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Merge pull request #56784 from elpaso/bugfix-gh56652-speed-regression-with-insane-paletted-classes

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Raster - paletted: fix slow rendering with huge number of classes
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Alessandro Pasotti 2024-04-04 08:49:08 +02:00 committed by GitHub
commit 810a61a791
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1 changed files with 20 additions and 8 deletions
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28
src/core/raster/qgspalettedrasterrenderer.cpp
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@ -41,21 +41,33 @@ QgsPalettedRasterRenderer::QgsPalettedRasterRenderer( QgsRasterInterface *input,
: QgsRasterRenderer( input, QStringLiteral( "paletted" ) ) : QgsRasterRenderer( input, QStringLiteral( "paletted" ) )
, mBand( bandNumber ) , mBand( bandNumber )
{ {
QHash<QString, QHash<QColor, QVector<QVariant>>> classData;
// Prepare for the worst case, where we have to store all the values for each class
classData.reserve( classes.size() );
// This is to keep the ordering of the labels, because hash is fast but unordered
QVector<QString> labels;
labels.reserve( classes.size() );
for ( const Class &klass : std::as_const( classes ) ) for ( const Class &klass : std::as_const( classes ) )
{ {
MultiValueClassData::iterator it = std::find_if( mMultiValueClassData.begin(), mMultiValueClassData.end(), [&klass]( const MultiValueClass & val ) -> bool if ( !classData.contains( klass.label ) )
{ {
return val.label == klass.label && val.color == klass.color ; labels.push_back( klass.label );
} );
if ( it != mMultiValueClassData.end() )
{
it->values.push_back( klass.value );
} }
else classData[klass.label][klass.color].push_back( klass.value );
}
mMultiValueClassData.reserve( classData.size() );
for ( auto labelIt = labels.constBegin(); labelIt != labels.constEnd(); ++labelIt )
{ {
mMultiValueClassData.push_back( MultiValueClass{ { klass.value }, klass.color, klass.label } ); for ( auto colorIt = classData[*labelIt].constBegin(); colorIt != classData[*labelIt].constEnd(); ++colorIt )
{
mMultiValueClassData.push_back( MultiValueClass{ colorIt.value(), colorIt.key(), *labelIt } );
} }
} }
updateArrays(); updateArrays();
} }