ICommand 命令在 Maui Preview 11 中不起作用

Question

我是 Maui 的新手，正在按照 Xamarin 表单教程设计登录页面。我似乎无法通过登录页面，因为按钮的绑定没有触发。
我在输出 window 中得到了这个，但无法在任何地方找到任何修复。
该应用程序似乎运行很好，只是两个按钮不响应用户交互。

[ViewRootImpl@ae55060[MainActivity]] MSG_RESIZED: frame=[0,0][800,1280] ci=[0,32][0,0] vi=[0,32][0,426] or=1
[0:] Microsoft.Maui.Controls.Element: Warning: Microsoft.Maui.Controls.StackLayout is already a child of Microsoft.Maui.Controls.GridLayout. Remove Microsoft.Maui.Controls.StackLayout from Microsoft.Maui.Controls.GridLayout before adding to Microsoft.Maui.Controls.GridLayout.
[0:] Microsoft.Maui.Controls.Element: Warning: Microsoft.Maui.Controls.StackLayout is already a child of Microsoft.Maui.Controls.GridLayout. Remove Microsoft.Maui.Controls.StackLayout from Microsoft.Maui.Controls.GridLayout before adding to Microsoft.Maui.Controls.GridLayout.
[0:] Microsoft.Maui.Controls.Element: Warning: Microsoft.Maui.Controls.StackLayout is already a child of Microsoft.Maui.Controls.GridLayout. Remove Microsoft.Maui.Controls.StackLayout from Microsoft.Maui.Controls.GridLayout before adding to Microsoft.Maui.Controls.GridLayout.
[0:] Microsoft.Maui.Controls.Element: Warning: Microsoft.Maui.Controls.StackLayout is already a child of Microsoft.Maui.Controls.GridLayout. Remove Microsoft.Maui.Controls.StackLayout from Microsoft.Maui.Controls.GridLayout before adding to Microsoft.Maui.Controls.GridLayout.
[0:] Microsoft.Maui.Controls.Element: Warning: Microsoft.Maui.Controls.Border is already a child of Microsoft.Maui.Controls.GridLayout. Remove Microsoft.Maui.Controls.Border from Microsoft.Maui.Controls.GridLayout before adding to Microsoft.Maui.Controls.GridLayout.
[0:] Microsoft.Maui.Controls.Element: Warning: Microsoft.Maui.Controls.Label is already a child of Microsoft.Maui.Controls.GridLayout. Remove Microsoft.Maui.Controls.Label from Microsoft.Maui.Controls.GridLayout before adding to Microsoft.Maui.Controls.GridLayout.

Login.xaml:

<StackLayout>
<StackLayout> Image and Label over here </StackLayout>
<StackLayout Margin="10" Padding="20" VerticalOptions="EndAndExpand">

            <Border Stroke="#620774"
                    StrokeThickness="4"
                    Padding="16,8"
                    BackgroundColor="Transparent"
                    HorizontalOptions="Center">
                <Border.StrokeShape>
                    <RoundRectangle CornerRadius="5,5,5,5" BackgroundColor="Transparent"/>
                </Border.StrokeShape>
                <Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="Auto"/>
                        <RowDefinition Height="Auto"/>
                    </Grid.RowDefinitions>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="Auto"/>
                        <ColumnDefinition Width="*"/>
                    </Grid.ColumnDefinitions>

                    <!--Email Address-->
                    <Image 
                        GridLayout.Column="0"
                        GridLayout.Row="0"
                        Source="email.png"
                           Aspect="AspectFit"
                           VerticalOptions="CenterAndExpand"
                           HorizontalOptions="CenterAndExpand"
                           WidthRequest="20"
                           HeightRequest="35"/>

                    <Entry
                        GridLayout.Column="1"
                        GridLayout.Row="0"
                        PlaceholderColor="#9d2888"
                        Margin="4,0,0,0"
                        TextColor="Black"
                        HeightRequest="50"
                        Placeholder="Email Address"
                        Keyboard="Email"/>

                    

                    <!--Password-->
                    <Image Source="key.png"
                           Aspect="AspectFit"
                        GridLayout.Column="0"
                           GridLayout.Row="1"
                           VerticalOptions="CenterAndExpand"
                           HorizontalOptions="CenterAndExpand"
                           WidthRequest="20"
                           HeightRequest="35"/>

                    <Entry
                        GridLayout.Column="1"
                        GridLayout.Row="1"
                        HeightRequest="50"
                        Margin="4,0,0,0"
                        PlaceholderColor="#9d2888"
                        TextColor="Black"
                        Placeholder="Password"
                        IsPassword="True"/>

                </Grid>
            </Border> 
    
            <Label Text="Forgot Password?"
                   HorizontalOptions="Center"
                   Margin="0,15,0,15"
                   VerticalOptions="StartAndExpand"
                   TextColor="#0052FF">
                <Label.GestureRecognizers>
                    <TapGestureRecognizer Command="{Binding ForgotPassword}"/>
                </Label.GestureRecognizers>
            </Label>

