플러터챌린지 9일차 기본문제 - 신현호

main.dart

import 'dart:math';

import 'package:flutter/material.dart';


void main() {
  runApp(
    const MaterialApp(
      debugShowCheckedModeBanner: false,
      home: MyRandomImageSliderScreen(),
    ),
  );
}

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

  @override
  State<MyRandomImageSliderScreen> createState() => _MyRandomImageSliderScreenState();
}

class _MyRandomImageSliderScreenState extends State<MyRandomImageSliderScreen> {
  List<String> imgSrcList = [];
  int _imageId = 0;
  
  void getRandomImgSrc() {
    String imgSrc = 'https://picsum.photos/id/${Random().nextInt(1000) + 1}/200/200';
    imgSrcList.add(imgSrc);
  }
  
  @override
  void initState() {
    super.initState();
    getRandomImgSrc();
  }

  @override
  Widget build(BuildContext context) {
    ThemeData themeData = Theme.of(context);
    
    return Scaffold(
      appBar: AppBar(
        title: Text(
          'Click left and right',
          style: themeData.textTheme.titleLarge?.copyWith(color: themeData.primaryColor),
        ),
      ),
      body: SafeArea(
        child: SingleChildScrollView(
          physics: const NeverScrollableScrollPhysics(),
          child: Column(
            children: [
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: [
                  ElevatedButton(
                    onPressed: () {
                      if (_imageId > 0) {
                        setState(() { 
                            _imageId--; 
                        });
                      }
                    }, 
                    child: const Icon(Icons.arrow_circle_left),
                  ),
                  ElevatedButton(
                    onPressed: () {
                      getRandomImgSrc();
                      setState(() {
                        _imageId++; 
                      });
                    }, 
                    child: const Icon(Icons.arrow_circle_right),
                  )
                ],
              ),
              SizedBox(
                width: double.infinity,
                child: Image.network(
                  imgSrcList[_imageId],
                  fit: BoxFit.cover,
                  frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
                    if (wasSynchronouslyLoaded) {
                      return child;
                    }
                    return frame != null ? child : const Center(child: Text('loading...'));
                  },
                  /* 로딩 진행 상태에 따라 변하지 않는 단순한 플레이스홀더를 표시하는 경우에는 frameBuilder를 사용하는 것이 더 효율적
                   * https://api.flutter.dev/flutter/widgets/Image/loadingBuilder.html
                   
                    loadingBuilder: (context, child, loadingProgress) {
                      if (loadingProgress == null) return child;
                      return const Center(
                        child: Text('waiting...'),
                      );
                    },

                   */
                  errorBuilder: (context, exception, stackTrace) {
                    return const Center(
                      child: Text('Oops! Something went wrong'),
                    );
                  },
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}