本文以实例简述了Delphi实现毫秒级别倒计时的方法。一般来说可以获得系统的高性能频率计数器在一毫秒内的震动次数，如果时钟震动次数超过10毫秒的次数则刷新edit3的显示，显示从开始记数到记数实际经过的时间，具体实现代码如下：
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
ExtCtrls, StdCtrls, mmsystem;
type
TForm1 = class(TForm)
Edit1: TEdit;
Edit2: TEdit;
Edit3: TEdit;
Button1: TButton;
Button2: TButton;
Timer1: TTimer;
Label1: TLabel;
Label2: TLabel;
Label3: TLabel;
procedure FormCreate(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure Timer1Timer(Sender: TObject);
procedure Button2Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
acttime1,acttime2:cardinal;
smmcount,stimercount,spcount:single;
htimeid:integer;
iten:integer;
protimecallback:tfntimecallback;
procedure timeproc(utimerid, umessage: uint; dwuser, dw1, dw2: dword) stdcall;
procedure proendcount;
implementation
{$R *.DFM}
//timesetevent的回调函数
procedure proendcount;
begin
acttime2:=gettickcount-acttime1;
form1.button2.enabled :=false;
form1.button1.enabled :=true;
form1.timer1.enabled :=false;
smmcount:=60;
stimercount:=60;
spcount:=-1;
timekillevent(htimeid);
end;
procedure timeproc(utimerid, umessage: uint; dwuser, dw1, dw2: dword) stdcall;
begin
form1.edit2.text:=floattostr(smmcount);
smmcount:=smmcount-0.01;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
button1.caption :='开始倒计时';
button2.caption :='结束倒计时';
button2.enabled :=false;
button1.enabled :=true;
timer1.enabled :=false;
smmcount:=60;
stimercount:=60;
spcount:=60;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
lgtick1,lgtick2,lgper:tlargeinteger;
ftemp:single;
begin
button2.enabled :=true;
button1.enabled :=false;
timer1.enabled :=true;
timer1.interval :=10;
protimecallback:=timeproc;
htimeid:=timesetevent(10,0,protimecallback,1,1);
acttime1:=gettickcount;
//获得系统的高性能频率计数器在一毫秒内的震动次数
queryperformancefrequency(lgper);
ftemp:=lgper/1000;
iten:=trunc(ftemp*10);
queryperformancecounter(lgtick1);
lgtick2:=lgtick1;
spcount:=60;
while spcount>0 do
begin
queryperformancecounter(lgtick2);
//如果时钟震动次数超过10毫秒的次数则刷新edit3的显示
if lgtick2 - lgtick1 > iten then
begin
lgtick1 := lgtick2;
spcount := spcount - 0.01;
edit3.text := floattostr(spcount);
application.processmessages;
end;
end;
end;
procedure TForm1.Timer1Timer(Sender: TObject);
begin
edit1.text := floattostr(stimercount);
stimercount:=stimercount-0.01;
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
proendcount;
//显示从开始记数到记数实际经过的时间
showmessage('实际经过时间'+inttostr(acttime2)+'毫秒');
end;
end.
