mult_image_picker_example.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:multi_image_picker/multi_image_picker.dart';
import 'package:permission_handler/permission_handler.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();

  SystemChrome.setEnabledSystemUIOverlays([
    SystemUiOverlay.bottom
  ]);

  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  List<Asset> _images = List<Asset>();
  String _error = 'No Error Dectected';

  @override
  void initState() {
    super.initState();
  }

  Widget buildGridView() {
    return GridView.count(
      crossAxisCount: 3,
      children: List.generate(_images.length, (index) {
        Asset asset = _images[index];
        return AssetThumb(
          asset: asset,
          width: 300,
          height: 300,
        );
      }),
    );
  }

  Future<void> loadAssets() async {
    if (!await Permission.camera.request().isGranted) {
      setState(() {
        _error = "Permissão não garantida!";
      });
      return;
    }

    List<Asset> resultList = List<Asset>();
    String error = 'No Error Dectected';

    try {
      resultList = await MultiImagePicker.pickImages(
        maxImages: 10,
        enableCamera: true,
        selectedAssets: _images,
        cupertinoOptions: CupertinoOptions(takePhotoIcon: "chat"),
        materialOptions: MaterialOptions(
          actionBarColor: "#abcdef",
          actionBarTitle: "ImageX",
          allViewTitle: "All Photos",
          useDetailsView: false,
          selectCircleStrokeColor: "#ffffff",
        ),
      );
    } on Exception catch (e) {
      error = e.toString();
    }

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;

    setState(() {
      _images = resultList;
      _error = error;
    });
  }

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new Scaffold(
        appBar: new AppBar(
          title: const Text('MUlti Image Picker App'),
        ),
        body: Column(
          children: <Widget>[
            const SizedBox(height: 32,),
            Center(child: Text('LOG: $_error', style: TextStyle(fontSize: 18),)),
            const SizedBox(height: 32,),
            RaisedButton(
              child: Text("Pick images"),
              onPressed: loadAssets,
            ),
            Expanded(
              child: buildGridView(),
            )
          ],
        ),
      ),
    );
  }
}