WinAPI: CreateEllipticRgn、CreateEllipticRgnIndirect - 建立椭圆区域

本例效果图:

---

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}



procedure TForm1.FormPaint(Sender: TObject);

const

  n = 50;

var

  Rgn: HRGN;

  x1,y1,x2,y2: Integer;

begin

  x1 := n;

  y1 := n div 2;

  x2 := ClientWidth - n;

  y2 := ClientHeight - n;



  {建立椭圆区域}

//  Rgn := CreateEllipticRgn(x1, y1, x2, y2);

  Rgn := CreateEllipticRgnIndirect(Rect(x1,y1,x2,y2)); {目的同上一行, 函数不同}



  {填充区域}

  Canvas.Brush.Color := clSilver;

  Canvas.Brush.Style := bsCross;

  FillRgn(Canvas.Handle, Rgn, Canvas.Brush.Handle);



  {绘制区域边界}

  Canvas.Brush.Color := clRed;

  Canvas.Brush.Style := bsSolid;

  FrameRgn(Canvas.Handle, Rgn, Canvas.Brush.Handle, 2, 2);



  DeleteObject(Rgn);

end;



end.