Title: Create non-rectangular forms
Question: This sample code shows how to create custom shaped forms. By creating simple Regions and combining them into complex Regions you can give your form any shape you want.
Answer:
// Code to set the form to an Elliptic shape (use alt+F4 to close)
procedure TForm1.FormCreate(Sender: TObject);
var
hRgn: THandle;
begin
// create a elliptic region 10 pixels smaller than the form
hRgn := CreateEllipticRgn(10, 10, Width - 20, Height - 20);
// set the new region
SetWindowRgn(Handle, hRgn, False);
end;
// Code to create a form with a hole
procedure TForm1.FormCreate(Sender: TObject);
var
hRgn1, hRgn2: THandle;
begin
// create a rectangular region with the same size as the form
hRgn1 := CreateRectRgn(0, 0, Width, Height);
// create a circular region 100 x 100 in the center of the form
hRgn2 := CreateEllipticRgn((Width div 2) - 50, (Height div 2) - 50, (Width div 2) + 50, (Height div 2) + 50);
// combine the regions by subtracting the circular region
// from the rectangular one
CombineRgn(hRgn1, hRgn1, hRgn2, RGN_DIFF);
// set the new region
SetWindowRgn(Handle, hRgn1, False);
// delete region 2, region 1 is owned and deleted by windows
DeleteObject(hRgn2);
end;