Starling OpenFl mask sample

package;

import openfl.system.System;

//import scenes.Scene;

import starling.events.Event;
import starling.display.Sprite;
import starling.display.Quad;
import starling.display.Canvas;
import starling.display.Image;
import starling.textures.Texture;
import starling.extensions.TextureMaskStyle;
import starling.utils.AssetManager;

@:keep class MainClass extends Sprite
{
    private static var sAssets:AssetManager;

    public function new()
    {
        super();
        // nothing to do here -- Startup will call "start" immediately.
    }

    public function start(assets:AssetManager):Void
    {
        sAssets = assets;

        showMask();
    }

    private function showMask():Void
    {
               // now would be a good time for a clean-up
        #if 0
        System.pauseForGCIfCollectionImminent(0);
        #end
        System.gc();

        var canvas:Canvas = new Canvas();
        canvas.beginFill(0x00FF00);
        canvas.drawCircle(100, 100, 100);
        canvas.endFill();
        this.addChild(canvas);

        var textures:openfl.Vector<Texture> = assets.getTextures("img_");
        _mask = new Image( textures[1] );
        //_mask = new Quad( 528, 110, 0 );
        _mask.x = -484;

        var style:TextureMaskStyle = new TextureMaskStyle();
        mask.style = style;
        canvas.mask = mask;
    }

    public static var assets(get, never):AssetManager;
    @:noCompletion private static function get_assets():AssetManager { return sAssets; }

}