Create a form with rounded corners

Author: Horst Kniebusch

{

Die CreateRoundRectRgn lässt eine Form mit abgerundeten Ecken erscheinen.

The CreateRoundRectRgn function creates a rectangular

region with rounded corners

}

procedure TForm1.FormCreate(Sender: TObject);

var

rgn: HRGN;

begin

Form1.Borderstyle := bsNone;

rgn := CreateRoundRectRgn(0,// x-coordinate of the region's upper-left corner

0, // y-coordinate of the region's upper-left corner

ClientWidth, // x-coordinate of the region's lower-right corner

ClientHeight, // y-coordinate of the region's lower-right corner

40, // height of ellipse for rounded corners

40); // width of ellipse for rounded corners

SetWindowRgn(Handle, rgn, True);

end

{ The CreatePolygonRgn function creates a polygonal region. }

procedure TForm1.FormCreate(Sender: TObject);

const

C = 20;

var

Points: array [0..7] of TPoint;

h, w: Integer;

begin

h := Form1.Height;

w := Form1.Width;

Points[0].X := C; Points[0].Y := 0;

Points[1].X := 0; Points[1].Y := C;

Points[2].X := 0; Points[2].Y := h - c;

Points[3].X := C; Points[3].Y := h;

Points[4].X := w - c; Points[4].Y := h;

Points[5].X := w; Points[5].Y := h - c;

Points[6].X := w; Points[6].Y := C;

Points[7].X := w - C; Points[7].Y := 0;

SetWindowRgn(Form1.Handle, CreatePolygonRgn(Points, 8, WINDING), True);

end;

Other source;

...make rounded windows

Author: Simon Grossenbacher

// The CreateEllipticRgn function creates an elliptical region.

function CreateEllipticRgn(

nLeftRect: Integer, // x-coordinate of the upper-left corner

nTopRect: Integer, // y-coordinate of the upper-left corner

nRightRect: Integer, // x-coordinate of the lower-right

nBottomRect: Integer // y-coordinate of the lower-right corner

): HRGN;

// The SetWindowRgn function sets the window region of a window.

function SetWindowRgn(

hWnd: HWND, // handle to window whose window region is to be set

hRgn: HRGN, // handle to region

bRedraw: Boolean // window redraw flag

);

// Example:

procedure TForm1.FormCreate(Sender: TObject);

var

hRegion: HRGN;

begin

BorderStyle := bsNone;

hRegion := CreateEllipticRgn(1, 1, 200, 200);

SetWindowRgn(Handle, hRegion, True);

end;