c# - 两个 Bindable 属性可以相互通信吗？

Question

我正在创建一个具有 ContentView 的控件(源自 Frame ) field :

public class SelectionFrame : ContentView
{
    Frame f1;
        public SelectionFrame()
        {
            f1 = new Frame
            {
                VerticalOptions = LayoutOptions.Center,
                BackgroundColor = BorderColor,
                HorizontalOptions = LayoutOptions.Center,
                Padding = new Thickness(0),
                CornerRadius = 7,
                HeightRequest = 14,
                WidthRequest = 14,
                Content = f2
            };
            Content = f1;
        }

我设置它的 BackgroundColor通过这个 BindableProperty :

   public static readonly BindableProperty BorderColorProperty = BindableProperty.Create(nameof(BorderColor), typeof(Color), typeof(SelectionFrame), defaultValue: Color.Black, defaultBindingMode: BindingMode.TwoWay, propertyChanged: ColorChanged);

   public Color BorderColor
        {
            get { return (Color)GetValue(BorderColorProperty); }
            set { SetValue(BorderColorProperty, value); }
        }

然后我在另一个自定义控件( RadioButtonsGroup )中使用这个控件，它有这个 FrontColor BindableProperty :

      public static readonly BindableProperty FrontColorProperty = BindableProperty.Create(nameof(FrontColor), typeof(Color), typeof(RadioButtonsGroup), defaultValue: Color.Black);

  public Color FrontColor
        {
            get { return (Color)GetValue(FrontColorProperty); }
            set { SetValue(FrontColorProperty, value); }
        }

在这里我设置了 BorderColor的 SelectionFrame :

SelectionFrame circle = new SelectionFrame { ClassId = "r", BorderColor = FrontColor, VerticalOptions = LayoutOptions.Center };

我像这样使用控件:

<local:RadioButtonsGroup FrontColor="Red" x:Name="rbs"/>

但是 BackgroundColor框架的颜色没有改变，仍然具有默认颜色(黑色)。

Answer 1

那是因为你没有绑定(bind)BackgroundColor框架的属性到您的自定义控件属性。您在构造函数上设置它，但您没有在监听更改，您在这一行中正在做什么:

SelectionFrame circle = new SelectionFrame { ClassId = "r", BorderColor = FrontColor, VerticalOptions = LayoutOptions.Center };

要更正它，只需将您的 SelectionFrame 构造函数的代码更改为:

public SelectionFrame()
{
    f1 = new Frame
    {
        VerticalOptions = LayoutOptions.Center,
        HorizontalOptions = LayoutOptions.Center,
        Padding = new Thickness(0),
        CornerRadius = 7,
        HeightRequest = 14,
        WidthRequest = 14,
        Content = f2
    };

    f1.SetBinding(Frame.BackgroundColorProperty, new Binding(nameof(BorderColor)));
    f1.BindingContext = this;

    Content = f1;
}

现在您将能够听到对此属性的更改。

我希望它有所帮助。