事件没有取消订阅

Question

事件没有被取消订阅我不知道为什么而且它杀了我...... 我有一个暂停按钮，使用与CompositionTarget.Rendering相同的想法 - = RenderingEvent;它被称为但似乎没有阻止它......

我的代码：

    private EventHandler RenderingEvent;

    StopSimulation(sender, t);// how i am calling it

    private void StopSimulation(object sender, ElapsedEventArgs e)
    {
        time = DateTime.Now;
        int removedtime = 0;
        InSimulation = false;
        aTimer.Enabled = false;
        CompositionTarget.Rendering -= RenderingEvent; // doesnt seem to stop it
    }


    private void OnLoaded(object sender, RoutedEventArgs e)
    {
        CompositionTarget.Rendering -= RenderingEvent;
        position = new Point(5, HighestPoint * MetresPerPixel);
        //acceleration = new Vector(0, 30); // y direction is downwards
        int removedtime = 0;
        time = DateTime.Now;
        RenderingEvent = (s, g) => OnRendering(s, g, removedtime, time);
        CompositionTarget.Rendering += RenderingEvent;
        btn_Pause.Content = "Pause";
    }

我的完成＆＃34;代码（删除所有垃圾）

       using System;
       using System.Collections.Generic;
       using System.Linq;
       using System.Text;
       using System.Threading.Tasks;
       using System.Windows;
       using System.Windows.Controls;
       using System.Windows.Data;
       using System.Windows.Documents;
       using System.Windows.Input;
       using System.Windows.Media;
       using System.Windows.Media.Imaging;
       using System.Windows.Navigation;
       using System.Windows.Shapes;
       using System.Threading;
       using System.Timers;
       using System.ComponentModel;
       using System.Windows.Media.Animation;
       using System.Text.RegularExpressions;
       namespace WpfApplication3
       {
public partial class MainWindow : Window
{
    bool LabelExist = false;
    int count = 1;
    bool InSimulation = false;
    bool ModelModeAsParticle;
    static System.Timers.Timer aTimer;
    public MainWindow()
    {
        InitializeComponent();
    }
    private Point position; // in pixels
    private Vector Velocity; // in pixels per second
    private Vector acceleration; // in pixels per square second
    private DateTime time;
    private EventHandler RenderingEvent;
    private System.Timers.ElapsedEventHandler TimerEvent;
    private double TimeConstant;
    private double TimersTime;
    private double MetresPerPixel;
    double HighestPoint, LowestPoint;
    private void OnLoaded(object sender, RoutedEventArgs e)
    {
        CompositionTarget.Rendering -= RenderingEvent;
        position = new Point(5, HighestPoint * MetresPerPixel);
        //acceleration = new Vector(0, 30); // y direction is downwards
        int removedtime = 0;
        time = DateTime.Now;
        RenderingEvent = (s, g) => OnRendering(s, g, removedtime, time);
        CompositionTarget.Rendering += RenderingEvent;
        btn_Pause.Content = "Pause";
    }
    private void OnRendering(object sender, EventArgs g, int removedtime, DateTime t)
    {
        var now = DateTime.Now.AddSeconds(-removedtime);
        var dt = (now - t).TotalSeconds;
        time = now;
        position += Velocity * dt;
        Velocity += acceleration * dt;
        projectileGeometry.Center = position;
    }
    void LoadStaticsAndStart(object sender, RoutedEventArgs e)
    {
        if (FormatCheck(txtb_AngleOLaunch) == false || FormatCheck(txtbox_InitialVelocity) == false || FormatCheck(txtbox_TimeOfFlight) == false)
        {
        }
        else
        {
            MPP(newParticle, newEnvironment);
            OnLoaded(this, e);
            double HVelTemp = newParticle.InitialVelocity.HorizontalVelocity * MetresPerPixel;
            double VVelTemp = newParticle.InitialVelocity.VerticalVelocity * MetresPerPixel * -1;
            Velocity = new Vector(HVelTemp, VVelTemp); // y direction is downwards
            acceleration = new Vector(0, -1*newEnvironment.gravity*MetresPerPixel); // y direction is downwards
            aTimer = new System.Timers.Timer(200);
            TimerEvent = (s, t) => onTimedEvent(s, t, newParticle, newEnvironment);
            aTimer.Elapsed += TimerEvent;
            InSimulation = true;
            aTimer.Enabled = true;
        }
    }
    int DigitAccuracy = 2;
    void onTimedEvent(Object sender, ElapsedEventArgs t, particle newProjectile, Environment newEnvironment)
    {
        if (newProjectile.Time < newProjectile.TimeOfFlight && InSimulation == true)
        {
        newProjectile.Time = Math.Round(TimersTime,1);
        }
        else if (newProjectile.TimeOfFlight == newProjectile.Time)
        {
            StopSimulation(sender, t);
        }
    }
    private void StopSimulation(object sender, ElapsedEventArgs e)
    {
        InSimulation = false;
        aTimer.Enabled = false;
        CompositionTarget.Rendering -= RenderingEvent;
    }
    private void btn_Pause_Click(object sender, RoutedEventArgs e)
    {
        if ((string)btn_Pause.Content == "Pause")
        {
            aTimer.Enabled = false;
            CompositionTarget.Rendering -= RenderingEvent;
        }
        else if (InSimulation == true && (string)btn_Pause.Content != "Pause")
        {
            aTimer.Enabled = true;
            RenderingEvent = (s, g) => OnRendering(s, g, removedtime, time);
            CompositionTarget.Rendering += RenderingEvent;
        }
        else if (InSimulation != true)
        {
        }
    }
    private void btn_fastforward_Click(object sender, RoutedEventArgs e)
    {
        if (InSimulation == true)
        {
        CompositionTarget.Rendering -= RenderingEvent;
        RenderingEvent = (s, g) => OnRendering(s, g, removedtime, time);
        CompositionTarget.Rendering += RenderingEvent;
        }
        else if (InSimulation == false)
        {
        }
    }
    private void btn_backwards_Click(object sender, RoutedEventArgs e)
    {
        if (InSimulation == true)
        {
        CompositionTarget.Rendering -= RenderingEvent;
        RenderingEvent = (s, g) => OnRendering(s, g, removedtime, time);
        CompositionTarget.Rendering += RenderingEvent;
        }
        else if (InSimulation == false)
        {
        }
    }

Answer 1

要进行诊断，可能会创建一个有效包装CompositionTarget.RenderingEvent事件的新事件，但在附加/分离时除外：

private int _eventSubscriptionCount = 0;
public event EventHandler<EventArgs> RenderingEventWrapper
{
    add
    {
        CompositionTarget.RenderingEvent += value;
        _eventSubscriptionCount++;
    }
    remove
    {
        CompositionTarget.RenderingEvent -= value;
        _eventSubscriptionCount--;
    }
} 

然后看看当你期望没有更多的订阅时仍然订阅了多少...调试添加/删除部分也将完成这个技巧并在执行中断时检查调用堆栈。