qgsgeometryvalidator.cpp

Go to the documentation of this file.

/***************************************************************************
  qgsgeometryvalidator.cpp - geometry validation thread
  -------------------------------------------------------------------
Date                 : 03.01.2012
Copyright            : (C) 2012 by Juergen E. Fischer
email                : jef at norbit dot de
 ***************************************************************************
 *                                                                         *
 *   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 "qgis.h"
#include "qgsgeometryvalidator.h"
#include "qgsgeometry.h"
#include "qgslogger.h"

#include <QSettings>

QgsGeometryValidator::QgsGeometryValidator( QgsGeometry *g, QList<QgsGeometry::Error> *errors )
    : QThread()
    , mErrors( errors )
    , mStop( false )
    , mErrorCount( 0 )
{
  Q_ASSERT( g );
  if ( g )
    mG = *g;
}

QgsGeometryValidator::~QgsGeometryValidator()
{
  stop();
  wait();
}

void QgsGeometryValidator::stop()
{
  mStop = true;
}

void QgsGeometryValidator::checkRingIntersections(
  int p0, int i0, const QgsPolyline &ring0,
  int p1, int i1, const QgsPolyline &ring1 )
{
  for ( int i = 0; !mStop && i < ring0.size() - 1; i++ )
  {
    QgsVector v = ring0[i+1] - ring0[i];

    for ( int j = 0; !mStop && j < ring1.size() - 1; j++ )
    {
      QgsVector w = ring1[j+1] - ring1[j];

      QgsPoint s;
      if ( intersectLines( ring0[i], v, ring1[j], w, s ) )
      {
        double d = -distLine2Point( ring0[i], v.perpVector(), s );

        if ( d >= 0 && d <= v.length() )
        {
          d = -distLine2Point( ring1[j], w.perpVector(), s );
          if ( d > 0 && d < w.length() )
          {
            QString msg = QObject::tr( "segment %1 of ring %2 of polygon %3 intersects segment %4 of ring %5 of polygon %6 at %7" )
                          .arg( i0 ).arg( i ).arg( p0 )
                          .arg( i1 ).arg( j ).arg( p1 )
                          .arg( s.toString() );
            QgsDebugMsg( msg );
            emit errorFound( QgsGeometry::Error( msg, s ) );
            mErrorCount++;
          }
        }
      }
    }
  }
}

void QgsGeometryValidator::validatePolyline( int i, QgsPolyline line, bool ring )
{
  if ( ring )
  {
    if ( line.size() < 4 )
    {
      QString msg = QObject::tr( "ring %1 with less than four points" ).arg( i );
      QgsDebugMsg( msg );
      emit errorFound( QgsGeometry::Error( msg ) );
      mErrorCount++;
      return;
    }

    if ( line[0] != line[ line.size()-1 ] )
    {
      QString msg = QObject::tr( "ring %1 not closed" ).arg( i );
      QgsDebugMsg( msg );
      emit errorFound( QgsGeometry::Error( msg ) );
      mErrorCount++;
      return;
    }
  }
  else if ( line.size() < 2 )
  {
    QString msg = QObject::tr( "line %1 with less than two points" ).arg( i );
    QgsDebugMsg( msg );
    emit errorFound( QgsGeometry::Error( msg ) );
    mErrorCount++;
    return;
  }

  int j = 0;
  while ( j < line.size() - 1 )
  {
    int n = 0;
    while ( j < line.size() - 1 && line[j] == line[j+1] )
    {
      line.remove( j );
      n++;
    }

    if ( n > 0 )
    {
      QString msg = QObject::tr( "line %1 contains %n duplicate node(s) at %2", "number of duplicate nodes", n ).arg( i ).arg( j );
      QgsDebugMsg( msg );
      emit errorFound( QgsGeometry::Error( msg, line[j] ) );
      mErrorCount++;
    }

    j++;
  }

  for ( j = 0; !mStop && j < line.size() - 3; j++ )
  {
    QgsVector v = line[j+1] - line[j];
    double vl = v.length();

    int n = ( j == 0 && ring ) ? line.size() - 2 : line.size() - 1;

    for ( int k = j + 2; !mStop && k < n; k++ )
    {
      QgsVector w = line[k+1] - line[k];

      QgsPoint s;
      if ( !intersectLines( line[j], v, line[k], w, s ) )
        continue;

      double d = -distLine2Point( line[j], v.perpVector(), s );
      if ( d < 0 || d > vl )
        continue;

      d = -distLine2Point( line[k], w.perpVector(), s );
      if ( d <= 0 || d >= w.length() )
        continue;

