@polar/plugin-draw/src/store/createInteractions/localSelector.ts

Draw plugin for POLAR that adds draw interactions to the map, allowing users to place various shapes and texts.

import { Collection, Feature, Map, MapBrowserEvent } from 'ol'
import { CreateInteractionsPayload } from '../../types'

/* sets the topmost hovered feature as singleton feature in collection */
export const makeLocalSelector =
  (
    map: Map,
    activeContainer: { active: boolean },
    features: Collection<Feature>,
    drawLayer: CreateInteractionsPayload['drawLayer']
  ) =>
  // bound event processor
  (e: MapBrowserEvent<UIEvent>) => {
    if (!activeContainer.active) {
      map.forEachFeatureAtPixel(
        e.pixel,
        (f) => {
          if (f !== features.item(0)) {
            features.setAt(0, f as Feature)
          }
          return true
        },
        {
          layerFilter: (l) => l === drawLayer,
        }
      )
    }
  }