小编R R*_*ara的帖子

我想在屏幕上显示 Web 视图数据之前先显示 Loading。怎么能这样？

这是我的代码：

class WebDetailPage extends StatelessWidget {
  final String title;
  final String webUrl;

  final Completer<WebViewController> _controller =
      Completer<WebViewController>();

  WebDetailPage({
    @required this.title,
    @required this.webUrl,
  });

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colour.white,
        title: Text(title, style: TextStyle(color: Colour.midnightBlue)),
        leading: IconButton(
            icon: Icon(Icons.arrow_back, color: Colour.midnightBlue),
            onPressed: () => Navigator.of(context).pop()),
      ),
      body: Center(
        child: WebView(
          initialUrl: webUrl,
          javascriptMode: JavascriptMode.unrestricted,
          onWebViewCreated: (WebViewController webViewController) {
            _controller.complete(webViewController);
          },
        ),
      )
    );
  }
}

有人可以帮我解决这个问题吗？因为我已经搜索和研究过它仍然可以找到解决方案。

我有一个自定义相机应用程序，它具有居中的矩形视图，如下所示：

当我拍照时，我想忽略矩形外的所有内容。这是我的 XML 布局：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/black_50">

    <TextureView
        android:id="@+id/viewFinder"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <View
        android:layout_width="match_parent"
        android:layout_height="250dp"
        android:layout_margin="16dp"
        android:background="@drawable/rectangle"
        app:layout_constraintBottom_toTopOf="@+id/cameraBottomView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <View
        android:id="@+id/cameraBottomView"
        android:layout_width="match_parent"
        android:layout_height="130dp"
        android:background="@color/black_50"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <ImageButton
        android:id="@+id/cameraCaptureImageButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@android:color/transparent"
        android:src="@drawable/ic_capture_image"
        app:layout_constraintBottom_toBottomOf="@id/cameraBottomView"
        app:layout_constraintEnd_toEndOf="@id/cameraBottomView"
        app:layout_constraintStart_toStartOf="@id/cameraBottomView"
        app:layout_constraintTop_toTopOf="@id/cameraBottomView"
        tools:ignore="ContentDescription" />

</androidx.constraintlayout.widget.ConstraintLayout>

这是我用于 cameraX 预览的 kotlin 代码：

class CameraFragment : Fragment() {

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the …

我已经谷歌搜索，我找到的解决方案正在使用path_provider，添加权限AndroidManifest.xml，是的，我已经尝试过。但我的仍然有错误。

这是我的功能

  Future<File> _takePicture() async {
    Directory root = await getTemporaryDirectory(); // this is using path_provider
    String directoryPath = '$root/bozzetto_camera';
    await Directory(directoryPath).create(recursive: true); // the error because of this line
    String filePath = '$directoryPath/${DateTime.now()}.jpg';
    try {
      await _cameraController.takePicture(filePath);
    } catch (e) {
      return null;
    }
    return File(filePath);
  }

这是我的AndroidManifest.xml

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

    <application
        ...
        android:requestLegacyExternalStorage="true">
        
        ...

    </application>

这充满了日志。

E/flutter (14879): [ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: FileSystemException: Creation failed, path = 'Directory: …

我有一个像这样的底部导航栏设计：

我尽力使用以下代码创建底部导航栏的自定义：

class FABBottomAppBarItem {
  FABBottomAppBarItem({this.iconData, this.text});
  IconData iconData;
  String text;
}

class FABBottomAppBar extends StatefulWidget {
  FABBottomAppBar({
    this.items,
    this.centerItemText,
    this.height: 60.0,
    this.iconSize: 24.0,
    this.backgroundColor,
    this.color,
    this.selectedColor,
    this.notchedShape,
    this.onTabSelected,
  }) {
    assert(this.items.length == 2 || this.items.length == 4);
  }
  final List<FABBottomAppBarItem> items;
  final String centerItemText;
  final double height;
  final double iconSize;
  final Color backgroundColor;
  final Color color;
  final Color selectedColor;
  final NotchedShape notchedShape;
  final ValueChanged<int> onTabSelected;

