C# 子属性更新调用它'；s的父母'；s`OnProperty已更改`

我正在尝试创建一个XF组件，它的某些属性属于继承自

BindableObject

的类型。为了进行说明，我使用了具有

双半径

和

颜色阴影颜色

属性的类

阴影

，以及具有

bool IsLoading

和

阴影阴影

属性的类

MyBoxText

我的

视图

和它的

绑定

按预期工作，但它的自定义渲染器有问题：

例如，当我更改

Ghost

属性时，我需要重新绘制整个视图（在

MyBoxText

控件中），以直观地更新阴影颜色

以下是一些mcve：

类别代码：

public class MyBoxText : Label /* It's bindable by inheritance */
{
    #region Properties
    public static readonly BindableProperty IsLoadingProperty = BindableProperty.Create(nameof(IsLoading), typeof(bool), typeof(MyBoxText), false) ;
    public bool IsLoading
    {
        get { return (bool)GetValue(IsLoadingProperty); }
        set { SetValue(IsLoadingProperty, value); }
    }

    public static readonly BindableProperty GhostProperty = BindableProperty.Create(nameof(Ghost), typeof(Shadow), typeof(MyBoxText), null) ;
    public Shadow Ghost
    {
        get { return (Shadow)GetValue(GhostProperty); }
        set { SetValue(GhostProperty, value); }
    }
    #endregion
}

public class Shadow : BindableObject /* It's explictly bindable */
{
    #region Properties
    public static readonly BindableProperty ShadowColorProperty = BindableProperty.Create(nameof(ShadowColor), typeof(Color), typeof(Shadow), Color.Black) ;
    public Color ShadowColor
    {
        get { return (Color)GetValue(ShadowColorProperty); }
        set { SetValue(ShadowColorProperty, value); }
    }

    public static readonly BindableProperty ShadowRadiusProperty = BindableProperty.Create(nameof(ShadowRadius), typeof(double), typeof(Shadow), 20) ;
    public double ShadowRadius
    {
        get { return (double)GetValue(ShadowRadiusProperty); }
        set { SetValue(ShadowRadiusProperty, value); }
    }
    #endregion

    public Shadow()
    {

    }
}

public class MyBoxText : LabelRenderer
{
    public MyBoxText()
    {
        SetWillNotDraw(false);
    }

    public override void Draw(Canvas canvas)
    {
        MyBoxText myView = (MyBoxText)this.Element;

        // Some drawing logic
    }

    protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        base.OnElementPropertyChanged(sender, e);

        if (e.PropertyName == MyBoxText.IsLoadingProperty.PropertyName  ||
            e.PropertyName == MyBoxText.GhostProperty.PropertyName )
            Invalidate();
    }
}

我的渲染器代码如下：

public class MyBoxText : Label /* It's bindable by inheritance */
{
    #region Properties
    public static readonly BindableProperty IsLoadingProperty = BindableProperty.Create(nameof(IsLoading), typeof(bool), typeof(MyBoxText), false) ;
    public bool IsLoading
    {
        get { return (bool)GetValue(IsLoadingProperty); }
        set { SetValue(IsLoadingProperty, value); }
    }

    public static readonly BindableProperty GhostProperty = BindableProperty.Create(nameof(Ghost), typeof(Shadow), typeof(MyBoxText), null) ;
    public Shadow Ghost
    {
        get { return (Shadow)GetValue(GhostProperty); }
        set { SetValue(GhostProperty, value); }
    }
    #endregion
}

public class Shadow : BindableObject /* It's explictly bindable */
{
    #region Properties
    public static readonly BindableProperty ShadowColorProperty = BindableProperty.Create(nameof(ShadowColor), typeof(Color), typeof(Shadow), Color.Black) ;
    public Color ShadowColor
    {
        get { return (Color)GetValue(ShadowColorProperty); }
        set { SetValue(ShadowColorProperty, value); }
    }

    public static readonly BindableProperty ShadowRadiusProperty = BindableProperty.Create(nameof(ShadowRadius), typeof(double), typeof(Shadow), 20) ;
    public double ShadowRadius
    {
        get { return (double)GetValue(ShadowRadiusProperty); }
        set { SetValue(ShadowRadiusProperty, value); }
    }
    #endregion

    public Shadow()
    {

    }
}

public class MyBoxText : LabelRenderer
{
    public MyBoxText()
    {
        SetWillNotDraw(false);
    }

    public override void Draw(Canvas canvas)
    {
        MyBoxText myView = (MyBoxText)this.Element;

