Merge pull request #7120 from nyalldawson/opts

Optimise geometry conversion to/from geos

python/core/auto_generated/geometry/qgslinestring.sip.in

@@ -89,6 +89,8 @@ Returns the specified point from inside the line string.
 
 
 
+
+
     double zAt( int index ) const;
 %Docstring
 Returns the z-coordinate of the specified node in the line string.

src/core/geometry/qgsgeos.cpp

@@ -1205,35 +1205,29 @@ std::unique_ptr<QgsLineString> QgsGeos::sequenceToLinestring( const GEOSGeometry
   const GEOSCoordSequence *cs = GEOSGeom_getCoordSeq_r( geosinit.ctxt, geos );
   unsigned int nPoints;
   GEOSCoordSeq_getSize_r( geosinit.ctxt, cs, &nPoints );
-  QVector< double > xOut;
-  xOut.reserve( nPoints );
-  QVector< double > yOut;
-  yOut.reserve( nPoints );
+  QVector< double > xOut( nPoints );
+  QVector< double > yOut( nPoints );
   QVector< double > zOut;
   if ( hasZ )
-    zOut.reserve( nPoints );
+    zOut.resize( nPoints );
   QVector< double > mOut;
   if ( hasM )
-    mOut.reserve( nPoints );
-  double x = 0;
-  double y = 0;
-  double z = 0;
-  double m = 0;
+    mOut.resize( nPoints );
+  double *x = xOut.data();
+  double *y = yOut.data();
+  double *z = zOut.data();
+  double *m = mOut.data();
   for ( unsigned int i = 0; i < nPoints; ++i )
   {
-    GEOSCoordSeq_getX_r( geosinit.ctxt, cs, i, &x );
-    xOut << x;
-    GEOSCoordSeq_getY_r( geosinit.ctxt, cs, i, &y );
-    yOut << y;
+    GEOSCoordSeq_getX_r( geosinit.ctxt, cs, i, x++ );
+    GEOSCoordSeq_getY_r( geosinit.ctxt, cs, i, y++ );
     if ( hasZ )
     {
-      GEOSCoordSeq_getZ_r( geosinit.ctxt, cs, i, &z );
-      zOut << z;
+      GEOSCoordSeq_getZ_r( geosinit.ctxt, cs, i, z++ );
     }
     if ( hasM )
     {
-      GEOSCoordSeq_getOrdinate_r( geosinit.ctxt, cs, i, 3, &m );
-      mOut << m;
+      GEOSCoordSeq_getOrdinate_r( geosinit.ctxt, cs, i, 3, m++ );
     }
   }
   std::unique_ptr< QgsLineString > line( new QgsLineString( xOut, yOut, zOut, mOut ) );
@@ -1769,35 +1763,57 @@ GEOSCoordSequence *QgsGeos::createCoordinateSequence( const QgsCurve *curve, dou
       QgsDebugMsg( QStringLiteral( "GEOS Exception: Could not create coordinate sequence for %1 points in %2 dimensions" ).arg( numPoints ).arg( coordDims ) );
       return nullptr;
     }
+
+    const double *xData = line->xData();
+    const double *yData = line->yData();
+    const double *zData = hasZ ? line->zData() : nullptr;
+    const double *mData = hasM ? line->mData() : nullptr;
+
     if ( precision > 0. )
     {
       for ( int i = 0; i < numOutPoints; ++i )
       {
-        GEOSCoordSeq_setX_r( geosinit.ctxt, coordSeq, i, std::round( line->xAt( i % numPoints ) / precision ) * precision );
-        GEOSCoordSeq_setY_r( geosinit.ctxt, coordSeq, i, std::round( line->yAt( i % numPoints ) / precision ) * precision );
+        if ( i >= numPoints )
+        {
+          // start reading back from start of line
+          xData = line->xData();
+          yData = line->yData();
+          zData = hasZ ? line->zData() : nullptr;
+          mData = hasM ? line->mData() : nullptr;
+        }
+        GEOSCoordSeq_setX_r( geosinit.ctxt, coordSeq, i, std::round( *xData++ / precision ) * precision );
+        GEOSCoordSeq_setY_r( geosinit.ctxt, coordSeq, i, std::round( *yData++ / precision ) * precision );
         if ( hasZ )
         {
-          GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, i, 2, std::round( line->zAt( i % numPoints ) / precision ) * precision );
+          GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, i, 2, std::round( *zData++ / precision ) * precision );
         }
         if ( hasM )
         {
-          GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, i, 3, line->mAt( i % numPoints ) );
+          GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, i, 3, line->mAt( *mData++ ) );
         }
       }
     }
     else
     {
       for ( int i = 0; i < numOutPoints; ++i )
       {
-        GEOSCoordSeq_setX_r( geosinit.ctxt, coordSeq, i, line->xAt( i % numPoints ) );
-        GEOSCoordSeq_setY_r( geosinit.ctxt, coordSeq, i, line->yAt( i % numPoints ) );
+        if ( i >= numPoints )
+        {
+          // start reading back from start of line
+          xData = line->xData();
+          yData = line->yData();
+          zData = hasZ ? line->zData() : nullptr;
+          mData = hasM ? line->mData() : nullptr;
+        }
+        GEOSCoordSeq_setX_r( geosinit.ctxt, coordSeq, i, *xData++ );
+        GEOSCoordSeq_setY_r( geosinit.ctxt, coordSeq, i, *yData++ );
         if ( hasZ )
         {
-          GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, i, 2, line->zAt( i % numPoints ) );
+          GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, i, 2, *zData++ );
         }
         if ( hasM )
         {
-          GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, i, 3, line->mAt( i % numPoints ) );
+          GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, i, 3, *mData++ );
         }
       }
     }

