wpf - WPF 中的 ResourceDictionary 中没有键的 DataTemplate

Question

我在 ResourceDictionary 中有几个 DataTemplate:

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:z="clr-namespace:ZoomPan">
    <DataTemplate DataType="{x:Type z:Circle}">
        <z:Circle Center="{Binding Center}" Radius="{Binding Radius}" x:Name="circle"/>
        <DataTemplate.Triggers>
            <DataTrigger ... />
        </DataTemplate.Triggers>
    </DataTemplate>
    .... etc.
</ResourceDictionary>

我在窗口中使用它:

<z:MyUserControl>
    <z:MyUserControl.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="Dictionary.xaml"/>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </z:MyUserControl.Resources>
</z:MyUserControl>

数据模板和触发器工作正常。

我有两个问题:

• 为什么 ResourceDictionary 中的 DataTemplate 不需要 x:Key？

• 我可以用 Key 以某种方式将 ResourceDictionary 划分为多个部分，然后指向一个部分中的 DataTemplates 吗？

Answer 1

Why do DataTemplates in a ResourceDictionary not need a x:Key?

当您缺少 Style 或 DataTemplate 的键时，此结构:

<DataTemplate TargetType="{x:Type local:MyType}">

自动转换为:

<DataTemplate x:Key="{x:Type local:MyType}" TargetType="{x:Type local:MyType}">

这意味着 Style/DataTemplate 将显式用于此类型的所有控件，因为在 ResourceDictionaries 中不能是没有键的元素，而是这样做是为了简化结构。引用自MSDN :

Setting the TargetType property to the TextBlock type without setting an x:Key implicitly sets the x:Key to {x:Type TextBlock}. This also means that if you give the above Style an x:Key value of anything other than {x:Type TextBlock}, the Style would not be applied to all TextBlock elements automatically. Instead, you need to apply the style to the TextBlock elements explicitly.

<小时/>

When I give the DataTemplates a Key they stop to work

当你为DataTemplate指定一个key时，应该使用这个key，如:

<ContentControl Name="MyContent"
                ContentTemplate="{StaticResource MainView}"> // here set the key

    <MainWindowViewModels:MainViewModel />
</ContentControl>

<小时/>

Can I divide the ResourceDictionary somehow in sections with a Key and then point to the DataTemplates in a section?

不幸的是，ResourceDictionary 是 Quote :

class is not derived from DictionaryBase. Instead, the ResourceDictionary class implements IDictionary but relies on a Hashtable internally.

在这种情况下，它不是有序字典，其中每个元素都分配给哈希。用于分离字典区域使用 ResourceDictionary.MergedDictionaries .