如何從子類中創建的依賴屬性中獲取系結資料

例如，在背景屬性中，我們可以這樣做

<cs:CustomControl.Background>
    <SolidColorBrush Color="{Binding BackGround}"/>
</cs:CustomControl.Background>

SolidColorBrush是一個單獨的類，包含單獨的依賴屬性，它作業正常，背景屬性按預期更新。

我正在嘗試在我的CustomControl.

我已經創建了一個具有這樣的依賴屬性的子類

public class SubClass : DependencyObject
{
    public double SubProperty1
    {
        get { return (double)GetValue(SubProperty1Property); }
        set { SetValue(SubProperty1Property, value); }
    }

    // Using a DependencyProperty as the backing store for SubProperty1.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty SubProperty1Property =
        DependencyProperty.Register("SubProperty1", typeof(double), typeof(SubClass), new PropertyMetadata(10.0d, OnSubProperty1Changed));

    private static void OnSubProperty1Changed(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        //never called;
    }

    public string SubProperty2
    {
        get { return (string)GetValue(SubProperty2Property); }
        set { SetValue(SubProperty2Property, value); }
    }

    // Using a DependencyProperty as the backing store for SubProperty1.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty SubProperty2Property =
        DependencyProperty.Register("SubProperty2", typeof(string), typeof(SubClass), new PropertyMetadata("test", OnSubProperty2Changed));

    private static void OnSubProperty2Changed(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        //never called;
    }
}

在我的自定義工具的主類中，我創建了依賴屬性，如下所示：

public SubClass MainProperty
{
    get { return (SubClass)GetValue(MainPropertyProperty); }
    set { SetValue(MainPropertyProperty, value); }
}

// Using a DependencyProperty as the backing store for MainProperty.  This enables animation, styling, binding, etc...
public static readonly DependencyProperty MainPropertyProperty =
        DependencyProperty.Register("MainProperty", typeof(SubClass), typeof(CustomControl), new PropertyMetadata((SubClass)null, OnMainPropertyChanged));

private static void OnMainPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    // called when object created only and not called again when the property changed on the UI
}

然后在我的 WPF 視窗中，我執行了以下操作

<cs:CustomControl.MainProperty>
    <cs:SubClass SubProperty1="{Binding Length}" SubProperty2="{Binding Title}"/>
</cs:CustomControl.MainProperty>

我的代碼編譯但依賴屬性沒有更新，并且視圖模型更新時沒有呼叫回呼函式

我怎樣才能使這項作業？我想念什么我希望有任何詳細代碼的想法提前謝謝

uj5u.com熱心網友回復：

在 Visual Studio 的輸出視窗中，您應該看到類似

System.Windows.Data 錯誤：2：找不到目標元素的管理 FrameworkElement 或 FrameworkContentElement。...

當你除錯你的應用程式時。這是因為您的控制元件及其 DependencyObject 屬性沒有形成邏輯樹。

為了構建邏輯樹，子類必須派生自Freezable

public class SubClass : Freezable
{
   ...

    protected override Freezable CreateInstanceCore()
    {
        return new SubClass();
    }
}

并且 CustomControl 必須將 SubClass 實體添加到其邏輯子集合中：

private static void OnMainPropertyChanged(
    DependencyObject o, DependencyPropertyChangedEventArgs e)
{
    if (e.OldValue != null)
    {
        ((CustomControl)o).RemoveLogicalChild(e.OldValue);
    }
    if (e.NewValue != null)
    {
        ((CustomControl)o).AddLogicalChild(e.NewValue);
    }
}

標籤：C＃ wpf 依赖属性

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