[FEATURE]: possibility to set the segmentation tolerance (maximum ang…

…le or maximum difference)

python/core/geometry/qgsabstractgeometryv2.sip

@@ -70,6 +70,14 @@ class QgsAbstractGeometryV2
 
     public:
 
+    /** Segmentation tolerance as maximum angle or maximum difference between approximation and circle*/
+    enum SegmentationToleranceType
+    {
+        MaximumAngle = 0,
+        MaximumDifference
+    };
+
+
     QgsAbstractGeometryV2();
     virtual ~QgsAbstractGeometryV2();
     QgsAbstractGeometryV2( const QgsAbstractGeometryV2& geom );
@@ -303,8 +311,10 @@ class QgsAbstractGeometryV2
 
     /** Returns a version of the geometry without curves. Caller takes ownership of
      * the returned geometry.
+     * @param tolerance segmentation tolerance
+     * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve
      */
-    virtual QgsAbstractGeometryV2* segmentize() const /Factory/;
+    virtual QgsAbstractGeometryV2* segmentize( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const /Factory/;
 
     /** Returns the geometry converted to the more generic curve type.
         E.g. QgsLineStringV2 -> QgsCompoundCurveV2, QgsPolygonV2 -> QgsCurvePolygonV2,

python/core/geometry/qgscircularstringv2.sip

@@ -54,10 +54,11 @@ class QgsCircularStringV2: public QgsCurveV2
      * @copydoc QgsCurveV2::endPoint()
      */
     virtual QgsPointV2 endPoint() const;
-    /**
-     * @copydoc QgsCurveV2::curveToLine()
-     */
-    virtual QgsLineStringV2* curveToLine() const;
+     /** Returns a new line string geometry corresponding to a segmentized approximation
+     * of the curve.
+     * @param tolerance segmentation tolerance
+     * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve*/
+    virtual QgsLineStringV2* curveToLine( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const;
 
     void draw( QPainter& p ) const;
 

python/core/geometry/qgscompoundcurvev2.sip

@@ -34,7 +34,11 @@ class QgsCompoundCurveV2: public QgsCurveV2
     virtual QgsPointV2 endPoint() const;
     virtual void points( QList<QgsPointV2>& pts ) const;
     virtual int numPoints() const;
-    virtual QgsLineStringV2* curveToLine() const;
+    /** Returns a new line string geometry corresponding to a segmentized approximation
+     * of the curve.
+     * @param tolerance segmentation tolerance
+     * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve*/
+    virtual QgsLineStringV2* curveToLine( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const;
 
     /** Returns the number of curves in the geometry.
      */

python/core/geometry/qgscurvepolygonv2.sip

@@ -34,7 +34,11 @@ class QgsCurvePolygonV2: public QgsSurfaceV2
     int numInteriorRings() const;
     const QgsCurveV2* exteriorRing() const;
     const QgsCurveV2* interiorRing( int i ) const;
-    virtual QgsPolygonV2* toPolygon() const;
+    /** Returns a new polygon geometry corresponding to a segmentized approximation
+     * of the curve.
+     * @param tolerance segmentation tolerance
+     * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve*/
+    virtual QgsPolygonV2* toPolygon( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const;
 
     /** Sets the exterior ring of the polygon. The CurvePolygon type will be updated to match the dimensionality
      * of the exterior ring. For instance, setting a 2D exterior ring on a 3D CurvePolygon will drop the z dimension
@@ -69,7 +73,10 @@ class QgsCurvePolygonV2: public QgsSurfaceV2
     bool nextVertex( QgsVertexId& id, QgsPointV2& vertex ) const;
 
     bool hasCurvedSegments() const;
-    QgsAbstractGeometryV2* segmentize() const /Factory/;
+    /** Returns a geometry without curves. Caller takes ownership
+     * @param tolerance segmentation tolerance
+     * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve*/
+    QgsAbstractGeometryV2* segmentize( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const /Factory/;
 
