C++ QgsSimplifyMethod类代码示例

bool QgsOgrFeatureIterator::prepareSimplification( const QgsSimplifyMethod& simplifyMethod )
{
  delete mGeometrySimplifier;
  mGeometrySimplifier = NULL;

  // setup simplification of OGR-geometries fetched
  if ( !( mRequest.flags() & QgsFeatureRequest::NoGeometry ) && simplifyMethod.methodType() != QgsSimplifyMethod::NoSimplification && !simplifyMethod.forceLocalOptimization() )
  {
    QgsSimplifyMethod::MethodType methodType = simplifyMethod.methodType();
    Q_UNUSED( methodType );

#if defined(GDAL_VERSION_NUM) && defined(GDAL_COMPUTE_VERSION)
#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(1,11,0)
    if ( methodType == QgsSimplifyMethod::OptimizeForRendering )
    {
      int simplifyFlags = QgsMapToPixelSimplifier::SimplifyGeometry | QgsMapToPixelSimplifier::SimplifyEnvelope;
      mGeometrySimplifier = new QgsOgrMapToPixelSimplifier( simplifyFlags, simplifyMethod.tolerance() );
      return true;
    }
#endif
#endif
#if defined(GDAL_VERSION_NUM) && GDAL_VERSION_NUM >= 1900
    if ( methodType == QgsSimplifyMethod::PreserveTopology )
    {
      mGeometrySimplifier = new QgsOgrTopologyPreservingSimplifier( simplifyMethod.tolerance() );
      return true;
    }
#endif

    QgsDebugMsg( QString( "Simplification method type (%1) is not recognised by OgrFeatureIterator class" ).arg( methodType ) );
  }
  return QgsAbstractFeatureIterator::prepareSimplification( simplifyMethod );
}

bool QgsPostgresFeatureIterator::prepareSimplification( const QgsSimplifyMethod& simplifyMethod )
{
    // setup simplification of geometries to fetch
    if ( !( mRequest.flags() & QgsFeatureRequest::NoGeometry ) &&
            simplifyMethod.methodType() != QgsSimplifyMethod::NoSimplification &&
            !simplifyMethod.forceLocalOptimization() )
    {
        QgsSimplifyMethod::MethodType methodType = simplifyMethod.methodType();

        if ( methodType == QgsSimplifyMethod::OptimizeForRendering || methodType == QgsSimplifyMethod::PreserveTopology )
        {
            return true;
        }
        else
        {
            QgsDebugMsg( QString( "Simplification method type (%1) is not recognised by PostgresFeatureIterator" ).arg( methodType ) );
        }
    }
    return QgsAbstractFeatureIterator::prepareSimplification( simplifyMethod );
}

bool QgsVectorLayerFeatureIterator::prepareSimplification( const QgsSimplifyMethod& simplifyMethod )
{
  delete mEditGeometrySimplifier;
  mEditGeometrySimplifier = NULL;

  // setup simplification for edited geometries to fetch
  if ( !( mRequest.flags() & QgsFeatureRequest::NoGeometry ) && simplifyMethod.methodType() != QgsSimplifyMethod::NoSimplification && L->hasGeometryType() && L->geometryType() != QGis::Point )
  {
    mEditGeometrySimplifier = QgsSimplifyMethod::createGeometrySimplifier( simplifyMethod );
    return mEditGeometrySimplifier != NULL;
  }
  return false;
}

bool QgsAbstractFeatureIterator::prepareSimplification( const QgsSimplifyMethod& simplifyMethod )
{
  mLocalSimplification = false;

  delete mGeometrySimplifier;
  mGeometrySimplifier = NULL;

  // setup the simplification of geometries to fetch
  if ( !( mRequest.flags() & QgsFeatureRequest::NoGeometry ) && simplifyMethod.methodType() != QgsSimplifyMethod::NoSimplification && ( simplifyMethod.forceLocalOptimization() || !providerCanSimplify( simplifyMethod.methodType() ) ) )
  {
    mGeometrySimplifier = QgsSimplifyMethod::createGeometrySimplifier( simplifyMethod );
    mLocalSimplification = mGeometrySimplifier != NULL;
    return mLocalSimplification;
  }
  return false;
}

//.........这里部分代码省略.........
  {
    double map2pixelTol = mSimplifyMethod.threshold();
    bool validTransform = true;

    const QgsMapToPixel& mtp = mContext.mapToPixel();
    map2pixelTol *= mtp.mapUnitsPerPixel();
    const QgsCoordinateTransform* ct = mContext.coordinateTransform();

