c# - 如何从 XAML 访问元素资源中的 Storyboard？

Question

考虑这段代码:

<UserControl x:Class="MyApp.MyControl"
             ...
         xmlns:local="clr-namespace:MyApp"
         DataContext="{Binding RelativeSource={RelativeSource Mode=Self}}">

    <UserControl.Template>
        <ControlTemplate>
            <ControlTemplate.Resources>
                <Storyboard x:Key="MyStory">
                    <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" Storyboard.TargetName="brdBase">
                        <SplineColorKeyFrame KeyTime="0:0:1" Value="Red"/>
                    </ColorAnimationUsingKeyFrames>
                </Storyboard>
            </ControlTemplate.Resources>

            <Border x:Name="brdBase" BorderThickness="1" BorderBrush="Cyan" Background="Black">
                ...
            </Border>

            <ControlTemplate.Triggers>
                <Trigger SourceName="brdBase" Property="IsMouseOver" Value="True">
                    <Trigger.EnterActions>
                        <BeginStoryboard Storyboard="{StaticResource MyStory}"/>
                    </Trigger.EnterActions>
                </Trigger>
            </ControlTemplate.Triggers>
        </ControlTemplate>
    </UserControl.Template>
</UserControl>

上面的代码没有问题。现在，我想绑定(bind) MyStory 的关键帧值到此用户控件的 DP(名为 SpecialColor)，如下所示:

<Storyboard x:Key="MyStory">
    <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" Storyboard.TargetName="brdBase">
        <SplineColorKeyFrame KeyTime="0:0:1" Value="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type local:MyControl}}, Path=SpecialColor}"/>
    </ColorAnimationUsingKeyFrames>
</Storyboard>

这会出错:

无法卡住此 Storyboard 时间线树以供跨线程使用。

可以使用隐藏代码来做到这一点。但我如何才能仅在 XAML 中执行此操作？

---

代码隐藏辅助解决方案:

►第 1 步:将 MyStory Storyboard进入brdBase资源。

<UserControl.Template>
    <ControlTemplate>
        <Border x:Name="brdBase" BorderThickness="1" BorderBrush="Cyan" Background="Black">
            <Border.Resources>
                <Storyboard x:Key="MyStory">
                    <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" Storyboard.TargetName="brdBase">
                        <SplineColorKeyFrame KeyTime="0:0:1" Value="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type local:MyControl}}, Path=SpecialColor}"/>
                    </ColorAnimationUsingKeyFrames>
                </Storyboard>
            </Border.Resources>
            ...
        </Border>

        <ControlTemplate.Triggers>
            <Trigger SourceName="brdBase" Property="IsMouseOver" Value="True">
                <Trigger.EnterActions>
                    <BeginStoryboard Storyboard="{StaticResource MyStory}"/>
                </Trigger.EnterActions>
            </Trigger>
        </ControlTemplate.Triggers>
    </ControlTemplate>
</UserControl.Template>

错误: 找不到名为“MyStory”的资源。资源名称区分大小写。

►第 2 步:消除 Trigger在 IsMouseOver属性并开始 MyStory来自代码背后。

<UserControl.Template>
    <ControlTemplate>
        <Border x:Name="brdBase" BorderThickness="1" BorderBrush="Cyan" Background="Black" MouseEnter="brdBase_MouseEnter">
            <Border.Resources>
                <Storyboard x:Key="MyStory">
                    <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" Storyboard.TargetName="brdBase">
                        <SplineColorKeyFrame KeyTime="0:0:1" Value="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type local:MyControl}}, Path=SpecialColor}"/>
                    </ColorAnimationUsingKeyFrames>
                </Storyboard>
            </Border.Resources>
        </Border>
    </ControlTemplate>
</UserControl.Template>

C# 代码隐藏:

private void brdBase_MouseEnter(object sender, MouseEventArgs e)
{
   Border grdRoot = (Border)this.Template.FindName("brdBase", this);
   Storyboard story = grdRoot.Resources["MyStory"] as Storyboard;

   story.Begin(this, this.Template);
}

►第 3 步: 解决方案已经完成，但第一次不起作用。幸运的是，这个问题有一个解决方法。放ControlTemplate就够了在Style .

(我需要其他 Trigger 类型而不是 EventTrigger 并且必须用 UserControl 包装 ControlTemplate 元素。)

---

更新:

关于使用 ObjectDataProvider 的想法失败了。

1. ObjectDataProvider 资源不能用于提供 Storyboard!!!错误报告是:
   • >XamlParseException: 设置属性“System.Windows.Media.Animation.BeginStoryboard.Storyboard”引发异常。
   • >InnerException:“System.Windows.Data.ObjectDataProvider”不是属性“Storyboard”的有效值。
2. AssociatedControl DP 始终为空。

代码如下:

