Question

您能建议一种在CachedNetworkImage内缩放图像的方法吗？

这是我的代码

CachedNetworkImage(
        imageUrl: "http://via.placeholder.com/350x150",
        placeholder: (context, url) => CircularProgressIndicator(),
        errorWidget: (context, url, error) => Icon(Icons.error),
     ),

我试图将CachedNetworkImage包装在photo_view窗口小部件中，但不起作用

@override
Widget build(BuildContext context) {
  return Container(
    child: PhotoView(
      imageProvider: CachedNetworkImage(
        imageUrl: "http://via.placeholder.com/350x150",
        placeholder: (context, url) => CircularProgressIndicator(),
        errorWidget: (context, url, error) => Icon(Icons.error),
      )
    )
  );
}

Answer 1

您可以在下面复制粘贴运行完整代码
软件包Cached network image提供了CachedNetworkImageProvider
代码段

PhotoView(
    imageProvider:
        CachedNetworkImageProvider("http://via.placeholder.com/350x150"),
  )

工作演示

完整代码

import 'package:flutter/material.dart';
import 'package:photo_view/photo_view.dart';
import 'package:cached_network_image/cached_network_image.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Expanded(flex: 1, child: PhotoViewTest()),
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}

class PhotoViewTest extends StatefulWidget {
  @override
  _PhotoViewTestState createState() => _PhotoViewTestState();
}

class _PhotoViewTestState extends State<PhotoViewTest> {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: PhotoView(
        imageProvider:
            CachedNetworkImageProvider("http://via.placeholder.com/350x150"),
      ),
    );
  }
}

Answer 2

您可以像下面的代码一样将“照片”视图包装在“缓存的网络”图像中，这样就可以同时利用“缓存的网络图像”和“照片”视图的优势

CachedNetworkImage(
    imageUrl: "http://via.placeholder.com/350x150",
    imageBuilder: (context, imageProvider) => PhotoView(
        imageProvider: imageProvider,
    ),
    placeholder: (context, url) =>
        CircularProgressIndicator(),
        errorWidget: (context, url, error) =>
            Icon(Icons.error),
)

Answer 3

Widget build(BuildContext context) { 
  return Container(
     child: CachedNetworkImage(
        imageUrl: "http://via.placeholder.com/350x150",
        imageBuilder: (context, imageProvider) => PhotoView(
           imageProvider: imageProvider,
        )
     ),
  );
}

如何使用CachedNetworkImage小部件缩放图像

3 个答案: