Question

我有DependencyProperty

public ObservableCollection<DataTemplate> WizardTemplateCollection
{
    get { return (ObservableCollection<DataTemplate>)GetValue(WizardTemplateCollectionProperty); }
    set { SetValue(WizardTemplateCollectionProperty, value); }
}

// Using a DependencyProperty as the backing store for MyProperty.  This enables animation, styling, binding, etc...
public static readonly DependencyProperty WizardTemplateCollectionProperty =
    DependencyProperty.Register("WizardTemplateCollection", typeof(ObservableCollection<DataTemplate>), typeof(CustomWizardControl), new PropertyMetadata(new ObservableCollection<DataTemplate>()));

想要这样做：

<custom:CustomWizardControl>
    <custom:CustomWizardControl.WizardTemplateCollection>
        <DataTemplate>
            <Rectangle></Rectangle>
        </DataTemplate>
        <DataTemplate>
            <Rectangle></Rectangle>
        </DataTemplate>
        <DataTemplate>
            <Rectangle></Rectangle>
        </DataTemplate>
    </custom:CustomWizardControl.WizardTemplateCollection>
</custom:CustomWizardControl>

我需要什么DataType？或者我如何初始化ObservableCollection中的XAML。

其他：

public class CustomWizardControl : Control {}

Answer 1

您的CustomWizardControl课程必须继承DepenedencyObject或其衍生类型之一，例如UIElement或Control：

public class CustomWizardControl : Control
{
    public ObservableCollection<DataTemplate> WizardTemplateCollection
    {
        get { return (ObservableCollection<DataTemplate>)GetValue(WizardTemplateCollectionProperty); }
        set { SetValue(WizardTemplateCollectionProperty, value); }
    }
    ...
}

这有效：

public class CustomWizardControl : Control
{
    public CustomWizardControl()
    {
        WizardTemplateCollection = new ObservableCollection<DataTemplate>();
    }

    public ObservableCollection<DataTemplate> WizardTemplateCollection
    {
        get { return (ObservableCollection<DataTemplate>)GetValue(WizardTemplateCollectionProperty); }
        set { SetValue(WizardTemplateCollectionProperty, value); }
    }

    public static readonly DependencyProperty WizardTemplateCollectionProperty =
        DependencyProperty.Register("WizardTemplateCollection", typeof(ObservableCollection<DataTemplate>), typeof(CustomWizardControl), new PropertyMetadata(null));
}

<local:CustomWizardControl x:Name="ctrl">
    <local:CustomWizardControl.WizardTemplateCollection>
        <DataTemplate>
            <Rectangle></Rectangle>
        </DataTemplate>
        <DataTemplate>
            <Rectangle></Rectangle>
        </DataTemplate>
        <DataTemplate>
            <Rectangle></Rectangle>
        </DataTemplate>
    </local:CustomWizardControl.WizardTemplateCollection>
</local:CustomWizardControl>

<TextBlock Text="{Binding WizardTemplateCollection.Count, ElementName=ctrl}" />

Answer 2

您无法直接在XAML中设置ObservableCollection<T>的通用参数。

相反，您应该创建从DataTemplateCollection继承的自定义ObservableCollection<DataTemplate>。然后你就可以像往常一样使用你的收藏。

public class DataTemplateCollection : ObservableCollection<DataTemplate>
{
}

<custom:CustomWizardControl>
    <custom:CustomWizardControl.WizardTemplateCollection>
        <custom:DataTemplateCollection>
            <DataTemplate>
                <Rectangle></Rectangle>
            </DataTemplate>
            <DataTemplate>
                <Rectangle></Rectangle>
            </DataTemplate>
            <DataTemplate>
                <Rectangle></Rectangle>
            </DataTemplate>
        </custom:DataTemplateCollection>
    </custom:CustomWizardControl.WizardTemplateCollection>
</custom:CustomWizardControl>

附加说明： NEVER 使用可变对象初始化依赖项属性的默认值，因为每个控件实例都将使用此单个可变实例。相反，您必须将默认值设置为null并在构造函数中确定初始值。

在XAML中初始化DataTemplates的集合

2 个答案: