Delphi下的GDI+编程[3] 绘制矩形

//在GDI+中，绘制矩形是通过TGPGraphics类的DrawRectangle方法实现的

unit Unit1;


interface


uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs;


type

  TForm1 = class(TForm)

    procedure FormPaint(Sender: TObject);

  end;


var

  Form1: TForm1;


implementation


{$R *.dfm}


uses GDIPOBJ, GDIPAPI;


procedure TForm1.FormPaint(Sender: TObject);

const

  w = 100;

  h = 50;

var

  g: TGPGraphics;

  p: TGPPen;

  x,y: Single;  //32位单精度浮点型变量

begin

  g := TGPGraphics.Create(Canvas.Handle);

  p := TGPPen.Create(0, 2);

  g.Clear(MakeColor(255,255,255));


  x := 20;

  y := 20;


  p.SetColor(aclRed);  //设置画笔颜色为红色

  g.DrawRectangle(p, x, y, w, h); //画一个矩形


  p.SetColor(aclGold); //设置画笔颜色为黄色

  x := x + w / 2;   {70}

  y := y + h /2;   {45}

  g.DrawRectangle(p, MakeRect(x, y, w, h)); //画另一个矩形


  g.Free;

  p.Free;

end;


end.