使用 MVVM 在 WPF 中设置焦点
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Setting focus in WPF with MVVM
提问by Farawin
I have Grid with multiple Textboxes. Depending on actions the user might take focus should be changed to one of the textboxes. My current solution uses a string property in the ViewModel and a data trigger in xaml to change focus. It works nicely but it seems a rather roundabout way to achieve this so I was wondering if it could be done in a clearner way?
我有多个文本框的网格。根据用户可能采取的操作，应将焦点更改为文本框之一。我当前的解决方案使用 ViewModel 中的字符串属性和 xaml 中的数据触发器来更改焦点。它工作得很好，但似乎是一种相当迂回的方式来实现这一点，所以我想知道是否可以以更清晰的方式完成？
<Grid.Style>
<Style TargetType="Grid">
<Style.Triggers>
<DataTrigger Binding="{Binding FocusedItem}" Value="number">
<Setter Property="FocusManager.FocusedElement" Value="{Binding ElementName=number}"/>
</DataTrigger>
<DataTrigger Binding="{Binding FocusedItem}" Value="name">
<Setter Property="FocusManager.FocusedElement" Value="{Binding ElementName=name}"/>
</DataTrigger>
<DataTrigger Binding="{Binding FocusedItem}" Value="id">
<Setter Property="FocusManager.FocusedElement" Value="{Binding ElementName=id}"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Grid.Style>
As you can see the value of the property and the name of the element is the same so I would like to do this i a single trigger instead of having one trigger per element.
正如您所看到的，属性的值和元素的名称是相同的，所以我想使用单个触发器来执行此操作，而不是每个元素有一个触发器。
Maybe someone can come up with a cleaner way?
也许有人可以想出更清洁的方法？
Thanks in advance
提前致谢
回答by Heinrich
The way I handled setting focus in one of my projects was by using a focus extension (I apologize I do not remember where I saw the original post this is from).
我在我的一个项目中处理设置焦点的方式是使用焦点扩展（很抱歉，我不记得我从哪里看到的原始帖子）。
public static class FocusExtension
{
public static bool GetIsFocused(DependencyObject obj)
{
return (bool)obj.GetValue(IsFocusedProperty);
}
public static void SetIsFocused(DependencyObject obj, bool value)
{
obj.SetValue(IsFocusedProperty, value);
}
public static readonly DependencyProperty IsFocusedProperty =
DependencyProperty.RegisterAttached(
"IsFocused", typeof(bool), typeof(FocusExtension),
new UIPropertyMetadata(false, OnIsFocusedPropertyChanged));
private static void OnIsFocusedPropertyChanged(DependencyObject d,
DependencyPropertyChangedEventArgs e)
{
var uie = (UIElement)d;
if ((bool)e.NewValue)
{
uie.Focus();
}
}
}
And then in xaml file I use it as a Dependency Property:
然后在 xaml 文件中我将它用作依赖属性：
<TextBox Uid="TB1" FontSize="13" localExtensions:FocusExtension.IsFocused="{Binding Path=TB1Focus}" Height="24" HorizontalAlignment="Left" Margin="113,56,0,0" Name="TB_UserName" VerticalAlignment="Top" Width="165" Text="{Binding Path=TB1Value, UpdateSourceTrigger=PropertyChanged}" />
You can then use a binding to set the focus.
然后，您可以使用绑定来设置焦点。
