlgorithm::createInstance() const
+{
+  return new QgsMultiRingBufferAlgorithm();
+}
+
+void QgsMultiRingBufferAlgorithm::initParameters( const QVariantMap & )
+{
+  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ), QList< int >() << QgsProcessing::TypeVectorPoint ) );
+
+  auto ringsParam = qgis::make_unique < QgsProcessingParameterNumber >( QStringLiteral( "RINGS" ), QObject::tr( "Number of rings" ), QgsProcessingParameterNumber::Integer, 1, false, 1 );
+  //ringsParam->setIsDynamic( true );
+  //ringsParam->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "Number of rings" ), QObject::tr( "Number of rings" ), QgsPropertyDefinition::Integer ) );
+  //ringsParam->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );
+  addParameter( ringsParam.release() );
+
+  auto distanceParam = qgis::make_unique < QgsProcessingParameterNumber >( QStringLiteral( "DISTANCE" ), QObject::tr( "Distance between rings" ), QgsProcessingParameterNumber::Double, 1 );
+  //distanceParam->setIsDynamic( true );
+  //distanceParam->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "Distance between rings" ), QObject::tr( "Distance between rings" ), QgsPropertyDefinition::Double ) );
+  //distanceParam->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );
+  addParameter( distanceParam.release() );
+}
+
+bool QgsMultiRingBufferAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
+{
+  mRingsNumber = parameterAsInt( parameters, QStringLiteral( "RINGS" ), context );
+  mDistance = parameterAsDouble( parameters, QStringLiteral( "DISTANCE" ), context );
+  return true;
+}
+
+QgsFields QgsMultiRingBufferAlgorithm::outputFields( const QgsFields &inputFields ) const
+{
+  QgsFields fields = inputFields;
+  fields.append( QgsField( QStringLiteral( "ringId" ), QVariant::Int, QString(), 10, 0 ) );
+  fields.append( QgsField( QStringLiteral( "distance" ), QVariant::Double, QString(), 20, 6 ) );
+  return fields;
+}
+
+QgsFeatureList QgsMultiRingBufferAlgorithm::processFeature( const QgsFeature &feature, QgsProcessingContext &, QgsProcessingFeedback *feedback )
+{
+  double currentDistance = 0;
+  QgsGeometry outputGeometry, previousGeometry;
+
+  QgsFeatureList outputs;
+
+  for ( int i = 1; i <= mRingsNumber; ++i )
+  {
+    QgsFeature out;
+    currentDistance = i * mDistance;
+    outputGeometry = feature.geometry().buffer( currentDistance, 40 );
+    if ( !outputGeometry )
+    {
+      feedback->reportError( QObject::tr( "Error calculating buffer for feature %1" ).arg( feature.id() ) );
+      continue;
+    }
+
+    if ( i == 1 )
+    {
+      out.setGeometry( outputGeometry );
+    }
+    else
+    {
+      out.setGeometry( outputGeometry.symDifference( previousGeometry ) );
+    }
+    previousGeometry = outputGeometry;
+    QgsAttributes attrs = feature.attributes();
+    attrs << i << currentDistance;
+    out.setAttributes( attrs );
+    outputs.append( out );
+  }
+  return outputs;
+}
+
+///@endcond
diff --git a/src/analysis/processing/qgsalgorithmmultiringbuffer.h b/src/analysis/processing/qgsalgorithmmultiringbuffer.h
@@ -0,0 +1,64 @@
+/***************************************************************************
+                         qgsalgorithmmultiringbuffer.h
+                         -------------------------
+    begin                : February 2018
+    copyright            : (C) 2018 by Alexander Bruy
+    email                : alexander dot bruy 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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGSALGORITHMMULTIRINGBUFFER_H
+#define QGSALGORITHMMULTIRINGBUFFER_H
+
+#define SIP_NO_FILE
+
+#include "qgis.h"
+#include "qgsprocessingalgorithm.h"
+
+///@cond PRIVATE
+
+/**
+ * Native multiring buffer algorithm.
+ */
+class QgsMultiRingBufferAlgorithm : public QgsProcessingFeatureBasedAlgorithm
+{
+
+  public:
+
+    QgsMultiRingBufferAlgorithm() = default;
+    QString name() const override;
+    QString displayName() const override;
+    QStringList tags() const override;
+    QString group() const override;
+    QString groupId() const override;
+    QString shortHelpString() const override;
+    QgsMultiRingBufferAlgorithm *createInstance() const override SIP_FACTORY;
+    void initParameters( const QVariantMap &configuration = QVariantMap() ) override;
+
+  protected:
+
+    QString outputName() const override;
+    QgsFields outputFields( const QgsFields &inputFields ) const override;
+    QgsProcessing::SourceType outputLayerType() const override { return QgsProcessing::TypeVectorPolygon; }
+    QgsWkbTypes::Type outputWkbType( QgsWkbTypes::Type inputWkbType ) const override { Q_UNUSED( inputWkbType ); return QgsWkbTypes::Polygon; }
+    bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+    QgsFeatureList processFeature( const QgsFeature &feature,  QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+
+  private:
+    int mRingsNumber = 0;
+    double mDistance = 0.0;
+};
+
+///@endcond PRIVATE
+
+#endif // QGSALGORITHMMULTIRINGBUFFER_H
+
+
diff --git a/src/analysis/processing/qgsnativealgorithms.cpp b/src/analysis/processing/qgsnativealgorithms.cpp
@@ -44,6 +44,7 @@
 #include "qgsalgorithmmergevector.h"
 #include "qgsalgorithmminimumenclosingcircle.h"
 #include "qgsalgorithmmultiparttosinglepart.h"
+#include "qgsalgorithmmultiringbuffer.h"
 #include "qgsalgorithmorderbyexpression.h"
 #include "qgsalgorithmorientedminimumboundingbox.h"
 #include "qgsalgorithmpackage.h"
@@ -134,6 +135,7 @@ void QgsNativeAlgorithms::loadAlgorithms()
   addAlgorithm( new QgsMergeVectorAlgorithm() );
   addAlgorithm( new QgsMinimumEnclosingCircleAlgorithm() );
   addAlgorithm( new QgsMultipartToSinglepartAlgorithm() );
+  addAlgorithm( new QgsMultiRingBufferAlgorithm() );
   addAlgorithm( new QgsOrderByExpressionAlgorithm() );
   addAlgorithm( new QgsOrientedMinimumBoundingBoxAlgorithm() );
   addAlgorithm( new QgsPackageAlgorithm() );