SetTimer在无窗口和有窗口线程的使用 . .

今天犯了一个粗心的错误,在无窗口线程中,SetTimer中设置计时器ID,而WM_TIMER消息响应函数中得到的计时器ID却不是之前设置的计时器ID.

// 111902.cpp : Defines the entry point for the console application.
//
//#include "stdafx.h"
#include "stdio.h"
#include "windows.h"
BOOL DispatchThreadMessage(MSG* pMsg);
VOID CALLBACK OnTimerProc(HWND hwnd,UINT uMsg,UINT_PTR idEvent,DWORD dwTime);
int main(int argc, char* argv[])
{
    printf("Hello World!
");
    ::SetTimer(NULL,45,1000,OnTimerProc);
    MSG msg;
    while (GetMessage(&msg, 0, 0, 0) > 0)
    {
        if (msg.hwnd == NULL && DispatchThreadMessage(&msg))
            continue;
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return 0;
}

BOOL DispatchThreadMessage(MSG* pMsg)
{
    if(pMsg->message == 0x0113)
    {
        printf("DispatchThreadMessage: %6d
",pMsg->wParam);
        return false;
    }
    return false;
}
VOID CALLBACK OnTimerProc(HWND hwnd,UINT uMsg,UINT_PTR idEvent,DWORD dwTime)
{
    printf("OnTimerProc: %6d
",idEvent);
}

// 111902.cpp : Defines the entry point for the console application.
//
//#include "stdafx.h"
#include "stdio.h"
#include "windows.h"
BOOL DispatchThreadMessage(MSG* pMsg);
VOID CALLBACK OnTimerProc(HWND hwnd,UINT uMsg,UINT_PTR idEvent,DWORD dwTime);
int main(int argc, char* argv[])
{
	printf("Hello World!
");
	::SetTimer(NULL,45,1000,OnTimerProc);
	MSG msg;
	while (GetMessage(&msg, 0, 0, 0) > 0)
	{
		if (msg.hwnd == NULL && DispatchThreadMessage(&msg))
			continue;
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return 0;
}

BOOL DispatchThreadMessage(MSG* pMsg)
{
	if(pMsg->message == 0x0113)
	{
		printf("DispatchThreadMessage: %6d
",pMsg->wParam);
		return false;		
	}
	return false;
} 
VOID CALLBACK OnTimerProc(HWND hwnd,UINT uMsg,UINT_PTR idEvent,DWORD dwTime)
{
	printf("OnTimerProc: %6d
",idEvent);
}

对应计时器ID的输出的是一个随机数字.

原来在msdn中

nIDEvent

[in] Specifies a nonzero timer identifier. If the hWnd parameter is NULL, and the nIDEvent does not match an existing timer then it is ignored and a new timer ID is generated. If the hWnd parameter is not NULL and the window specified by hWnd already has a timer with the value nIDEvent , then the existing timer is replaced by the new timer. When SetTimer replaces a timer, the timer is reset. Therefore, a message will be sent after the current time-out value elapses, but the previously set time-out value is ignored. If the call is not intended to replace an existing timer, nIDEvent should be 0 if the hWnd is NULL.

注:只有当hWnd参数为非空时,计时器的ID为设置的 nIDEvent,  否则系统为你自动生成一个计时器ID,可由返回时值获取.