在 WPF 中，有哪些好的方法可以调试这样的触发器？
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="FontWeight" Value="Bold"/>
</Trigger>
理想情况下：
Debug 窗口；【问题讨论】：
标签： c# .net wpf datatrigger
有一篇题为How to debug triggers using Trigger-Tracing（缓存版here）的关于WPF Mentor的优秀文章。
我已经无数次使用它来调试触发器，对于任何在专业级别使用 WPF 的人来说，这都是一项了不起的技术。
不幸的是，源代码的链接已部分损坏，因此我将其镜像到 SO 上，以防原始文章消失。
更新：原来的页面确实消失了 - 幸运的是我镜像了它！
调试触发器是一个痛苦的过程：它们在幕后工作， 没有地方可以放置断点，也没有调用堆栈来帮助你。这 通常采用的方法是基于反复试验的，而且几乎总是 花费比它应该更长的时间来解决问题所在。
这篇文章描述了一种调试触发器的新技术，允许 您可以记录所有触发操作以及正在执行的元素 在：
这很好，因为它：
- 帮助您解决各种问题:)
- 适用于所有类型的触发器：Trigger、DataTrigger、MultiTrigger 等。
- 允许您在输入和/或退出任何触发器时添加断点
易于设置：只需将一个源文件 (TriggerTracing.cs) 拖放到您的应用中，并将这些附加属性设置为触发器 追踪：
<Trigger my:TriggerTracing.TriggerName="BoldWhenMouseIsOver" my:TriggerTracing.TraceEnabled="True" Property="IsMouseOver" Value="True"> <Setter Property="FontWeight" Value="Bold"/> </Trigger>并且还将
my命名空间与xmlns:my="clr-namespace:DebugTriggers"添加。它的工作原理：
- 使用附加属性将虚拟动画故事板添加到触发器
- 激活 WPF 动画跟踪并将结果过滤到仅具有虚拟情节提要的条目
代码：
using System.Diagnostics;
using System.Windows;
using System.Windows.Markup;
using System.Windows.Media.Animation;
// Code from http://www.wpfmentor.com/2009/01/how-to-debug-triggers-using-trigger.html
// No license specified - this code is trimmed out from Release build anyway so it should be ok using it this way
// HOWTO: add the following attached property to any trigger and you will see when it is activated/deactivated in the output window
// TriggerTracing.TriggerName="your debug name"
// TriggerTracing.TraceEnabled="True"
// Example:
// <Trigger my:TriggerTracing.TriggerName="BoldWhenMouseIsOver"
// my:TriggerTracing.TraceEnabled="True"
// Property="IsMouseOver"
// Value="True">
// <Setter Property = "FontWeight" Value="Bold"/>
// </Trigger>
//
// As this works on anything that inherits from TriggerBase, it will also work on <MultiTrigger>.
namespace DebugTriggers
{
#if DEBUG
/// <summary>
/// Contains attached properties to activate Trigger Tracing on the specified Triggers.
/// This file alone should be dropped into your app.
/// </summary>
public static class TriggerTracing
{
static TriggerTracing()
{
// Initialise WPF Animation tracing and add a 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.
/// </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.
/// </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.
/// </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
/// </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
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
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
private enum TriggerTraceStoryboardType
{
Enter, Exit
}
/// <summary>
/// A dummy storyboard for tracing purposes
/// </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.
/// </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
// the element being acted upon
object targetElement = args[5];
// the namescope of the element being acted upon
INameScope namescope = (INameScope)args[7];
TriggerBase triggerBase = storyboard.TriggerBase;
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)
{
}
}
}
#endif
}
【讨论】：
xmlns:my="clr-namespace:DebugTriggers"添加“my”命名空间。
TriggerTraceStoryboardType 枚举中的Enter 和Exit 重命名为TriggerCondition_True 和TriggerCondition_False 之类的名称。