double Heatmap::calculateKernelValue( double distance, int bandwidth, int kernelShape ) { switch ( kernelShape ) { case Heatmap::Triangular: return triangularKernel( distance , bandwidth ); case Heatmap::Uniform: return uniformKernel( distance, bandwidth ); case Heatmap::Quartic: return quarticKernel( distance, bandwidth ); case Heatmap::Triweight: return triweightKernel( distance, bandwidth ); case Heatmap::Epanechnikov: return epanechnikovKernel( distance, bandwidth ); } return 0; }
double Heatmap::calculateKernelValue( const double distance, const int bandwidth, const KernelShape shape, const OutputValues outputType ) { switch ( shape ) { case Heatmap::Triangular: return triangularKernel( distance, bandwidth, outputType ); case Heatmap::Uniform: return uniformKernel( distance, bandwidth, outputType ); case Heatmap::Quartic: return quarticKernel( distance, bandwidth, outputType ); case Heatmap::Triweight: return triweightKernel( distance, bandwidth, outputType ); case Heatmap::Epanechnikov: return epanechnikovKernel( distance, bandwidth, outputType ); } return 0; }
bool QgsHeatmapRenderer::renderFeature( QgsFeature& feature, QgsRenderContext& context, int layer, bool selected, bool drawVertexMarker ) { Q_UNUSED( layer ); Q_UNUSED( selected ); Q_UNUSED( drawVertexMarker ); if ( !context.painter() ) { return false; } if ( !feature.constGeometry() || feature.constGeometry()->type() != QGis::Point ) { //can only render point type return false; } double weight = 1.0; if ( !mWeightExpressionString.isEmpty() ) { QVariant value; if ( mWeightAttrNum == -1 ) { Q_ASSERT( mWeightExpression.data() ); value = mWeightExpression->evaluate( &feature ); } else { QgsAttributes attrs = feature.attributes(); value = attrs.value( mWeightAttrNum ); } bool ok = false; double evalWeight = value.toDouble( &ok ); if ( ok ) { weight = evalWeight; } } int width = context.painter()->device()->width() / mRenderQuality; int height = context.painter()->device()->height() / mRenderQuality; //transform geometry if required QgsGeometry* transformedGeom = 0; const QgsCoordinateTransform* xform = context.coordinateTransform(); if ( xform ) { transformedGeom = new QgsGeometry( *feature.constGeometry() ); transformedGeom->transform( *xform ); } //convert point to multipoint QgsMultiPoint multiPoint = convertToMultipoint( transformedGeom ? transformedGeom : feature.constGeometry() ); delete transformedGeom; transformedGeom = 0; //loop through all points in multipoint for ( QgsMultiPoint::const_iterator pointIt = multiPoint.constBegin(); pointIt != multiPoint.constEnd(); ++pointIt ) { QgsPoint pixel = context.mapToPixel().transform( *pointIt ); int pointX = pixel.x() / mRenderQuality; int pointY = pixel.y() / mRenderQuality; for ( int x = qMax( pointX - mRadiusPixels, 0 ); x < qMin( pointX + mRadiusPixels, width ); ++x ) { for ( int y = qMax( pointY - mRadiusPixels, 0 ); y < qMin( pointY + mRadiusPixels, height ); ++y ) { int index = y * width + x; if ( index >= mValues.count( ) ) { continue; } double distanceSquared = pow( pointX - x, 2.0 ) + pow( pointY - y, 2.0 ); if ( distanceSquared > mRadiusSquared ) { continue; } double score = weight * quarticKernel( sqrt( distanceSquared ), mRadiusPixels ); double value = mValues[ index ] + score; if ( value > mCalculatedMaxValue ) { mCalculatedMaxValue = value; } mValues[ index ] = value; } } } mFeaturesRendered++; #if 0 //TODO - enable progressive rendering if ( mFeaturesRendered % 200 == 0 ) { renderImage( context ); } #endif return true; }