从StatefulWidget获取图像并通过共享对话框共享它

Question

在我的项目中，我有wc_flutter_share库用于共享内容。我也有qr_flutter用于生成QR码。

在QRView中是一个StatefulWidget。我可以通过正在使用的库共享QRCode图像吗，因为在该示例中，它们仅显示了从磁盘共享图像：

final ByteData bytes = await rootBundle.load('assets/wisecrab.png');  
await WcFlutterShare.share(
    sharePopupTitle: 'share',  
    fileName: 'share.png',  
    mimeType: 'image/png',  
    bytesOfFile: bytes.buffer.asUint8List());

主要问题是从StatefulWidget获取库提供的图像。

Answer 1

您可以在下面复制粘贴运行完整代码我提供了base64图像以证明它可以正常工作您可以使用RepaintBoundary包装QRView并获取Widget图片并返回Uint8List代码段

RepaintBoundary(key: _globalKey, child: QRView())
...
Future<Uint8List> _capturePng() async {
    try {
      print('inside');
      RenderRepaintBoundary boundary =
          _globalKey.currentContext.findRenderObject();
      ui.Image image = await boundary.toImage(pixelRatio: 3.0);
      ByteData byteData =
          await image.toByteData(format: ui.ImageByteFormat.png);
      var pngBytes = byteData.buffer.asUint8List();
      var bs64 = base64Encode(pngBytes);
      print(pngBytes);
      print(bs64);
      setState(() {});
      return pngBytes;
    } catch (e) {
      print(e);
    }
  }

工作演示

完整代码

import 'dart:async';
import 'dart:typed_data';
import 'dart:ui' as ui;
import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:qr_flutter/qr_flutter.dart';
import 'package:flutter/rendering.dart';
import 'package:wc_flutter_share/wc_flutter_share.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  GlobalKey _globalKey = new GlobalKey();

  Future<Uint8List> _capturePng() async {
    try {
      print('inside');
      RenderRepaintBoundary boundary =
          _globalKey.currentContext.findRenderObject();
      ui.Image image = await boundary.toImage(pixelRatio: 3.0);
      ByteData byteData =
          await image.toByteData(format: ui.ImageByteFormat.png);
      var pngBytes = byteData.buffer.asUint8List();
      var bs64 = base64Encode(pngBytes);
      print(pngBytes);
      print(bs64);
      setState(() {});
      return pngBytes;
    } catch (e) {
      print(e);
    }
  }

  void _incrementCounter() async {
    var imageUint8List = await _capturePng();
    await WcFlutterShare.share(
        sharePopupTitle: 'share',
        fileName: 'share.png',
        mimeType: 'image/png',
        bytesOfFile: imageUint8List);
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Expanded(child: RepaintBoundary(key: _globalKey, child: QRView())),
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}

class QRView extends StatefulWidget {
  @override
  _QRViewState createState() => _QRViewState();
}

class _QRViewState extends State<QRView> {
  @override
  Widget build(BuildContext context) {
    final message =
        // ignore: lines_longer_than_80_chars
        'Hey this is a QR code. Change this value in the main_screen.dart file.';

    final qrFutureBuilder = FutureBuilder(
      future: _loadOverlayImage(),
      builder: (ctx, snapshot) {
        final size = 280.0;
        if (!snapshot.hasData) {
          return Container(width: size, height: size);
        }
        return CustomPaint(
          size: Size.square(size),
          painter: QrPainter(
            data: message,
            version: QrVersions.auto,
            color: Color(0xff1a5441),
            emptyColor: Color(0xffeafcf6),
            // size: 320.0,
            embeddedImage: snapshot.data,
            embeddedImageStyle: QrEmbeddedImageStyle(
              size: Size.square(60),
            ),
          ),
        );
      },
    );

    return Material(
      color: Colors.white,
      child: SafeArea(
        top: true,
        bottom: true,
        child: Container(
          child: Column(
            children: <Widget>[
              Expanded(
                child: Center(
                  child: Container(
                    width: 280,
                    child: qrFutureBuilder,
                  ),
                ),
              ),
              Padding(
                padding: EdgeInsets.symmetric(vertical: 20, horizontal: 40)
                    .copyWith(bottom: 40),
                child: Text(message),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Future<ui.Image> _loadOverlayImage() async {
    final completer = Completer<ui.Image>();
    final byteData = await rootBundle.load('assets/images/logo_yakka.png');
    ui.decodeImageFromList(byteData.buffer.asUint8List(), completer.complete);
    return completer.future;
  }
}