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;
}