wpf - 附加属性

Question

我对 WPF 附加属性有点困惑。当您使用附加属性时，该附加属性只能由定义它的类读取和使用，对吗？例如，如果我想在按钮上使用一些附加属性作为悬停颜色，我可以从按钮的模板中获取附加属性值，并且我可以从按钮访问附加属性以设置悬停颜色吗？

Answer 1

添加到 H.B. 的答案。使用一个例子:

For example if I wanted to use some attached property as a hover color on a button, can I get the attached property value from the button's template, and will I be able access the attached property from the button to set the hover color?

是的，你当然可以。假设您有一个名为 HoverBrush 的附加属性在名为 SomeClass 的类中定义，您可以在实例上设置值并在模板中绑定(bind)到它

<StackPanel>
    <StackPanel.Resources>
        <ControlTemplate x:Key="MyButtonTemplate" TargetType="{x:Type Button}">
            <Border x:Name="border" Background="Gray">
                <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
            </Border>
            <ControlTemplate.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Setter TargetName="border"
                            Property="Background"
                            Value="{Binding RelativeSource={RelativeSource TemplatedParent},
                                            Path=(local:SomeClass.HoverBrush)}"/>
                </Trigger>
            </ControlTemplate.Triggers>
        </ControlTemplate>
    </StackPanel.Resources>
    <Button Content="Blue Hover"
            local:SomeClass.HoverBrush="Blue"
            Template="{StaticResource MyButtonTemplate}"/>
    <Button Content="Green Hover"
            local:SomeClass.HoverBrush="Green"
            Template="{StaticResource MyButtonTemplate}"/>
</StackPanel>

有问题的附加属性定义如下

public class SomeClass
{
    public static DependencyProperty HoverBrushProperty =
        DependencyProperty.RegisterAttached("HoverBrush",
                                            typeof(Brush),
                                            typeof(SomeClass),
                                            new PropertyMetadata(null));
    public static void SetHoverBrush(DependencyObject obj, Brush value)
    {
        obj.SetValue(HoverBrushProperty, value);
    }
    public static Brush GetHoverBrush(DependencyObject obj)
    {
        return (Brush)obj.GetValue(HoverBrushProperty);
    }
}