c# - Storyboard中的模板绑定(bind) | ObjectAnimationUsingKeyFrames 不工作

Question

我有以下设置。问题是，如果我切换到 VisualState“Alarm”，则未设置 AlarmBrush。我尝试了不同的“绑定(bind)”(见下文)，但我只收到类似 System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element 的错误。 BindingExpression:Path=AlarmBrush;数据项=空；目标元素是 'DiscreteObjectKeyFrame' (HashCode=39320280)；目标属性是“值”(类型“对象”)。

如果我用 ResourceKey 替换该值，那么一切都很好。但是我想让这个 State 动态，所以静态资源不是 opionion。

基类

[TemplateVisualState(GroupName = "FooGroup", Name = "Alarm")]
public abstract class BaseClass : Control
{
    public static readonly DependencyProperty AlarmBrushProperty = DependencyProperty.Register("AlarmBrush", typeof(Brush), typeof(BaseClass), null);
    public Brush AlarmBrush
    {
        get { return (Brush)GetValue(AlarmBrushProperty); }
        set { SetValue(AlarmBrushProperty, value); }
    }
}

派生类

public class DerivedClass : BaseClass
{
    public DerivedClass()
    {
        this.DefaultStyleKey = typeof(DerivedClass);
    }

    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate();
        VisualStateManager.GoToState(this, "Alarm", true);
    }
}

XAML 样式

<Style TargetType="Basic:DerivedClass">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Basic:DerivedClass">
                <Grid>
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="FooGroup">
                            <VisualState x:Name="Alarm">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(Panel.Background)" Storyboard.TargetName="AlarmBorder">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{Binding AlarmBrush, RelativeSource={RelativeSource TemplatedParent}}"/>
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type Basic:DerivedClass}}, Path=AlarmBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <Border x:Name="AlarmBorder" BorderBrush="{TemplateBinding BorderBrush}" Padding="{TemplateBinding Padding}"  BorderThickness="{TemplateBinding BorderThickness}">
                        <TextBlock Text="test" Foreground="{TemplateBinding Foreground}" TextWrapping="Wrap" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                    </Border>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Setter Property="BorderThickness" Value="5"/>
</Style>

xaml

<Foo:DerivedClass BorderBrush="#FFDA1F1F" AlarmBrush="#FF00FF0C"/>

Answer 1

你会讨厌这个，但我记得这是 WPF 的限制之一。 Value 属性需要被卡住，这意味着您不能使用绑定(bind)来动态更改它。 ColorAnimation 的 To 属性也是如此。

因为您实际上并没有动画颜色(动画Brush只会立即改变颜色)，您总是可以获得AlarmBorder<的引用 并手动设置其 Background。