src/core/qgsvectorlayer.cpp

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/***************************************************************************
                               qgsvectorlayer.cpp
  This class implements a generic means to display vector layers. The features
  and attributes are read from the data store using a "data provider" plugin.
  QgsVectorLayer can be used with any data store for which an appropriate
  plugin is available.
                              -------------------
          begin                : Oct 29, 2003
          copyright            : (C) 2003 by Gary E.Sherman
          email                : sherman at mrcc.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.                                   *
 *                                                                         *
 ***************************************************************************/
/*  $Id: qgsvectorlayer.cpp 9897 2008-12-26 21:07:03Z jef $ */

#include <cassert>
#include <cfloat>
#include <cstring>
#include <climits>
#include <cmath>
#include <iosfwd>
#include <limits>
#include <memory>
#include <set>
#include <sstream>
#include <utility>

#include <QImage>
#include <QPainter>
#include <QPainterPath>
#include <QPolygonF>
#include <QSettings>
#include <QString>

#include "qgsvectorlayer.h"

// renderers
#include "qgscontinuouscolorrenderer.h"
#include "qgsgraduatedsymbolrenderer.h"
#include "qgsrenderer.h"
#include "qgssinglesymbolrenderer.h"
#include "qgsuniquevaluerenderer.h"

#include "qgsattributeaction.h"

#include "qgis.h" //for globals
#include "qgsapplication.h"
#include "qgscoordinatetransform.h"
#include "qgsfeature.h"
#include "qgsfield.h"
#include "qgsgeometry.h"
#include "qgslabel.h"
#include "qgslogger.h"
#include "qgsmaptopixel.h"
#include "qgspoint.h"
#include "qgsproviderregistry.h"
#include "qgsrectangle.h"
#include "qgsrendercontext.h"
#include "qgssinglesymbolrenderer.h"
#include "qgscoordinatereferencesystem.h"
#include "qgsvectordataprovider.h"
#include "qgslogger.h"

#ifdef Q_WS_X11
#include "qgsclipper.h"
#endif

#ifdef TESTPROVIDERLIB
#include <dlfcn.h>
#endif


static const char * const ident_ = "$Id: qgsvectorlayer.cpp 9897 2008-12-26 21:07:03Z jef $";

// typedef for the QgsDataProvider class factory
typedef QgsDataProvider * create_it( const QString* uri );



QgsVectorLayer::QgsVectorLayer( QString vectorLayerPath,
                                QString baseName,
                                QString providerKey,
                                bool loadDefaultStyleFlag )
    : QgsMapLayer( VectorLayer, baseName, vectorLayerPath ),
    mUpdateThreshold( 0 ),     // XXX better default value?
    mDataProvider( NULL ),
    mProviderKey( providerKey ),
    mEditable( false ),
    mModified( false ),
    mMaxUpdatedIndex( -1 ),
    mRenderer( 0 ),
    mLabel( 0 ),
    mLabelOn( false ),
    mFetching( false )
{
  mActions = new QgsAttributeAction;

  // if we're given a provider type, try to create and bind one to this layer
  if ( ! mProviderKey.isEmpty() )
  {
    setDataProvider( mProviderKey );
  }
  if ( mValid )
  {
    // check if there is a default style / propertysheet defined
    // for this layer and if so apply it
    //
    if ( loadDefaultStyleFlag )
    {
      bool defaultLoadedFlag = false;
      loadDefaultStyle( defaultLoadedFlag );
      if ( !defaultLoadedFlag )
      {
        setCoordinateSystem();
        // add single symbol renderer as default
        QgsSingleSymbolRenderer *renderer = new QgsSingleSymbolRenderer( geometryType() );
        setRenderer( renderer );
      }
    }
    else  // Otherwise use some very basic defaults
    {
      setCoordinateSystem();
      // add single symbol renderer as default
      QgsSingleSymbolRenderer *renderer = new QgsSingleSymbolRenderer( geometryType() );
      setRenderer( renderer );
    }
    // Get the update threshold from user settings. We
    // do this only on construction to avoid the penality of
    // fetching this each time the layer is drawn. If the user
    // changes the threshold from the preferences dialog, it will
    // have no effect on existing layers
    // TODO: load this setting somewhere else [MD]
    //QSettings settings;
    //mUpdateThreshold = settings.readNumEntry("Map/updateThreshold", 1000);
  }
} // QgsVectorLayer ctor



QgsVectorLayer::~QgsVectorLayer()
{
  QgsDebugMsg( "In QgsVectorLayer destructor" );

  emit layerDeleted();

  mValid = false;

  if ( mRenderer )
  {
    delete mRenderer;
  }
  // delete the provider object
  delete mDataProvider;

  delete mLabel;

