QgsMapHitTest class

Class that runs a hit test with given map settings.

Based on the hit test it returns which symbols will be visible on the map - this is useful for content based legend.

Public types

using LayerFilterExpression = QMap<QString, QString>: Maps an expression string to a layer id.

QgsMapHitTest(const QgsMapSettings& settings, const QgsGeometry& polygon = QgsGeometry(), const QgsMapHitTest::LayerFilterExpression& layerFilterExpression = QgsMapHitTest::LayerFilterExpression())
QgsMapHitTest(const QgsMapSettings& settings, const QgsMapHitTest::LayerFilterExpression& layerFilterExpression): Constructor version used with only expressions to filter symbols (no extent or polygon intersection)

auto legendKeyVisible(const QString& ruleKey, QgsVectorLayer* layer) const -> bool: Tests whether a given legend key is visible for a specified layer.
void run(): Runs the map hit test.
auto symbolVisible(QgsSymbol* symbol, QgsVectorLayer* layer) const -> bool: Tests whether a symbol is visible for a specified layer.

Parameters
settings	Map settings used to evaluate symbols
polygon	Polygon geometry to refine the hit test
layerFilterExpression	Expression string for each layer id to evaluate in order to refine the symbol selection

Tests whether a given legend key is visible for a specified layer.

Parameters
ruleKey	legend rule key
layer	vector layer

Tests whether a symbol is visible for a specified layer.

Parameters
symbol	symbol to find
layer	vector layer