    // resize the tolerance using the change of size of an 1-BBOX from the source CoordinateSystem to the target CoordinateSystem
    if ( ct && !( ct->isShortCircuited() ) )
    {
      try
      {
        QgsPoint center = mContext.extent().center();
        double rectSize = ct->sourceCrs().geographicFlag() ? 0.0008983 /* ~100/(40075014/360=111319.4833) */ : 100;

        QgsRectangle sourceRect = QgsRectangle( center.x(), center.y(), center.x() + rectSize, center.y() + rectSize );
        QgsRectangle targetRect = ct->transform( sourceRect );

        QgsDebugMsg( QString( "Simplify - SourceTransformRect=%1" ).arg( sourceRect.toString( 16 ) ) );
        QgsDebugMsg( QString( "Simplify - TargetTransformRect=%1" ).arg( targetRect.toString( 16 ) ) );

        if ( !sourceRect.isEmpty() && sourceRect.isFinite() && !targetRect.isEmpty() && targetRect.isFinite() )
        {
          QgsPoint minimumSrcPoint( sourceRect.xMinimum(), sourceRect.yMinimum() );
          QgsPoint maximumSrcPoint( sourceRect.xMaximum(), sourceRect.yMaximum() );
          QgsPoint minimumDstPoint( targetRect.xMinimum(), targetRect.yMinimum() );
          QgsPoint maximumDstPoint( targetRect.xMaximum(), targetRect.yMaximum() );

          double sourceHypothenuse = sqrt( minimumSrcPoint.sqrDist( maximumSrcPoint ) );
          double targetHypothenuse = sqrt( minimumDstPoint.sqrDist( maximumDstPoint ) );

          QgsDebugMsg( QString( "Simplify - SourceHypothenuse=%1" ).arg( sourceHypothenuse ) );
          QgsDebugMsg( QString( "Simplify - TargetHypothenuse=%1" ).arg( targetHypothenuse ) );

          if ( !qgsDoubleNear( targetHypothenuse, 0.0 ) )
            map2pixelTol *= ( sourceHypothenuse / targetHypothenuse );
        }
      }
      catch ( QgsCsException &cse )
      {
        QgsMessageLog::logMessage( QObject::tr( "Simplify transform error caught: %1" ).arg( cse.what() ), QObject::tr( "CRS" ) );
        validTransform = false;
      }
    }

    if ( validTransform )
    {
      QgsSimplifyMethod simplifyMethod;
      simplifyMethod.setMethodType( QgsSimplifyMethod::OptimizeForRendering );
      simplifyMethod.setTolerance( map2pixelTol );
      simplifyMethod.setThreshold( mSimplifyMethod.threshold() );

      simplifyMethod.setForceLocalOptimization( mSimplifyMethod.forceLocalOptimization() );

      featureRequest.setSimplifyMethod( simplifyMethod );

      QgsVectorSimplifyMethod vectorMethod = mSimplifyMethod;
      mContext.setVectorSimplifyMethod( vectorMethod );
    }
    else
    {
      QgsVectorSimplifyMethod vectorMethod;
      vectorMethod.setSimplifyHints( QgsVectorSimplifyMethod::NoSimplification );
      mContext.setVectorSimplifyMethod( vectorMethod );
    }
  }
  else
  {
    QgsVectorSimplifyMethod vectorMethod;
    vectorMethod.setSimplifyHints( QgsVectorSimplifyMethod::NoSimplification );
    mContext.setVectorSimplifyMethod( vectorMethod );
  }

  QgsFeatureIterator fit = mSource->getFeatures( featureRequest );

  if (( mRendererV2->capabilities() & QgsFeatureRendererV2::SymbolLevels ) && mRendererV2->usingSymbolLevels() )
    drawRendererV2Levels( fit );
  else
    drawRendererV2( fit );

  if ( usingEffect )
  {
    mRendererV2->paintEffect()->end( mContext );
  }

  //apply layer transparency for vector layers
  if ( mContext.useAdvancedEffects() && mLayerTransparency != 0 )
  {
    // a layer transparency has been set, so update the alpha for the flattened layer
    // by combining it with the layer transparency
    QColor transparentFillColor = QColor( 0, 0, 0, 255 - ( 255 * mLayerTransparency / 100 ) );
    // use destination in composition mode to merge source's alpha with destination
    mContext.painter()->setCompositionMode( QPainter::CompositionMode_DestinationIn );
    mContext.painter()->fillRect( 0, 0, mContext.painter()->device()->width(),
                                  mContext.painter()->device()->height(), transparentFillColor );
  }

  return true;
}

//.........这里部分代码省略.........