  // Destroy any cached geometries and clear the references to them
  deleteCachedGeometries();

  delete mActions;
}

QString QgsVectorLayer::storageType() const
{
  if ( mDataProvider )
  {
    return mDataProvider->storageType();
  }
  return 0;
}


QString QgsVectorLayer::capabilitiesString() const
{
  if ( mDataProvider )
  {
    return mDataProvider->capabilitiesString();
  }
  return 0;
}

QString QgsVectorLayer::dataComment() const
{
  if ( mDataProvider )
  {
    return mDataProvider->dataComment();
  }
  return QString();
}


QString QgsVectorLayer::providerType() const
{
  return mProviderKey;
}

void QgsVectorLayer::setDisplayField( QString fldName )
{
  // If fldName is provided, use it as the display field, otherwise
  // determine the field index for the feature column of the identify
  // dialog. We look for fields containing "name" first and second for
  // fields containing "id". If neither are found, the first field
  // is used as the node.
  QString idxName = "";
  QString idxId = "";

  if ( !fldName.isEmpty() )
  {
    mDisplayField = fldName;
  }
  else
  {
    const QgsFieldMap &fields = pendingFields();
    int fieldsSize = fields.size();

    for ( QgsFieldMap::const_iterator it = fields.begin(); it != fields.end(); ++it )
    {
      QString fldName = it.value().name();
      QgsDebugMsg( "Checking field " + fldName + " of " + QString::number( fieldsSize ) + " total" );

      // Check the fields and keep the first one that matches.
      // We assume that the user has organized the data with the
      // more "interesting" field names first. As such, name should
      // be selected before oldname, othername, etc.
      if ( fldName.indexOf( "name", false ) > -1 )
      {
        if ( idxName.isEmpty() )
        {
          idxName = fldName;
        }
      }
      if ( fldName.indexOf( "descrip", false ) > -1 )
      {
        if ( idxName.isEmpty() )
        {
          idxName = fldName;
        }
      }
      if ( fldName.indexOf( "id", false ) > -1 )
      {
        if ( idxId.isEmpty() )
        {
          idxId = fldName;
        }
      }
    }

    //if there were no fields in the dbf just return - otherwise qgis segfaults!
    if ( fieldsSize == 0 )
      return;

    if ( idxName.length() > 0 )
    {
      mDisplayField = idxName;
    }
    else
    {
      if ( idxId.length() > 0 )
      {
        mDisplayField = idxId;
      }
      else
      {
        mDisplayField = fields[0].name();
      }
    }

  }
}

// NOTE this is a temporary method added by Tim to prevent label clipping
// which was occurring when labeller was called in the main draw loop
// This method will probably be removed again in the near future!
void QgsVectorLayer::drawLabels( QgsRenderContext& rendererContext )
{
  QgsDebugMsg( "Starting draw of labels" );

  if ( mRenderer && mLabelOn &&
       ( !label()->scaleBasedVisibility() ||
         ( label()->minScale() <= rendererContext.rendererScale() &&
           rendererContext.rendererScale() <= label()->maxScale() ) ) )
  {
    QgsAttributeList attributes = mRenderer->classificationAttributes();

    // Add fields required for labels
    mLabel->addRequiredFields( attributes );

    QgsDebugMsg( "Selecting features based on view extent" );

    int featureCount = 0;

    try
    {
      // select the records in the extent. The provider sets a spatial filter
      // and sets up the selection set for retrieval
      select( attributes, rendererContext.extent() );

      QgsFeature fet;
      while ( nextFeature( fet ) )
      {
        if ( mRenderer->willRenderFeature( &fet ) )
        {
          bool sel = mSelectedFeatureIds.contains( fet.id() );
          mLabel->renderLabel( rendererContext.painter(), rendererContext.extent(), rendererContext.coordinateTransform(), &( rendererContext.mapToPixel() ), fet, sel, 0, rendererContext.scaleFactor(), rendererContext.rasterScaleFactor() );
        }
        featureCount++;
      }
    }
    catch ( QgsCsException &e )
    {
      Q_UNUSED( e );
      QgsLogger::critical( "Error projecting label locations, caught in " + QString( __FILE__ ) + ", line " + QString( __LINE__ ) );
    }

#ifdef QGISDEBUG
    QgsLogger::debug( "Total features processed", featureCount, 1, __FILE__, __FUNCTION__, __LINE__ );
#endif

    // XXX Something in our draw event is triggering an additional draw event when resizing [TE 01/26/06]
    // XXX Calling this will begin processing the next draw event causing image havoc and recursion crashes.
    //qApp->processEvents();