     /** Returns approximate rotation angle for a vertex. Usually average angle between adjacent segments.
      *  @param vertex the vertex id

python/core/geometry/qgscurvev2.sip

@@ -32,8 +32,10 @@ class QgsCurveV2: public QgsAbstractGeometryV2
 
     /** Returns a new line string geometry corresponding to a segmentized approximation
      * of the curve.
+     * @param tolerance segmentation tolerance
+     * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve
      */
-    virtual QgsLineStringV2* curveToLine() const = 0;
+    virtual QgsLineStringV2* curveToLine( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const = 0;
 
     /** Adds a curve to a painter path.
      */
@@ -73,8 +75,10 @@ class QgsCurveV2: public QgsAbstractGeometryV2
      */
     virtual QgsCurveV2* reversed() const = 0 /Factory/;
 
-    /** Returns a geometry without curves. Caller takes ownership*/
-    virtual QgsCurveV2* segmentize() const /Factory/;
+    /** Returns a geometry without curves. Caller takes ownership
+    * @param tolerance segmentation tolerance
+    * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve*/
+    virtual QgsCurveV2* segmentize( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const /Factory/;
 
     virtual int vertexCount( int part = 0, int ring = 0 ) const;
     virtual int ringCount( int part = 0 ) const;

python/core/geometry/qgsgeometrycollectionv2.sip

@@ -83,8 +83,10 @@ class QgsGeometryCollectionV2: public QgsAbstractGeometryV2
 
     bool hasCurvedSegments() const;
 
-    /** Returns a geometry without curves. Caller takes ownership*/
-    QgsAbstractGeometryV2* segmentize() const;
+    /** Returns a geometry without curves. Caller takes ownership
+    * @param tolerance segmentation tolerance
+    * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve*/
+    QgsAbstractGeometryV2* segmentize( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const;
 
     /** Returns approximate rotation angle for a vertex. Usually average angle between adjacent segments.
      * @param vertex the vertex id

python/core/geometry/qgslinestringv2.sip

@@ -131,7 +131,11 @@ class QgsLineStringV2: public QgsCurveV2
     virtual double length() const;
     virtual QgsPointV2 startPoint() const;
     virtual QgsPointV2 endPoint() const;
-    virtual QgsLineStringV2* curveToLine() const /Factory/;
+    /** Returns a new line string geometry corresponding to a segmentized approximation
+     * of the curve.
+     * @param tolerance segmentation tolerance
+     * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve*/
+    virtual QgsLineStringV2* curveToLine( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const /Factory/;
 
     int numPoints() const;
     void points( QList<QgsPointV2>& pt ) const;

python/core/qgsmapsettings.sip

@@ -211,6 +211,18 @@ class QgsMapSettings
 
     void writeXML( QDomNode& theNode, QDomDocument& theDoc );
 
+    /** Sets the segmentation tolerance applied when rendering curved geometries
+    @param tolerance the segmentation tolerance*/
+    void setSegmentationTolerance( double tolerance );
+    /** Gets the segmentation tolerance applied when rendering curved geometries*/
+    double segmentationTolerance() const;
+    /** Sets segmentation tolerance type (maximum angle or maximum difference between curve and approximation)
+    @param type the segmentation tolerance typename*/
+    void setSegmentationToleranceType( QgsAbstractGeometryV2::SegmentationToleranceType type );
+    /** Gets segmentation tolerance type (maximum angle or maximum difference between curve and approximation)*/
+    QgsAbstractGeometryV2::SegmentationToleranceType segmentationToleranceType() const;
+
+
   protected:
 
     void updateDerived();