      QString msg = QObject::tr( "segments %1 and %2 of line %3 intersect at %4" ).arg( j ).arg( k ).arg( i ).arg( s.toString() );
      QgsDebugMsg( msg );
      emit errorFound( QgsGeometry::Error( msg, s ) );
      mErrorCount++;
    }
  }
}

void QgsGeometryValidator::validatePolygon( int idx, const QgsPolygon &polygon )
{
  // check if holes are inside polygon
  for ( int i = 1; !mStop && i < polygon.size(); i++ )
  {
    if ( !ringInRing( polygon[i], polygon[0] ) )
    {
      QString msg = QObject::tr( "ring %1 of polygon %2 not in exterior ring" ).arg( i ).arg( idx );
      QgsDebugMsg( msg );
      emit errorFound( QgsGeometry::Error( msg ) );
      mErrorCount++;
    }
  }

  // check holes for intersections
  for ( int i = 1; !mStop && i < polygon.size(); i++ )
  {
    for ( int j = i + 1; !mStop && j < polygon.size(); j++ )
    {
      checkRingIntersections( idx, i, polygon[i], idx, j, polygon[j] );
    }
  }

  // check if rings are self-intersecting
  for ( int i = 0; !mStop && i < polygon.size(); i++ )
  {
    validatePolyline( i, polygon[i], true );
  }
}

void QgsGeometryValidator::run()
{
  mErrorCount = 0;
#if defined(GEOS_VERSION_MAJOR) && defined(GEOS_VERSION_MINOR) && \
    ( (GEOS_VERSION_MAJOR==3 && GEOS_VERSION_MINOR>=3) || GEOS_VERSION_MAJOR>3)
  QSettings settings;
  if ( settings.value( "/qgis/digitizing/validate_geometries", 1 ).toInt() == 2 )
  {
    char *r = 0;
    const GEOSGeometry *g0 = mG.asGeos();
    GEOSContextHandle_t handle = QgsGeometry::getGEOSHandler();
    if ( !g0 )
    {
      emit errorFound( QgsGeometry::Error( QObject::tr( "GEOS error:could not produce geometry for GEOS (check log window)" ) ) );
    }
    else
    {
      GEOSGeometry *g1 = 0;
      if ( GEOSisValidDetail_r( handle, g0, GEOSVALID_ALLOW_SELFTOUCHING_RING_FORMING_HOLE, &r, &g1 ) != 1 )
      {
        if ( g1 )
        {
          const GEOSCoordSequence *cs = GEOSGeom_getCoordSeq_r( handle, g1 );

          unsigned int n;
          if ( GEOSCoordSeq_getSize_r( handle, cs, &n ) && n == 1 )
          {
            double x, y;
            GEOSCoordSeq_getX_r( handle, cs, 0, &x );
            GEOSCoordSeq_getY_r( handle, cs, 0, &y );
            emit errorFound( QgsGeometry::Error( QObject::tr( "GEOS error:%1" ).arg( r ), QgsPoint( x, y ) ) );
            mErrorCount++;
          }

          GEOSGeom_destroy_r( handle, g1 );
        }
        else
        {
          emit errorFound( QgsGeometry::Error( QObject::tr( "GEOS error:%1" ).arg( r ) ) );
          mErrorCount++;
        }

        GEOSFree_r( handle, r );
      }
    }

    return;
  }
#endif

  QgsDebugMsg( "validation thread started." );

  switch ( mG.wkbType() )
  {
    case QGis::WKBPoint:
    case QGis::WKBPoint25D:
    case QGis::WKBMultiPoint:
    case QGis::WKBMultiPoint25D:
      break;

    case QGis::WKBLineString:
    case QGis::WKBLineString25D:
      validatePolyline( 0, mG.asPolyline() );
      break;

    case QGis::WKBMultiLineString:
    case QGis::WKBMultiLineString25D:
    {
      QgsMultiPolyline mp = mG.asMultiPolyline();
      for ( int i = 0; !mStop && i < mp.size(); i++ )
        validatePolyline( i, mp[i] );
    }
    break;

    case QGis::WKBPolygon:
    case QGis::WKBPolygon25D:
    {
      validatePolygon( 0, mG.asPolygon() );
    }
    break;

    case QGis::WKBMultiPolygon:
    case QGis::WKBMultiPolygon25D:
    {
      QgsMultiPolygon mp = mG.asMultiPolygon();
      for ( int i = 0; !mStop && i < mp.size(); i++ )
      {
        validatePolygon( i, mp[i] );
      }

