如何在Flutter中实现自定义对话框？

Question

我是一个新手，需要创建一个图库应用程序，并且需要一个自定义对话框才能看到所选图像，如何实现呢？

Answer 1

截屏：

简单地对这个方法进行分类：

void showDialog() {
  showGeneralDialog(
    barrierLabel: "Barrier",
    barrierDismissible: true,
    barrierColor: Colors.black.withOpacity(0.5),
    transitionDuration: Duration(milliseconds: 700),
    context: context,
    pageBuilder: (_, __, ___) {
      return Align(
        alignment: Alignment.bottomCenter,
        child: Container(
          height: 300,
          child: SizedBox.expand(child: FlutterLogo()),
          margin: EdgeInsets.only(bottom: 50, left: 12, right: 12),
          decoration: BoxDecoration(
            color: Colors.white,
            borderRadius: BorderRadius.circular(40),
          ),
        ),
      );
    },
    transitionBuilder: (_, anim, __, child) {
      return SlideTransition(
        position: Tween(begin: Offset(0, 1), end: Offset(0, 0)).animate(anim),
        child: child,
      );
    },
  );
}

来源

Answer 2

使用Dialog类，它是Flutter中AlertDialog类的父类。对话框小部件具有参数“ shape”，可用于对对话框的边缘进行整形。

这是一个代码示例：

 Dialog errorDialog = Dialog(
  shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12.0)), //this right here
  child: Container(
    height: 300.0,
    width: 300.0,

    child: Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        Padding(
          padding:  EdgeInsets.all(15.0),
          child: Text('Cool', style: TextStyle(color: Colors.red),),
        ),
        Padding(
          padding: EdgeInsets.all(15.0),
          child: Text('Awesome', style: TextStyle(color: Colors.red),),
        ),
        Padding(padding: EdgeInsets.only(top: 50.0)),
        FlatButton(onPressed: (){
          Navigator.of(context).pop();
        },
            child: Text('Got It!', style: TextStyle(color: Colors.purple, fontSize: 18.0),))
      ],
    ),
  ),
);
showDialog(context: context, builder: (BuildContext context) => errorDialog);}

Answer 3

1. 警报对话框
2. 自定义对话框
3. 全屏对话框

参考：Flutter 警报对话框到自定义对话框 | 作者：伊尚·费尔南多 | 代码柴 | 中等的

警报对话框

showDialog(
  context: context,
  builder: (BuildContext context) {
    return AlertDialog(
      title: Text("Alert Dialog"),
      content: Text("Dialog Content"),
      actions: [
        TextButton(
          child: Text("Close"),
          onPressed: () {
            Navigator.of(context).pop();
            },
        )
      ],
    );
  },
);

自定义对话框

showDialog(
        context: context,
        builder: (BuildContext context) {
          return Dialog(
            shape: RoundedRectangleBorder(
                borderRadius:
                    BorderRadius.circular(20.0)), //this right here
            child: Container(
              height: 200,
              child: Padding(
                padding: const EdgeInsets.all(12.0),
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    TextField(
                      decoration: InputDecoration(
                          border: InputBorder.none,
                          hintText: 'What do you want to remember?'),
                    ),
                    SizedBox(
                      width: 320.0,
                      child: RaisedButton(
                        onPressed: () {},
                        child: Text(
                          "Save",
                          style: TextStyle(color: Colors.white),
                        ),
                        color: const Color(0xFF1BC0C5),
                      ),
                    )
                  ],
                ),
              ),
            ),
          );
        });

全屏对话框

showGeneralDialog(
      context: context,
      barrierDismissible: true,
      barrierLabel: MaterialLocalizations.of(context)
          .modalBarrierDismissLabel,
      barrierColor: Colors.black45,
      transitionDuration: const Duration(milliseconds: 200),
      pageBuilder: (BuildContext buildContext,
          Animation animation,
          Animation secondaryAnimation) {
        return Center(
          child: Container(
            width: MediaQuery.of(context).size.width - 10,
            height: MediaQuery.of(context).size.height -  80,
            padding: EdgeInsets.all(20),
            color: Colors.white,
            child: Column(
              children: [
                RaisedButton(
                  onPressed: () {
                    Navigator.of(context).pop();
                  },
                  child: Text(
                    "Save",
                    style: TextStyle(color: Colors.white),
                  ),
                  color: const Color(0xFF1BC0C5),
                )
              ],
            ),
          ),
        );
      });

Answer 4

在按钮上单击将对话框显示为 -

showDialog(
        context: context,
        builder: (_) => LogoutOverlay(),
      );

带有两个按钮的对话框设计 -

class LogoutOverlay extends StatefulWidget {
      @override
      State<StatefulWidget> createState() => LogoutOverlayState();
    }

    class LogoutOverlayState extends State<LogoutOverlay>
        with SingleTickerProviderStateMixin {
      AnimationController controller;
      Animation<double> scaleAnimation;

