Dart 2.14 & Flutter 2.5 Image_picker example

main.dart

import 'dart:typed_data';
import 'package:camera/camera.dart';
import 'package:flutter/material.dart';
import 'package:gallery_saver/gallery_saver.dart';
import 'package:image_picker/image_picker.dart';
import 'package:permission_handler/permission_handler.dart';

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

class Sys extends StatelessWidget {
  const Sys({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Main(),
    );
  }
}

class Main extends StatefulWidget {

  @override
  State<Main> createState() => _MainState();
}

class _MainState extends State<Main> {
  final ImagePicker _picker = ImagePicker();

  Uint8List? imgFile;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Camera & ImagePicker & SaverGallery"),
        centerTitle: true
      ),
      body: Container(
        width: MediaQuery.of(context).size.width,
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: [
            this.imgFile == null
              ? Container(
                  width: 200.0,
                  height: 200.0,
                  color: Colors.red,
                  alignment: Alignment.center,
                  child: Text(
                    "await...",
                    style: TextStyle(
                      color: Colors.white
                    )
                  )
                )
              : Container(
                  width: 200.0,
                  height: 200.0,
                  decoration: BoxDecoration(
                    image: DecorationImage(
                      image: MemoryImage(this.imgFile!)
                    )
                  ),
                ),
            MaterialButton(
              color: Colors.blue,
              textColor: Colors.white,
              shape: RoundedRectangleBorder(
                borderRadius: BorderRadius.circular(10.0)
              ),
              child: Text("Cam & Picker"),
              onPressed: () => this._camAndPick(context: context),
            ),
          ],
        ),
      ),
    );
  }

  Future<void> _camAndPick({required BuildContext context}) async{
    if(!await Permission.camera.isGranted){
      PermissionStatus camState = await Permission.camera.request();
      if(!camState.isGranted) return;
    }
    if(!await Permission.storage.isGranted){
      PermissionStatus storageState = await Permission.storage.request();
      if(!storageState.isGranted) return;
    }
    if(!await Permission.mediaLibrary.isGranted) {
      PermissionStatus libState = await Permission.mediaLibrary.request();
      if(!libState.isGranted) return;
    }
    XFile? imgFile = await _picker.pickImage(source: ImageSource.camera);
    if(imgFile == null){
      ScaffoldMessenger.of(context).showMaterialBanner(
        MaterialBanner(
          content: Text('No Cam'),
          actions:  [
            TextButton(
              child: Text('Close'),
              onPressed: () => ScaffoldMessenger.of(context).clearMaterialBanners(),
            ),
          ],
        )
      );
      return;
    }
    bool? _imgSaveCheck = await GallerySaver.saveImage(imgFile.path);
    if(_imgSaveCheck == null || !_imgSaveCheck){
      ScaffoldMessenger.of(context).showMaterialBanner(
        MaterialBanner(
          content: Text('Save Err'),
          actions:  [
            TextButton(
              child: Text('Close'),
              onPressed: () => ScaffoldMessenger.of(context).clearMaterialBanners(),
            ),
          ],
        )
      );
      return;
    }
    XFile? _selectFile = await _picker.pickImage(source: ImageSource.gallery);
    if(_selectFile == null){
      ScaffoldMessenger.of(context).showMaterialBanner(
        MaterialBanner(
          content: Text('No File'),
          actions:  [
            TextButton(
              child: Text('Close'),
              onPressed: () => ScaffoldMessenger.of(context).clearMaterialBanners(),
            ),
          ],
        )
      );
      return;
    }
    this.imgFile = await _selectFile.readAsBytes();
    setState((){});
    return;
  }
}