WPF、用户控件或数据模板

发布于 2024-08-12 13:32:48 字数 1556 浏览 6 评论 0原文

最近我尝试在我的应用程序中重用一些 UI 元素。当我开始使用 WPF 编程时，我被告知 DataTemplate 是重用 UI 元素的最佳方式。您可以为数据实体定义模板并在任何地方使用它。听起来非常好。但是，我也发现了一些缺点，特别是与 UserControl 相比时。

您不能重用在另一个窗口或用户控件中定义的数据模板。例如，如果 UserDataTemplate 是在 WindowA.xaml 中定义的，则不能在 WindowB.xaml 中使用它。解决方案可能是将 DataTemplate 作为资源放入全局资源字典中。
DataTemplate 很难有一些代码隐藏。如第 1 项所述，如果将 DataTemplate 放入 ResourceDictionary 中，则默认情况下没有地方放置代码。我用谷歌搜索了这个问题，是的，我找到了一个让 ResourceDictionary 有一个 cs 文件的技巧。但它还有另一个问题。
DataTemplate的另一个问题是你必须清楚DataTemplate本身的实例和DataTemplate内容的实例之间的区别。一个 DataTemplate 将只有一个“DataTemplate 实例”，并且可能有许多 DataTemplate 内容的实例。让我用一个例子来解释一下：
<前><代码><数据模板>><网格.资源>> 公共部分类CodeBehind { 点 mousePos = new Point(); 私有无效OnMouseLeftButtonDown（对象发送者，MouseButtonEventArgs e） { mousePos = e.Pos...; } }

结果将是：User1只会有一个实例，但是一旦应用DataTemplate就会创建一个User2实例，这意味着如果多次应用datatemplate，User2将有很多实例。然而，与 UserControl 不同，“mousePos”字段不会有很多副本。如果 DataTemplate 被应用 100 次，mousePos 将不会有 100 个副本，这意味着 100 个 Grid 将同时使用唯一的一个 mousePos 字段，这可能会导致问题。在 UserControl 中，您定义的字段将仅由控件使用。 100 个 UserControl 实例将有 100 个字段副本。

也许我使用 DataTemplate 的方式错误。任何评论表示赞赏。

最好的问候，

扎克

原文

Recently I'm trying to reuse some UI elements in my application. When I started programming with WPF I'm told that DataTemplate is the best way to reuse UI elements. You can define a template for your data entity and use it everywhere. It sounds very good.
However, I also found some disadvantages, especially when it is compared with UserControl.

You cannot reuse a DataTemplate defined in another Window or UserControl. For example, if UserDataTemplate is define in WindowA.xaml, you cannot use it in WindowB.xaml. The solution might be that put the DataTemplate as a resource in a global Resource Dictionary.
DataTemplate is hard to have some code behind. As mentioned in item 1, if you put the DataTemplate in a ResourceDictionary, there is no place to put your code by default. I googled the problem and yes, I found a trick to make the ResourceDictionary have a cs file. But it still has another problem.

Another problem of DataTemplate is that you must be clear with the difference between the instance of DataTemplate itself and the instances of the content of DataTemplate. A DataTemplate will have only one "instance of DataTemplate", and may have many instances of the content of the DataTemplate. Let me explain it with an Example:

<DataTemplate>
        <DataTemplate.Resources>
                <my:User x:key="User1"/>
        </DataTemplate.Resources>                
        <Grid MouseLeftButtonDown="OnMouseLeftButtonDown">
                <Grid.Resources>
                        <my:User x:key="User2"/>
                </Grid.Resources>
        </Grid>        
</DataTemplate>


public partial class CodeBehind
{
         Point mousePos = new Point();

        private void OnMouseLeftButtonDown(object sender, MouseButtonEventArgs e)  
        {
                mousePos = e.Pos...;
        }
}

The result will be that : User1 will only have one instance, however, a User2 instance will be created once the DataTemplate is applied, which means User2 will have many instances if the datatemplate is being applied many times.
However, unlike UserControl, the field "mousePos" will NOT have many copies. If the DataTemplate is being applied 100 times, the mousePos won't have 100 copies, which mean the 100 Grids will use the only one mousePos field as the same time, which may cause problems.
In UserControl, the field you defined will only be used by the control. 100 UserControl instances will have 100 field copies.

Maybe I'm using DataTemplate in the wrong way. Any comment is appreciated.

Best regards,

Zach

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