ScrollController如何检测Scroll的开始，停止和滚动? [英] ScrollController how can I detect Scroll start, stop and scrolling?

问题描述

我正在将ScrollController用于 SingleChildScrollView 小部件，我想在其中检测何时滚动开始，结束/停止以及仍在滚动?

I'm using ScrollController for SingleChildScrollView widget where I want to detect when scroll start, end/stop and still scrolling?

如何检测到我正在使用 Listene

How can I detect, I'm using Listene

scrollController = ScrollController()
      ..addListener(() {
        scrollOffset = _scrollController.offset;
      });

也尝试使用 _scrollController.position.activity.velocity ，但对我没有帮助.

Also try with _scrollController.position.activity.velocity but didn't help me.

也有

_scrollController.position.didEndScroll();
_scrollController.position.didStartScroll();

但是我怎么使用它呢?

推荐答案

通过此链接 https://medium.com/@diegoveloper/flutter-lets-know-the-scrollcontroller-and-scrollnotification-652b2685a4ac

只需将您的 SingleChildScrollView 包装到 NotificationListener 并更新您的代码，例如..

Just Wrap your SingleChildScrollView to NotificationListener and update your code like ..

NotificationListener<ScrollNotification>(
                onNotification: (scrollNotification) {
                  if (scrollNotification is ScrollStartNotification) {
                    _onStartScroll(scrollNotification.metrics);
                  } else if (scrollNotification is ScrollUpdateNotification) {
                    _onUpdateScroll(scrollNotification.metrics);
                  } else if (scrollNotification is ScrollEndNotification) {
                    _onEndScroll(scrollNotification.metrics);
                  }
                },
                child: SingleChildScrollView(
                /// YOUR OWN CODE HERE
               )
)

然后声明

_onStartScroll(ScrollMetrics metrics) {
    print("Scroll Start");
  }

  _onUpdateScroll(ScrollMetrics metrics) {
    print("Scroll Update");
  }

  _onEndScroll(ScrollMetrics metrics) {
    print("Scroll End");
  }

将通过特定方法通知您.

You will be notify by particular method.

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