在 .NET MAUI ContentView 中充当可绑定属性

Question

ContentView 中的 Bindable 属性可以是

Func<bool>

 类型吗？也就是说，像这样：

public partial class MyControl : ContentView
{
    public static readonly BindableProperty DoSomethingProperty = BindableProperty.Create(
            nameof(DoSomething),
            typeof(Func<bool>),
            typeof(MyControl);

    public Func<bool> DoSomething
    {
        get => (Func<bool>)GetValue(DoSomethingProperty);
        set => SetValue(DoSomethingProperty, value);
    }
}

然后你可以在这样的页面中使用它：

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:controls="clr-namespace:MauiPlayground.Controls"
             x:DataType="vm:MainPageViewModel"
             x:Class="MauiPlayground.MainPage">
    <ContentPage.Content>
        <VerticalStackLayout>
            <controls:MyControl DoSomething="{Binding ViewModelDoSomething}" />
        </VerticalStackLayout>
    </ContentPage.Content>
</ContentPage>

MainPageViewModel 将包含此方法：

public bool ViewModelSoSomething()
{
    return true;
}

（这不是实际代码，只是想知道理论上是否可以完成。例如，如果您想将回调函数或方法传递给 ContentView）

我尝试做这样的事情，编译器没有抱怨，但 DoSomething 属性的值从未设置。也许还有另一种方法可以做到这一点？

Answer 1

您可以通过将

BindableProperty

 类型的 

ICommand

 添加到 

ContentView

 来实现此目的，还可以通过添加 

BindableProperty

 类型的 

object

 将数据传递到命令。

我这边实现了这个功能，并且我还给我的ContentView添加了一个公共属性

YourName

。

请参考以下代码：

MyControl.xaml

public partial class MyControl : ContentView 
{
    public String YourName
    {
        get
        {
            String value = (String)GetValue(YourNameProperty);
            return value;
        }
        set
        {
            SetValue(YourNameProperty, value);
        }
    }

    public static readonly BindableProperty YourNameProperty = BindableProperty.Create(nameof(YourName)
    , typeof(String)
    , typeof(MyControl), defaultBindingMode: BindingMode.TwoWay, propertyChanged: OnYourNameChanged);

    static void OnYourNameChanged(BindableObject bindable, object oldValue, object newValue)
    {
        Console.WriteLine("-----------------> " + newValue);
    }

   // add BindableProperty:ChildCommandProperty

    public static readonly BindableProperty ChildCommandProperty =
            BindableProperty.Create(nameof(ChildCommand), typeof(ICommand), typeof(MyControl));

    public ICommand ChildCommand
    {
        get => (ICommand)GetValue(ChildCommandProperty);
        set => SetValue(ChildCommandProperty, value);
    }


   // add BindableProperty:ChildCommandParameterProperty

    public static BindableProperty ChildCommandParameterProperty =
        BindableProperty.Create(nameof(ChildCommandParameter), typeof(object), typeof(MyControl));

    public object ChildCommandParameter
    {
        get => (object)GetValue(ChildCommandParameterProperty);
        set => SetValue(ChildCommandParameterProperty, value);
    }

    public MyControl()
      {
            InitializeComponent();
      }
}

MyControl.xaml.cs

<?xml version="1.0" encoding="utf-8" ?> 
<ContentView xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="MauiMyContentViewApp.Controls.MyControl"
             
               x:Name="TestControlView"
             >
    <ContentView.Content>
        <VerticalStackLayout>
            <Label   Text="{Binding Source={x:Reference TestControlView}, Path=YourName}" x:Name="NameLabel"  Margin="10"
            VerticalOptions="Center" 
            HorizontalOptions="Center" />


            <Button Text="Do Something"
                Command="{Binding Source={x:Reference TestControlView}, Path= ChildCommand}"  
                CommandParameter="{Binding Source={x:Reference TestControlView}, Path= ChildCommandParameter}"
                 />
        </VerticalStackLayout>
    </ContentView.Content>
</ContentView>