多线程编程(18) - 再从一个小例子出发

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.
　　本例效果图:

   　代码文件:
unit Unit1;
interface
uses
　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:

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
　end
end

　　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):

unit Unit1;
interface
uses
　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):

unit Unit1;
interface
uses
　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 := 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);
end;
end.