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转载自：万一的博客
本次专门研究下 SetWaitableTimer的第二个参数（起始时间）
它有正值、负值、0值这三种情况，前面已经用过 0 值
先学习负值（相对时间），也就是从当前算起隔多长时间开始执行
这个相对时间是以 1/100 纳秒为单位的，譬如赋值：3*10000000 相当于 3 秒
1 s(秒) = 1,000 ms(毫秒); 1 s(秒) = 1,000,000 µs(微妙); 1 s(秒) = 1,000,000,000 ns(纳秒); 1 s(秒) = 1,000,000,000,000 ps(皮秒);
本例的效果图
代码文件
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
procedure FormDestroy(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
var
f: Integer;
hWaitableTimer: THandle;
function MyThreadFun(p: Pointer): DWORD; stdcall;
var
i, y: Integer;
y:= 20* f;
if WaitForSingleObject(hWaitableTimer, INFINITE)=WAIT_OBJECT_0 then
begin
for i:= 0 to 1000 do
begin
Form1.Canvas.Lock;
Form1.Canvas.TextOut(20, y, IntToStr(i));
Form1.Canvas.UnLock;
Sleep(1);
end;
end;
Result:= 0;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
ThreadID: DWORD;
DueTime: Int64;
begin
hWaitableTimer:= CreateWaitableTimer(nil, True, nil);
DueTime:= -3*10000000; //3秒钟之后执行
SetWaitableTimer(hWaitableTimer, DueTime, 0, nil, nil, False);
Repaint; f:= 0;
CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);
CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);
CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
CloseHandle(hWaitableTimer);
end;
end.
窗体文件
object Form1: TForm1
Left = 0
Top = 0
Caption = ‘Form1‘
ClientHeight = 116
ClientWidth = 179
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = ‘Tahoma‘
Font.Style = []
OldCreateOrder = False
OnDestroy = FormDestroy
PixelsPerInch = 96
TextHeight = 13
object Button1: TButton
Left = 96
Top = 83
Width = 75
Height = 25
Caption = ‘Button1‘
TabOrder = 0
OnClick = Button1Click
end
end
当我们需要一个绝对时间，譬如 2009-2-18 13:10:5，函数需要的Int64 值应该是 TFileTime格式的时间
先看三种相关时间类型（TFileTime、TSystemTime、TDateTime）的定义
//TFileTime 又名 FILETIME或_FILETIME
_FILETIME = record
dwLowDateTime: DWORD;
dwHighDateTime: DWORD;
end;
//TSystemTime 又名 SYTEMTIME 或 _SYSTEMTIME
_SYSTEMTIME=record
wYear: Word;
wMonth: Word;
wDayOfWeek: Word;
wDay: Word;
wHour: Word;
wMinute: Word;
wSecond: Word;
wMilliseconds: Word;
end;
TDateTime= type Double;
TFileTime 相当于一个Int64， 一般要通过 TSystemTime 或TDateTime 赋值，然后转换过去
在例子中，我是通过下面过程转换过去的：
StrToDateTime->DateTimeToSystemTime->SystemTimeToFileTime->LocalFileTimeToFileTime
下面程序执行在2009年2月18号下午1点10分5秒时运行三个线程（窗体同上，我已经找到了合适的时间测试成功）
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
procedure FormDestroy(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
var
f: Integer;
hWaitableTimer: THandle;
function MyThreadFun(p: Pointer): DWORD; stdcall;
var
i,y: Integer;
begin
Inc(f);
y := 20 * f;
if WaitForSingleObject(hWaitableTimer, INFINITE) = WAIT_OBJECT_0 then
begin
for i := 0 to 1000 do
begin
Form1.Canvas.Lock;
Form1.Canvas.TextOut(20, y, IntToStr(i));
Form1.Canvas.Unlock;
Sleep(1);
end;
end;
Result := 0;
end;
procedure TForm1.Button1Click(Sender: TObject);
const
strTime = ‘2009-2-18 13:10:5‘;
var
ThreadID: DWORD;
DueTime: Int64;
st: TSystemTime;
ft,UTC: TFileTime;
dt: TDateTime;
begin
DateTimeToSystemTime(StrToDateTime(strTime), st); {从 TDateTime 到 TSystemTime}
SystemTimeToFileTime(st, ft); {从 TSystemTime 到 TFileTime}
LocalFileTimeToFileTime(ft, UTC); {从本地时间到国际标准时间 UTC}
DueTime := Int64(UTC); {函数需要的是 Int64}
hWaitableTimer := CreateWaitableTimer(nil, True, nil);
SetWaitableTimer(hWaitableTimer, DueTime, 0, nil, nil, False);
Repaint; f := 0;
CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);
CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);
CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
CloseHandle(hWaitableTimer);
end;
end.
接下来该是WaitableTimer 对象的回调函数了
Delphi多线程编程(15)--多线程同步之WaitableTimer（等待定时器对象）[续]
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原文地址：http://www.cnblogs.com/xumenger/p/4499518.html
