.NET MAUI 7：自定义Bindable Property绑定Attached Property无响应求助

1. 修正XAML中的自定义视图类型错误 #

你的XAML中使用了<views:CustomView>，但自定义属性ShouldAnimateOut是定义在UserCredentialsView类中的，两者不匹配会直接导致绑定失效。将XAML中的视图类型改为正确的类名：

<views:UserCredentialsView
    Margin="0,0,0,20" 
    attached:AttachedProperty.Animate="False" 
    ShouldAnimateOut="{Binding (attached:AttachedProperty.Animate), Source={RelativeSource Mode=Self}}"
    StrokeThickness="0" 
    x:Name="myCustomView" 
    Padding="10,10" 
    VerticalOptions="End" 
    Background="#345173" 
    HeightRequest="200">

    <views:UserCredentialsView.GestureRecognizers>
        <TapGestureRecognizer Tapped="TapGestureRecognizer_Tapped"/>
    </views:UserCredentialsView.GestureRecognizers>

</views:UserCredentialsView>

2. 调整自定义属性的绑定模式避免循环更新 #

ShouldAnimateOut设置为TwoWay绑定模式，同时在其变更事件中强制将AttachedProperty.Animate设为false，会触发双向绑定的循环冲突：附加属性变更→自定义属性变更→附加属性被强制重置→自定义属性再次变更，干扰绑定系统的正常同步逻辑。

根据你的需求，ShouldAnimateOut仅需同步AttachedProperty.Animate的变更，将绑定模式改为OneWay即可：

public class UserCredentialsView : Border
{
    public static readonly BindableProperty ShouldAnimateOutProperty =
        BindableProperty.Create(nameof(ShouldAnimateOut), typeof(bool), typeof(UserCredentialsView), false, BindingMode.OneWay, propertyChanged: ShouldAnimateOutPropertyChanged);

    private static void ShouldAnimateOutPropertyChanged(BindableObject bindable, object oldValue, object newValue)
    {
        AttachedProperty.SetAnimate(bindable, false);
    }

    public bool ShouldAnimateOut
    {
        get => (bool)GetValue(ShouldAnimateOutProperty);
        set => SetValue(ShouldAnimateOutProperty, value);
    }
}

3. 优化点击事件的类型转换 #

将点击事件中的sender转换为准确的UserCredentialsView类型，避免不必要的类型转换问题：

private void TapGestureRecognizer_Tapped(object sender, TappedEventArgs e)
{
    var mControl = sender as UserCredentialsView;
    if (mControl == null) return;
    
    AttachedProperty.SetAnimate(mControl, !AttachedProperty.GetAnimate(mControl));
}

核心问题总结 #

• 视图类型不匹配：XAML中使用的视图类无ShouldAnimateOut属性，绑定系统无法识别目标属性，导致变更事件无法触发。
• 双向绑定循环：TwoWay模式下自定义属性的反向更新与手动强制重置附加属性的逻辑冲突，干扰了绑定值的同步流程。

内容的提问来源于stack exchange，提问作者yigit sertac