Flutter之Dialog加载弹窗提示

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class Dialogs {
  static CustomDialog normalProgressDialog(String message) {
    return CustomDialog(
      child: Container(
        height: 150,
        alignment: Alignment.center,
        child: Row(
          crossAxisAlignment: CrossAxisAlignment.center,
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            SizedBox(
               20.0,
              height: 20.0,
              child: CircularProgressIndicator(
                strokeWidth: 2.0,
              ),
            ),
            Text('  $message'),
          ],
        ),
      ),
    );
  }

  static Future<T> showNormalProgressDialog<T>(BuildContext context,
      String message, AsyncValueGetter<T> callback) async {
    T result;
    bool isDialogShowing = false;

    BuildContext _context;
    showDialog(
        context: context,
        barrierDismissible: false,
        builder: (context) {
          _context = context;
          return WillPopScope(
              child: Dialogs.normalProgressDialog(message),
              onWillPop: () {
                return Future.value(!isDialogShowing);
              });
        });

    if (callback != null) result = await callback();

    isDialogShowing = false;
    if (_context != null) {
      Navigator.pop(_context);
    } else {
      Navigator.pop(context);
    }

    return result;
  }
}

class CustomDialog extends StatelessWidget {
  /// Creates a dialog.
  ///
  /// Typically used in conjunction with [showDialog].
  const CustomDialog({
    Key key,
    this.backgroundColor,
    this.elevation,
    this.insetAnimationDuration = const Duration(milliseconds: 100),
    this.insetAnimationCurve = Curves.decelerate,
    this.shape,
    this.child,
    this.padding = const EdgeInsets.symmetric(horizontal: 40.0, vertical: 24.0),
  }) : super(key: key);

  /// {@template flutter.material.dialog.backgroundColor}
  /// The background color of the surface of this [CustomDialog].
  ///
  /// This sets the [Material.color] on this [CustomDialog]'s [Material].
  ///
  /// If `null`, [ThemeData.cardColor] is used.
  /// {@endtemplate}
  final Color backgroundColor;

  /// {@template flutter.material.dialog.elevation}
  /// The z-coordinate of this [CustomDialog].
  ///
  /// If null then [DialogTheme.elevation] is used, and if that's null then the
  /// dialog's elevation is 24.0.
  /// {@endtemplate}
  /// {@macro flutter.material.material.elevation}
  final double elevation;

  /// The duration of the animation to show when the system keyboard intrudes
  /// into the space that the dialog is placed in.
  ///
  /// Defaults to 100 milliseconds.
  final Duration insetAnimationDuration;

  /// The curve to use for the animation shown when the system keyboard intrudes
  /// into the space that the dialog is placed in.
  ///
  /// Defaults to [Curves.fastOutSlowIn].
  final Curve insetAnimationCurve;

  /// {@template flutter.material.dialog.shape}
  /// The shape of this dialog's border.
  ///
  /// Defines the dialog's [Material.shape].
  ///
  /// The default shape is a [RoundedRectangleBorder] with a radius of 2.0.
  /// {@endtemplate}
  final ShapeBorder shape;

  /// The widget below this widget in the tree.
  ///
  /// {@macro flutter.widgets.child}
  final Widget child;

  /// The amount of space by which to inset the child.
  final EdgeInsetsGeometry padding;

  static const RoundedRectangleBorder _defaultDialogShape =
  RoundedRectangleBorder(
      borderRadius: BorderRadius.all(Radius.circular(2.0)));
  static const double _defaultElevation = 24.0;

  @override
  Widget build(BuildContext context) {
    final DialogTheme dialogTheme = DialogTheme.of(context);
    return AnimatedPadding(
      padding: MediaQuery.of(context).viewInsets + padding,
      duration: insetAnimationDuration,
      curve: insetAnimationCurve,
      child: MediaQuery.removeViewInsets(
        removeLeft: true,
        removeTop: true,
        removeRight: true,
        removeBottom: true,
        context: context,
        child: Center(
          child: ConstrainedBox(
            constraints: const BoxConstraints(minWidth: 280.0),
            child: Material(
              color: backgroundColor ??
                  dialogTheme.backgroundColor ??
                  Theme.of(context).dialogBackgroundColor,
              elevation:
              elevation ?? dialogTheme.elevation ?? _defaultElevation,
              shape: shape ?? dialogTheme.shape ?? _defaultDialogShape,
              type: MaterialType.card,
              child: child,
            ),
          ),
        ),
      ),
    );
  }
}

使用：

 ListTile(
        leading: Text("弹窗提示"),
        onTap: () async {
          await Dialogs.showNormalProgressDialog(context, '加载中，请稍后。。。',
              () async {
            try {
              // todo 网络请求处理，耗时操作等
              setState(() {});
            } catch (error) {
              // todo 错误提示
            }
          });
        },
     )，