Conditional symbol elements

Optional

The OptionalSymbolElement is used to make a symbol element optional. When an element is optional it can be rendered or not depending on the display_child property. The child element of the optional is rendered when the property is true.

Variant

The VariantSymbolElement is used to select which of its children to render. The child to render is selected by using the displayed_child_index property. The children are indexed from 0 to N. The property can be set per feature in styling scripts. It can be used, for instance, to select which sub-part of a symbol to render based on an attribute.