diag

{$loadlib pumbaa.dll}

procedure DebugBitmap(bmp: Integer);
var
  w, h: Integer;
begin
  GetBitmapSize(bmp, w, h);
  DisplayDebugImgWindow(w, h);
  DrawBitmapDebugImg(bmp);
end;

function TPADiagonals2(bx: TBox): TPointArray;
var
  x, y, z, l, r, w, h, e, o: Integer;
  c: TPoint;
begin
  l := pp_BoxSize(bx);
  SetLength(Result, l);
  if (l > 0) then
  begin
    pp_BoxDimensions(bx, w, h);
    z := ((bx.X1 + h) - 1);
    c := Point(bx.X1, bx.Y1);
    e := 0;
    o := 0;
    repeat
      if (c.X > z) then
        e := (c.X - z);
      if (c.X > bx.X2) then
        o := (c.X - bx.X2);
      y := (bx.Y1 + o);
      for x := (c.X - o) downto (bx.X1 + e) do
      begin
        Result[r] := Point(x, y);
        if (y < bx.Y2) then
          y := (y + 1);
        r := (r + 1);
      end;
      c.X := (c.X + 1);
    until (c.X > (bx.X2 + h));
  end;
end;

function TPADiagonals(bx: TBox): TPointArray;
var
  x, y, z, l, r, w, h, e, o: Integer;
  c: TPoint;
begin
  l := pp_BoxSize(bx);
  SetLength(Result, l);
  if (l > 0) then
  begin
    pp_BoxDimensions(bx, w, h);
    z := ((bx.X1 + h) - 1);
    c := Point(bx.X1, bx.Y1);
    e := 0;
    o := 0;
    repeat
      if (c.X > z) then
        e := (c.X - z);
      if (c.X > bx.X2) then
        o := (c.X - bx.X2);
      y := (bx.Y2 - o);
      for x := (c.X - o) downto (bx.X1 + e) do
      begin
        Result[r] := Point(x, y);
        if (y > bx.Y1) then
          y := (y - 1);
        r := (r + 1);
      end;
      c.X := (c.X + 1);
    until (c.X > (bx.X2 + h));
  end;
end;

var
  bmp, w, h, i: Integer;
  TPA: TPointArray;
  bx: TBox;

begin
  bx := IntToBox(0, 0, 50, 99);
  pp_BoxDimensions(bx, w, h);
  bmp := CreateBitmap(w, h);
  TPA := TPADiagonals2(bx);
  for i := 0 to High(TPA) do
  begin
    FastSetPixel(bmp, TPA[i].X, TPA[i].Y, 255);
    DebugBitmap(bmp);
  end;
end.