【笔记】Flutter的PageView轮播图组件

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前言

Flutter的PageView轮播图组件

PageView手动渲染轮播图

scrollDirection：滑动方向

Axis.horizontal：缺省值，水平方向，从右向左滑翻页
Axis.vertical：垂直方向，从下向上滑翻页

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import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      appBar: AppBar(
        title: const Text("文本内容"),
      ),
      body: const App(),
    ),
  ));
}

class App extends StatefulWidget {
  const App({super.key});

  @override
  State<App> createState() => _AppState();
}

class _AppState extends State<App> {
  @override
  Widget build(BuildContext context) {
    return PageView(
      scrollDirection: Axis.vertical,
      children: [
        Center(
            child: Text("第1屏")
        ),
        Center(
            child: Text("第2屏")
        ),
        Center(
            child: Text("第3屏")
        ),
      ],
    );
  }
}

通过onPageChanged实现无限的轮播图

onPageChanged：页面改变事件

index：改变后页面的索引

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import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      appBar: AppBar(
        title: const Text("文本内容"),
      ),
      body: const App(),
    ),
  ));
}

class App extends StatefulWidget {
  const App({super.key});

  @override
  State<App> createState() => _AppState();
}

class _AppState extends State<App> {

  List<Widget> children = [];

  int index = 0;

  // 向数组中添加指定个数的元素
  void addChildren(int count) {
    for (var i = 0; i < count; i++) {
      index += 1;
      children.add(Center(
          child: Text("第$index屏")
      ));
    }
  }

  @override
  void initState() {
    super.initState();
    // 初始化时添加3个元素
    addChildren(3);
  }

  @override
  Widget build(BuildContext context) {
    return PageView(
      scrollDirection: Axis.vertical,
      onPageChanged: (index) {
        // 每次改变为最后一个元素时，再添加3个元素
        if (index == children.length - 1) {
          setState(() {
            addChildren(3);
          });
        }
      },
      children: children,
    );
  }
}

PageView.builder()批量渲染轮播图

scrollDirection：滑动方向

Axis.horizontal：缺省值，水平方向，从右向左滑翻页
Axis.vertical：垂直方向，从下向上滑翻页

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import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      appBar: AppBar(
        title: const Text("文本内容"),
      ),
      body: const App(),
    ),
  ));
}

class App extends StatefulWidget {
  const App({super.key});

  @override
  State<App> createState() => _AppState();
}

class _AppState extends State<App> {
  @override
  Widget build(BuildContext context) {
    return PageView.builder(
      scrollDirection: Axis.vertical,
      itemCount: 3,
      itemBuilder: (context, index) {
        return Center(
          child: Text("第${index+1}屏"),
        );
      }
    );
  }
}

完成

参考文献

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