# Source: src/core/Stage.js

    /**
    * @author       Richard Davey <rich@photonstorm.com>
    * @copyright    2016 Photon Storm Ltd.
    * @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
    */

    /**
    * The Stage controls root level display objects upon which everything is displayed.
    * It also handles browser visibility handling and the pausing due to loss of focus.
    *
    * @class Phaser.Stage
    * @extends PIXI.DisplayObjectContainer
    * @constructor
    * @param {Phaser.Game} game - Game reference to the currently running game.
     */
    Phaser.Stage = function (game) {

        /**
        * @property {Phaser.Game} game - A reference to the currently running Game.
        */
        this.game = game;

        PIXI.DisplayObjectContainer.call(this);

        /**
        * @property {string} name - The name of this object.
        * @default
        */
        this.name = '_stage_root';

        /**
        * By default if the browser tab loses focus the game will pause.
        * You can stop that behavior by setting this property to true.
        * Note that the browser can still elect to pause your game if it wishes to do so,
        * for example swapping to another browser tab. This will cause the RAF callback to halt,
        * effectively pausing your game, even though no in-game pause event is triggered if you enable this property.
        * @property {boolean} disableVisibilityChange
        * @default
        */
        this.disableVisibilityChange = false;

        /**
        * @property {boolean} exists - If exists is true the Stage and all children are updated, otherwise it is skipped.
        * @default
        */
        this.exists = true;

        /**
        * @property {PIXI.Matrix} worldTransform - Current transform of the object based on world (parent) factors
        * @private
        * @readOnly
        */
        this.worldTransform = new PIXI.Matrix();

        /**
        * @property {Phaser.Stage} stage - The stage reference (the Stage is its own stage)
        * @private
        * @readOnly
        */
        this.stage = this;

        /**
        * @property {number} currentRenderOrderID - Reset each frame, keeps a count of the total number of objects updated.
        */
        this.currentRenderOrderID = 0;

        /**
        * @property {string} hiddenVar - The page visibility API event name.
        * @private
        */
        this._hiddenVar = 'hidden';

        /**
        * @property {function} _onChange - The blur/focus event handler.
        * @private
        */
        this._onChange = null;

        /**
        * @property {number} _bgColor - Stage background color object. Populated by setBackgroundColor.
        * @private
        */
        this._bgColor = { r: 0, g: 0, b: 0, a: 0, color: 0, rgba: '#000000' };

        if (!this.game.transparent)
        {
            //  transparent = 0,0,0,0 - otherwise r,g,b,1
            this._bgColor.a = 1;
        }

        if (game.config)
        {
            this.parseConfig(game.config);
        }

    };

    Phaser.Stage.prototype = Object.create(PIXI.DisplayObjectContainer.prototype);
    Phaser.Stage.prototype.constructor = Phaser.Stage;

    /**
    * Parses a Game configuration object.
    *
    * @method Phaser.Stage#parseConfig
    * @protected
    * @param {object} config -The configuration object to parse.
    */
    Phaser.Stage.prototype.parseConfig = function (config) {

        if (config['disableVisibilityChange'])
        {
            this.disableVisibilityChange = config['disableVisibilityChange'];
        }

        if (config['backgroundColor'])
        {
            this.setBackgroundColor(config['backgroundColor']);
        }

    };

    /**
    * Initialises the stage and adds the event listeners.
    * @method Phaser.Stage#boot
    * @private
    */
    Phaser.Stage.prototype.boot = function () {

        Phaser.DOM.getOffset(this.game.canvas, this.offset);

        Phaser.Canvas.setUserSelect(this.game.canvas, 'none');
        Phaser.Canvas.setTouchAction(this.game.canvas, 'none');

        this.checkVisibility();

    };

    /**
    * This is called automatically after the plugins preUpdate and before the State.update.
    * Most objects have preUpdate methods and it's where initial movement and positioning is done.
    *
    * @method Phaser.Stage#preUpdate
    */
    Phaser.Stage.prototype.preUpdate = function () {

        this.currentRenderOrderID = 0;

        //  This can't loop in reverse, we need the renderOrderID to be in sequence
        for (var i = 0; i < this.children.length; i++)
        {
            this.children[i].preUpdate();
        }

    };

    /**
    * This is called automatically after the State.update, but before particles or plugins update.
    *
    * @method Phaser.Stage#update
    */
    Phaser.Stage.prototype.update = function () {

        //  Goes in reverse, because it's highly likely the child will destroy itself in `update`
        var i = this.children.length;

        while (i--)
        {
            this.children[i].update();
        }

    };

    /**
    * This is called automatically before the renderer runs and after the plugins have updated.
    * In postUpdate this is where all the final physics calculations and object positioning happens.
    * The objects are processed in the order of the display list.
    *
    * @method Phaser.Stage#postUpdate
    */
    Phaser.Stage.prototype.postUpdate = function () {

        //  Apply the camera shake, fade, bounds, etc
        this.game.camera.update();

        //  Camera target first?
        if (this.game.camera.target)
        {
            this.game.camera.target.postUpdate();

            this.updateTransform();

            this.game.camera.updateTarget();
        }

        for (var i = 0; i < this.children.length; i++)
        {
            this.children[i].postUpdate();
        }

        this.updateTransform();

    };

