一個使用多媒體定時器的簡單例子

2019-11-17 05:29:37

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來源：轉載

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　　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_PERIODICTIME_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：點擊按鈕后，Label1開始顯示時間
測試環境：BCB5 + WIN98

作者信息：
"Mao Yanwei(citiz)" <myw_fool@citiz.net>

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