使用 Dart (Flutter) 为我的应用程序创建屏幕截图按钮的问题

Question

我正在尝试捕获小部件的屏幕截图并将其保存到手机图库，但它给了我如下错误。我需要帮助>

W/System.err(23529): java.io.FileNotFoundException: /storage/emulated/0/hsp_app/1575363381281.png（没有这样的文件或 目录）W / System.err（23529）：在 java.io.FileOutputStream.open0(Native Method) W/System.err(23529): at java.io.FileOutputStream.open(FileOutputStream.java:287) W / System.err（23529）：在 java.io.FileOutputStream.(FileOutputStream.java:223) W / System.err（23529）：在 java.io.FileOutputStream.(FileOutputStream.java:171) W / System.err（23529）：在 com.example.imagegallerysaver.ImageGallerySaverPlugin.saveImageToGallery(ImageGallerySaverPlugin.kt:61) W / System.err（23529）：在 com.example.imagegallerysaver.ImageGallerySaverPlugin.onMethodCall(ImageGallerySaverPlugin.kt:33) W / System.err（23529）：在 io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:222) W / System.err（23529）：在 io.flutter.embedding.engine.dart.DartMessenger.handleMessageFromDart(DartMessenger.java:96) W / System.err（23529）：在 io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(FlutterJNI.java:656) W/System.err(23529)：在 android.os.MessageQueue.nativePollOnce(Native 方法）W/System.err（23529）：在 android.os.MessageQueue.next(MessageQueue.java:325) W/System.err(23529): 在 android.os.Looper.loop(Looper.java:142) W / System.err（23529）：在 android.app.ActivityThread.main(ActivityThread.java:6494) W/System.err(23529): 在 java.lang.reflect.Method.invoke(Native 方法）W/System.err（23529）：在 com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) W / System.err（23529）：在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

这是我的代码：

import 'package:screenshot/screenshot.dart';
import 'package:image_gallery_saver/image_gallery_saver.dart';

//...

body: new Container(
child: Screenshot(
              controller: screenshotController,
              // contents...
),),
floatingActionButton: FloatingActionButton.extended(
            onPressed: () {
              _imageFile = null;
              screenshotController
                  .capture()
                  .then((File image) async {
                print("Capture Done");
                setState(() {
                  _imageFile = image;
                });
                final result =
                await ImageGallerySaver.saveImage(image.readAsBytesSync()); // Save image to gallery
                print("File Saved to Gallery");
              }).catchError((onError) {
                print(onError);
              });
            },
            tooltip: 'Capture Result as Screenshot',
            icon: Icon(Icons.save),
            label: Text("Save")
          ),

Answer 1

您可以在下面复制粘贴运行完整代码
你需要权限WRITE_EXTERNAL_STORAGE

第一步：在AndroidManifest.xml中添加权限。

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

第二步：使用包simple_permissions获取权限
代码sn-p

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

  _requestWritePermission() async {
    PermissionStatus permissionStatus = await SimplePermissions.requestPermission(Permission.WriteExternalStorage);

    if (permissionStatus == PermissionStatus.authorized) {
      setState(() {
        _allowWriteFile = true;
      });
    }
  }

工作演示

完整代码

import 'dart:io';
import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:screenshot/screenshot.dart';
import 'package:image_gallery_saver/image_gallery_saver.dart';
import 'package:simple_permissions/simple_permissions.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Screenshot Demo Home Page'),
    );
  }
}

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

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  File _imageFile;
  bool _allowWriteFile = false;

  //Create an instance of ScreenshotController
  ScreenshotController screenshotController = ScreenshotController();

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

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

  _requestWritePermission() async {
    PermissionStatus permissionStatus = await SimplePermissions.requestPermission(Permission.WriteExternalStorage);

    if (permissionStatus == PermissionStatus.authorized) {
      setState(() {
        _allowWriteFile = true;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Container(
        child: new Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Screenshot(
                controller: screenshotController,
                child: Column(
                  children: <Widget>[
                    Text(
                      'You have pushed the button this many times:' +
                          _counter.toString(),
                    ),
                    FlutterLogo(),
                  ],
                ),
              ),
              _imageFile != null ? Image.file(_imageFile) : Container(),
            ],
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          _incrementCounter();
          _imageFile = null;
          screenshotController
              .capture(delay: Duration(seconds: 3))
              .then((File image) async {
            print("image path  ${image.path}");
            setState(() {
              _imageFile = image;
            });
            final result =
            await ImageGallerySaver.saveImage(image.readAsBytesSync());
            print("File Saved to Gallery");
          }).catchError((onError) {
            print(onError);
          });
        },
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }

  _saved(File image) async {
    final result = await ImageGallerySaver.saveImage(image.readAsBytesSync());
    print("File Saved to Gallery");
  }
}