    /**
    * Updates the transforms for all objects on the display list.
    * This overrides the Pixi default as we don't need the interactionManager, but do need the game property check.
    *
    * @method Phaser.Stage#updateTransform
    */
    Phaser.Stage.prototype.updateTransform = function () {

        this.worldAlpha = 1;

        for (var i = 0; i < this.children.length; i++)
        {
            this.children[i].updateTransform();
        }

    };

    /**
    * Starts a page visibility event listener running, or window.onpagehide/onpageshow if not supported by the browser.
    * Also listens for window.onblur and window.onfocus.
    *
    * @method Phaser.Stage#checkVisibility
    */
    Phaser.Stage.prototype.checkVisibility = function () {

        if (document.hidden !== undefined)
        {
            this._hiddenVar = 'visibilitychange';
        }
        else if (document.webkitHidden !== undefined)
        {
            this._hiddenVar = 'webkitvisibilitychange';
        }
        else if (document.mozHidden !== undefined)
        {
            this._hiddenVar = 'mozvisibilitychange';
        }
        else if (document.msHidden !== undefined)
        {
            this._hiddenVar = 'msvisibilitychange';
        }
        else
        {
            this._hiddenVar = null;
        }

        var _this = this;

        this._onChange = function (event) {
            return _this.visibilityChange(event);
        };

        //  Does browser support it? If not (like in IE9 or old Android) we need to fall back to blur/focus
        if (this._hiddenVar)
        {
            document.addEventListener(this._hiddenVar, this._onChange, false);
        }

        window.onblur = this._onChange;
        window.onfocus = this._onChange;

        window.onpagehide = this._onChange;
        window.onpageshow = this._onChange;

        if (this.game.device.cocoonJSApp)
        {
            CocoonJS.App.onSuspended.addEventListener(function () {
                Phaser.Stage.prototype.visibilityChange.call(_this, { type: "pause" });
            });

            CocoonJS.App.onActivated.addEventListener(function () {
                Phaser.Stage.prototype.visibilityChange.call(_this, { type: "resume" });
            });
        }

    };

    /**
    * This method is called when the document visibility is changed.
    *
    * @method Phaser.Stage#visibilityChange
    * @param {Event} event - Its type will be used to decide whether the game should be paused or not.
    */
    Phaser.Stage.prototype.visibilityChange = function (event) {

        if (event.type === 'pagehide' || event.type === 'blur' || event.type === 'pageshow' || event.type === 'focus')
        {
            if (event.type === 'pagehide' || event.type === 'blur')
            {
                this.game.focusLoss(event);
            }
            else if (event.type === 'pageshow' || event.type === 'focus')
            {
                this.game.focusGain(event);
            }

            return;
        }

        if (this.disableVisibilityChange)
        {
            return;
        }

        if (document.hidden || document.mozHidden || document.msHidden || document.webkitHidden || event.type === "pause")
        {
            this.game.gamePaused(event);
        }
        else
        {
            this.game.gameResumed(event);
        }

    };

    /**
    * Sets the background color for the Stage.
    *
    * The color can be given as a hex string (`'#RRGGBB'`), a CSS color string (`'rgb(r,g,b)'`), or a numeric value (`0xRRGGBB`).
    *
    * An alpha channel is _not_ supported and will be ignored.
    *
    * If you've set your game to be transparent then calls to setBackgroundColor are ignored.
    *
    * @method Phaser.Stage#setBackgroundColor
    * @param {number|string} color - The color of the background.
    */
    Phaser.Stage.prototype.setBackgroundColor = function (color) {

        if (this.game.transparent) { return; }

        Phaser.Color.valueToColor(color, this._bgColor);
        Phaser.Color.updateColor(this._bgColor);

        //  For gl.clearColor (canvas uses _bgColor.rgba)
        this._bgColor.r /= 255;
        this._bgColor.g /= 255;
        this._bgColor.b /= 255;
        this._bgColor.a = 1;

    };

    /**
    * Destroys the Stage and removes event listeners.
    *
    * @method Phaser.Stage#destroy
    */
    Phaser.Stage.prototype.destroy = function () {

        if (this._hiddenVar)
        {
            document.removeEventListener(this._hiddenVar, this._onChange, false);
        }

        window.onpagehide = null;
        window.onpageshow = null;

        window.onblur = null;
        window.onfocus = null;

    };

    /**
    * @name Phaser.Stage#backgroundColor
    * @property {number|string} backgroundColor - Gets and sets the background color of the stage. The color can be given as a number: 0xff0000 or a hex string: '#ff0000'
    */
    Object.defineProperty(Phaser.Stage.prototype, "backgroundColor", {

        get: function () {

            return this._bgColor.color;

        },

        set: function (color) {

            this.setBackgroundColor(color);

        }

    });

    /**
    * Enable or disable texture smoothing for all objects on this Stage. Only works for bitmap/image textures. Smoothing is enabled by default.
    *
    * @name Phaser.Stage#smoothed
    * @property {boolean} smoothed - Set to true to smooth all sprites rendered on this Stage, or false to disable smoothing (great for pixel art)
    */
    Object.defineProperty(Phaser.Stage.prototype, "smoothed", {

        get: function () {

            return PIXI.scaleModes.DEFAULT === PIXI.scaleModes.LINEAR;

        },

        set: function (value) {

            if (value)
            {
                PIXI.scaleModes.DEFAULT = PIXI.scaleModes.LINEAR;
            }
            else
            {
                PIXI.scaleModes.DEFAULT = PIXI.scaleModes.NEAREST;
            }
        }

    });