在实现FadeInImage时永久加载占位符图像

import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';

class PermanentPlaceholderFadeInImage extends StatefulWidget {
  final String placeholderAssetPath;
  final String imageAssetPath;

  PermanentPlaceholderFadeInImage({
    required this.placeholderAssetPath,
    required this.imageAssetPath,
  });

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

class _PermanentPlaceholderFadeInImageState extends State<PermanentPlaceholderFadeInImage> {
  @override
  void initState() {
    super.initState();
    _loadImage();
  }

  Future<void> _loadImage() async {
    try {
      await precacheImage(AssetImage(widget.imageAssetPath), context);
    } catch (e) {
      print('Error precaching image: $e');
    }
  }

  @override
  Widget build(BuildContext context) {
    return FadeInImage(
      placeholder: Image.asset(widget.placeholderAsset路径),
      image: Image.asset(widget.imageAssetPath),
      fadeInDuration: Duration(milliseconds: 300),
      fadeOutDuration: Duration(milliseconds: 300),
    );
  }
}

import 'package:flutter/material.dart';
import 'permanent_placeholder_fade_in_image.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('FadeInImage with Permanent Placeholder'),
        ),
        body: Center(
          child: PermanentPlaceholderFadeInImage(
            placeholderAssetPath: 'assets/placeholder.png',
            imageAssetPath: 'assets/image.png',
          ),
        ),
      ),
    );
}