一個使用多媒體定時器的簡單例子

1)新建一個工程，保存

2)添加一個Button和一個Label

3)修改unit1.h代碼如下：

// ---------------------------------------------------------------------------
#ifndef Unit1H
#define Unit1H
// ---------------------------------------------------------------------------
#include <Classes.hpp>
#include <Controls.hpp>
#include <StdCtrls.hpp>
#include <Forms.hpp>
// ---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published: // IDE-managed Components
TButton *Button1;
TLabel *Label1;
void __fastcall Button1Click(TObject *Sender);
void __fastcall FormCloseQuery(TObject *Sender, bool &CanClose);
private: // User declarations
public:　// User declarations
__fastcall TForm1(TComponent* Owner);
static void CALLBACK TimeProc(UINT uID,UINT uMsg,
DWORD dwUser,DWORD dw1,DWORD dw2); // 定時器回調函數
int TimerID; // 定時器ID
};
// ---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
// ---------------------------------------------------------------------------
#endif
4)unit1.cpp代碼如下：
// ---------------------------------------------------------------------------
#include <vcl.h>
#include "mmsystem.h"
#pragma hdrstop
#include "Unit1.h"
// ---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
// ---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
TimerID = 0;
}
// ---------------------------------------------------------------------------
void CALLBACK TForm1::TimeProc(UINT uID,UINT uMsg, DWORD dwUser,DWORD dw1,DWORD dw2)
{
Form1->Label1->Caption = Now();
}
// ---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
TimerID = timeSetEvent(1000, 0, (LPTIMECALLBACK)TimeProc, 0,
TIME_PERIODIC|TIME_CALLBACK_FUNCTION); // 設定多媒體定時器,1000ms
if(TimerID == 0)　　{
ShowMessage("創建失敗");
}
}
// ---------------------------------------------------------------------------
void __fastcall TForm1::FormCloseQuery(TObject *Sender, bool &CanClose)
{
if(TimerID != 0)　　{
timeKillEvent(TimerID); // 釋放定時器
}
}
// ---------------------------------------------------------------------------

運行效果：點擊按鈕後，Label1開始顯示時間

測試環境：BCB5 + WIN98

作者信息：

"Mao Yanwei(citiz)" <[email protected]>