  }
}


unsigned char* QgsVectorLayer::drawLineString(
  unsigned char *feature,
  QPainter* p,
  const QgsMapToPixel* mtp,
  const QgsCoordinateTransform* ct,
  bool drawingToEditingCanvas )
{
  unsigned char *ptr = feature + 5;
  unsigned int wkbType = *(( int* )( feature + 1 ) );
  unsigned int nPoints = *(( int* )ptr );
  ptr = feature + 9;

  bool hasZValue = ( wkbType == QGis::WKBLineString25D );

  std::vector<double> x( nPoints );
  std::vector<double> y( nPoints );
  std::vector<double> z( nPoints, 0.0 );

  // Extract the points from the WKB format into the x and y vectors.
  for ( register unsigned int i = 0; i < nPoints; ++i )
  {
    x[i] = *(( double * ) ptr );
    ptr += sizeof( double );
    y[i] = *(( double * ) ptr );
    ptr += sizeof( double );

    if ( hasZValue ) // ignore Z value
      ptr += sizeof( double );
  }

  // Transform the points into map coordinates (and reproject if
  // necessary)

  transformPoints( x, y, z, mtp, ct );

#if defined(Q_WS_X11)
  // Work around a +/- 32768 limitation on coordinates in X11

  // Look through the x and y coordinates and see if there are any
  // that need trimming. If one is found, there's no need to look at
  // the rest of them so end the loop at that point.
  for ( register unsigned int i = 0; i < nPoints; ++i )
  {
    if ( std::abs( x[i] ) > QgsClipper::MAX_X ||
         std::abs( y[i] ) > QgsClipper::MAX_Y )
    {
      QgsClipper::trimFeature( x, y, true ); // true = polyline
      nPoints = x.size(); // trimming may change nPoints.
      break;
    }
  }
#endif

  // set up QPolygonF class with transformed points
  QPolygonF pa( nPoints );
  for ( register unsigned int i = 0; i < nPoints; ++i )
  {
    pa[i].setX( x[i] );
    pa[i].setY( y[i] );
  }

#ifdef QGISDEBUGVERBOSE
  // this is only used for verbose debug output
  for ( int i = 0; i < pa.size(); ++i )
  {
    QgsDebugMsgLevel( "pa" + QString::number( pa.point( i ).x() ), 2 );
    QgsDebugMsgLevel( "pa" + QString::number( pa.point( i ).y() ), 2 );
  }
#endif

  // The default pen gives bevelled joins between segements of the
  // polyline, which is good enough for the moment.
  //preserve a copy of the pen before we start fiddling with it
  QPen pen = p->pen(); // to be kept original

  //
  // experimental alpha transparency
  // 255 = opaque
  //
  QPen myTransparentPen = p->pen(); // store current pen
  QColor myColor = myTransparentPen.color();
  //only set transparency from layer level if renderer does not provide
  //transparency on class level
  if ( !mRenderer->usesTransparency() )
  {
    myColor.setAlpha( mTransparencyLevel );
  }
  myTransparentPen.setColor( myColor );
  p->setPen( myTransparentPen );
  p->drawPolyline( pa );

  // draw vertex markers if in editing mode, but only to the main canvas
  if ( mEditable && drawingToEditingCanvas )
  {
    QgsVectorLayer::VertexMarkerType markerType = currentVertexMarkerType();

    std::vector<double>::const_iterator xIt;
    std::vector<double>::const_iterator yIt;
    for ( xIt = x.begin(), yIt = y.begin(); xIt != x.end(); ++xIt, ++yIt )
    {
      drawVertexMarker(( int )( *xIt ), ( int )( *yIt ), *p, markerType );
    }
  }

  //restore the pen
  p->setPen( pen );

  return ptr;
}

unsigned char *QgsVectorLayer::drawPolygon(
  unsigned char *feature,
  QPainter *p,
  const QgsMapToPixel *mtp,
  const QgsCoordinateTransform *ct,
  bool drawingToEditingCanvas )
{
  typedef std::pair<std::vector<double>, std::vector<double> > ringType;
  typedef ringType* ringTypePtr;
  typedef std::vector<ringTypePtr> ringsType;

  // get number of rings in the polygon
  unsigned int numRings = *(( int* )( feature + 1 + sizeof( int ) ) );

  if ( numRings == 0 )  // sanity check for zero rings in polygon
    return feature + 9;

  unsigned int wkbType = *(( int* )( feature + 1 ) );

  bool hasZValue = ( wkbType == QGis::WKBPolygon25D );

  int total_points = 0;