  @override
  State<StatefulWidget> createState() => FABBottomAppBarState();
}

class FABBottomAppBarState extends State<FABBottomAppBar> {
  int _selectedIndex = …

在 Android 原生上分离每个应用程序功能，构建项目，实现架构组件并使其更容易在团队中工作，您可以使用模块化，这样每个人都可以通过只专注于模块来专注于各自的工作。如果我想使用 3 个应用程序功能（登录、注册、配置文件）的示例制作一个 Flutter 应用程序，并希望为每个功能实现模块化以使其更易于团队合作。你如何实现模块化？是否有参考其模块化 Flutter 的最佳实践？因为如果在 Android Native 上已经有很多相关的文章了，而我在检查 Flutter 时还没有找到。

BottomSheet在Flutter中，以便高度跟随项数（来自JSON的数据）是什么？因为我使高度不跟随数据量，而是跟随每个手机屏幕的1/2。因此，如果电话很长，则底部会有空白空间。如果手机短，则下面的屏幕会剪切数据。

这是用于创建底部工作表的代码：

void _showModalBottomSheet(AsyncSnapshot<CatlistResult> snapshot) {
    showModalBottomSheet(
        context: context,
        builder: (BuildContext bc) {
          return Card(
            elevation: 3.0,
            shape: RoundedRectangleBorder(
                borderRadius: BorderRadius.only(topLeft: Radius.circular(15), topRight: Radius.circular(15))),
            child: Container(
              padding: EdgeInsets.only(left: 16.0, top: 10.0, right: 16.0),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.center,
                mainAxisSize: MainAxisSize.max,
                children: <Widget>[
                  Container(
                    margin: EdgeInsets.only(bottom: 10.0),
                    child: Image.asset('assets/images/main/more_2lines_20dp.png', scale: 3.5),
                  ),
                  Expanded(
                    child: GridView.builder(
                      physics: NeverScrollableScrollPhysics(), //kill scrollable
                      shrinkWrap: true,
                      itemCount: snapshot == null ? 0 : snapshot.data.catlist.length,
                      gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 4),
                      itemBuilder: (BuildContext context, int index) {
                        var numItems = …

我的自定义 CameraX 流程如下：

• 打开相机预览（实时）
• 点击按钮拍照
• 单击该按钮时有一个过程（将路径转换为位图、旋转图像、自动裁剪图像、保存到设备中）
• 运行所有进程并成功后，将图像发送到其他Fragment并将其显示为glide

问题是何时running all the process (in step 3)有 adelayed 2 seconds并且相机预览静止live（not freeze或lock）。怎么做camera preview freeze or lock when running the process？

这是我在 Camera X 中运行相机预览的代码：

class CameraFragment : Fragment() {

        override fun onCreateView(
            inflater: LayoutInflater, container: ViewGroup?,
            savedInstanceState: Bundle?
        ): View? {
            // Inflate the layout for this fragment
            return inflater.inflate(R.layout.fragment_camera, container, false)
        }

        override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
            super.onViewCreated(view, savedInstanceState) …

我已经设置了构建应用程序版本，如 pro-guard、icon、manifest 等，但没有flavor. 我将 dir 迁移/android到，AndroidX因为如果没有，运行时无法构建应用程序版本flutter build apk。所以我迁移它并成功。像下面这样：

rifafauzi6@Anonymous-X456UR:/media/rifafauzi6/NM/Materi/BackUp Aplikasi Android/Flutter Project/vallery$ flutter build apk
You are building a fat APK that includes binaries for android-arm, android-arm64.
If you are deploying the app to the Play Store, it's recommended to use app bundles or split the APK to reduce the APK size.
    To generate an app bundle, run:
        flutter build appbundle --target-platform android-arm,android-arm64
        Learn more on: https://developer.android.com/guide/app-bundle
    To split the APKs per …

