function CleanAndSortTPA(TPA: TPointArray): TPointArray;
var
  Matrix: array of TBoolArray;
  i, c, H, j, idx, x, y: Integer;
  area: TBox;
begin
  area := GetTPABounds(TPA);
  H := High(TPA);
  SetLength(Matrix, ((area.Y2 - area.Y1) + 1));
  for i := 0 to (area.Y2 - area.Y1) do
    SetLength(Matrix[i], ((area.X2 - area.X1) + 1));
  C := 0;
  for i :=0 to H do
  begin
    if Matrix[(TPA[i].y - area.X1)][(TPA[i].x - area.Y1)] then
      Continue;
    Matrix[(TPA[i].y - area.X1)][(TPA[i].x - area.Y1)] := True;
    Inc(C);
  end;
  SetLength(Result, C);
  idx := 0;
  for x := area.X1 to area.X2 do
    for y := area.Y1 to area.Y2 do
      if Matrix[(y - area.X1)][(x - area.Y1)] then
      begin
        Result[idx] := Point(x, y);
        Inc(idx);
        if (idx >= C) then
          Exit;
      end;
end;

function RandomTPA(Amount:Integer; MinX,MinY,MaxX,MaxY:Integer): TPointArray;
var i:Integer;
begin
  SetLength(Result, Amount+1);
  for i:=0 to Amount do
  begin
    Result[i] := Point(RandomRange(MinX, MaxX), RandomRange(MinY, MaxY));
  end;
end;

var
  a, b: TPointArray;

begin
  b := RandomTPA(10, -2, -2, 2, 2);
  WriteLn('BEFORE: ' + ToStr(b));
  a := CleanAndSortTPA(b);
  WriteLn('AFTER: ' + ToStr(a));
end.