<UserControl.Template>
    <ControlTemplate>
        <ControlTemplate.Resources>
            <local:StoryboardFinder x:Key="StoryboardFinder1" AssociatedControl="{Binding ElementName=brdBase}"/>
            <ObjectDataProvider x:Key="dataProvider" ObjectInstance="{StaticResource StoryboardFinder1}" MethodName="Finder">
                <ObjectDataProvider.MethodParameters>
                    <sys:String>MyStory</sys:String>
                </ObjectDataProvider.MethodParameters>
            </ObjectDataProvider>
        </ControlTemplate.Resources>

        <Border x:Name="brdBase" BorderThickness="1" BorderBrush="Cyan" Background="Black">
            <Border.Resources>
                <Storyboard x:Key="MyStory">
                    <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" Storyboard.TargetName="brdBase">
                        <SplineColorKeyFrame KeyTime="0:0:1" Value="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type local:MyControl}}, Path=SpecialColor}"/>
                    </ColorAnimationUsingKeyFrames>
                </Storyboard>
            </Border.Resources>
            ...
        </Border>

        <ControlTemplate.Triggers>
            <Trigger SourceName="brdBase" Property="IsMouseOver" Value="True">
                <Trigger.EnterActions>
                    <BeginStoryboard Storyboard="{StaticResource dataProvider}"/>
                </Trigger.EnterActions>
            </Trigger>
        </ControlTemplate.Triggers>
    </ControlTemplate>
</UserControl.Template>

StoryboardFinder 类:

public class StoryboardFinder : DependencyObject
{
    #region ________________________________________  AssociatedControl

    public Control AssociatedControl
    {
        get { return (Control)GetValue(AssociatedControlProperty); }
        set { SetValue(AssociatedControlProperty, value); }
    }

    public static readonly DependencyProperty AssociatedControlProperty =
        DependencyProperty.Register("AssociatedControl",
                                    typeof(Control),
                                    typeof(StoryboardFinder),
                                    new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.None));

    #endregion

    public Storyboard Finder(string resourceName)
    {
        //
        // Associated control is always null :(
        //
        return new Storyboard();
    }
}

Answer 1

如果这个代码是真的呢？

<UserControl x:Class="MyApp.MyControl"
             ...
             xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
             xmlns:l="clr-namespace:MyApp"
             DataContext="{Binding RelativeSource={RelativeSource Mode=Self}}">

    <UserControl.Resources>
        <Style TargetType="{x:Type l:MyControl}">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type l:MyControl}">
                        <Border x:Name="brdBase" BorderThickness="1" BorderBrush="Cyan" Background="Black">
                            <Border.Resources>
                                <Storyboard x:Key="MyStory">
                                    <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" Storyboard.TargetName="brdBase">
                                        <SplineColorKeyFrame KeyTime="0:0:1" Value="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type l:MyControl}}, Path=SpecialColor}"/>
                                    </ColorAnimationUsingKeyFrames>
                                </Storyboard>
                            </Border.Resources>

                            <i:Interaction.Triggers>
                                <l:InteractiveTrigger Property="IsMouseOver" Value="True">
                                    <l:InteractiveTrigger.CommonActions>
                                        <BeginStoryboard Storyboard="{StaticResource MyStory}"/>
                                    </l:InteractiveTrigger.CommonActions>
                                </l:InteractiveTrigger>
                            </i:Interaction.Triggers>
                        </Border>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </UserControl.Resources>
</UserControl>

如果是这样，我可以在 IsMouseOver 上设置触发器属性(property)...

我很高兴地说这是一个工作代码 :) 我只能使用 EventTrigger在<Border.Triggers>标签。这是限制。所以我开始考虑这个想法:如果我可以有一个可以在 FrameworkElement.Triggers 中工作的自定义触发器会怎样？范围？这是代码:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows;
using System.Windows.Interactivity;
using System.Windows.Media.Animation;

namespace TriggerTest
{
    /// <summary>
    /// InteractiveTrigger is a trigger that can be used as the System.Windows.Trigger but in the System.Windows.Interactivity.
    /// <para>
    /// Note: There is neither `EnterActions` nor `ExitActions` in this class. The `CommonActions` can be used instead of `EnterActions`.
    /// Also, the `Actions` property which is of type System.Windows.Interactivity.TriggerAction can be used.
    /// </para>
    /// <para> </para>
    /// <para>
    /// There is only one kind of triggers (i.e. EventTrigger) in the System.Windows.Interactivity. So you can use the following triggers in this namespace:
    /// <para>1- InteractiveTrigger : Trigger</para>
    /// <para>2- InteractiveMultiTrigger : MultiTrigger</para>
    /// <para>3- InteractiveDataTrigger : DataTrigger</para>
    /// <para>4- InteractiveMultiDataTrigger : MultiDataTrigger</para>
    /// </para>
    /// </summary>
    public class InteractiveTrigger : TriggerBase<FrameworkElement>
    {
        #region ___________________________________________________________________________________  Properties

        #region ________________________________________  Value

        /// <summary>
        /// [Wrapper property for ValueProperty]
        /// <para>
        /// Gets or sets the value to be compared with the property value of the element. The comparison is a reference equality check.
        /// </para>
        /// </summary>
        public object Value
        {
            get { return (object)GetValue(ValueProperty); }
            set { SetValue(ValueProperty, value); }
        }

        public static readonly DependencyProperty ValueProperty =
            DependencyProperty.Register("Value",
                                        typeof(object),
                                        typeof(InteractiveTrigger),
                                        new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.None, OnValuePropertyChanged));

        private static void OnValuePropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
        {
            InteractiveTrigger instance = sender as InteractiveTrigger;

            if (instance != null)
            {
                if (instance.CanFire)
                    instance.Fire();
            }
        }

        #endregion


        /// <summary>
        /// Gets or sets the name of the object with the property that causes the associated setters to be applied.
        /// </summary>
        public string SourceName
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the property that returns the value that is compared with this trigger.Value property. The comparison is a reference equality check.
        /// </summary>
        public DependencyProperty Property
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets a collection of System.Windows.Setter objects, which describe the property values to apply when the trigger object becomes active.
        /// </summary>
        public List<Setter> Setters
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the collection of System.Windows.TriggerAction objects to apply when this trigger object becomes active.
        /// </summary>
        public List<System.Windows.TriggerAction> CommonActions
        {
            get;
            set;
        }

        /// <summary>
        /// Gets a value indicating whether this trigger can be active to apply setters and actions.
        /// </summary>
        private bool CanFire
        {
            get
            {
                if (this.AssociatedObject == null)
                {
                    return false;
                }
                else
                {
                    object associatedValue;

                    if (string.IsNullOrEmpty(SourceName))
                        associatedValue = this.AssociatedObject.GetValue(Property);
                    else
                        associatedValue = (this.AssociatedObject.FindName(SourceName) as DependencyObject).GetValue(Property);

                    TypeConverter typeConverter = TypeDescriptor.GetConverter(Property.PropertyType);
                    object realValue = typeConverter.ConvertFromString(Value.ToString());

                    return associatedValue.Equals(realValue);
                }
            }
        }

        #endregion


        #region ___________________________________________________________________________________  Methods

        /// <summary>
        /// Fires (activates) current trigger by setting setter values and invoking all actions.
        /// </summary>
        private void Fire()
        {
            //
            // Setting setters values to their associated properties..
            //
            foreach (Setter setter in Setters)
            {
                if (string.IsNullOrEmpty(setter.TargetName))
                    this.AssociatedObject.SetValue(setter.Property, setter.Value);
                else
                    (this.AssociatedObject.FindName(setter.TargetName) as DependencyObject).SetValue(setter.Property, setter.Value);
            }

            //
            // Firing actions.. 
            //
            foreach (System.Windows.TriggerAction action in CommonActions)
            {
                Type actionType = action.GetType();

                if (actionType == typeof(BeginStoryboard))
                {
                    (action as BeginStoryboard).Storyboard.Begin();
                }
                else
                    throw new NotImplementedException();
            }

            this.InvokeActions(null);
        }

        #endregion


        #region ___________________________________________________________________________________  Events

        public InteractiveTrigger()
        {
            Setters = new List<Setter>();
            CommonActions = new List<System.Windows.TriggerAction>();
        }

        protected override void OnAttached()
        {
            base.OnAttached();

            if (Property != null)
            {
                object propertyAssociatedObject;

                if (string.IsNullOrEmpty(SourceName))
                    propertyAssociatedObject = this.AssociatedObject;
                else
                    propertyAssociatedObject = this.AssociatedObject.FindName(SourceName);

                //
                // Adding a property changed listener to the property associated-object..
                //
                DependencyPropertyDescriptor dpDescriptor = DependencyPropertyDescriptor.FromProperty(Property, propertyAssociatedObject.GetType());
                dpDescriptor.AddValueChanged(propertyAssociatedObject, PropertyListener_ValueChanged);
            }
        }

        protected override void OnDetaching()
        {
            base.OnDetaching();

            if (Property != null)
            {
                object propertyAssociatedObject;

                if (string.IsNullOrEmpty(SourceName))
                    propertyAssociatedObject = this.AssociatedObject;
                else
                    propertyAssociatedObject = this.AssociatedObject.FindName(SourceName);

                //
                // Removing previously added property changed listener from the associated-object..
                //
                DependencyPropertyDescriptor dpDescriptor = DependencyPropertyDescriptor.FromProperty(Property, propertyAssociatedObject.GetType());
                dpDescriptor.RemoveValueChanged(propertyAssociatedObject, PropertyListener_ValueChanged);
            }
        }

        private void PropertyListener_ValueChanged(object sender, EventArgs e)
        {
            if (CanFire)
                Fire();
        }

        #endregion
    }
}

我还创建了其他触发器类型(即 InteractiveMultiTrigger 、 InteractiveDataTrigger 、 InteractiveMultiDataTrigger )以及一些其他操作，这使得有条件和多条件 EventTriggers 成为可能。如果你们专业人士确认这个解决方案，我会把它们全部发布。

感谢您的关注!