addListener method

void addListener(
  1. ValueCallback<int> callback
)
inherited

下面是对ValueNotifier的简单封装

Implementation

void addListener(ValueCallback<int> callback) {
  if (_listenerMap[callback] != null) {
    _notifier.removeListener(() {
      _listenerMap[callback]!;
    });
  }
  voidCallback() {
    callback.call(_notifier.value.value);
  }

  _listenerMap[callback] = voidCallback;
  _notifier.addListener(voidCallback);
}