react/packages/react-native-renderer/src/ReactNativeBridgeEventPlugin.js

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow
 */

import type {AnyNativeEvent} from 'events/PluginModuleType';
import {
  accumulateTwoPhaseDispatches,
  accumulateDirectDispatches,
} from 'events/EventPropagators';
import type {TopLevelType} from 'events/TopLevelEventTypes';
import * as ReactNativeViewConfigRegistry from 'ReactNativeViewConfigRegistry';
import SyntheticEvent from 'events/SyntheticEvent';
import invariant from 'shared/invariant';

const {
  customBubblingEventTypes,
  customDirectEventTypes,
  eventTypes,
} = ReactNativeViewConfigRegistry;

const ReactNativeBridgeEventPlugin = {
  eventTypes: eventTypes,

  /**
   * @see {EventPluginHub.extractEvents}
   */
  extractEvents: function(
    topLevelType: TopLevelType,
    targetInst: null | Object,
    nativeEvent: AnyNativeEvent,
    nativeEventTarget: Object,
  ): ?Object {
    if (targetInst == null) {
      // Probably a node belonging to another renderer's tree.
      return null;
    }
    const bubbleDispatchConfig = customBubblingEventTypes[topLevelType];
    const directDispatchConfig = customDirectEventTypes[topLevelType];
    invariant(
      bubbleDispatchConfig || directDispatchConfig,
      'Unsupported top level event type "%s" dispatched',
      topLevelType,
    );
    const event = SyntheticEvent.getPooled(
      bubbleDispatchConfig || directDispatchConfig,
      targetInst,
      nativeEvent,
      nativeEventTarget,
    );
    if (bubbleDispatchConfig) {
      accumulateTwoPhaseDispatches(event);
    } else if (directDispatchConfig) {
      accumulateDirectDispatches(event);
    } else {
      return null;
    }
    return event;
  },
};

export default ReactNativeBridgeEventPlugin;