HaxePunk maintain ratio

Main.hx

import com.haxepunk.Engine;
import com.haxepunk.HXP;
import com.haxepunk.utils.Draw;

class Main extends Engine
{

	override public function init()
	{
#if debug
		HXP.console.enable();
#end
		HXP.scene = new MainScene();
	}

	@:access(com.haxepunk.HXP)
	override private function resize()
	{		
		var sw = HXP.stage.stageWidth / baseContainerWidth;
		var sh = HXP.stage.stageHeight / baseContainerHeight;
		
		if (baseContainerHeight * sw > HXP.stage.stageHeight)
		{
			HXP.screen.scale = sh;
			HXP.screen.x = Std.int((HXP.stage.stageWidth - baseContainerWidth * sh) / 2);
			HXP.screen.y = 0;
		}
		else
		{
			HXP.screen.scale = sw;
			HXP.screen.x = 0;
			HXP.screen.y = Std.int((HXP.stage.stageHeight - baseContainerHeight * sw) / 2);
		}
		
		HXP.windowWidth = HXP.stage.stageWidth;
		HXP.windowHeight = HXP.stage.stageHeight;
		HXP.resize(HXP.stage.stageWidth, HXP.stage.stageHeight);
		
		HXP.width = baseContainerWidth;
		HXP.height = baseContainerHeight;
		HXP.halfWidth = baseContainerWidth / 2;
		HXP.halfHeight = baseContainerHeight / 2;
	}
	
	public override function render()
	{
        	super.render();

		if (HXP.screen.x > 0)
		{
			Draw.rect(0, 0, HXP.screen.x, HXP.stage.stageHeight, 0);
			Draw.rect(HXP.stage.stageWidth - HXP.screen.x, 0, HXP.screen.x, HXP.stage.stageHeight, 0);
		}
		else if (HXP.screen.y > 0)
		{
			Draw.rect(0, 0, HXP.stage.stageWidth, HXP.screen.y, 0);
			Draw.rect(0, HXP.stage.stageHeight - HXP.screen.y, HXP.stage.stageWidth, HXP.screen.y, 0);
		}
    	}
	
	private static inline var baseContainerWidth:Int = 800;
    	private static inline var baseContainerHeight:Int = 600;
	
	public static function main() { new Main(); }

}