</StackLayout>
<StackLayout>
            <Button Text="LOGIN"
                    MaximumHeightRequest="45"
                    CornerRadius="10"
                    HeightRequest="45"
                    TextColor="White"
                    Margin="2"
                    BackgroundColor="#620774"
                    Command="{Binding LoginCommand}"/>


            <Button Text="Dont have an account? Register here!"
                    MaximumHeightRequest="45"
                    CornerRadius="10"
                    HeightRequest="45"
                    TextColor="White"
                    BackgroundColor="#620774"
                    Margin="2"
                    Command="{Binding RegisterCommand}"/>
</StackLayout>
<StackLayout> 2 Labels here </StackLayout>
</StackLayout>

Login.xaml.cs

public partial class Login : ContentPage
    {
        public Login()
        {
            InitializeComponent();
            BindingContext = new LoginViewModel();
        }
    }

LoginViewModel.cs

public class LoginViewModel : BaseViewModel
    {
        //private fields
        private string _username;
        private string _password;

        public string Username
        {
            get { return _username; }
            set { _username = value; OnPropertyChanged(); }
        }
        public string Password
        {
            get { return _password; }
            set { _password = value; OnPropertyChanged(); }
        }

        //Commands
        public ICommand LoginCommand { get; set; }
        public ICommand RegisterCommand { get; set; }
        public ICommand ForgotPassword { get; set; }

        public LoginViewModel()
        {
            System.Console.WriteLine("INSIDE LOGIN VIEWMODEL");
            LoginCommand = new Command(UserLogin);
            RegisterCommand = new Command(NewUser);
            ForgotPassword = new Command(ResetPassword);
        }
        public async void UserLogin()
        {
        }
   }

Answer 1

通过进行 2 处更改，我能够使其正常工作。但是，这些更改会影响页面的垂直间距。看看这是否适合您，然后尝试找到其他方法来获得所需的布局。

从 StackLayout 中删除 VerticalOptions="EndAndExpand"。
从 Label 中删除 VerticalOptions="StartAndExpand"。

Login.xaml:

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="MauiTests.Login"
             Title="Login"
             BackgroundColor="White">
    <StackLayout>
        <Button Text="LOGIN"
                    MaximumHeightRequest="45"
                    CornerRadius="10"
                    HeightRequest="45"
                    TextColor="White"
                    Margin="2"
                    BackgroundColor="#620774"
                    Command="{Binding LoginCommand}"/>

        <!-- VerticalOptions="EndAndExpand" -->
        <StackLayout Margin="10" Padding="20">

            <Border Stroke="#620774"
                    StrokeThickness="4"
                    Padding="16,8"
                    BackgroundColor="Transparent"
                    HorizontalOptions="Center">
                <Border.StrokeShape>
                    <RoundRectangle CornerRadius="5,5,5,5" BackgroundColor="Transparent"/>
                </Border.StrokeShape>
                <Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="Auto"/>
                        <RowDefinition Height="Auto"/>
                    </Grid.RowDefinitions>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="Auto"/>
                        <ColumnDefinition Width="*"/>
                    </Grid.ColumnDefinitions>

                    <!--Email Address-->

                    <Entry
                        GridLayout.Column="1"
                        GridLayout.Row="0"
                        PlaceholderColor="#9d2888"
                        Margin="4,0,0,0"
                        TextColor="Black"
                        HeightRequest="50"
                        Placeholder="Email Address"
                        Keyboard="Email"/>



                    <!--Password-->
                    <Entry
                        GridLayout.Column="1"
                        GridLayout.Row="1"
                        HeightRequest="50"
                        Margin="4,0,0,0"
                        PlaceholderColor="#9d2888"
                        TextColor="Black"
                        Placeholder="Password"
                        IsPassword="True"/>

                </Grid>
            </Border>

            <!-- VerticalOptions="StartAndExpand" -->
            <Label Text="Forgot Password?"
                   HorizontalOptions="Center"
                   Margin="0,15,0,15"
                   
                   TextColor="#0052FF">
                <Label.GestureRecognizers>
                    <TapGestureRecognizer Command="{Binding ForgotPassword}"/>
                </Label.GestureRecognizers>
            </Label>

        </StackLayout>


        <Button Text="Dont have an account? Register here!"
                    MaximumHeightRequest="45"
                    CornerRadius="10"
                    HeightRequest="45"
                    TextColor="White"
                    BackgroundColor="#620774"
                    Margin="2"
                    Command="{Binding RegisterCommand}"/>
    </StackLayout>
</ContentPage>

ICommand 命令在 Maui Preview 11 中不起作用

ICommand Command not working in Maui Preview 11

.net

xamarin.forms

maui

Login.xaml:

Login.xaml.cs

LoginViewModel.cs