  // A vector containing a pointer to a pair of double vectors.The
  // first vector in the pair contains the x coordinates, and the
  // second the y coordinates.
  ringsType rings;

  // Set pointer to the first ring
  unsigned char* ptr = feature + 1 + 2 * sizeof( int );

  for ( register unsigned int idx = 0; idx < numRings; idx++ )
  {
    unsigned int nPoints = *(( int* )ptr );

    ringTypePtr ring = new ringType( std::vector<double>( nPoints ), std::vector<double>( nPoints ) );
    ptr += 4;

    // create a dummy vector for the z coordinate
    std::vector<double> zVector( nPoints, 0.0 );
    // Extract the points from the WKB and store in a pair of
    // vectors.
    for ( register unsigned int jdx = 0; jdx < nPoints; jdx++ )
    {
      ring->first[jdx] = *(( double * ) ptr );
      ptr += sizeof( double );
      ring->second[jdx] = *(( double * ) ptr );
      ptr += sizeof( double );

      if ( hasZValue )
        ptr += sizeof( double );
    }
    // If ring has fewer than two points, what is it then?
    // Anyway, this check prevents a crash
    if ( nPoints < 1 )
    {
      QgsDebugMsg( "Ring has only " + QString::number( nPoints ) + " points! Skipping this ring." );
      continue;
    }

    transformPoints( ring->first, ring->second, zVector, mtp, ct );

#if defined(Q_WS_X11)
    // Work around a +/- 32768 limitation on coordinates in X11

    // Look through the x and y coordinates and see if there are any
    // that need trimming. If one is found, there's no need to look at
    // the rest of them so end the loop at that point.
    for ( register unsigned int i = 0; i < nPoints; ++i )
    {
      if ( std::abs( ring->first[i] ) > QgsClipper::MAX_X ||
           std::abs( ring->second[i] ) > QgsClipper::MAX_Y )
      {
        QgsClipper::trimFeature( ring->first, ring->second, false );
        break;
      }
    }
#endif

    // Don't bother keeping the ring if it has been trimmed out of
    // existence.
    if ( ring->first.size() == 0 )
      delete ring;
    else
    {
      rings.push_back( ring );
      total_points += ring->first.size();
    }
  }

  // Now we draw the polygons

  // use painter paths for drawing polygons with holes
  // when adding polygon to the path they invert the area
  // this means that adding inner rings to the path creates
  // holes in outer ring
  QPainterPath path; // OddEven fill rule by default

  // Only try to draw polygons if there is something to draw
  if ( total_points > 0 )
  {
    // Store size here and use it in the loop to avoid penalty of
    // multiple calls to size()
    int numRings = rings.size();
    for ( register int i = 0; i < numRings; ++i )
    {
      // Store the pointer in a variable with a short name so as to make
      // the following code easier to type and read.
      ringTypePtr r = rings[i];
      // only do this once to avoid penalty of additional calls
      unsigned ringSize = r->first.size();

      // Transfer points to the array of QPointF
      QPolygonF pa( ringSize );
      for ( register unsigned int j = 0; j != ringSize; ++j )
      {
        pa[j].setX( r->first[j] );
        pa[j].setY( r->second[j] );
      }

      path.addPolygon( pa );

      // Tidy up the pointed to pairs of vectors as we finish with them
      delete rings[i];
    }

#ifdef QGISDEBUGVERBOSE
    // this is only for verbose debug output -- no optimzation is
    // needed :)
    QgsDebugMsg( "Pixel points are:" );
    for ( int i = 0; i < pa.size(); ++i )
    {
      QgsDebugMsgLevel( "i" + QString::number( i ), 2 );
      QgsDebugMsgLevel( "pa[i].x()" + QString::number( pa[i].x() ), 2 );
      QgsDebugMsgLevel( "pa[i].y()" + QString::number( pa[i].y() ), 2 );
    }
    QgsDebugMsg( "Ring positions are:" );
    QgsDebugMsg( "Ring positions are:" );
    for ( int i = 0; i < ringDetails.size(); ++i )
    {
      QgsDebugMsgLevel( "ringDetails[i].first" + QString::number( ringDetails[i].first ), 2 );
      QgsDebugMsgLevel( "ringDetails[i].second" + QString::number( ringDetails[i].second ), 2 );
    }
    QgsDebugMsg( "Outer ring point is " + QString::number( outerRingPt.x() ) + ", " + QString::number( outerRingPt.y() ) );
#endif