我有如下测试：

      blocTest(
        'emits [ViewData.loading and ViewData.loaded] when GetRepositories is added',
        build: () {
          when(
            () => useCase.getRepositories(),
          ).thenAnswer((_) async => Right(repositoriesDummyEntityFromRemote));
          return homeBloc;
        },
        act: (HomeBloc bloc) => bloc.add(GetRepositories()),
        expect: () => [
          HomeState(
            statusRepositories: ViewData.loading(message: 'Loading'),
            isShowTitle: false,
          ),
          HomeState(
            statusRepositories:
                ViewData.loaded(data: repositoriesDummyEntityFromRemote),
            isShowTitle: false,
          ),
        ],
      );

当我运行时出现错误：

package:bloc_test/src/bloc_test.dart 229:13  testBloc.<fn>.<fn>
dart:async                                   _completeOnAsyncError
package:bloc_test/src/bloc_test.dart         testBloc.<fn>.<fn>
===== asynchronous gap ===========================
dart:async                                   _asyncThenWrapperHelper
package:bloc_test/src/bloc_test.dart         testBloc.<fn>.<fn>
dart:async                                   runZonedGuarded
package:bloc_test/src/bloc_test.dart 192:13  testBloc.<fn>
package:bloc_test/src/bloc_test.dart 191:5   testBloc.<fn>
dart:async                                   runZoned
package:bloc/src/bloc_overrides.dart 46:26   BlocOverrides.runZoned
package:bloc_test/src/bloc_test.dart 190:23 …

通过实现 BLOC 和 RX Dart，我在我的应用程序上有一个文章搜索功能。我已经根据成为搜索关键字的“标题”成功搜索了文章，但是当我错误地填写“标题”时，结果并没有出现“文章不存在/其他任何东西”之类的错误根据关键“标题”的意思，结果不是实时的，而是在 LogCat 中得到如下错误：

E/flutter (25135): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: NoSuchMethodError: Class 'String' has no instance method 'forEach'.
E/flutter (25135): Receiver: "Data not found"
E/flutter (25135): Tried calling: forEach(Closure: (dynamic) => Null)
E/flutter (25135): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:50:5)
E/flutter (25135): #1      new Articles.fromJson (package:vallery/src/models/articles/articles.dart:11:22)
E/flutter (25135): #2      ApiProvider.searchArticle (package:vallery/src/resources/api/api_provider.dart:65:23)
E/flutter (25135): <asynchronous suspension>
E/flutter (25135): #3      Repository.searchArticlesRepository (package:vallery/src/resources/repository/repository.dart:19:74)
E/flutter (25135): #4      SearchArticleBloc.searchArticleBloc (package:vallery/src/blocs/article/articles_search_bloc.dart:12:42)
E/flutter (25135): <asynchronous suspension>
E/flutter (25135): #5      EditableTextState._formatAndSetValue (package:flutter/src/widgets/editable_text.dart:1335:14)
E/flutter (25135): #6      EditableTextState.updateEditingValue (package:flutter/src/widgets/editable_text.dart:971:5)
E/flutter (25135): …

我尝试使用自定义预测试脚本在 Codemagic 上运行测试。这是我的预测试脚本：

#!/bin/sh
cd libraries
cd dependencies
flutter pub get
cd ..
cd core
flutter pub get
flutter pub run build_runner build --delete-conflicting-outputs
cd ..
cd ..
cd features
cd splash
flutter pub get
flutter pub run build_runner build --delete-conflicting-outputs
cd ..
cd proposal
flutter pub get
flutter pub run build_runner build --delete-conflicting-outputs

这是我的 flutter 项目结构：

但是当pre-test运行时，我收到此错误：

Running "flutter pub get" in dependencies...                        2.5s
Running "flutter pub get" in core...                                4.9s
The pubspec.lock file has changed since …

我想在 Flutter 应用程序中使用横幅滑块，所以我找到了一个库来制作它，即Carousel. 这是一个很好的图书馆，但我发现这个图书馆有问题，How to set image from API into Carousel?或者have any library for support image from API (list), have dot indicator, autoplay like Carousel?