@react-navigation/core/lib/commonjs/useFocusEvents.js

Core utilities for building navigators

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.useFocusEvents = useFocusEvents;
var React = _interopRequireWildcard(require("react"));
var _NavigationContext = require("./NavigationContext.js");
function _getRequireWildcardCache(e) { if ("function" != typeof WeakMap) return null; var r = new WeakMap(), t = new WeakMap(); return (_getRequireWildcardCache = function (e) { return e ? t : r; })(e); }
function _interopRequireWildcard(e, r) { if (!r && e && e.__esModule) return e; if (null === e || "object" != typeof e && "function" != typeof e) return { default: e }; var t = _getRequireWildcardCache(r); if (t && t.has(e)) return t.get(e); var n = { __proto__: null }, a = Object.defineProperty && Object.getOwnPropertyDescriptor; for (var u in e) if ("default" !== u && {}.hasOwnProperty.call(e, u)) { var i = a ? Object.getOwnPropertyDescriptor(e, u) : null; i && (i.get || i.set) ? Object.defineProperty(n, u, i) : n[u] = e[u]; } return n.default = e, t && t.set(e, n), n; }
/**
 * Hook to take care of emitting `focus` and `blur` events.
 */
function useFocusEvents({
  state,
  emitter
}) {
  const navigation = React.useContext(_NavigationContext.NavigationContext);
  const lastFocusedKeyRef = React.useRef();
  const currentFocusedKey = state.routes[state.index].key;

  // When the parent screen changes its focus state, we also need to change child's focus
  // Coz the child screen can't be focused if the parent screen is out of focus
  React.useEffect(() => navigation?.addListener('focus', () => {
    lastFocusedKeyRef.current = currentFocusedKey;
    emitter.emit({
      type: 'focus',
      target: currentFocusedKey
    });
  }), [currentFocusedKey, emitter, navigation]);
  React.useEffect(() => navigation?.addListener('blur', () => {
    lastFocusedKeyRef.current = undefined;
    emitter.emit({
      type: 'blur',
      target: currentFocusedKey
    });
  }), [currentFocusedKey, emitter, navigation]);
  React.useEffect(() => {
    const lastFocusedKey = lastFocusedKeyRef.current;
    lastFocusedKeyRef.current = currentFocusedKey;

    // We wouldn't have `lastFocusedKey` on initial mount
    // Fire focus event for the current route on mount if there's no parent navigator
    if (lastFocusedKey === undefined && !navigation) {
      emitter.emit({
        type: 'focus',
        target: currentFocusedKey
      });
    }

    // We should only emit events when the focused key changed and navigator is focused
    // When navigator is not focused, screens inside shouldn't receive focused status either
    if (lastFocusedKey === currentFocusedKey || !(navigation ? navigation.isFocused() : true)) {
      return;
    }
    if (lastFocusedKey === undefined) {
      // Only fire events after initial mount
      return;
    }
    emitter.emit({
      type: 'blur',
      target: lastFocusedKey
    });
    emitter.emit({
      type: 'focus',
      target: currentFocusedKey
    });
  }, [currentFocusedKey, emitter, navigation]);
}
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