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

        controller =
            AnimationController(vsync: this, duration: Duration(milliseconds: 450));
        scaleAnimation =
            CurvedAnimation(parent: controller, curve: Curves.elasticInOut);

        controller.addListener(() {
          setState(() {});
        });

        controller.forward();
      }

      @override
      Widget build(BuildContext context) {
        return Center(
          child: Material(
            color: Colors.transparent,
            child: ScaleTransition(
              scale: scaleAnimation,
              child: Container(
                margin: EdgeInsets.all(20.0),
                  padding: EdgeInsets.all(15.0),
                  height: 180.0,

                  decoration: ShapeDecoration(
                      color: Color.fromRGBO(41, 167, 77, 10),
                      shape: RoundedRectangleBorder(
                          borderRadius: BorderRadius.circular(15.0))),
                  child: Column(
                    children: <Widget>[
                      Expanded(
                          child: Padding(
                        padding: const EdgeInsets.only(
                            top: 30.0, left: 20.0, right: 20.0),
                        child: Text(
                          "Are you sure, you want to logout?",
                          style: TextStyle(color: Colors.white, fontSize: 16.0),
                        ),
                      )),
                      Expanded(
                          child: Row(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: <Widget>[
                          Padding(
                            padding: const EdgeInsets.all(10.0),
                            child: ButtonTheme(
                                height: 35.0,
                                minWidth: 110.0,
                                child: RaisedButton(
                                  color: Colors.white,
                                  shape: RoundedRectangleBorder(
                                      borderRadius: BorderRadius.circular(5.0)),
                                  splashColor: Colors.white.withAlpha(40),
                                  child: Text(
                                    'Logout',
                                    textAlign: TextAlign.center,
                                    style: TextStyle(
                                        color: Colors.green,
                                        fontWeight: FontWeight.bold,
                                        fontSize: 13.0),
                                  ),
                                  onPressed: () {
                                    setState(() {
                                      Route route = MaterialPageRoute(
                                          builder: (context) => LoginScreen());
                                      Navigator.pushReplacement(context, route);
                                    });
                                  },
                                )),
                          ),
                          Padding(
                            padding: const EdgeInsets.only(
                                left: 20.0, right: 10.0, top: 10.0, bottom: 10.0),
                            child:  ButtonTheme(
                                height: 35.0,
                                minWidth: 110.0,
                                child: RaisedButton(
                                  color: Colors.white,
                                  shape: RoundedRectangleBorder(
                                      borderRadius: BorderRadius.circular(5.0)),
                                  splashColor: Colors.white.withAlpha(40),
                                  child: Text(
                                    'Cancel',
                                    textAlign: TextAlign.center,
                                    style: TextStyle(
                                        color: Colors.green,
                                        fontWeight: FontWeight.bold,
                                        fontSize: 13.0),
                                  ),
                                  onPressed: () {
                                    setState(() {
                                      /* Route route = MaterialPageRoute(
                                          builder: (context) => LoginScreen());
                                      Navigator.pushReplacement(context, route);
                                   */ });
                                  },
                                ))
                          ),
                        ],
                      ))
                    ],
                  )),
            ),
          ),
        );
      }
    }

Answer 5

您只需将此类放在您的项目中并调用其显示对话框的方法。
使用这个类你不需要到处写对话代码

class DialogUtils {
  static DialogUtils _instance = new DialogUtils.internal();

  DialogUtils.internal();

  factory DialogUtils() => _instance;

  static void showCustomDialog(BuildContext context,
      {@required String title, 
      String okBtnText = "Ok",
      String cancelBtnText = "Cancel",
      @required Function okBtnFunction}) {
    showDialog(
        context: context,
        builder: (_) {
          return AlertDialog(
            title: Text(title),
            content: /* Here add your custom widget  */,
            actions: <Widget>[
              FlatButton(
                child: Text(okBtnText),
                onPressed: okBtnFunction,
              ),
              FlatButton(
                  child: Text(cancelBtnText),
                  onPressed: () => Navigator.pop(context))
            ],
          );
        });
  }
 }

你可以像这样调用这个方法：

GestureDetector(
      onTap: () =>
              DialogUtils.showCustomDialog(context,
          title: "Gallary",
          okBtnText: "Save",
          cancelBtnText: "Cancel",
          okBtnFunction: () => /* call method in which you have write your logic and save process  */),
      child: Container(),
)

Answer 6

我通常为与应用程序主题匹配的对话框构建一个包装器，并避免大量冗余代码。

占位符对话框

class PlaceholderDialog extends StatelessWidget {
  const PlaceholderDialog({
    this.icon,
    this.title,
    this.message,
    this.actions = const [],
    Key? key,
  }) : super(key: key);

  final Widget? icon;
  final String? title;
  final String? message;
  final List<Widget> actions;

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(20.0),
      ),
      icon: icon,
      title: title == null
          ? null
          : Text(
              title!,
              textAlign: TextAlign.center,
            ),
      titleTextStyle: AppStyle.bodyBlack,
      content: message == null
          ? null
          : Text(
              message!,
              textAlign: TextAlign.center,
            ),
      contentTextStyle: AppStyle.textBlack,
      actionsAlignment: MainAxisAlignment.center,
      actionsOverflowButtonSpacing: 8.0,
      actions: actions,
    );
  }
}

用法

    showDialog(
      context: context,
      builder: (ctx) => PlaceholderDialog(
        icon: Icon(
          Icons.add_circle,
          color: Colors.teal,
          size: 80.0,
        ),
        title: 'Save Failed',
        message: 'An error occurred when attempt to save the message',
        actions: [
          TextButton(
            onPressed: () => Navigator.of(ctx).pop(),
            child: Text('!Got It'),
          ),
        ],
      ),
    );

结果

Answer 7

一个一般的例子

showDialog(context: context,builder: (context) => _onTapImage(context)); // Call the Dialog.

_onTapImage(BuildContext context) {
    return Stack(
      alignment: Alignment.center,
      children: <Widget>[
        Image.network('https://via.placeholder.com/150',fit: BoxFit.contain,), // Show your Image
        Align(
          alignment: Alignment.topRight,
          child: RaisedButton.icon(
              color: Theme.of(context).accentColor,
              textColor: Colors.white,
              onPressed: () => Navigator.pop(context),
              icon: Icon(
                Icons.close,
                color: Colors.white,
              ),
              label: Text('Close')),
        ),
      ],
    );
  }