Class new title: Turtle
	subclassof: BitBlt
	fields: 'frame location direction pen pendown inking'
	declare: ''

color: t1 
	[color _ t1]

drawfrom: t1 to: t2 | t3 t4 t5 t6 t7 t8 t9 t10   
	[[pen is: Integer 
		[function _ 12 + (function land: 3).
		height _ pen.
		width _ height.
		t3 _ pen / 2  (pen / 2)]
	pen is: Form 
		[function _ function land: 3.
		super sourceForm_ pen.
		width _ pen width.
		height _ pen height.
		t3 _ pen offset]
	user notify: 'pen must be a Form or Integer'].
	destx _ (t1 x - t3 x) asInteger.
	desty _ (t1 y - t3 y) asInteger.
	t4 _ (t2 x - t1 x) asInteger  (t2 y - t1 y) asInteger.
	t5 _ t4 x sign.
	t6 _ t4 y sign.
	t7 _ t4 y abs.
	t8 _ t4 x abs.
	super callBLT.
	[t8 > t7 
		[t9 _ t8 / 2.
		for t10 to: t8 do
			[destx _ destx + t5.
			t9 _ t9 - t7.
			[t9 < 0 
				[desty _ desty + t6.
				t9 _ t9 + t8]].
			super callBLT]]
	t9 _ t7 / 2.
	for t10 to: t7 do
		[desty _ desty + t6.
		t9 _ t9 - t8.
		[t9 < 0 
			[destx _ destx + t5.
			t9 _ t9 + t7]].
		super callBLT]].
	pen is: Form  [super release: pen]]

erase 
	[super window clear: white]

go: t1 
	[self goto: direction asRadians asDirection * t1 + location]

goto: t1 | t2 
	[t2 _ location.
	location _ t1.
	pendown  [self drawfrom: t2 to: location]]

home 
	[location _ frame center]

init 
	[sourceraster _ 0.
	sourcebase _ sourceraster.
	super init.
	super toDisplay.
	frame _ user screenrect.
	self pendn.
	self color: black.
	self width: 1.
	self inking: storing.
	self home.
	self up]

inking: t1 
	[function _ t1]

pen: t1 
	[pen _ t1]

pendn 
	[pendown _ true]

penup 
	[pendown _ false]

turn: t1 
	[direction _ direction + t1]

up 
	[direction _ 270.0]

width: t1 
	[self pen: t1]