[FEATURE][tracing curves] Trace tools generates curved geometries

src/gui/qgsmaptoolcapture.cpp

@@ -13,8 +13,10 @@
  *                                                                         *
  ***************************************************************************/
 
-#include "qgsmaptoolcapture.h"
+#include <ogr_api.h>
+#include <ogr_geometry.h>
 
+#include "qgsmaptoolcapture.h"
 #include "qgsexception.h"
 #include "qgsfeatureiterator.h"
 #include "qgsgeometryvalidator.h"
@@ -289,10 +291,40 @@ bool QgsMapToolCapture::tracingAddVertex( const QgsPointXY &point )
     mSnappingMatches.append( QgsPointLocator::Match() );
   }
 
+  // If the layer supports curves, we de-approximate curves
+  QgsVectorLayer *vlayer = qobject_cast<QgsVectorLayer *>( mCanvas->currentLayer() );
+  if ( vlayer->dataProvider()->capabilities().testFlag( QgsVectorDataProvider::Capability::CircularGeometries ) )
+  {
+    // We convert the capture curve to OGR geometry
+    OGRGeometry *ogrCaptureCurve;
+    OGRGeometryFactory::createFromWkt( mCaptureCurve.asWkt().toLocal8Bit().data(), nullptr, &ogrCaptureCurve );
+
+    // We de-approximate the curves using OGR (the geometry must be forced to linear first, as a mCaptureCurve is a CompoundCurve)
+    OGRGeometry *ogrLinestring = ogrCaptureCurve->getLinearGeometry(); // it must be forced to linear, as captuecurve is a compound curve
+    OGRGeometry *ogrRecurved = ogrLinestring->getCurveGeometry();
+
+    // We save back to mCaptureCurve
+    mCaptureCurve.clear();
+    mCaptureCurve.fromWkt( QString::fromStdString( ogrRecurved->exportToWkt() ) );
+  }
+
   tracer->reportError( QgsTracer::ErrNone, true ); // clear messagebar if there was any error
   return true;
 }
 
+// Required to avoid this (took values from https://github.com/OSGeo/gdal/blob/master/gdal/ogr/ogrgeometry.cpp):
+// qgsmaptoolcapture.cpp.obj : error LNK2019: unresolved external symbol "private: static int __cdecl OGRWktOptions::getDefaultPrecision(void)" (?getDefaultPrecision@OGRWktOptions@@CAHXZ) referenced in function "public: __cdecl OGRWktOptions::OGRWktOptions(void)" (??0OGRWktOptions@@QEAA@XZ)
+// qgsmaptoolcapture.cpp.obj : error LNK2019: unresolved external symbol "private: static bool __cdecl OGRWktOptions::getDefaultRound(void)" (?getDefaultRound@OGRWktOptions@@CA_NXZ) referenced in function "public: __cdecl OGRWktOptions::OGRWktOptions(void)" (??0OGRWktOptions@@QEAA@XZ)
+// output\bin\qgis_gui.dll : fatal error LNK1120: 2 unresolved externals
+int OGRWktOptions::getDefaultPrecision( void )
+{
+  return 15;
+}
+bool OGRWktOptions::getDefaultRound( void )
+{
+  return true;
+}
+
 QgsRubberBand *QgsMapToolCapture::takeRubberBand()
 {
   return mRubberBand.release();