C# WPF：更改ContentControl时'；s内容时，新内容对象不会触发加载的事件

问题：

<controls:KeyboardHost Grid.Row="0" 
                       ContentTemplateSelector="{StaticResource KeyboardDataTemplateSelector}">
    <ContentControl.Content>
        <MultiBinding Converter="{StaticResource KeyboardCriteriaValueConverter}" Mode="OneWay">
            <Binding Source="{x:Static properties:Settings.Default}" Path="Language" />
            <Binding Path="Keyboard" />
        </MultiBinding>
    </ContentControl.Content>
</controls:KeyboardHost>

public class KeyboardDataTemplateSelector : DataTemplateSelector
{
    //TEMPLATE PROPERTIES HERE - THESE ARE SET IN THE RESOURCE DEFINITION

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        var criteria = item as KeyboardCriteria;

        //LOGIC TO RETURN THE APPROPRIATE KEYBOARD DATA TEMPLATE BASED ON THE criteria
    }
}

更改ContentControl的内容后，我无法连接到时间点，已应用DataTemplateSelector中的DataTemplate，并且已完成所有可视化布局，即加载新内容

设置：

<controls:KeyboardHost Grid.Row="0" 
                       ContentTemplateSelector="{StaticResource KeyboardDataTemplateSelector}">
    <ContentControl.Content>
        <MultiBinding Converter="{StaticResource KeyboardCriteriaValueConverter}" Mode="OneWay">
            <Binding Source="{x:Static properties:Settings.Default}" Path="Language" />
            <Binding Path="Keyboard" />
        </MultiBinding>
    </ContentControl.Content>
</controls:KeyboardHost>

public class KeyboardDataTemplateSelector : DataTemplateSelector
{
    //TEMPLATE PROPERTIES HERE - THESE ARE SET IN THE RESOURCE DEFINITION

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        var criteria = item as KeyboardCriteria;

        //LOGIC TO RETURN THE APPROPRIATE KEYBOARD DATA TEMPLATE BASED ON THE criteria
    }
}

一个名为“KeyboardHost”的自定义控件，它扩展了ContentControl

ContentControl.Content通过值转换器绑定（使用多重绑定）到2个通知属性，该值转换器将2个绑定属性组合到“KeyboardCriteria”类型的对象中

“KeyboardCriteria”是一个公共类，但我也尝试将其设置为FrameworkElement、Control和UserControl，以便尝试挂接到初始化、加载的etc事件中

ContentControl.ContentTemplateSelector是一个自定义选择器类（如下），它返回 基于ContentControl.Content（“KeyboardCriteria”）的数据模板

ContentControl.ContentTemplateSelector的DataTemplates是选择器上的属性，在my MainView的参考资料部分进行初始化和分配

尝试：

<controls:KeyboardHost Grid.Row="0" 
                       ContentTemplateSelector="{StaticResource KeyboardDataTemplateSelector}">
    <ContentControl.Content>
        <MultiBinding Converter="{StaticResource KeyboardCriteriaValueConverter}" Mode="OneWay">
            <Binding Source="{x:Static properties:Settings.Default}" Path="Language" />
            <Binding Path="Keyboard" />
        </MultiBinding>
    </ContentControl.Content>
</controls:KeyboardHost>

public class KeyboardDataTemplateSelector : DataTemplateSelector
{
    //TEMPLATE PROPERTIES HERE - THESE ARE SET IN THE RESOURCE DEFINITION

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        var criteria = item as KeyboardCriteria;

        //LOGIC TO RETURN THE APPROPRIATE KEYBOARD DATA TEMPLATE BASED ON THE criteria
    }
}

我已附加/覆盖以下ContentControl事件：

Initialized

Loaded

OnContentChanged

OnContentTemplateChanged

我已附加/覆盖以下“KeyboardCriteria”（定义为FrameworkElement）事件：

观察结果：

<controls:KeyboardHost Grid.Row="0" 
                       ContentTemplateSelector="{StaticResource KeyboardDataTemplateSelector}">
    <ContentControl.Content>
        <MultiBinding Converter="{StaticResource KeyboardCriteriaValueConverter}" Mode="OneWay">
            <Binding Source="{x:Static properties:Settings.Default}" Path="Language" />
            <Binding Path="Keyboard" />
        </MultiBinding>
    </ContentControl.Content>
</controls:KeyboardHost>

public class KeyboardDataTemplateSelector : DataTemplateSelector
{
    //TEMPLATE PROPERTIES HERE - THESE ARE SET IN THE RESOURCE DEFINITION

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        var criteria = item as KeyboardCriteria;

        //LOGIC TO RETURN THE APPROPRIATE KEYBOARD DATA TEMPLATE BASED ON THE criteria
    }
}

启动时：

KeyboardHost: OnTemplateChanged

KeyboardHost: ContentChanged

KeyboardCriteria: Initialized

KeyboardCriteria: Loaded

更改某个绑定条件属性（从而创建新的KeyboardCriteria对象）时：

注意：ContentControl.Content对象（“KeyboardCriteria”）上缺少加载的事件。

下一步：

<controls:KeyboardHost Grid.Row="0" 
                       ContentTemplateSelector="{StaticResource KeyboardDataTemplateSelector}">
    <ContentControl.Content>
        <MultiBinding Converter="{StaticResource KeyboardCriteriaValueConverter}" Mode="OneWay">
            <Binding Source="{x:Static properties:Settings.Default}" Path="Language" />
            <Binding Path="Keyboard" />
        </MultiBinding>
    </ContentControl.Content>
</controls:KeyboardHost>

public class KeyboardDataTemplateSelector : DataTemplateSelector
{
    //TEMPLATE PROPERTIES HERE - THESE ARE SET IN THE RESOURCE DEFINITION

