一个使用多媒体定时器的简单例子

2019-11-17 05:29:37

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　　1)新建一个工程，保存

2)添加一个Button和一个Label

3)修改unit1.h代码如下：
// ---------------------------------------------------------------------------
#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); // 定时器回调函数
    int TimerID; // 定时器ID
};
// ---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
// ---------------------------------------------------------------------------
#endif

4)unit1.cpp代码如下：
// ---------------------------------------------------------------------------

#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); // 设定多媒体定时器,1000ms

    if(TimerID == 0)    {
        ShowMessage("创建失败");
    }
}
// ---------------------------------------------------------------------------
void __fastcall TForm1::FormCloseQuery(TObject *Sender, bool &CanClose)
{
    if(TimerID != 0)    {
        timeKillEvent(TimerID); // 释放定时器
    }
}
// ---------------------------------------------------------------------------

运行效果：点击按钮后，Label1开始显示时间
测试环境：BCB5 + WIN98

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

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