Windows多媒体定时器（精确到1ms）（二）

谁借莪１个温暖的怀抱￠ 2022-06-17 03:52 1033阅读 0赞

这里还是聊的是 Windows多媒体定时器。 之前做的那个。感觉哪儿不对劲儿： 头文件封装没有做好， 回调函数没有写好。

今天，看了一个已经投入使用 的定时器（用示波器测试过，精确到1ms）。废话不多多说了。上代码：

\------------------------- 我是分割线 ------------------------------------------------------

timer.h

//
    //																			//
    //					Timer.h: interface for the CTimer class.				//
    //							    	  
    //
    //多媒体计时器，用于最低间隔至5ms，误差不大于1ms的高精度计时
    //CPU占用极低，可忽略不计
    
    #if !defined(AFX_TIMER_H__263E5861_FE82_11D3_A4A2_5A5A5A5A5A5A__INCLUDED_)
    #define AFX_TIMER_H__263E5861_FE82_11D3_A4A2_5A5A5A5A5A5A__INCLUDED_
    
    #if _MSC_VER >= 1000
    #pragma once
    #endif // _MSC_VER >= 1000
    
    typedef BOOL (*TIMERCALLBACK)(DWORD); 
    
    class CTimer  
    {
    public:
    	CTimer();
    	virtual ~CTimer();
        BOOL Create (UINT nPeriod, UINT nRes, DWORD dwUser,  TIMERCALLBACK pfnCallback);
    protected:
        static void CALLBACK TimeProc(UINT uID, UINT uMsg, DWORD dwUser, DWORD dw1, DWORD dw2);
        TIMERCALLBACK m_pfnCallback;
        DWORD m_dwUser;
        UINT m_nPeriod;
        UINT m_nRes;
        UINT m_nIDTimer;
    };
    
    #endif // !defined(AFX_TIMER_H__263E5861_FE82_11D3_A4A2_5A5A5A5A5A5A__INCLUDED_)

timer.cpp

// Timer.cpp: implementation of the CTimer class.
    //
    //
    
    #include "stdafx.h"
    #include <mmsystem.h>
    #include "timer.h"
    
    #ifdef _DEBUG
    #undef THIS_FILE
    static char THIS_FILE[]=__FILE__;
    #define new DEBUG_NEW
    #endif
    
    #pragma comment(lib, "winmm.lib")
    
    
    //
    // Construction/Destruction
    //
    
    CTimer::CTimer()
    {
    
        m_nIDTimer = NULL;
    
    }
    
    CTimer::~CTimer()
    {
    
        if (m_nIDTimer)
        {
            timeKillEvent (m_nIDTimer);
    		TRACE("多媒体定时器终止\n");
        }
    
    }
    
    
    // Create
    BOOL CTimer::Create (UINT nPeriod, UINT nRes, DWORD dwUser, TIMERCALLBACK pfnCallback)
    {
    
        ASSERT (pfnCallback);
        ASSERT (nPeriod >= 5);
        ASSERT (nPeriod >= nRes);
    
        m_nPeriod = nPeriod;
        m_nRes = nRes;
        m_dwUser = dwUser;
        m_pfnCallback = pfnCallback;
    
        if ((m_nIDTimer = timeSetEvent (m_nPeriod, m_nRes, TimeProc, reinterpret_cast<DWORD>(this), TIME_PERIODIC)) == NULL)
        {
            return FALSE;
        }
    
    	TRACE("多媒体定时器启动\n");
        return TRUE;
    }
    
    
    // Timer proc for multimedia timer callback set with timeSetTime().
    //
    // Calls procedure specified when Timer object was created. The 
    // dwUser parameter contains "this" pointer for associated Timer object.
    // 
    void CALLBACK CTimer::TimeProc(UINT uID, UINT uMsg, DWORD dwUser, DWORD dw1, DWORD dw2)
    {
        // dwUser contains ptr to Timer object
    	CTimer * pRecvTimer = reinterpret_cast<CTimer *>(dwUser);
    
        // Call user-specified callback and pass back user specified data
        (pRecvTimer->m_pfnCallback) (pRecvTimer->m_dwUser);
    }