flutter_dropzone 4.0.3

A drag-and-drop Flutter plugin (Web only).

example/lib/main.dart

// ignore_for_file: avoid_print

import 'dart:async' show Completer;
import 'dart:math' show min;
import 'dart:typed_data' show Uint8List, BytesBuilder;

import 'package:flutter/material.dart';
import 'package:flutter_dropzone/flutter_dropzone.dart';
import 'package:web/web.dart' as web;

void main() => runApp(const MyApp());

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  late DropzoneViewController controller1;
  late DropzoneViewController controller2;
  String message1 = 'Drop something here';
  String message2 = 'Drop something here';
  bool highlighted1 = false;

  @override
  Widget build(BuildContext context) => MaterialApp(
        home: Scaffold(
          appBar: AppBar(
            title: const Text('Dropzone example'),
          ),
          body: Column(
            children: [
              Expanded(
                child: Container(
                  color: highlighted1 ? Colors.red : Colors.transparent,
                  child: Stack(
                    children: [
                      buildZone1(context),
                      Center(child: Text(message1)),
                    ],
                  ),
                ),
              ),
              Expanded(
                child: Stack(
                  children: [
                    buildZone2(context),
                    Center(child: Text(message2)),
                  ],
                ),
              ),
              ElevatedButton(
                onPressed: () async {
                  print(await controller1
                      .pickFiles(mime: ['image/jpeg', 'image/png']));
                },
                child: const Text('Pick file'),
              ),
            ],
          ),
        ),
      );

  Widget buildZone1(BuildContext context) => Builder(
        builder: (context) => DropzoneView(
          operation: DragOperation.copy,
          cursor: CursorType.grab,
          onCreated: (ctrl) => controller1 = ctrl,
          onLoaded: () => print('Zone 1 loaded'),
          onError: (ev) => print('Zone 1 error: $ev'),
          onHover: () {
            setState(() => highlighted1 = true);
            print('Zone 1 hovered');
          },
          onLeave: () {
            setState(() => highlighted1 = false);
            print('Zone 1 left');
          },
          onDrop: (ev) async {
            if (ev is web.File) {
              print('Zone 1 drop: ${ev.name}');
              setState(() {
                message1 = '${ev.name} dropped';
                highlighted1 = false;
              });
              final bytes = await controller1.getFileData(ev);
              print('Read bytes with length ${bytes.length}');
              print(bytes.sublist(0, min(bytes.length, 20)));
            } else if (ev is String) {
              print('Zone 1 drop: $ev');
              setState(() {
                message1 = 'text dropped';
                highlighted1 = false;
              });
              print(ev.substring(0, min(ev.length, 20)));
            } else
              print('Zone 1 unknown type: ${ev.runtimeType}');
          },
          onDropInvalid: (ev) => print('Zone 1 invalid MIME: $ev'),
          onDropMultiple: (ev) async {
            print('Zone 1 drop multiple: $ev');
          },
        ),
      );

  Widget buildZone2(BuildContext context) => Builder(
        builder: (context) => DropzoneView(
          operation: DragOperation.move,
          mime: const ['image/jpeg'],
          onCreated: (ctrl) => controller2 = ctrl,
          onLoaded: () => print('Zone 2 loaded'),
          onError: (ev) => print('Zone 2 error: $ev'),
          onHover: () => print('Zone 2 hovered'),
          onLeave: () => print('Zone 2 left'),
          onDrop: (ev) async {
            if (ev is web.File) {
              print('Zone 2 drop: ${ev.name}');
              setState(() {
                message2 = '${ev.name} dropped';
              });
              final fileStream = controller2.getFileStream(ev);
              final bytes = await collectBytes(fileStream);
              print('Streamed bytes with length ${bytes.length}');
              print(bytes.sublist(0, min(bytes.length, 20)));
            } else if (ev is String) {
              print('Zone 2 drop: $ev');
              setState(() {
                message2 = 'text dropped';
              });
              print(ev.substring(0, min(ev.length, 20)));
            } else
              print('Zone 2 unknown type: ${ev.runtimeType}');
          },
          onDropInvalid: (ev) => print('Zone 2 invalid MIME: $ev'),
          onDropMultiple: (ev) async {
            print('Zone 2 drop multiple: $ev');
          },
        ),
      );

  Future<Uint8List> collectBytes(Stream<List<int>> source) {
    var bytes = BytesBuilder(copy: false);
    var completer = Completer<Uint8List>.sync();
    source.listen(
      bytes.add,
      onError: completer.completeError,
      onDone: () => completer.complete(bytes.takeBytes()),
      cancelOnError: true,
    );
    return completer.future;
  }
}