      for ( int i = 0; !mStop && i < mp.size(); i++ )
      {
        if ( mp[i].isEmpty() )
        {
          emit errorFound( QgsGeometry::Error( QObject::tr( "polygon %1 has no rings" ).arg( i ) ) );
          mErrorCount++;
          continue;
        }

        for ( int j = i + 1;  !mStop && j < mp.size(); j++ )
        {
          if ( mp[j].isEmpty() )
            continue;

          if ( ringInRing( mp[i][0], mp[j][0] ) )
          {
            emit errorFound( QgsGeometry::Error( QObject::tr( "polygon %1 inside polygon %2" ).arg( i ).arg( j ) ) );
            mErrorCount++;
          }
          else if ( ringInRing( mp[j][0], mp[i][0] ) )
          {
            emit errorFound( QgsGeometry::Error( QObject::tr( "polygon %1 inside polygon %2" ).arg( j ).arg( i ) ) );
            mErrorCount++;
          }
          else
          {
            checkRingIntersections( i, 0, mp[i][0], j, 0, mp[j][0] );
          }
        }
      }
    }
    break;

    case QGis::WKBNoGeometry:
    case QGis::WKBUnknown:
      QgsDebugMsg( QObject::tr( "Unknown geometry type" ) );
      emit errorFound( QgsGeometry::Error( QObject::tr( "Unknown geometry type %1" ).arg( mG.wkbType() ) ) );
      mErrorCount++;
      break;
  }

  QgsDebugMsg( "validation finished." );

  if ( mStop )
  {
    emit errorFound( QObject::tr( "Geometry validation was aborted." ) );
  }
  else if ( mErrorCount > 0 )
  {
    emit errorFound( QObject::tr( "Geometry has %1 errors." ).arg( mErrorCount ) );
  }
#if 0
  else
  {
    emit errorFound( QObject::tr( "Geometry is valid." ) );
  }
#endif
}

void QgsGeometryValidator::addError( QgsGeometry::Error e )
{
  if ( mErrors )
    *mErrors << e;
}

void QgsGeometryValidator::validateGeometry( QgsGeometry *g, QList<QgsGeometry::Error> &errors )
{
  QgsGeometryValidator *gv = new QgsGeometryValidator( g, &errors );
  connect( gv, SIGNAL( errorFound( QgsGeometry::Error ) ), gv, SLOT( addError( QgsGeometry::Error ) ) );
  gv->run();
  gv->wait();
}

//
// distance of point q from line through p in direction v
// return >0  => q lies left of the line
//        <0  => q lies right of the line
//
double QgsGeometryValidator::distLine2Point( QgsPoint p, QgsVector v, QgsPoint q )
{
  if ( v.length() == 0 )
  {
    throw QgsException( QObject::tr( "invalid line" ) );
  }

  return ( v.x()*( q.y() - p.y() ) - v.y()*( q.x() - p.x() ) ) / v.length();
}

bool QgsGeometryValidator::intersectLines( QgsPoint p, QgsVector v, QgsPoint q, QgsVector w, QgsPoint &s )
{
  double d = v.y() * w.x() - v.x() * w.y();

  if ( d == 0 )
    return false;

  double dx = q.x() - p.x();
  double dy = q.y() - p.y();
  double k = ( dy * w.x() - dx * w.y() ) / d;

  s = p + v * k;

  return true;
}

bool QgsGeometryValidator::pointInRing( const QgsPolyline &ring, const QgsPoint &p )
{
  bool inside = false;
  int j = ring.size() - 1;

  for ( int i = 0; !mStop && i < ring.size(); i++ )
  {
    if ( ring[i].x() == p.x() && ring[i].y() == p.y() )
      return true;

    if (( ring[i].y() < p.y() && ring[j].y() >= p.y() ) ||
        ( ring[j].y() < p.y() && ring[i].y() >= p.y() ) )
    {
      if ( ring[i].x() + ( p.y() - ring[i].y() ) / ( ring[j].y() - ring[i].y() )*( ring[j].x() - ring[i].x() ) <= p.x() )
        inside = !inside;
    }

    j = i;
  }

  return inside;
}

bool QgsGeometryValidator::ringInRing( const QgsPolyline &inside, const QgsPolyline &outside )
{
  for ( int i = 0; !mStop && i < inside.size(); i++ )
  {
    if ( !pointInRing( outside, inside[i] ) )
      return false;
  }

  return true;
}