unit fonts;

{$MODE OBJFPC}
{$M+}

interface
uses mipmaps, images, type_fixes;

{ TODO use fixed point? floating point? }

// TODO avoid refcounting of the IFont by just using (and deriving from) TFont throughout.

type
  // the only one TCharacterSet = (csUnicode);
  TTextDirection = (tdLeftToRight, tdRightToLeft, tdTopToBottom, tdBottomToTop);

  TGlyphPoint = record
    X : Integer;
    Y : Integer;
    IsOnCurve : Boolean;
  end;

  TGlyphPointArray = array of TGlyphPoint;

  TGlyphP = ^TGlyph;
  
  TCoordinate = TCardinal; // FIXME fractional coordinates?
  
  TGlyphBox = record
    Ascent : TCoordinate;
    LeftSideBearing : TCoordinate;
    AdvanceWidth : TCoordinate;
    __Reserved1 : TCoordinate;
    __Reserved2 : TCoordinate;
    __Reserved3 : TCoordinate;
    __Reserved4 : TCoordinate;
    __Reserved5 : TCoordinate;
    __Reserved6 : Pointer;
  end;
  
  TGlyphBoxArray = array of TGlyphBox;

  { this "class" has some very questionable optimizations so that it will have that last bit of speed since it's used in an inner loop. }
  TGlyph = object { faster. }
    Boxes : TGlyphBoxArray; // Boxes[0] is the bezier (non-bitmap) box.
    // FIXME vertical fonts?
    // FIXME log which font it is (the TFont); maybe here or else in the TFont itself...
    Bitmaps : TMipmap; // for bitmap glyph.
    // FIXME ComposeWithGlyph : TGlyphP; // if any. this only makes sense with bezier Points, that is, with non-bitmap glyphs. FIXME: add the transform matrix and scale etc.
    Points : TGlyphPointArray;
    PointsReferenceHeight : TCardinal;
    
    function AddBitmap(const aImage : IImage) : TCardinal; // returns index in "Boxes".
    destructor Done();
    constructor Init();
  end;
  
  TGlyphArray = array of TGlyph;

  // not neccessarily just one font, just an access interface for someone wanting to display some text (can also be a Fontset, why does the user care?).
  IFont = interface
    function GetGlyph(aCode : TCardinal) : TGlyphP{or nil};
    function GetFallbackGlyph : TGlyphP; // not nil.
  end;

const
  cFallbackGlyph : TGlyphP = nil;
  
implementation

uses sysutils;

constructor TGlyph.Init();
begin
  //ComposeWithGlyph := nil;
  Bitmaps := nil;
  SetLength(Points, 0);
  PointsReferenceHeight := 1024;
end;

destructor TGlyph.Done();
begin
  // ComposeWithGlyph ?
  SetLength(Boxes, 0);
  SetLength(Points, 0);
  FreeAndNil(Bitmaps);
end;

function TGlyph.AddBitmap(const aImage : IImage) : TCardinal; // returns index in "Boxes".
begin
  if not Assigned(Bitmaps) then
    Bitmaps := TMipmap.Create();
    
  Result := Bitmaps.Add(aImage) + 1;
  if Length(Boxes) <= Result then
    SetLength(Boxes, Result + 1);
end;

initialization
  New(cFallbackGlyph, Init());
  cFallbackGlyph^.Bitmaps := nil;
  SetLength(cFallbackGlyph^.Points, 0);
  
finalization
  Dispose(cFallbackGlyph, Done());

end.