Question

通常，以下行为本质上是快速的。但是，在GridView（或我假定的任何ScrollView（也尝试过ListView）中），性能似乎非常差。当我点击屏幕时，容器的不透明度会增加，但是会延迟一段时间。知道我缺少什么吗？

import "package:flutter/material.dart";
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
  @override
    Widget build(BuildContext context) {
      return MaterialApp(
        home: Scaffold(
          body: MyWidget()
        )
      );
    }
}
class MyWidgetState extends State<MyWidget> {
  double opacity = 0.2;
  @override
    Widget build(BuildContext context) {
      return GridView.builder(
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: 3
        ),
        itemBuilder: (context, index) {
          return GestureDetector(
            onTap: () {
              setState(() {
                opacity = 0.2;                
              });
            },
            onTapDown: (details) {
              setState(() {
                opacity = 1.0;                
              });
            },
            child: Container(
              color: Colors.red.withAlpha((255 * opacity).toInt())
            )
          );
        },
      );
    }
}
class MyWidget extends StatefulWidget {
  @override
    State<StatefulWidget> createState() {
      return MyWidgetState();
    }
}

Answer 1

在您的情况下，也许Listener会更快

Listener(
      onPointerDown: (PointerDownEvent event) {
        setState(() {
          opacity = 1.0;
        });
      },
      onPointerUp: (PointerUpEvent event) {
        setState(() {
          opacity = 0.2;
        });
      },
      child: Container(
          color: Colors.red.withAlpha((255 * opacity).toInt())
      ),
    )

颤振：在GridView的图块中使用GestureDetector抽头延迟

1 个答案: