WPF 调试触发器

翻译自In WPF, how to debug triggers?
本来不想发的，但搜索了一下国内好像没人写这个，so.......

效果如图

工作原理

使用附加属性将虚拟动画storyboards添加到触发器
激活WPF动画跟踪并将结果过滤到仅包含storyboards

TriggerTracing

将TriggerTracing添加到项目中

/// <summary>
/// Contains attached properties to activate Trigger Tracing on the specified Triggers.
/// 包含附加属性以激活指定触发器上的触发器跟踪
/// This file alone should be dropped into your app.
/// 仅此文件应放入您的应用程序
/// </summary>
public static class TriggerTracing
{
    static TriggerTracing()
    {
        // Initialise WPF Animation tracing and add a TriggerTraceListener
        //初始化WPF动画跟踪并添加TriggerTraceListener
        PresentationTraceSources.Refresh();
        PresentationTraceSources.AnimationSource.Listeners.Clear();
        PresentationTraceSources.AnimationSource.Listeners.Add(new TriggerTraceListener());
        PresentationTraceSources.AnimationSource.Switch.Level = SourceLevels.All;
    }

    #region TriggerName attached property

    /// <summary>
    /// Gets the trigger name for the specified trigger. This will be used
    /// to identify the trigger in the debug output.
    /// 获取指定触发器的触发器名称。 这将用于在调试输出中标识触发器。
    /// </summary>
    /// <param name="trigger">The trigger.</param>
    /// <returns></returns>
    public static string GetTriggerName(TriggerBase trigger)
    {
        return (string)trigger.GetValue(TriggerNameProperty);
    }

    /// <summary>
    /// Sets the trigger name for the specified trigger. This will be used
    /// to identify the trigger in the debug output.
    /// 设置指定触发器的触发器名称。 这将用于在调试输出中标识触发器。
    /// </summary>
    /// <param name="trigger">The trigger.</param>
    /// <returns></returns>
    public static void SetTriggerName(TriggerBase trigger, string value)
    {
        trigger.SetValue(TriggerNameProperty, value);
    }

    public static readonly DependencyProperty TriggerNameProperty =
        DependencyProperty.RegisterAttached(
        "TriggerName",
        typeof(string),
        typeof(TriggerTracing),
        new UIPropertyMetadata(string.Empty));

    #endregion

    #region TraceEnabled attached property

    /// <summary>
    /// Gets a value indication whether trace is enabled for the specified trigger.
    /// 获取一个值指示是否为指定的触发器启用跟踪
    /// </summary>
    /// <param name="trigger">The trigger.</param>
    /// <returns></returns>
    public static bool GetTraceEnabled(TriggerBase trigger)
    {
        return (bool)trigger.GetValue(TraceEnabledProperty);
    }

    /// <summary>
    /// Sets a value specifying whether trace is enabled for the specified trigger
    /// 设置一个值，该值指定是否为指定的触发器启用跟踪
    /// </summary>
    /// <param name="trigger"></param>
    /// <param name="value"></param>
    public static void SetTraceEnabled(TriggerBase trigger, bool value)
    {
        trigger.SetValue(TraceEnabledProperty, value);
    }

    public static readonly DependencyProperty TraceEnabledProperty =
        DependencyProperty.RegisterAttached(
        "TraceEnabled",
        typeof(bool),
        typeof(TriggerTracing),
        new UIPropertyMetadata(false, OnTraceEnabledChanged));

    private static void OnTraceEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var triggerBase = d as TriggerBase;

        if (triggerBase == null)
            return;

        if (!(e.NewValue is bool))
            return;

        if ((bool)e.NewValue)
        {
            // insert dummy story-boards which can later be traced using WPF animation tracing
            //添加虚拟storyboards，以后可以使用WPF动画跟踪对其进行跟踪
            var storyboard = new TriggerTraceStoryboard(triggerBase, TriggerTraceStoryboardType.Enter);
            triggerBase.EnterActions.Insert(0, new BeginStoryboard() { Storyboard = storyboard });

            storyboard = new TriggerTraceStoryboard(triggerBase, TriggerTraceStoryboardType.Exit);
            triggerBase.ExitActions.Insert(0, new BeginStoryboard() { Storyboard = storyboard });
        }
        else
        {
            // remove the dummy storyboards
            //移除虚拟storyboards
            foreach (TriggerActionCollection actionCollection in new[] { triggerBase.EnterActions, triggerBase.ExitActions })
            {
                foreach (TriggerAction triggerAction in actionCollection)
                {
                    BeginStoryboard bsb = triggerAction as BeginStoryboard;

                    if (bsb != null && bsb.Storyboard != null && bsb.Storyboard is TriggerTraceStoryboard)
                    {
                        actionCollection.Remove(bsb);
                        break;
                    }
                }
            }
        }
    }

    #endregion

    /// <summary>
    /// 触发器跟踪Storyboard类型
    /// </summary>
    private enum TriggerTraceStoryboardType
    {
        //进入
        Enter, 
        //退出
        Exit
    }

    /// <summary>
    /// A dummy storyboard for tracing purposes
    /// 用于跟踪的虚拟storyboard
    /// </summary>
    private class TriggerTraceStoryboard : Storyboard
    {
        public TriggerTraceStoryboardType StoryboardType { get; private set; }
        public TriggerBase TriggerBase { get; private set; }

        public TriggerTraceStoryboard(TriggerBase triggerBase, TriggerTraceStoryboardType storyboardType)
        {
            TriggerBase = triggerBase;
            StoryboardType = storyboardType;
        }
    }

    /// <summary>
    /// A custom tracelistener.
    /// 自定义跟踪侦听器
    /// </summary>
    private class TriggerTraceListener : TraceListener
    {
        public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id, string format, params object[] args)
        {
            base.TraceEvent(eventCache, source, eventType, id, format, args);

            if (format.StartsWith("Storyboard has begun;"))
            {
                TriggerTraceStoryboard storyboard = args[1] as TriggerTraceStoryboard;
                if (storyboard != null)
                {
                    // add a breakpoint here to see when your trigger has been
                    // entered or exited
                    //在此处添加断点，以查看何时输入或退出触发器

                    // the element being acted upon
                    //被作用的元素
                    object targetElement = args[5];

                    // the namescope of the element being acted upon
                    //所作用元素的名称范围
                    INameScope namescope = (INameScope)args[7];

                    TriggerBase triggerBase = storyboard.TriggerBase;
                    //获得TriggerTracing.TriggerName
                    string triggerName = GetTriggerName(storyboard.TriggerBase);

                    Debug.WriteLine(string.Format("Element: {0}, {1}: {2}: {3}",
                        targetElement,
                        triggerBase.GetType().Name,
                        triggerName,
                        storyboard.StoryboardType));
                }
            }
        }

        public override void Write(string message)
        {
        }

        public override void WriteLine(string message)
        {
        }
    }
}

使用

将以下附加属性添加到任何触发器，将在输出窗口中看到它何时被激活/停用

TriggerTracing.TriggerName="your debug name"
TriggerTracing.TraceEnabled="True"

例子

<Trigger my:TriggerTracing.TriggerName="BoldWhenMouseIsOver"  
        my:TriggerTracing.TraceEnabled="True"  
        Property="IsMouseOver"  
        Value="True">  
    <Setter Property = "FontWeight" Value="Bold"/>  
</Trigger> 

示例代码

DebugTriggers