Img: module {
	PATH : con "/dis/charon/img.dis";

	Mimerror, Mimnone, Mimpartial, Mimdone: con iota + 1;

	# Getmim returns image and possible mask;
	# the int returned is either Mimnone, Mimpartial or Mimdone, depending on
	# how much of returned mim is filled in.
	# if the image is animated, successive calls to getmim return subsequent frames.
	# Errors are indicated by returning Mimerror, with the err field non empty.
	# Should call free() when don't intend to call getmim any more
	ImageSource: adt
	{
		width:	int;
		height:	int;
		origw:	int;
		origh:	int;
		mtype:	int;
		i:		int;
		curframe:	int;
		bs:		ref CharonUtils->ByteSource;
		gstate:	ref Gifstate;
		jstate:	ref Jpegstate;
		err:		string;

		new: fn(bs: ref CharonUtils->ByteSource, w, h: int) : ref ImageSource;
		getmim: fn(is: self ref ImageSource) : (int, ref CharonUtils->MaskedImage);
		free: fn(is: self ref ImageSource);
	};

	# Following are private to implementation
	Jpegstate: adt
	{
		# variables in i/o routines
		sr:	int;	# shift register, right aligned
		cnt:	int;	# # bits in right part of sr
	
		Nf:		int;
		comp:	array of Framecomp;
		mode:	byte;
		X,Y:		int;
		qt:		array of array of int;	# quantization tables
		dcht:		array of ref Huffman;
		acht:		array of ref Huffman;
		Ns:		int;
		scomp:	array of Scancomp;
		Ss:		int;
		Se:		int;
		Ah:		int;
		Al:		int;
		ri:		int;
		nseg:	int;
		nblock:	array of int;
	
		# progressive scan
		dccoeff:	array of array of int;
		accoeff:	array of array of array of int;	# only need 8 bits plus quantization
		nacross:	int;
		ndown:	int;
		Hmax:	int;
		Vmax:	int;
	};

	Huffman: adt
	{
		bits:	array of int;
		size:	array of int;
		code:	array of int;
		val:	array of int;
		mincode:	array of int;
		maxcode:	array of int;
		valptr:	array of int;
		# fast lookup
		value:	array of int;
		shift:	array of int;
	};
	
	Framecomp: adt	# Frame component specifier from SOF marker
	{
		C:	int;
		H:	int;
		V:	int;
		Tq:	int;
	};

	Scancomp: adt	# Frame component specifier from SOF marker
	{
		C:	int;
		tdc:	int;
		tac:	int;
	};

	Gifstate: adt
	{
		fields: int;
		bgrnd: int;
		aspect: int;
		flags: int;
		delay: int;
		trindex: byte;
		tbl: array of GifEntry;
		globalcmap: array of byte;
		cmap: array of byte;
	};

	GifEntry: adt
	{
		prefix: int;
		exten: int;
	};

	init: fn(cu: CharonUtils);
	supported: fn(mtype: int) : int;
	closest_rgbpix: fn(r, g, b: int) : int;
};