src/core/geometry/qgslinestring.cpp

@@ -560,6 +560,22 @@ const double *QgsLineString::yData() const
   return mY.constData();
 }
 
+const double *QgsLineString::zData() const
+{
+  if ( mZ.empty() )
+    return nullptr;
+  else
+    return mZ.constData();
+}
+
+const double *QgsLineString::mData() const
+{
+  if ( mM.empty() )
+    return nullptr;
+  else
+    return mM.constData();
+}
+
 double QgsLineString::zAt( int index ) const
 {
   if ( index >= 0 && index < mZ.size() )

src/core/geometry/qgslinestring.h

@@ -112,6 +112,26 @@ class CORE_EXPORT QgsLineString: public QgsCurve
      */
     const double *yData() const SIP_SKIP;
 
+    /**
+     * Returns a const pointer to the z vertex data, or a nullptr if the linestring does
+     * not have z values.
+     * \note Not available in Python bindings
+     * \see xData()
+     * \see yData()
+     * \since QGIS 3.2
+     */
+    const double *zData() const SIP_SKIP;
+
+    /**
+     * Returns a const pointer to the m vertex data, or a nullptr if the linestring does
+     * not have m values.
+     * \note Not available in Python bindings
+     * \see xData()
+     * \see yData()
+     * \since QGIS 3.2
+     */
+    const double *mData() const SIP_SKIP;
+
     /**
      * Returns the z-coordinate of the specified node in the line string.
      * \param index index of node, where the first node in the line is 0

tests/src/core/testqgsgeometry.cpp

@@ -2796,6 +2796,19 @@ void TestQgsGeometry::lineString()
   QCOMPARE( fromArray8.zAt( 2 ), 23.0 );
   QCOMPARE( fromArray8.mAt( 2 ), 33.0 );
 
+  QCOMPARE( *fromArray8.xData(), 1.0 );
+  QCOMPARE( *( fromArray8.xData() + 1 ), 2.0 );
+  QCOMPARE( *( fromArray8.xData() + 2 ), 3.0 );
+  QCOMPARE( *fromArray8.yData(), 11.0 );
+  QCOMPARE( *( fromArray8.yData() + 1 ), 12.0 );
+  QCOMPARE( *( fromArray8.yData() + 2 ), 13.0 );
+  QCOMPARE( *fromArray8.zData(), 21.0 );
+  QCOMPARE( *( fromArray8.zData() + 1 ), 22.0 );
+  QCOMPARE( *( fromArray8.zData() + 2 ), 23.0 );
+  QCOMPARE( *fromArray8.mData(), 31.0 );
+  QCOMPARE( *( fromArray8.mData() + 1 ), 32.0 );
+  QCOMPARE( *( fromArray8.mData() + 2 ), 33.0 );
+
   // from QList<QgsPointXY>
   QgsLineString fromPtsA = QgsLineString( QVector< QgsPoint >() );
   QVERIFY( fromPtsA.isEmpty() );