Frame für mismatching Window Size

/*:
* @param ImagePath
* @desc The Background Image as PNG
* @type file
* @dir img
*/

(function () {
    var PLUGIN_NAME = "BackgroundImage";
    var pluginParams = PluginManager.parameters(PLUGIN_NAME);
    var imagePath = pluginParams.ImagePath;

    loadImageBackgroundEvent = function (event) {
        var canvas = document.getElementById("background-canvas")
        var ctx = canvas.getContext('2d')
        var w = canvas.width
        var h = canvas.height
        ctx.drawImage(this, 0, 0, w, h);
    };

    Graphics._createCanvas = function () {
        this._canvas = document.createElement('canvas');
        this._canvas.id = 'GameCanvas';
        document.body.appendChild(this._canvas);

        document.body.style.overflow = "hidden";
        this._bg_canvas = document.createElement('canvas')
        this._bg_canvas.id = 'background-canvas'

        this.bg_image = new Image();
        this.bg_image.onload = loadImageBackgroundEvent
        document.body.appendChild(this._bg_canvas);
        this._updateCanvas();
    };

    Graphics._updateCanvas = function () {
        this._canvas.width = this._width;
        this._canvas.height = this._height;
        this._canvas.style.zIndex = 1;
        this._centerElement(this._canvas);

        this._bg_canvas.width = window.innerWidth
        this._bg_canvas.height = window.innerHeight
        this.bg_image.src = imagePath + ".png"
    };
})();