python/core/qgsrendercontext.sip

@@ -177,4 +177,16 @@ class QgsRenderContext
      * @see setFeatureFilterProvider()
      */
     const QgsFeatureFilterProvider* featureFilterProvider() const;
+
+    /** Sets the segmentation tolerance applied when rendering curved geometries
+    @param tolerance the segmentation tolerance*/
+    void setSegmentationTolerance( double tolerance );
+    /** Gets the segmentation tolerance applied when rendering curved geometries*/
+    double segmentationTolerance() const;
+
+    /** Sets segmentation tolerance type (maximum angle or maximum difference between curve and approximation)
+    @param type the segmentation tolerance typename*/
+    void setSegmentationToleranceType( QgsAbstractGeometryV2::SegmentationToleranceType type );
+    /** Gets segmentation tolerance type (maximum angle or maximum difference between curve and approximation)*/
+    QgsAbstractGeometryV2::SegmentationToleranceType segmentationToleranceType() const;
 };

python/gui/qgsmapcanvas.sip

@@ -393,6 +393,13 @@ class QgsMapCanvas : QGraphicsView
      */
     // const QgsExpressionContextScope& expressionContextScope() const;
 
+     /** Sets the segmentation tolerance applied when rendering curved geometries
+    @param tolerance the segmentation tolerance*/
+    void setSegmentationTolerance( double tolerance );
+    /** Sets segmentation tolerance type (maximum angle or maximum difference between curve and approximation)
+    @param type the segmentation tolerance typename*/
+    void setSegmentationToleranceType( QgsAbstractGeometryV2::SegmentationToleranceType type );
+
   public slots:
 
     /** Repaints the canvas map*/

src/app/qgisapp.cpp

@@ -8641,6 +8641,9 @@ void QgisApp::showOptionsDialog( QWidget *parent, const QString& currentPage )
 
     bool otfTransformAutoEnable = mySettings.value( "/Projections/otfTransformAutoEnable", true ).toBool();
     mLayerTreeCanvasBridge->setAutoEnableCrsTransform( otfTransformAutoEnable );
+
+    mMapCanvas->setSegmentationTolerance( mySettings.value( "/qgis/segmentationTolerance", "0.01745" ).toDouble() );
+    mMapCanvas->setSegmentationToleranceType( QgsAbstractGeometryV2::SegmentationToleranceType( mySettings.value( "/qgis/segmentationToleranceType", "0" ).toInt() ) );
   }
 
   delete optionsDialog;

src/app/qgsoptions.cpp

@@ -584,6 +584,23 @@ QgsOptions::QgsOptions( QWidget *parent, Qt::WindowFlags fl )
   mSimplifyDrawingSpinBox->setValue( mSettings->value( "/qgis/simplifyDrawingTol", QGis::DEFAULT_MAPTOPIXEL_THRESHOLD ).toFloat() );
   mSimplifyDrawingAtProvider->setChecked( !mSettings->value( "/qgis/simplifyLocal", true ).toBool() );
 
+  //segmentation tolerance type
+  mToleranceTypeComboBox->addItem( tr( "Maximum angle" ), 0 );
+  mToleranceTypeComboBox->addItem( tr( "Maximum difference" ), 1 );
+  int toleranceType = mSettings->value( "/qgis/segmentationToleranceType", "0" ).toInt();
+  int toleranceTypeIndex = mToleranceTypeComboBox->findData( toleranceType );
+  if ( toleranceTypeIndex != -1 )
+  {
+    mToleranceTypeComboBox->setCurrentIndex( toleranceTypeIndex );
+  }
+
+  double tolerance = mSettings->value( "/qgis/segmentationTolerance", "0.01745" ).toDouble();
+  if ( toleranceType == 0 )
+  {
+    tolerance = tolerance * 180.0 / M_PI; //value shown to the user is degree, not rad
+  }
+  mSegmentationToleranceSpinBox->setValue( tolerance );
+
   QStringList myScalesList = PROJECT_SCALES.split( ',' );
   myScalesList.append( "1:1" );
   mSimplifyMaximumScaleComboBox->updateScales( myScalesList );
@@ -1202,6 +1219,16 @@ void QgsOptions::saveOptions()
   // magnification
   mSettings->setValue( "/qgis/magnifier_level", doubleSpinBoxMagnifierDefault->value() );
 
