mirror of https://github.com/flutter/samples.git
[platform_channels] adds Platform Image demo (#475)
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After Width: | Height: | Size: 70 KiB |
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// Copyright 2020 The Flutter team. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'dart:typed_data';
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import 'package:flutter/services.dart';
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/// This class manages a [BasicMessageChannel] that can return an image loaded
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/// from a native asset. The [BasicMessageChannel] uses [StandardMessageCodec]
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/// since it supports [Uint8List], which is used to transport the image data.
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class PlatformImageFetcher {
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static final _basicMessageChannel = const BasicMessageChannel<dynamic>(
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'platformImageDemo', StandardMessageCodec());
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/// Method responsible for providing the platform image.
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static Future<Uint8List> getImage() async {
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final reply = await _basicMessageChannel.send('getImage') as Uint8List;
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if (reply == null) {
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throw PlatformException(
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code: 'Error',
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message: 'Failed to load Platform Image',
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details: null,
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);
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}
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return reply;
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}
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}
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// Copyright 2020 The Flutter team. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'dart:typed_data';
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import 'package:flutter/material.dart';
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import 'package:flutter/services.dart';
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import 'package:platform_channels/src/image_basic_message_channel.dart';
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/// Demonstrates how to use [BasicMessageChannel] to get an image from platform.
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///
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/// The widget uses [Image.memory] to display the image obtained from the
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/// platform.
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class PlatformImageDemo extends StatefulWidget {
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@override
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_PlatformImageDemoState createState() => _PlatformImageDemoState();
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}
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class _PlatformImageDemoState extends State<PlatformImageDemo> {
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Future<Uint8List> imageData;
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@override
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Widget build(BuildContext context) {
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return Scaffold(
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appBar: AppBar(
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title: Text('Platform Image Demo'),
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),
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body: Center(
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child: Column(
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mainAxisAlignment: MainAxisAlignment.center,
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children: [
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Flexible(
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child: FractionallySizedBox(
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widthFactor: 1,
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heightFactor: 0.6,
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child: FutureBuilder<Uint8List>(
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future: imageData,
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builder: (context, snapshot) {
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if (snapshot.connectionState == ConnectionState.none) {
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return Placeholder();
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} else if (snapshot.hasError) {
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return Center(
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child: Text(snapshot.error.toString()),
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);
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} else if (snapshot.connectionState ==
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ConnectionState.done) {
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return Image.memory(
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snapshot.data,
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fit: BoxFit.fill,
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);
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}
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return CircularProgressIndicator();
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},
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),
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),
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),
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SizedBox(
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height: 16,
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),
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RaisedButton(
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onPressed: imageData != null
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? null
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: () {
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setState(() {
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imageData = PlatformImageFetcher.getImage();
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});
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},
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child: Text('Get Image'),
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)
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],
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),
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),
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);
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}
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}
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// Copyright 2020 The Flutter team. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'package:flutter/material.dart';
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import 'package:flutter/services.dart';
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import 'package:flutter_test/flutter_test.dart';
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import 'package:platform_channels/src/platform_image_demo.dart';
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void main() {
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group('Platform Image Demo tests', () {
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setUpAll(() {
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// Register a mock for MessageHandler.
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BasicMessageChannel<dynamic>('platformImageDemo', StandardMessageCodec())
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.setMockMessageHandler((dynamic message) async {
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var byteData = await rootBundle.load('assets/eat_new_orleans.jpg');
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return byteData.buffer.asUint8List();
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});
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});
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testWidgets('Platform Image test', (tester) async {
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await tester.pumpWidget(MaterialApp(
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home: PlatformImageDemo(),
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));
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// Initially a PlaceHolder is displayed when imageData is null.
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expect(find.byType(Placeholder), findsOneWidget);
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expect(find.byType(Image), findsNothing);
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// Tap on RaisedButton to get Image.
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await tester.tap(find.byType(RaisedButton));
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await tester.pumpAndSettle();
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expect(find.byType(Placeholder), findsNothing);
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expect(find.byType(Image), findsOneWidget);
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});
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});
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}
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