Janilabo | TPA stuff

// Based on ShellSort() algorithm.
procedure SortTPAByColumn(var TPA: TPointArray);
var
  x, a, b, l: Integer;
begin
  l := Length(TPA);
  x := 0;
  while (x < (l div 3)) do
    x := ((x * 3) + 1);
  while (x >= 1) do
  begin
    for a := x to (l - 1) do
    begin
      b := a;
      while ((b >= x) and ((TPA[b].Y < TPA[(b - x)].Y) and (TPA[b].X < TPA[(b - x)].X))) do
      begin
        Swap(TPA[b], TPA[(b - x)]);
        DecEx(b, x);
      end;
    end;
    x := (x div 3);
  end;
end;

function TPAFromBoxEx(bx: TBox; method: (ROWbyROW, COLUMNbyCOLUMN)): TPointArray;
var
  x, y, z: Integer;
begin
  if ((bx.X1 > bx.X2) or (bx.Y1 > bx.Y2)) then
    Exit;
  SetLength(Result, (((bx.X2 - bx.X1) + 1) * ((bx.Y2 - bx.Y1) + 1)));
  case method of
    ROWbyROW:
      for y := bx.Y1 to bx.Y2 do
        for x := bx.X1 to bx.X2 do
        begin
          Result[z].X := x;
          Result[z].Y := y;
          z := (z + 1);
        end;
    COLUMNbyCOLUMN:
      for x := bx.X1 to bx.X2 do
        for y := bx.Y1 to bx.Y2 do
        begin
          Result[z].X := x;
          Result[z].Y := y;
          z := (z + 1);
        end;
  end;
end;

var
  TPA: TPointArray;

begin
  ClearDebug;
  TPA := TPAFromBox(Box(0, 0, 3, 3));
  WriteLn('TPAFromBox(): ' + TPAToStr(TPA));
  SortTPAByRow(TPA);
  WriteLn('..after SortTPAByRow(): ' + TPAToStr(TPA));
  WriteLn('');
  SetLength(TPA, 0);
  TPA := TPAFromBoxEx(Box(0, 0, 3, 3), COLUMNbyCOLUMN);
  WriteLn('TPAFromBoxEx() [CbC]: ' + TPAToStr(TPA));
  SortTPAByColumn(TPA);
  WriteLn('..after SortTPAByColumn(): ' + TPAToStr(TPA));
  WriteLn('');
  SetLength(TPA, 0);
  TPA := TPAFromBoxEx(Box(0, 0, 4, 4), ROWbyROW);
  WriteLn('TPAFromBoxEx() [RbR]: ' + TPAToStr(TPA));
  SortTPA(TPA);
  WriteLn('..after SortTPA(): ' + TPAToStr(TPA));
  SetLength(TPA, 0);
end.