多线程编程(18) - 再从一个小例子出发

前面的例子都是让若干线程做同样的事情, 下面这个例子中的三个线程将分别在三个画板上随机画不同颜色的椭圆.
接下来的很多事情我想要基于这个例子来做.

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本例效果图:

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代码文件:

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unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, StdCtrls, ExtCtrls;type  TForm1 = class(TForm)    PaintBox1: TPaintBox;    PaintBox2: TPaintBox;    PaintBox3: TPaintBox;    Button1: TButton;    procedure Button1Click(Sender: TObject);    procedure FormDestroy(Sender: TObject);  end;var  Form1: TForm1;implementation{$R *.dfm}var  h1,h2,h3: THandle;{第一个线程的入口函数: 画红色椭圆}function ThreadFun1(p: Pointer): Integer; stdcall;var  i, x1,y1,x2,y2: Integer;begin  Form1.PaintBox1.Canvas.Brush.Color := clRed;  for i := 0 to 50000 do with Form1.PaintBox1 do  begin    x1 := Random(Width); y1 := Random(Height);    x2 := Random(Width); y2 := Random(Height);    Canvas.Lock;    Canvas.Ellipse(x1,y1,x2,y2);    Canvas.Unlock;    Sleep(0);  end;  Result := 0;end;{第二个线程的入口函数: 画绿色椭圆}function ThreadFun2(p: Pointer): Integer; stdcall;var  i, x1,y1,x2,y2: Integer;begin  Form1.PaintBox2.Canvas.Brush.Color := clGreen;  for i := 0 to 50000 do with Form1.PaintBox2 do  begin    x1 := Random(Width); y1 := Random(Height);    x2 := Random(Width); y2 := Random(Height);    Canvas.Lock;    Canvas.Ellipse(x1,y1,x2,y2);    Canvas.Unlock;    Sleep(0);  end;  Result := 0;end;{第三个线程的入口函数: 画蓝色椭圆}function ThreadFun3(p: Pointer): Integer; stdcall;var  i, x1,y1,x2,y2: Integer;begin  Form1.PaintBox3.Canvas.Brush.Color := clBlue;  for i := 0 to 50000 do with Form1.PaintBox3 do  begin    x1 := Random(Width); y1 := Random(Height);    x2 := Random(Width); y2 := Random(Height);    Canvas.Lock;    Canvas.Ellipse(x1,y1,x2,y2);    Canvas.Unlock;    Sleep(0);  end;  Result := 0;end;procedure TForm1.Button1Click(Sender: TObject);var  ID: DWORD;begin  h1 := CreateThread(nil, 0, @ThreadFun1, nil, 0, ID);  h2 := CreateThread(nil, 0, @ThreadFun2, nil, 0, ID);  h3 := CreateThread(nil, 0, @ThreadFun3, nil, 0, ID);end;procedure TForm1.FormDestroy(Sender: TObject);begin  CloseHandle(h1);  CloseHandle(h2);  CloseHandle(h3);end;end.

窗体文件:

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object Form1: TForm1  Left = 0  Top = 0  Caption = 'Form1'  ClientHeight = 206  ClientWidth = 371  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 PaintBox1: TPaintBox    Left = 8    Top = 8    Width = 114    Height = 153  end  object PaintBox2: TPaintBox    Left = 128    Top = 8    Width = 114    Height = 153  end  object PaintBox3: TPaintBox    Left = 248    Top = 8    Width = 114    Height = 153  end  object Button1: TButton    Left = 288    Top = 172    Width = 75    Height = 25    Caption = 'Button1'    TabOrder = 0    OnClick = Button1Click  endend

可以借助入口函数的参数, 把这个程序简化一下(窗体和运行效果不变):

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unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, StdCtrls, ExtCtrls;type  TForm1 = class(TForm)    PaintBox1: TPaintBox;    PaintBox2: TPaintBox;    PaintBox3: TPaintBox;    Button1: TButton;    procedure Button1Click(Sender: TObject);    procedure FormDestroy(Sender: TObject);  end;var  Form1: TForm1;implementation{$R *.dfm}var  h1,h2,h3: THandle;{线程的入口函数: 不同的线程画不同颜色的椭圆}function ThreadFun(p: Pointer): Integer; stdcall;var  i,x1,y1,x2,y2: Integer;  paint: TPaintBox;begin  case Integer(p) of    1: begin      paint := Form1.PaintBox1;      paint.Canvas.Brush.Color := clRed;    end;    2: begin      paint := Form1.PaintBox2;      paint.Canvas.Brush.Color := clGreen    end;    3: begin      paint := Form1.PaintBox3;      paint.Canvas.Brush.Color := clBlue;    end;  end;  for i := 0 to 5000 do with paint do  begin    x1 := Random(Width); y1 := Random(Height);    x2 := Random(Width); y2 := Random(Height);    Canvas.Lock;    Canvas.Ellipse(x1,y1,x2,y2);    Canvas.Unlock;    Sleep(0);  end;  Result := 0;end;procedure TForm1.Button1Click(Sender: TObject);var  ID: DWORD;begin  h1 := CreateThread(nil, 0, @ThreadFun, Ptr(1), 0, ID);  h2 := CreateThread(nil, 0, @ThreadFun, Ptr(2), 0, ID);  h3 := CreateThread(nil, 0, @ThreadFun, Ptr(3), 0, ID);end;procedure TForm1.FormDestroy(Sender: TObject);begin  CloseHandle(h1);  CloseHandle(h2);  CloseHandle(h3);end;end.

多用点数组, 再简化一下(窗体与效果一样):

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unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, StdCtrls, ExtCtrls;type  TForm1 = class(TForm)    PaintBox1: TPaintBox;    PaintBox2: TPaintBox;    PaintBox3: TPaintBox;    Button1: TButton;    procedure Button1Click(Sender: TObject);    procedure FormDestroy(Sender: TObject);  end;var  Form1: TForm1;implementation{$R *.dfm}const  colors: array[0..2] of TColor = (clRed, clGreen, clBlue);var  hArr: array[0..2] of THandle;  panitArr: array[0..2] of TPaintBox;function ThreadFun(p: Pointer): Integer; stdcall;var  i,n,x1,y1,x2,y2: Integer;begin  n := Integer(p);  panitArr[n].Color := colors[n];  for i := 0 to 5000 do with panitArr[n] do  begin    x1 := Random(Width); y1 := Random(Height);    x2 := Random(Width); y2 := Random(Height);    Canvas.Lock;    Canvas.Ellipse(x1,y1,x2,y2);    Canvas.Unlock;    Sleep(0);  end;  Result := 0;end;procedure TForm1.Button1Click(Sender: TObject);var  ID: DWORD;  i: Integer;begin  panitArr[0] := PaintBox1;  panitArr[1] := PaintBox2;  panitArr[2] := PaintBox3;  for i := 0 to Length(hArr) - 1 do    hArr[i] := CreateThread(nil, 0, @ThreadFun, Ptr(i), 0, ID);end;procedure TForm1.FormDestroy(Sender: TObject);var  i: Integer;begin  for i := 0 to Length(hArr) - 1 do CloseHandle(hArr[i]);end;end.

转帖：http://www.cnblogs.com/del/archive/2009/02/19/1394317.html