TIEMask.SetRectangle

procedure SetRectangle(Rect: TRect; Alpha: integer); overload;
procedure SetRectangle(x1, y1, x2, y2: integer; Alpha: integer); overload;

Set a rectangular selection. A pixel with mask 1 or >0 is selected.

Parameter	Description
Rect	Rectangle to select
Alpha	Alpha value (0 = not selected, >0 selected)

// Select rectangle (10, 10 - 14, 14)
ImageEnView1.SelectionMask.SetRectangle(Rect(10, 10, 14, 14), 1);
ImageEnView1.SelectCustom();