如何用 C# 建立高解析度計時器？

C 中的高解析度計時器

在 C# 中，System.Timer 類別可用於建立以指定時間間隔引發事件的計時器。但是，System.Timer 類別的解析度有限，可能不適合需要高解析度計時的應用程式。

要建立以特定時間間隔引發事件的高解析度計時器，您可以使用多媒體計時器 API。多媒體計時器 API 是一個 Windows API，提供高解析度計時器，可用於以小至 1 毫秒的間隔引發事件。

要使用多媒體計時器 API 建立高解析度計時器，您需要可以使用以下程式碼：

using System.Runtime.InteropServices;

public class HighResolutionTimer
{
    private bool disposed = false;
    private int interval, resolution;
    private UInt32 timerId; 

    // Hold the timer callback to prevent garbage collection.
    private readonly MultimediaTimerCallback Callback;

    public HighResolutionTimer()
    {
        Callback = new MultimediaTimerCallback(TimerCallbackMethod);
        Resolution = 5;
        Interval = 10;
    }

    ~HighResolutionTimer()
    {
        Dispose(false);
    }

    public int Interval
    {
        get
        {
            return interval;
        }
        set
        {
            CheckDisposed();

            if (value < 0)
                throw new ArgumentOutOfRangeException(&quot;value&quot;);

            interval = value;
            if (Resolution > Interval)
                Resolution = value;
        }
    }

    // Note minimum resolution is 0, meaning highest possible resolution.
    public int Resolution
    {
        get
        {
            return resolution;
        }
        set
        {
            CheckDisposed();

            if (value < 0)
                throw new ArgumentOutOfRangeException(&quot;value&quot;);

            resolution = value;
        }
    }

    public bool IsRunning
    {
        get { return timerId != 0; }
    }

    public void Start()
    {
        CheckDisposed();

        if (IsRunning)
            throw new InvalidOperationException(&quot;Timer is already running&quot;);

        // Event type = 0, one off event
        // Event type = 1, periodic event
        UInt32 userCtx = 0;
        timerId = NativeMethods.TimeSetEvent((uint)Interval, (uint)Resolution, Callback, ref userCtx, 1);
        if (timerId == 0)
        {
            int error = Marshal.GetLastWin32Error();
            throw new Win32Exception(error);
        }
    }

    public void Stop()
    {
        CheckDisposed();

        if (!IsRunning)
            throw new InvalidOperationException(&quot;Timer has not been started&quot;);

        StopInternal();
    }

    private void StopInternal()
    {
        NativeMethods.TimeKillEvent(timerId);
        timerId = 0;
    }

    public event EventHandler Elapsed;

    public void Dispose()
    {
        Dispose(true);
    }

    private void TimerCallbackMethod(uint id, uint msg, ref uint userCtx, uint rsv1, uint rsv2)
    {
        var handler = Elapsed;
        if (handler != null)
        {
            handler(this, EventArgs.Empty);
        }
    }

    private void CheckDisposed()
    {
        if (disposed)
            throw new ObjectDisposedException(&quot;MultimediaTimer&quot;);
    }

    private void Dispose(bool disposing)
    {
        if (disposed)
            return;
        
        disposed = true;
        if (IsRunning)
        {
            StopInternal();
        }
        

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