Function push_filter_layer 

pub fn push_filter_layer<D>(
    recorder: &mut CommandRecorder<D>,
    props: LayerProps,
    filter: LayerFilter,
    transform: Affine,
) -> Result<(), EngineError>

Opens a filtered layer on recorder — the engine-internal counterpart of CommandRecorder::push_layer for a layer that carries a filter.

Close it with CommandRecorder::pop_layer, exactly like a regular layer. Popping is what computes the layer’s bounds, and for a filtered layer those bounds are the expanded ones the filter paints into, which is what the scheduler sizes the layer’s pages from.

Errors

Whatever LayerFilter::filter_data refuses; nothing is recorded when it does, so a refused filter leaves the recording exactly as it was rather than opening a layer no pop_layer will balance.