#if 0
    // A bit of code to aid in working out what values of
    // QgsClipper::minX, etc cause the X11 zoom bug.
    int largestX  = -std::numeric_limits<int>::max();
    int smallestX = std::numeric_limits<int>::max();
    int largestY  = -std::numeric_limits<int>::max();
    int smallestY = std::numeric_limits<int>::max();

    for ( int i = 0; i < pa.size(); ++i )
    {
      largestX  = std::max( largestX,  pa.point( i ).x() );
      smallestX = std::min( smallestX, pa.point( i ).x() );
      largestY  = std::max( largestY,  pa.point( i ).y() );
      smallestY = std::min( smallestY, pa.point( i ).y() );
    }
    QgsDebugMsg( QString( "Largest  X coordinate was %1" ).arg( largestX ) );
    QgsDebugMsg( QString( "Smallest X coordinate was %1" ).arg( smallestX ) );
    QgsDebugMsg( QString( "Largest  Y coordinate was %1" ).arg( largestY ) );
    QgsDebugMsg( QString( "Smallest Y coordinate was %1" ).arg( smallestY ) );
#endif

    //preserve a copy of the brush and pen before we start fiddling with it
    QBrush brush = p->brush(); //to be kept as original
    QPen pen = p->pen(); // to be kept original
    //
    // experimental alpha transparency
    // 255 = opaque
    //
    QBrush myTransparentBrush = p->brush();
    QColor myColor = brush.color();

    //only set transparency from layer level if renderer does not provide
    //transparency on class level
    if ( !mRenderer->usesTransparency() )
    {
      myColor.setAlpha( mTransparencyLevel );
    }
    myTransparentBrush.setColor( myColor );
    QPen myTransparentPen = p->pen(); // store current pen
    myColor = myTransparentPen.color();

    //only set transparency from layer level if renderer does not provide
    //transparency on class level
    if ( !mRenderer->usesTransparency() )
    {
      myColor.setAlpha( mTransparencyLevel );
    }
    myTransparentPen.setColor( myColor );

    p->setBrush( myTransparentBrush );
    p->setPen( myTransparentPen );

    //
    // draw the polygon
    //
    p->drawPath( path );


    // draw vertex markers if in editing mode, but only to the main canvas
    if ( mEditable && drawingToEditingCanvas )
    {
      QgsVectorLayer::VertexMarkerType markerType = currentVertexMarkerType();

      for ( int i = 0; i < path.elementCount(); ++i )
      {
        const QPainterPath::Element & e = path.elementAt( i );
        drawVertexMarker(( int )e.x, ( int )e.y, *p, markerType );
      }
    }

    //
    //restore brush and pen to original
    //
    p->setBrush( brush );
    p->setPen( pen );

  } // totalPoints > 0

  return ptr;
}

bool QgsVectorLayer::draw( QgsRenderContext& rendererContext )
{
  //set update threshold before each draw to make sure the current setting is picked up
  QSettings settings;
  mUpdateThreshold = settings.value( "Map/updateThreshold", 0 ).toInt();
  //draw ( p, viewExtent, theMapToPixelTransform, ct, drawingToEditingCanvas, 1., 1.);

  if ( mRenderer )
  {
    // painter is active (begin has been called
    /* Steps to draw the layer
       1. get the features in the view extent by SQL query
       2. read WKB for a feature
       3. transform
       4. draw
    */

    QPen pen;
    /*Pointer to a marker image*/
    QImage marker;

    if ( mEditable )
    {
      // Destroy all cached geometries and clear the references to them
      deleteCachedGeometries();
    }

    updateFeatureCount();
    int totalFeatures = pendingFeatureCount();
    int featureCount = 0;
    QgsFeature fet;
    QgsAttributeList attributes = mRenderer->classificationAttributes();
    select( attributes, rendererContext.extent() );

    try
    {
      while ( nextFeature( fet ) )
      {

        if ( rendererContext.renderingStopped() )
        {
          break;
        }

#ifndef Q_WS_MAC //MH: disable this on Mac for now to avoid problems with resizing
        if ( mUpdateThreshold > 0 && 0 == featureCount % mUpdateThreshold )
        {
          emit screenUpdateRequested();
          emit drawingProgress( featureCount, totalFeatures );
          qApp->processEvents();
        }
        else if ( featureCount % 1000 == 0 )
        {
          emit drawingProgress( featureCount, totalFeatures );
          qApp->processEvents();
        }
#else
        Q_UNUSED( totalFeatures );
#endif //Q_WS_MAC

        if ( mEditable )
        {
          // Cache this for the use of (e.g.) modifying the feature's uncommitted geometry.
          mCachedGeometries[fet.id()] = *fet.geometry();
        }