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        var criteria = item as KeyboardCriteria;

        //LOGIC TO RETURN THE APPROPRIATE KEYBOARD DATA TEMPLATE BASED ON THE criteria
    }
}

我想我会完全放弃使用DataTemplateSelector的想法，将选择逻辑构建到ContentControl中，因为这已经是一个CustomControl了。我希望通过手动创建内容（并填充内容），可以避免使用当前在选择逻辑中使用的数据模板，因为我怀疑这是问题的一部分

代码示例：

<controls:KeyboardHost Grid.Row="0" 
                       ContentTemplateSelector="{StaticResource KeyboardDataTemplateSelector}">
    <ContentControl.Content>
        <MultiBinding Converter="{StaticResource KeyboardCriteriaValueConverter}" Mode="OneWay">
            <Binding Source="{x:Static properties:Settings.Default}" Path="Language" />
            <Binding Path="Keyboard" />
        </MultiBinding>
    </ContentControl.Content>
</controls:KeyboardHost>

public class KeyboardDataTemplateSelector : DataTemplateSelector
{
    //TEMPLATE PROPERTIES HERE - THESE ARE SET IN THE RESOURCE DEFINITION

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        var criteria = item as KeyboardCriteria;

        //LOGIC TO RETURN THE APPROPRIATE KEYBOARD DATA TEMPLATE BASED ON THE criteria
    }
}

MainViewModel:

<controls:KeyboardHost Grid.Row="0" 
                       ContentTemplateSelector="{StaticResource KeyboardDataTemplateSelector}">
    <ContentControl.Content>
        <MultiBinding Converter="{StaticResource KeyboardCriteriaValueConverter}" Mode="OneWay">
            <Binding Source="{x:Static properties:Settings.Default}" Path="Language" />
            <Binding Path="Keyboard" />
        </MultiBinding>
    </ContentControl.Content>
</controls:KeyboardHost>

public class KeyboardDataTemplateSelector : DataTemplateSelector
{
    //TEMPLATE PROPERTIES HERE - THESE ARE SET IN THE RESOURCE DEFINITION

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        var criteria = item as KeyboardCriteria;

        //LOGIC TO RETURN THE APPROPRIATE KEYBOARD DATA TEMPLATE BASED ON THE criteria
    }
}

公开最初具有非空值的“键盘”属性

MainView:

<controls:KeyboardHost Grid.Row="0" 
                       ContentTemplateSelector="{StaticResource KeyboardDataTemplateSelector}">
    <ContentControl.Content>
        <MultiBinding Converter="{StaticResource KeyboardCriteriaValueConverter}" Mode="OneWay">
            <Binding Source="{x:Static properties:Settings.Default}" Path="Language" />
            <Binding Path="Keyboard" />
        </MultiBinding>
    </ContentControl.Content>
</controls:KeyboardHost>

public class KeyboardDataTemplateSelector : DataTemplateSelector
{
    //TEMPLATE PROPERTIES HERE - THESE ARE SET IN THE RESOURCE DEFINITION

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        var criteria = item as KeyboardCriteria;

        //LOGIC TO RETURN THE APPROPRIATE KEYBOARD DATA TEMPLATE BASED ON THE criteria
    }
}

键盘数据模板选择器：

<controls:KeyboardHost Grid.Row="0" 
                       ContentTemplateSelector="{StaticResource KeyboardDataTemplateSelector}">
    <ContentControl.Content>
        <MultiBinding Converter="{StaticResource KeyboardCriteriaValueConverter}" Mode="OneWay">
            <Binding Source="{x:Static properties:Settings.Default}" Path="Language" />
            <Binding Path="Keyboard" />
        </MultiBinding>
    </ContentControl.Content>
</controls:KeyboardHost>

public class KeyboardDataTemplateSelector : DataTemplateSelector
{
    //TEMPLATE PROPERTIES HERE - THESE ARE SET IN THE RESOURCE DEFINITION

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        var criteria = item as KeyboardCriteria;

        //LOGIC TO RETURN THE APPROPRIATE KEYBOARD DATA TEMPLATE BASED ON THE criteria
    }
}

---

感谢您提供的任何见解。

我知道这是一个老问题，但我最近遇到了同样的问题。 这就是我所做的，为了解决它，以防其他人可以使用它

设置ContentControl的内容后，我将执行以下操作：

Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Render, (Action)OnAfterRendered);

---

然后，在“OnAfterRendered”方法中，我可以使用带有应用数据模板的ContentControl

抱歉，我没有阅读整篇文章，因为我现在没有足够的时间/注意力阅读它，但是当它加载时，

ContentControl

只会启动一次

Loaded

。我发现，当您将某个内容绑定到

内容时，
DataContextChanged
事件将在绑定到内容的对象更改时触发（并触发通知）。我很高兴ContentControl的Loaded事件不会在内容更改时触发，但我正在尝试获取内容的Loaded事件。ContentControl.ContentChanged持续激发，因此我知道内容何时发生更改，但我很难知道新内容何时加载。我需要知道布局过程何时完成，因为我的下一步是根据新内容及其子元素的呈现位置创建一组坐标。如果我将方法更改为不使用数据模板和内容数据模板选择器（即，创建内容控件并将其设置为自己的内容属性的内容控件）然后，新的content属性正确地触发加载的事件。我认为最初的问题与内容不是可视化树的一部分有关，即KeyboardCriteria是模板化的，永远不会出现在可视化树本身中，因此永远不会触发加载的事件。我猜它是初始化的，然后模板化，然后模板化元素ENT自己触发加载的事件？？？