+  //curve segmentation
+  int segmentationType = mToleranceTypeComboBox->itemData( mToleranceTypeComboBox->currentIndex() ).toInt();
+  mSettings->setValue( "/qgis/segmentationToleranceType", segmentationType );
+  double segmentationTolerance = mSegmentationToleranceSpinBox->value();
+  if ( segmentationType == 0 )
+  {
+    segmentationTolerance = segmentationTolerance / 180.0 * M_PI; //user sets angle tolerance in degrees, internal classes need value in rad
+  }
+  mSettings->setValue( "/qgis/segmentationTolerance", segmentationTolerance );
+
   // project
   mSettings->setValue( "/qgis/projOpenAtLaunch", mProjectOnLaunchCmbBx->currentIndex() );
   mSettings->setValue( "/qgis/projOpenAtLaunchPath", mProjectOnLaunchLineEdit->text() );

src/core/geometry/qgsabstractgeometryv2.cpp

@@ -244,3 +244,12 @@ bool QgsAbstractGeometryV2::isEmpty() const
   QgsPointV2 vertex;
   return !nextVertex( vId, vertex );
 }
+
+
+QgsAbstractGeometryV2* QgsAbstractGeometryV2::segmentize( double tolerance, SegmentationToleranceType toleranceType ) const
+{
+  Q_UNUSED( tolerance );
+  Q_UNUSED( toleranceType );
+  return clone();
+}
+

src/core/geometry/qgsabstractgeometryv2.h

@@ -43,6 +43,14 @@ typedef QList< QgsRingSequenceV2 > QgsCoordinateSequenceV2;
 class CORE_EXPORT QgsAbstractGeometryV2
 {
   public:
+
+    /** Segmentation tolerance as maximum angle or maximum difference between approximation and circle*/
+    enum SegmentationToleranceType
+    {
+      MaximumAngle = 0,
+      MaximumDifference
+    };
+
     QgsAbstractGeometryV2();
     virtual ~QgsAbstractGeometryV2();
     QgsAbstractGeometryV2( const QgsAbstractGeometryV2& geom );
@@ -288,8 +296,10 @@ class CORE_EXPORT QgsAbstractGeometryV2
 
     /** Returns a version of the geometry without curves. Caller takes ownership of
      * the returned geometry.
+     * @param tolerance segmentation tolerance
+     * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve
      */
-    virtual QgsAbstractGeometryV2* segmentize() const { return clone(); }
+    virtual QgsAbstractGeometryV2* segmentize( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const;
 
     /** Returns the geometry converted to the more generic curve type.
         E.g. QgsLineStringV2 -> QgsCompoundCurveV2, QgsPolygonV2 -> QgsCurvePolygonV2,

src/core/geometry/qgscircularstringv2.cpp

@@ -351,15 +351,15 @@ QgsPointV2 QgsCircularStringV2::endPoint() const
   return pointN( numPoints() - 1 );
 }
 
-QgsLineStringV2* QgsCircularStringV2::curveToLine() const
+QgsLineStringV2* QgsCircularStringV2::curveToLine( double tolerance, SegmentationToleranceType toleranceType ) const
 {
   QgsLineStringV2* line = new QgsLineStringV2();
   QgsPointSequenceV2 points;
   int nPoints = numPoints();
 
   for ( int i = 0; i < ( nPoints - 2 ) ; i += 2 )
   {
-    segmentize( pointN( i ), pointN( i + 1 ), pointN( i + 2 ), points );
+    segmentize( pointN( i ), pointN( i + 1 ), pointN( i + 2 ), points, tolerance, toleranceType );
   }
 
   line->setPoints( points );
@@ -473,7 +473,7 @@ void QgsCircularStringV2::setPoints( const QgsPointSequenceV2 &points )
   }
 }
 
-void QgsCircularStringV2::segmentize( const QgsPointV2& p1, const QgsPointV2& p2, const QgsPointV2& p3, QgsPointSequenceV2 &points ) const
+void QgsCircularStringV2::segmentize( const QgsPointV2& p1, const QgsPointV2& p2, const QgsPointV2& p3, QgsPointSequenceV2 &points, double tolerance, SegmentationToleranceType toleranceType ) const
 {
   //adapted code from postgis
   double radius = 0;
@@ -496,7 +496,12 @@ void QgsCircularStringV2::segmentize( const QgsPointV2& p1, const QgsPointV2& p2
     clockwise = true;
   }
 