        // check if feature is selected
        // only show selections of the current layer
        // TODO: create a mechanism to let layer know whether it's current layer or not [MD]
        bool sel = mSelectedFeatureIds.contains( fet.id() );

        //QgsDebugMsg(QString("markerScale before renderFeature(): %1").arg(markerScaleFactor));
        // markerScalerFactore reflects the wanted scaling of the marker
        mRenderer->renderFeature(
          rendererContext.painter(),
          fet,
          &marker,
          sel,
          rendererContext.scaleFactor(),
          rendererContext.rasterScaleFactor() );
        // markerScalerFactore now reflects the actual scaling of the marker that the render performed.
        //QgsDebugMsg(QString("markerScale after renderFeature(): %1").arg(markerScaleFactor));

        //double scale = rendererContext.scaleFactor() /  markerScaleFactor;
        drawFeature(
          rendererContext.painter(),
          fet,
          &rendererContext.mapToPixel(),
          rendererContext.coordinateTransform(),
          &marker,
          rendererContext.scaleFactor(),
          rendererContext.rasterScaleFactor(),
          rendererContext.drawEditingInformation() );

        ++featureCount;
      }
    }
    catch ( QgsCsException &cse )
    {
      QString msg( "Failed to transform a point while drawing a feature of type '"
                   + fet.typeName() + "'. Ignoring this feature." );
      msg += cse.what();
      QgsLogger::warning( msg );
    }

  }
  else
  {
    QgsLogger::warning( "QgsRenderer is null in QgsVectorLayer::draw()" );
  }

  return TRUE; // Assume success always
}

void QgsVectorLayer::deleteCachedGeometries()
{
  // Destroy any cached geometries
  mCachedGeometries.clear();
}

void QgsVectorLayer::drawVertexMarker( int x, int y, QPainter& p, QgsVectorLayer::VertexMarkerType type )
{
  if ( type == QgsVectorLayer::SemiTransparentCircle )
  {
    p.setPen( QColor( 50, 100, 120, 200 ) );
    p.setBrush( QColor( 200, 200, 210, 120 ) );
    p.drawEllipse( QRectF( x - 7, y - 7, 14, 14 ) );
  }
  else
  {
    int size = 15;
    int m = ( size - 1 ) / 2;
    p.setPen( QColor( 255, 0, 0 ) );
    p.drawLine( x - m, y + m, x + m, y - m );
    p.drawLine( x - m, y - m, x + m, y + m );
  }
}

void QgsVectorLayer::select( int number, bool emitSignal )
{
  mSelectedFeatureIds.insert( number );

  if ( emitSignal )
  {
    emit selectionChanged();
  }
}

void QgsVectorLayer::deselect( int number, bool emitSignal )
{
  mSelectedFeatureIds.remove( number );

  if ( emitSignal )
  {
    emit selectionChanged();
  }
}

void QgsVectorLayer::select( QgsRectangle & rect, bool lock )
{
  // normalize the rectangle
  rect.normalize();

  if ( lock == false )
  {
    removeSelection( FALSE ); // don't emit signal
  }

  //select all the elements
  select( QgsAttributeList(), rect, false, true );

  QgsFeature f;
  while ( nextFeature( f ) )
  {
    select( f.id(), false ); // don't emit signal (not to redraw it everytime)
  }

  emit selectionChanged(); // now emit signal to redraw layer
}

void QgsVectorLayer::invertSelection()
{
  // copy the ids of selected features to tmp
  QgsFeatureIds tmp = mSelectedFeatureIds;

  removeSelection( FALSE ); // don't emit signal

  select( QgsAttributeList(), QgsRectangle(), false );

  QgsFeature fet;
  while ( nextFeature( fet ) )
  {
    select( fet.id(), false ); // don't emit signal
  }

  for ( QgsFeatureIds::iterator iter = tmp.begin(); iter != tmp.end(); ++iter )
  {
    mSelectedFeatureIds.remove( *iter );
  }

  emit selectionChanged();
}

void QgsVectorLayer::invertSelectionInRectangle( QgsRectangle & rect )
{
  // normalize the rectangle
  rect.normalize();

  select( QgsAttributeList(), rect, false, true );

