WinAPI: CreateEllipticRgn、CreateEllipticRgnIndirect - 建立椭圆区域

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.