        // Some drawing logic
    }

    protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        base.OnElementPropertyChanged(sender, e);

        if (e.PropertyName == MyBoxText.IsLoadingProperty.PropertyName  ||
            e.PropertyName == MyBoxText.GhostProperty.PropertyName )
            Invalidate();
    }
}

问题是，当我更改Ghost.ShadowColor属性时，不会调用我的“OnElementPropertyChanged”覆盖，并且视图在屏幕上保留旧颜色

是否有方法将子级的“属性更新”事件传播到父级视图“属性已更改”或其他方法来实现此目的

问题是，当我更改Ghost.ShadowColor属性时，不会调用我的“OnElementPropertyChanged”覆盖，视图将保留屏幕上的旧颜色。 是否有方法将子级的“属性更新”事件传播到父级视图“属性已更改”或其他方法来实现此目的

是的，有办法。因为您的阴影继承自

BindableObject

，后者实现了

INotifyPropertyChanged

接口。您可以设置通知

ShadowColor

更改：

将

OnPropertyChanged（）

添加到Shadow.cs中的

ShadowColor

的Setter中：

public class Shadow : BindableObject /* It's explictly bindable */
{
    #region Properties
    public static readonly BindableProperty ShadowColorProperty = BindableProperty.Create(nameof(ShadowColor), typeof(Color), typeof(Shadow), Color.Black);
    public Color ShadowColor
    {
        get { return (Color)GetValue(ShadowColorProperty); }
        set { SetValue(ShadowColorProperty, value);
            //Notify the ShadowColorProperty Changed
            OnPropertyChanged();
        }
    }
   ...
}

修改您的

MyBoxText.cs

如下：

public class MyBoxText : Label /* It's bindable by inheritance */
{
 ...

    public static readonly BindableProperty GhostProperty = BindableProperty.Create(nameof(Ghost), typeof(Shadow), typeof(MyBoxText), null);
    public Shadow Ghost
    {
        get { return (Shadow)GetValue(GhostProperty); }
        set {
            //register the ShadowColor change event
            value.PropertyChanged += ShadowColor_PropertyChanged;
            SetValue(GhostProperty, value); }
    }

    private void ShadowColor_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
    {
        //unregister the event
        this.Ghost.PropertyChanged -= ShadowColor_PropertyChanged;
        //set this.Ghost to a new object with new ShadowColor to trigger the OnPropertyChanged
        this.Ghost = new Shadow
        {
            ShadowColor = (sender as Shadow).ShadowColor,
            ShadowRadius = Ghost.ShadowRadius
        };
    }
}

---

多亏埃尔维斯的回答，我才明白。基于他的想法，我做了一些修改，在其他组件上重用它，现在我正在共享它，以防其他人需要类似的东西

我认为通过这种方式，我们可以得到更清晰、简单的代码：

public class MyBoxText : Label /* It's bindable by inheritance */
{
    // Added this as private property
    private ChangingPropagator changingPropagator;
    private ChangingPropagator ChangingPropagator
    {
        get
        {
            if (changingPropagator == null)
                changingPropagator = new ChangingPropagator(this, OnPropertyChanged, nameof(Shadow.ShadowColor), nameof(Shadow.ShadowRadius));

            return changingPropagator;
        }
    }

    #region Properties
    public static readonly BindableProperty IsLoadingProperty = BindableProperty.Create(nameof(IsLoading), typeof(bool), typeof(MyBoxText), false) ;
    public bool IsLoading
    {
        get { return (bool)GetValue(IsLoadingProperty); }
        set { SetValue(IsLoadingProperty, value); }
    }

    public static readonly BindableProperty GhostProperty = BindableProperty.Create(nameof(Ghost), typeof(Shadow), typeof(MyBoxText), null) ;
    public Shadow Ghost
    {
        // Here I use the ChangingPropagator's Getter and Setter instead of the deafult ones:
        get { return ChangingPropagator.GetValue<Shadow>(GhostProperty); }
        set { ChangingPropagator.SetValue(GhostProperty,ref value); }
    }
    #endregion
}

---

它看起来确实像是一个解决方案，正如我所需要的，但它有一个小错误：当我从XAML上的绑定设置

MyBoxText.Ghost

时，它没有命中

set

方法（我们开始听的地方）。。。我将根据这些解决方案进行一些尝试，并让您知道。谢谢你的时间和努力。我也在

get

方法中消除并添加了侦听器，避免了这个错误。现在很好用了，谢谢。我根据您的答案创建了一个单独的类来重用该解决方案，为了进一步的重用，我将在这里发布它。