Attempt at simple Haxe painting.. but..

SimpleHaxePainting.hx

package;

import nme.Lib;
import nme.display.Bitmap;
import nme.display.BitmapData;
import nme.display.Sprite;
import nme.events.MouseEvent;

class TestScene extends Sprite
{
  private var _mouseDown:Bool;
  private var _lastX:Float;
  private var _lastY:Float;

  private var _sketch:Sprite;
  private var _sketcharea:Bitmap;
  private var _screenW:Float;
  private var _screenH:Float;

  private var _color:Int;
  private var _lineDiameter:Float;

  public function new ()
  {
    super ();

    _mouseDown = false;
    _lastX = 0.0;
    _lastY = 0.0;
    _screenW = Lib.current.stage.stageWidth;
    _screenH = Lib.current.stage.stageHeight;
    _color = 0x00ff00;
    _lineDiameter = _screenW*0.007;

    _sketch = new Sprite();
    _sketch.cacheAsBitmap = true;
    _sketcharea = new Bitmap(new BitmapData(Std.int(_screenW*0.7), Std.int(_screenH*0.9), true));
    _sketcharea.alpha = 0;
    _sketch.addChild(_sketcharea);
    _sketch.graphics.beginFill(0x222222);
    _sketch.graphics.drawRect(0,0,_sketch.width,_sketch.height);
    _sketch.addEventListener(MouseEvent.MOUSE_DOWN, handleMouseDown);
    _sketch.addEventListener(MouseEvent.MOUSE_UP, handleMouseUp);
    _sketch.addEventListener(MouseEvent.MOUSE_MOVE, handleMouseMove);
    _sketch.addEventListener(MouseEvent.MOUSE_OUT, handleMouseOut);

    resize();

    addChild(_sketch);
  }

  private function resize()
  {
    _screenW = Lib.current.stage.stageWidth;
    _screenH = Lib.current.stage.stageHeight;

    _sketch.width = _screenW * 0.7;
    _sketch.height = _screenH * 0.7;

    _sketch.x = _screenW * 0.5 - _sketch.width*0.5;
    _sketch.y = _screenH * 0.5 - _sketch.height*0.5;
  }

  private function handleMouseDown(e)
  {
    _mouseDown = true;
    _lastX = e.localX;
    _lastY = e.localY;
    _sketch.graphics.lineStyle(_lineDiameter, _color);
  }

  private function handleMouseUp(e)
  {
    _mouseDown = false;
  }

  private function handleMouseOut(e)
  {
    _mouseDown = false;
  }

  private function handleMouseMove(e)
  {
    if (!_mouseDown) return;

    _sketch.graphics.moveTo(_lastX, _lastY);
    _sketch.graphics.lineTo(e.localX, e.localY);

    _lastX = e.localX;
    _lastY = e.localY;
  }
}