public static double getScreenPhysicalSize(Activity ctx) {
            DisplayMetrics dm = new DisplayMetrics();
            ctx.getWindowManager().getDefaultDisplay().getMetrics(dm);
            double diagonalPixels = Math.sqrt(Math.pow(dm.widthPixels, 2) + Math.pow(dm.heightPixels, 2));
            return diagonalPixels / (160 * dm.density);
        }