  QgsFeature fet;
  while ( nextFeature( fet ) )
  {
    if ( mSelectedFeatureIds.contains( fet.id() ) )
    {
      deselect( fet.id(), false ); // don't emit signal
    }
    else
    {
      select( fet.id(), false ); // don't emit signal
    }
  }

  emit selectionChanged();
}

void QgsVectorLayer::removeSelection( bool emitSignal )
{
  mSelectedFeatureIds.clear();

  if ( emitSignal )
    emit selectionChanged();
}

void QgsVectorLayer::triggerRepaint()
{
  emit repaintRequested();
}

QgsVectorDataProvider* QgsVectorLayer::dataProvider()
{
  return mDataProvider;
}

const QgsVectorDataProvider* QgsVectorLayer::dataProvider() const
{
  return mDataProvider;
}

void QgsVectorLayer::setProviderEncoding( const QString& encoding )
{
  if ( mDataProvider )
  {
    mDataProvider->setEncoding( encoding );
  }
}


const QgsRenderer* QgsVectorLayer::renderer() const
{
  return mRenderer;
}

void QgsVectorLayer::setRenderer( QgsRenderer * r )
{
  if ( r != mRenderer )
  {
    delete mRenderer;
    mRenderer = r;
  }
}

QGis::GeometryType QgsVectorLayer::geometryType() const
{
  if ( mDataProvider )
  {
    int type = mDataProvider->geometryType();
    switch ( type )
    {
      case QGis::WKBPoint:
      case QGis::WKBPoint25D:
        return QGis::Point;

      case QGis::WKBLineString:
      case QGis::WKBLineString25D:
        return QGis::Line;

      case QGis::WKBPolygon:
      case QGis::WKBPolygon25D:
        return QGis::Polygon;

      case QGis::WKBMultiPoint:
      case QGis::WKBMultiPoint25D:
        return QGis::Point;

      case QGis::WKBMultiLineString:
      case QGis::WKBMultiLineString25D:
        return QGis::Line;

      case QGis::WKBMultiPolygon:
      case QGis::WKBMultiPolygon25D:
        return QGis::Polygon;
    }
#ifdef QGISDEBUG
    QgsLogger::debug( "Warning: Data Provider Geometry type is not recognised, is", type, 1, __FILE__, __FUNCTION__, __LINE__ );
#endif

  }
  else
  {
#ifdef QGISDEBUG
    qWarning( "warning, pointer to mDataProvider is null in QgsVectorLayer::type()" );
#endif

  }

  // We shouldn't get here, and if we have, other things are likely to
  // go wrong. Code that uses the type() return value should be
  // rewritten to cope with a value of QGis::Unknown. To make this
  // need known, the following message is printed every time we get
  // here.
  QgsDebugMsg( "WARNING: This code should never be reached. Problems may occur..." );

  return QGis::UnknownGeometry;
}

QGis::WkbType QgsVectorLayer::wkbType() const
{
  return ( QGis::WkbType )( mWkbType );
}

QgsRectangle QgsVectorLayer::boundingBoxOfSelected()
{
  if ( mSelectedFeatureIds.size() == 0 )//no selected features
  {
    return QgsRectangle( 0, 0, 0, 0 );
  }

  QgsRectangle r, retval;


  select( QgsAttributeList(), QgsRectangle(), true );

  retval.setMinimal();

  QgsFeature fet;
  while ( nextFeature( fet ) )
  {
    if ( mSelectedFeatureIds.contains( fet.id() ) )
    {
      if ( fet.geometry() )
      {
        r = fet.geometry()->boundingBox();
        retval.combineExtentWith( &r );
      }
    }
  }

  if ( retval.width() == 0.0 || retval.height() == 0.0 )
  {
    // If all of the features are at the one point, buffer the
    // rectangle a bit. If they are all at zero, do something a bit
    // more crude.

    if ( retval.xMinimum() == 0.0 && retval.xMaximum() == 0.0 &&
         retval.yMinimum() == 0.0 && retval.yMaximum() == 0.0 )
    {
      retval.set( -1.0, -1.0, 1.0, 1.0 );
    }
    else
    {
      const double padFactor = 1e-8;
      double widthPad = retval.xMinimum() * padFactor;
      double heightPad = retval.yMinimum() * padFactor;
      double xmin = retval.xMinimum() - widthPad;
      double xmax = retval.xMaximum() + widthPad;
      double ymin = retval.yMinimum() - heightPad;
      double ymax = retval.yMaximum() + heightPad;
      retval.set( xmin, ymin, xmax, ymax );
    }
  }

  return retval;
}



long QgsVectorLayer::featureCount() const
{
  if ( !mDataProvider )
  {
    QgsLogger::warning( " QgsVectorLayer::featureCount() invoked with null mDataProvider" );
    return 0;
  }

  return mDataProvider->featureCount();
} // QgsVectorLayer::featureCount

long QgsVectorLayer::updateFeatureCount() const
{
  if ( !mDataProvider )
  {
    QgsLogger::warning( " QgsVectorLayer::updateFeatureCount() invoked with null mDataProvider" );
    return 0;
  }
  return mDataProvider->updateFeatureCount();
}

