flutter_integrated_whb/lib/customWidget/single_image_viewer.dart

import 'dart:io';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:photo_view/photo_view.dart';
import 'package:qhd_prevention/pages/my_appbar.dart';

// 查看大图
class SingleImageViewer extends StatelessWidget {
  final String imageUrl;
  const SingleImageViewer({Key? key, required this.imageUrl}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    ImageProvider provider;

    // 选择图片来源：网络 / asset / 本地文件（优先检测 http，然后 asset，再文件）
    if (imageUrl.toLowerCase().startsWith('http')) {
      provider = NetworkImage(imageUrl);
    } else if (imageUrl.startsWith('assets/') ||
        imageUrl.startsWith('package:') ||
        imageUrl.startsWith('packages/')) {
      // 明确标记为工程资源（asset）
      provider = AssetImage(imageUrl) as ImageProvider;
    } else {
      // 不是明确的网络或 asset 路径 —— 在非 web 平台尝试作为文件路径
      if (!kIsWeb) {
        try {
          final file = File(imageUrl);
          if (file.existsSync()) {
            provider = FileImage(file);
          } else {
            // 文件不存在时尝试作为 asset 路径回退
            provider = AssetImage(imageUrl) as ImageProvider;
          }
        } catch (e) {
          // 任何异常都回退为 asset 尝试（避免抛出）
          provider = AssetImage(imageUrl) as ImageProvider;
        }
      } else {
        // web 平台没有 File API，可直接尝试当作 asset
        provider = AssetImage(imageUrl) as ImageProvider;
      }
    }

    return Scaffold(
      backgroundColor: Colors.black.withValues(alpha: 0.5),
      appBar: MyAppbar(
        isBack: false,
        actions: [
          IconButton(
            onPressed: () {
              Navigator.of(context).pop();
            },
            icon: const Icon(
              Icons.close,
              color: Colors.white,
              size: 40,
            ),
          )
        ],
        backgroundColor: Colors.black.withValues(alpha: 0.5),
        title: '',
      ),
      body: Center(
        child: PhotoView(
          imageProvider: provider,
          backgroundDecoration: BoxDecoration(color: Colors.black.withValues(alpha: 0.5)),
          minScale: PhotoViewComputedScale.contained,
          maxScale: PhotoViewComputedScale.covered * 2,
          onTapUp: (context, details, controllerValue) {
            Navigator.of(context).pop();
          },
        ),
      ),
    );
  }
}