unit mipmaps;

{$MODE OBJFPC}
{$M+}

interface
uses contnrs, classes, images, type_fixes, colors;

// TODO don't refcount all over the place!!!

// a mipmap is a set of images.
// the images usually, but not always, have different sizes.
// the images usually, but not always, have different color spaces.

type
  TMipmap = class
  private
    fItems : TInterfaceList; // list of bitmaps in order of size (smallest first).
    // TODO on-demand loading of more detailed mipmaps.
  public
    destructor Destroy(); override;
  protected
    function GetItemCount() : Integer; inline;
  published
    constructor Create();
    property ItemCount : Integer read GetItemCount;
    function GetItem(aIndex : Integer) : IImage; inline;
    // add: return index.
  public
    property Items[aIndex : Integer] : IImage read GetItem;
    function GetBestFit(aColorspace : TColorspace; aScaleWidth, aScaleHeight : TCardinal) : Integer; // index into "Items", or -1. IImage;
  public
    function Add(const aImage : IImage) : Integer;
  end;
  
implementation
uses sysutils;

destructor TMipmap.Destroy();
begin
  FreeAndNil(fItems);
  inherited Destroy();
end;

function TMipmap.GetItem(aIndex : Integer) : IImage; inline;
begin
  Result := IImage(fItems[aIndex]);
end;

function TMipmap.GetItemCount() : Integer; inline;
begin
  Result := fItems.Count;
end;
  
constructor TMipmap.Create();
begin
  inherited Create();
  fItems := TInterfaceList.Create();
end;

{ returns the first pixmap that is >= a given size. }
function TMipmap.GetBestFit(aColorspace : TColorspace; aScaleWidth, aScaleHeight : TCardinal) : Integer;
var
  vIndex : Integer;
  vItem : IImage;
begin
  // FIXME handle aColorspace.
  
  Result := -1;
  if fItems.Count = 0 then
    Exit;
    
  // TODO binary search.
  for vIndex := 0 to fItems.Count - 1 do begin
    vItem := GetItem(vIndex);
    if (vItem.Width >= aScaleWidth) and (vItem.Height >= aScaleHeight) then begin
      Result := vIndex; // Item;
      Exit;
    end;
  end;

  Result := fItems.Count - 1; // GetItem(fItems.Count - 1);
end;

function TMipmap.Add(const aImage : IImage) : Integer;
begin
  Result := fItems.Count;
  fItems.Add(aImage);
end;

end.