GetTPALine()

{==============================================================================]
  Explanation: Returns the line of points fromPt => toPt.
[==============================================================================}
function GetTPALine(fromPt, toPt: TPoint): TPointArray;
var
  i, h: Integer;
begin
  if (fromPt <> toPt) then
  begin
    h := Max(Round(Abs(fromPt.X - toPt.X)), Round(Abs(fromPt.Y - toPt.Y)))
    SetLength(Result, (h + 1));
    for i := 0 to h do
    begin
      Result[i].X := (fromPt.X + Round((toPt.X - fromPt.X) * (i / h)));
      Result[i].Y := (fromPt.Y + Round((toPt.Y - fromPt.Y) * (i / h)));
    end;
  end else
    Result := [fromPt];
end;

procedure DebugLine(start, finish: TPoint; color: Integer);
var
  t: Integer;
  bmp: TSCARBitmap;
begin
  bmp := TSCARBitmap.Create('');
  bmp.SetSize(500, 500);
  t := GetSystemTime;
  bmp.SetPixels(GetTPALine(start, finish), color);
  Status(PointToStr(start) + ' => ' + PointToStr(finish) + ' [' + IntToStr(GetSystemTime - t) + ' ms.]');
  DebugBitmap(bmp);
  bmp.Free;
end;

var
  c: TIntArray;
  s, f: TPoint;
  l, i: Integer;

begin
  c := [clRed, clYellow, clBlue, clGreen];
  s := Point(10, 10);
  f := Point(490, 490);
  repeat
    for l := 0 to 3 do
      for i := 10 to 489 do
      begin
        case l of
          0:
          begin
            Inc(s.Y);
            Dec(f.Y);
          end;
          1:
          begin
            Inc(s.X);
            Dec(f.X);
          end;
          2:
          begin
            Dec(s.Y);
            Inc(f.Y);
          end;
          3:
          begin
            Dec(s.X);
            Inc(f.X);
          end;
        end;
        DebugLine(s, f, c[l]);
      end;
  until False;
end.