本例效果圖:
代碼文件:unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
Edit1: TEdit;
procedure Button1Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure Edit1KeyPress(Sender: TObject; var Key: Char);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
var
f: Integer; {用這個變量協調一下各線程輸出的位置}
hSemaphore: THandle; {信號對象的句柄}
function MyThreadFun(p: Pointer): DWord; stdcall;
var
i,y: Integer;
begin
Inc(f);
y := 20 * f;
if WaitForSingleObject(hSemaphore, 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); {以免 Canvas 忙不過來}
end;
end;
ReleaseSemaphore(hSemaphore, 1, nil);
Result := 0;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
ThreadID: DWord;
begin
{不知是不是之前創建過 Semaphore 對象, 假如有先關閉}
CloseHandle(hSemaphore);
{創建 Semaphore 對象}
hSemaphore := CreateSemaphore(nil, StrToInt(Edit1.Text), 5, nil);
Self.Repaint;
f := 0;
CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);
CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);
CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);
CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);
CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);
end;
{讓 Edit 只接受 1 2 3 4 5 五個數}
procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
if not CharInSet(Key, ['1'..'5']) then Key := #0;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
Edit1.Text := '1';
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
CloseHandle(hSemaphore);
end;
end.
窗體文件:object Form1: TForm1
Left = 0
Top = 0
Caption = 'Form1'
ClIEntHeight = 140
ClIEntWidth = 192
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
OldCreateOrder = False
OnCreate = FormCreate
PixelsPerInch = 96
TextHeight = 13
object Button1: TButton
Left = 109
Top = 107
Width = 75
Height = 25
Caption = 'Button1'
TabOrder = 0
OnClick = Button1Click
end
object Edit1: TEdit
Left = 109
Top = 80
Width = 75
Height = 21
TabOrder = 1
Text = 'Edit1'
OnKeyPress = Edit1KeyPress
end
end