void QgsVectorLayer::updateExtents()
{
  mLayerExtent.setMinimal();

  if ( !mDataProvider )
    QgsLogger::warning( " QgsVectorLayer::updateExtents() invoked with null mDataProvider" );

  if ( mDeletedFeatureIds.isEmpty() && mChangedGeometries.isEmpty() )
  {
    // get the extent of the layer from the provider
    // but only when there are some features already
    if ( mDataProvider->featureCount() != 0 )
    {
      QgsRectangle r = mDataProvider->extent();
      mLayerExtent.combineExtentWith( &r );
    }

    for ( QgsFeatureList::iterator it = mAddedFeatures.begin(); it != mAddedFeatures.end(); it++ )
    {
      QgsRectangle r = it->geometry()->boundingBox();
      mLayerExtent.combineExtentWith( &r );
    }
  }
  else
  {
    select( QgsAttributeList(), QgsRectangle(), true );

    QgsFeature fet;
    while ( nextFeature( fet ) )
    {
      if ( fet.geometry() )
      {
        QgsRectangle bb = fet.geometry()->boundingBox();
        mLayerExtent.combineExtentWith( &bb );
      }
    }
  }

  if ( mLayerExtent.xMinimum() > mLayerExtent.xMaximum() && mLayerExtent.yMinimum() > mLayerExtent.yMaximum() )
  {
    // special case when there are no features in provider nor any added
    mLayerExtent = QgsRectangle(); // use rectangle with zero coordinates
  }

  // Send this (hopefully) up the chain to the map canvas
  emit recalculateExtents();
}

QString QgsVectorLayer::subsetString()
{
  if ( ! mDataProvider )
  {
    QgsLogger::warning( " QgsVectorLayer::subsetString() invoked with null mDataProvider" );
    return 0;
  }
  return mDataProvider->subsetString();
}

void QgsVectorLayer::setSubsetString( QString subset )
{
  if ( ! mDataProvider )
  {
    QgsLogger::warning( " QgsVectorLayer::setSubsetString() invoked with null mDataProvider" );
    return;
  }

  mDataProvider->setSubsetString( subset );
  // get the updated data source string from the provider
  mDataSource = mDataProvider->dataSourceUri();
  updateExtents();
}

void QgsVectorLayer::updateFeatureAttributes( QgsFeature &f )
{
  // do not update when we aren't in editing mode
  if ( ! mEditable )
    return;

  if ( mChangedAttributeValues.contains( f.id() ) )
  {
    const QgsAttributeMap &map = mChangedAttributeValues[f.id()];
    for ( QgsAttributeMap::const_iterator it = map.begin(); it != map.end(); it++ )
      f.changeAttribute( it.key(), it.value() );
  }

  // remove all attributes that will disappear
  const QgsAttributeMap &map = f.attributeMap();
  for ( QgsAttributeMap::const_iterator it = map.begin(); it != map.end(); it++ )
    if ( !mUpdatedFields.contains( it.key() ) )
      f.deleteAttribute( it.key() );

  // null/add all attributes that were added, but don't exist in the feature yet
  for ( QgsFieldMap::const_iterator it = mUpdatedFields.begin(); it != mUpdatedFields.end(); it++ )
    if ( !map.contains( it.key() ) )
      f.changeAttribute( it.key(), QVariant( QString::null ) );
}

void QgsVectorLayer::updateFeatureGeometry( QgsFeature &f )
{
  if ( mChangedGeometries.contains( f.id() ) )
    f.setGeometry( mChangedGeometries[f.id()] );
}


void QgsVectorLayer::select( QgsAttributeList attributes, QgsRectangle rect, bool fetchGeometries, bool useIntersect )
{
  if ( !mDataProvider )
    return;

  mFetching        = true;
  mFetchRect       = rect;
  mFetchAttributes = attributes;
  mFetchGeometry   = fetchGeometries;

  mFetchConsidered = mDeletedFeatureIds;

  if ( mEditable )
  {
    mFetchAddedFeaturesIt = mAddedFeatures.begin();
    mFetchChangedGeomIt = mChangedGeometries.begin();
  }

  //look in the normal features of the provider
  if ( mFetchAttributes.size() > 0 )
  {
    if ( mEditable )
    {
      // fetch only available field from provider
      QgsAttributeList provAttributes;
      for ( QgsAttributeList::iterator it = mFetchAttributes.begin(); it != mFetchAttributes.end(); it++ )
      {
        if ( !mUpdatedFields.contains( *it ) || mAddedAttributeIds.contains( *it ) )
          continue;

        provAttributes << *it;
      }

      mDataProvider->select(