假設(shè)我有以下課程：public class MyClass : System.Windows.FrameworkElement{ public static readonly DependencyProperty HasFocusProperty = DependencyProperty.RegisterAttached("HasFocus", typeof(bool), typeof(MyClass), new PropertyMetadata(default(bool))); public bool HasFocus { get => (bool)GetValue(HasFocusProperty); set => SetValue(HasFocusProperty, value); } public System.Windows.Controls.TextBox TextBox { get; set; }}我想根據(jù) property 更改TextBoxvia XAML Template Trigger 的一些 UI 屬性HasFocus，所以我執(zhí)行以下操作：<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:win="clr-namespace:System.Windows.Controls"> <Style TargetType="{x:Type win:TextBox}"> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type win:TextBox}"> <ControlTemplate.Triggers> <Trigger Property="MyClass.HasFocus" Value="True"> <Setter TargetName="Border" Property="BorderBrush" Value="Red" /> <Setter TargetName="Border" Property="BorderThickness" Value="2" /> </Trigger> </ControlTemplate.Triggers> </ControlTemplate> </Setter.Value> </Setter> </Style> </ResourceDictionary>但是，設(shè)置時不應(yīng)用樣式HasFocus = true。在 的屬性中TextBox，我可以看到觸發(fā)器已注冊。如果我更改<Trigger Property="MyClass.HasFocus" Value="True">為<Trigger Property="MyClass.HasFocus" Value="False">，則最初會應(yīng)用我的樣式。所以我認(rèn)為我的 XAML 定義沒問題。任何想法如何解決這個問題？
1 回答
侃侃爾雅
TA貢獻(xiàn)1801條經(jīng)驗 獲得超16個贊
應(yīng)用于 a 的模板中的元素TextBox不能綁定到 a 的屬性MyClass，除非有一個MyClass元素可以綁定到可視化樹中的某處。
如果您希望能夠設(shè)置 a 的自定義HasFocus屬性TextBox，您應(yīng)該創(chuàng)建一個附加屬性：
public class FocusExtensions
{
public static readonly DependencyProperty SetHasFocusProperty = DependencyProperty.RegisterAttached(
"HasFocus",
typeof(bool),
typeof(FocusExtensions),
new FrameworkPropertyMetadata(false)
);
public static void SetHasFocus(TextBox element, bool value)
{
element.SetValue(SetHasFocusProperty, value);
}
public static bool GetHasFocus(TextBox element)
{
return (bool)element.GetValue(SetHasFocusProperty);
}
}
它可以為任何TextBox元素設(shè)置：
<TextBox local:FocusExtensions.HasFocus="True">
<TextBox.Style>
<Style TargetType="{x:Type TextBox}">
<Style.Triggers>
<Trigger Property="local:FocusExtensions.HasFocus" Value="True">
<Setter Property="BorderBrush" Value="Red" />
<Setter Property="BorderThickness" Value="2" />
</Trigger>
</Style.Triggers>
</Style>
</TextBox.Style>
</TextBox>
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