Jittering with Neko and drawing API

Haxe
#1

I am having an issue where if I use the openfl drawing API with neko as the target, whenever I move an object, the entire frame jitters back and forth by about a pixel. Does anyone know why this happens? The following code illustrates the problem:

package;

import openfl.display.Sprite;
import openfl.Lib;
import openfl.events.Event;

/**
 * ...
 * @author Graham Reid
 */
class Main extends Sprite 
{
   var theta:Float = 0;
	
	public function new() 
	{
		super();
	}

	public function update(e:Event):Void
	{		
		theta += 0.01;
	
		var testx:Float = 10 * Math.cos(theta);
		var testy:Float = 10 * Math.sin(theta);
	
		this.graphics.clear();
		this.graphics.lineStyle(1, 0xFF0000);
		this.graphics.moveTo(testx, testy);
		this.graphics.lineTo(testx + 10, testy);
		this.graphics.lineTo(testx + 10, testy + 10);
		this.graphics.lineTo(testx, testy + 10);
		this.graphics.lineTo(testx, testy);
	
		this.graphics.drawRect(160, 160, 50, 50);
	}
}

If I modify the line drawing to:

this.graphics.clear();
this.graphics.lineStyle(1, 0xFF0000);
this.graphics.moveTo(Std.int(testx), Std.int(testy));
this.graphics.lineTo(Std.int(testx + 10), Std.int(testy));
this.graphics.lineTo(Std.int(testx + 10), Std.int(testy + 10));
this.graphics.lineTo(Std.int(testx), Std.int(testy + 10));
this.graphics.lineTo(Std.int(testx), Std.int(testy));

there is no jitter, but there are significant aliasing effects

#2

Did you try same code in flash and had a different result? do you have antialiasing in something diferent than 0?
The jitter may be a result of rounding the number, but if you are using antialiasing it shouldn’t be noticable.

PS
in second example use:
var testx:Int= Std.int(10 * Math.cos(theta));
var testy:Int= Std.int(10 * Math.sin(theta));

#3

It only happens in Neko and the antialiasing is set to a value other than zero. The casts were just meant to be illustrative. I am mostly just wondering if this is a known problem since it seems to occur generically using the line drawing api in Neko (at least on my computer). Its not an overly serious problem for me as I only use this drawing mode for debugging, but I imagine that it would be very bothersome for games which use procedurally generated graphics.

#4

can it be that neko is not using antialiasing at all?