  // enable the simplification of the geometries (Using the current map2pixel context) before send it to renderer engine.
  if ( mSimplifyGeometry )
  {
    double map2pixelTol = mSimplifyMethod.threshold();
    bool validTransform = true;

    const QgsMapToPixel &mtp = mContext.mapToPixel();
    map2pixelTol *= mtp.mapUnitsPerPixel();
    QgsCoordinateTransform ct = mContext.coordinateTransform();

    // resize the tolerance using the change of size of an 1-BBOX from the source CoordinateSystem to the target CoordinateSystem
    if ( ct.isValid() && !ct.isShortCircuited() )
    {
      try
      {
        QgsPointXY center = mContext.extent().center();
        double rectSize = ct.sourceCrs().isGeographic() ? 0.0008983 /* ~100/(40075014/360=111319.4833) */ : 100;

        QgsRectangle sourceRect = QgsRectangle( center.x(), center.y(), center.x() + rectSize, center.y() + rectSize );
        QgsRectangle targetRect = ct.transform( sourceRect );

        QgsDebugMsgLevel( QStringLiteral( "Simplify - SourceTransformRect=%1" ).arg( sourceRect.toString( 16 ) ), 4 );
        QgsDebugMsgLevel( QStringLiteral( "Simplify - TargetTransformRect=%1" ).arg( targetRect.toString( 16 ) ), 4 );

        if ( !sourceRect.isEmpty() && sourceRect.isFinite() && !targetRect.isEmpty() && targetRect.isFinite() )
        {
          QgsPointXY minimumSrcPoint( sourceRect.xMinimum(), sourceRect.yMinimum() );
          QgsPointXY maximumSrcPoint( sourceRect.xMaximum(), sourceRect.yMaximum() );
          QgsPointXY minimumDstPoint( targetRect.xMinimum(), targetRect.yMinimum() );
          QgsPointXY maximumDstPoint( targetRect.xMaximum(), targetRect.yMaximum() );

          double sourceHypothenuse = std::sqrt( minimumSrcPoint.sqrDist( maximumSrcPoint ) );
          double targetHypothenuse = std::sqrt( minimumDstPoint.sqrDist( maximumDstPoint ) );

          QgsDebugMsgLevel( QStringLiteral( "Simplify - SourceHypothenuse=%1" ).arg( sourceHypothenuse ), 4 );
          QgsDebugMsgLevel( QStringLiteral( "Simplify - TargetHypothenuse=%1" ).arg( targetHypothenuse ), 4 );

          if ( !qgsDoubleNear( targetHypothenuse, 0.0 ) )
            map2pixelTol *= ( sourceHypothenuse / targetHypothenuse );
        }
      }
      catch ( QgsCsException &cse )
      {
        QgsMessageLog::logMessage( QObject::tr( "Simplify transform error caught: %1" ).arg( cse.what() ), QObject::tr( "CRS" ) );
        validTransform = false;
      }
    }

    if ( validTransform )
    {
      QgsSimplifyMethod simplifyMethod;
      simplifyMethod.setMethodType( QgsSimplifyMethod::OptimizeForRendering );
      simplifyMethod.setTolerance( map2pixelTol );
      simplifyMethod.setThreshold( mSimplifyMethod.threshold() );
      simplifyMethod.setForceLocalOptimization( mSimplifyMethod.forceLocalOptimization() );
      featureRequest.setSimplifyMethod( simplifyMethod );

      QgsVectorSimplifyMethod vectorMethod = mSimplifyMethod;
      vectorMethod.setTolerance( map2pixelTol );
      mContext.setVectorSimplifyMethod( vectorMethod );
    }
    else
    {
      QgsVectorSimplifyMethod vectorMethod;
      vectorMethod.setSimplifyHints( QgsVectorSimplifyMethod::NoSimplification );
      mContext.setVectorSimplifyMethod( vectorMethod );
    }
  }
  else
  {
    QgsVectorSimplifyMethod vectorMethod;
    vectorMethod.setSimplifyHints( QgsVectorSimplifyMethod::NoSimplification );
    mContext.setVectorSimplifyMethod( vectorMethod );
  }

  QgsFeatureIterator fit = mSource->getFeatures( featureRequest );
  // Attach an interruption checker so that iterators that have potentially
  // slow fetchFeature() implementations, such as in the WFS provider, can
  // check it, instead of relying on just the mContext.renderingStopped() check
  // in drawRenderer()
  fit.setInterruptionChecker( mInterruptionChecker.get() );

  if ( ( mRenderer->capabilities() & QgsFeatureRenderer::SymbolLevels ) && mRenderer->usingSymbolLevels() )
    drawRendererLevels( fit );
  else
    drawRenderer( fit );

  if ( !fit.isValid() )
  {
    mErrors.append( QStringLiteral( "Data source invalid" ) );
  }

  if ( usingEffect )
  {
    mRenderer->paintEffect()->end( mContext );
  }

  return true;
}