flutter - flutter 设定事件的频率

Question

假设我不断地更改Slider的值，并在onChanged回调函数中对服务器进行一些调用。是否可以有效地更改两次回调之间的最短时间？

  Slider showSoundBar(){
    return Slider(
      value: this.volume,
      activeColor: Colors.blue,
      onChanged: (vol){
        // Don't send too often
        send('volume', vol);
      },
    );
  }

Answer 1

您可以使用Timer中的dart:async执行类似的操作。

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  
  Timer timer;
  int timePassedInMilliseconds = 1500;
  
  @override
  void initState(){
    super.initState();
    timer = Timer.periodic(Duration(milliseconds: 100), (_){
      timePassedInMilliseconds = timePassedInMilliseconds + 100;
    });
  }
  
  @override
  Widget build(BuildContext context) {
    return Slider(
      value: 10,
      activeColor: Colors.blue,
      onChanged: (vol){
        // Don't send too often
        if(timePassedInMilliseconds > 1500){
          send('volume', vol);
          timePassedInMilliseconds = 0;
        }
        
      },
    );
  }
  
  void send(String sendWhat, double value){
    
  }
  
  
  @override
  void dispose(){
    timer.cancel();
    super.dispose();
  }
  
}