-  double increment = fabs( M_PI_2 / 90 ); //one segment per degree
+  double increment = tolerance; //one segment per degree
+  if ( toleranceType == QgsAbstractGeometryV2::MaximumDifference )
+  {
+    double halfAngle = acos( -tolerance / radius + 1 );
+    increment = 2 * halfAngle;
+  }
 
   //angles of pt1, pt2, pt3
   double a1 = atan2( p1.y() - centerY, p1.x() - centerX );

src/core/geometry/qgscircularstringv2.h

@@ -79,10 +79,11 @@ class CORE_EXPORT QgsCircularStringV2: public QgsCurveV2
      * @copydoc QgsCurveV2::endPoint()
      */
     virtual QgsPointV2 endPoint() const override;
-    /**
-     * @copydoc QgsCurveV2::curveToLine()
-     */
-    virtual QgsLineStringV2* curveToLine() const override;
+    /** Returns a new line string geometry corresponding to a segmentized approximation
+     * of the curve.
+     * @param tolerance segmentation tolerance
+     * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve*/
+    virtual QgsLineStringV2* curveToLine( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const override;
 
     void draw( QPainter& p ) const override;
 
@@ -143,7 +144,7 @@ class CORE_EXPORT QgsCircularStringV2: public QgsCurveV2
     QVector<double> mM;
 
     //helper methods for curveToLine
-    void segmentize( const QgsPointV2& p1, const QgsPointV2& p2, const QgsPointV2& p3, QgsPointSequenceV2 &points ) const;
+    void segmentize( const QgsPointV2& p1, const QgsPointV2& p2, const QgsPointV2& p3, QgsPointSequenceV2 &points, double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const;
     int segmentSide( const QgsPointV2& pt1, const QgsPointV2& pt3, const QgsPointV2& pt2 ) const;
     double interpolateArc( double angle, double a1, double a2, double a3, double zm1, double zm2, double zm3 ) const;
     static void arcTo( QPainterPath& path, QPointF pt1, QPointF pt2, QPointF pt3 );

src/core/geometry/qgscompoundcurvev2.cpp

@@ -357,14 +357,14 @@ int QgsCompoundCurveV2::numPoints() const
   return nPoints;
 }
 
-QgsLineStringV2* QgsCompoundCurveV2::curveToLine() const
+QgsLineStringV2* QgsCompoundCurveV2::curveToLine( double tolerance, SegmentationToleranceType toleranceType ) const
 {
   QList< QgsCurveV2* >::const_iterator curveIt = mCurves.constBegin();
   QgsLineStringV2* line = new QgsLineStringV2();
   QgsLineStringV2* currentLine = nullptr;
   for ( ; curveIt != mCurves.constEnd(); ++curveIt )
   {
-    currentLine = ( *curveIt )->curveToLine();
+    currentLine = ( *curveIt )->curveToLine( tolerance, toleranceType );
     line->append( currentLine );
     delete currentLine;
   }

src/core/geometry/qgscompoundcurvev2.h

@@ -58,7 +58,11 @@ class CORE_EXPORT QgsCompoundCurveV2: public QgsCurveV2
     virtual QgsPointV2 endPoint() const override;
     virtual void points( QgsPointSequenceV2 &pts ) const override;
     virtual int numPoints() const override;
-    virtual QgsLineStringV2* curveToLine() const override;
+    /** Returns a new line string geometry corresponding to a segmentized approximation
+     * of the curve.
+     * @param tolerance segmentation tolerance
+     * @param toleranceType maximum segmentation angle or maximum difference between approximation and curve*/
+    virtual QgsLineStringV2* curveToLine( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const override;
 
     /** Returns the number of curves in the geometry.
      */