Package io.flutter.plugin.common

Interface EventChannel.StreamHandler

Enclosing class:
EventChannel
public static interface EventChannel.StreamHandler
Handler of stream setup and teardown requests.

Implementations must be prepared to accept sequences of alternating calls to onListen(Object, EventChannel.EventSink) and onCancel(Object). Implementations should ideally consume no resources when the last such call is not onListen. In typical situations, this means that the implementation should register itself with platform-specific event sources onListen and deregister again onCancel.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    onCancel(Object arguments)
    Handles a request to tear down the most recently created event stream.
    void
    onListen(Object arguments, EventChannel.EventSink events)
    Handles a request to set up an event stream.

  • Method Details

    • onListen

      void onListen(Object arguments, EventChannel.EventSink events)
      Handles a request to set up an event stream.

      Any uncaught exception thrown by this method will be caught by the channel implementation and logged. An error result message will be sent back to Flutter.

      Parameters:
      arguments - stream configuration arguments, possibly null.
      events - an EventChannel.EventSink for emitting events to the Flutter receiver.

    • onCancel

      void onCancel(Object arguments)
      Handles a request to tear down the most recently created event stream.

      Any uncaught exception thrown by this method will be caught by the channel implementation and logged. An error result message will be sent back to Flutter.

      The channel implementation may call this method with null arguments to separate a pair of two consecutive set up requests. Such request pairs may occur during Flutter hot restart. Any uncaught exception thrown in this situation will be logged without notifying Flutter.

      Parameters:
      arguments - stream configuration arguments, possibly null.