Phaser Source: src/pixi/renderers/canvas/CanvasRenderer.js

# Source: src/pixi/renderers/canvas/CanvasRenderer.js

    /**
     * @author Mat Groves http://matgroves.com/ @Doormat23
     */

    /**
     * The CanvasRenderer draws the Stage and all its content onto a 2d canvas. This renderer should be used for browsers that do not support webGL.
     * Don't forget to add the CanvasRenderer.view to your DOM or you will not see anything :)
     *
     * @class CanvasRenderer
     * @constructor
     * @param game {Phaser.Game} A reference to the Phaser Game instance
     */
    PIXI.CanvasRenderer = function (game) {

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

        if (!PIXI.defaultRenderer)
        {
            PIXI.defaultRenderer = this;
        }

        /**
         * The renderer type.
         *
         * @property type
         * @type Number
         */
        this.type = PIXI.CANVAS_RENDERER;

        /**
         * The resolution of the canvas.
         *
         * @property resolution
         * @type Number
         */
        this.resolution = game.resolution;

        /**
         * This sets if the CanvasRenderer will clear the canvas or not before the new render pass.
         * If the Stage is NOT transparent Pixi will use a canvas sized fillRect operation every frame to set the canvas background color.
         * If the Stage is transparent Pixi will use clearRect to clear the canvas every frame.
         * Disable this by setting this to false. For example if your game has a canvas filling background image you often don't need this set.
         *
         * @property clearBeforeRender
         * @type Boolean
         * @default
         */
        this.clearBeforeRender = game.clearBeforeRender;

        /**
         * Whether the render view is transparent
         *
         * @property transparent
         * @type Boolean
         */
        this.transparent = game.transparent;

        /**
         * Whether the render view should be resized automatically
         *
         * @property autoResize
         * @type Boolean
         */
        this.autoResize = false;

        /**
         * The width of the canvas view
         *
         * @property width
         * @type Number
         * @default 800
         */
        this.width = game.width * this.resolution;

        /**
         * The height of the canvas view
         *
         * @property height
         * @type Number
         * @default 600
         */
        this.height = game.height * this.resolution;

        /**
         * The canvas element that everything is drawn to.
         *
         * @property view
         * @type HTMLCanvasElement
         */
        this.view = game.canvas;

        /**
         * The canvas 2d context that everything is drawn with
         * @property context
         * @type CanvasRenderingContext2D
         */
        this.context = this.view.getContext("2d", { alpha: this.transparent } );

        /**
         * Boolean flag controlling canvas refresh.
         *
         * @property refresh
         * @type Boolean
         */
        this.refresh = true;

        /**
         * Internal var.
         *
         * @property count
         * @type Number
         */
        this.count = 0;

        /**
         * Instance of a PIXI.CanvasMaskManager, handles masking when using the canvas renderer
         * @property CanvasMaskManager
         * @type CanvasMaskManager
         */
        this.maskManager = new PIXI.CanvasMaskManager();

        /**
         * The render session is just a bunch of parameter used for rendering
         * @property renderSession
         * @type Object
         */
        this.renderSession = {
            context: this.context,
            maskManager: this.maskManager,
            scaleMode: null,
            smoothProperty: Phaser.Canvas.getSmoothingPrefix(this.context),

            /**
             * If true Pixi will Math.floor() x/y values when rendering, stopping pixel interpolation.
             * Handy for crisp pixel art and speed on legacy devices.
             */
            roundPixels: false
        };

        this.mapBlendModes();

        this.resize(this.width, this.height);

    };

    // constructor
    PIXI.CanvasRenderer.prototype.constructor = PIXI.CanvasRenderer;

    /**
     * Renders the DisplayObjectContainer, usually the Phaser.Stage, to this canvas view.
     *
     * @method render
     * @param root {Phaser.Stage|PIXI.DisplayObjectContainer} The root element to be rendered.
     */
    PIXI.CanvasRenderer.prototype.render = function (root) {

        this.context.setTransform(1, 0, 0, 1, 0, 0);

        this.context.globalAlpha = 1;

        this.renderSession.currentBlendMode = 0;
        this.renderSession.shakeX = this.game.camera._shake.x;
        this.renderSession.shakeY = this.game.camera._shake.y;

        this.context.globalCompositeOperation = 'source-over';

        if (navigator.isCocoonJS && this.view.screencanvas)
        {
            this.context.fillStyle = "black";
            this.context.clear();
        }

        if (this.clearBeforeRender)
        {
            if (this.transparent)
            {
                this.context.clearRect(0, 0, this.width, this.height);
            }
            else if (root._bgColor)
            {
                this.context.fillStyle = root._bgColor.rgba;
                this.context.fillRect(0, 0, this.width , this.height);
            }
        }

        this.renderDisplayObject(root);

    };

    /**
     * Removes everything from the renderer and optionally removes the Canvas DOM element.
     *
     * @method destroy
     * @param [removeView=true] {boolean} Removes the Canvas element from the DOM.
     */
    PIXI.CanvasRenderer.prototype.destroy = function (removeView) {

        if (removeView === undefined) { removeView = true; }

        if (removeView && this.view.parent)
        {
            this.view.parent.removeChild(this.view);
        }

        this.view = null;
        this.context = null;
        this.maskManager = null;
        this.renderSession = null;

    };

    /**
     * Resizes the canvas view to the specified width and height
     *
     * @method resize
     * @param width {Number} the new width of the canvas view
     * @param height {Number} the new height of the canvas view
     */
    PIXI.CanvasRenderer.prototype.resize = function (width, height) {

        this.width = width * this.resolution;
        this.height = height * this.resolution;

        this.view.width = this.width;
        this.view.height = this.height;

        if (this.autoResize)
        {
            this.view.style.width = this.width / this.resolution + "px";
            this.view.style.height = this.height / this.resolution + "px";
        }

        if (this.renderSession.smoothProperty)
        {
            this.context[this.renderSession.smoothProperty] = (this.renderSession.scaleMode === PIXI.scaleModes.LINEAR);
        }

    };

    /**
     * Renders a display object
     *
     * @method renderDisplayObject
     * @param displayObject {DisplayObject} The displayObject to render
     * @param context {CanvasRenderingContext2D} the context 2d method of the canvas
     * @param [matrix] {Matrix} Optional matrix to apply to the display object before rendering.
     * @private
     */
    PIXI.CanvasRenderer.prototype.renderDisplayObject = function (displayObject, context, matrix) {

        this.renderSession.context = context || this.context;
        this.renderSession.resolution = this.resolution;
        displayObject._renderCanvas(this.renderSession, matrix);

    };

    /**
     * Maps Pixi blend modes to canvas blend modes.
     *
     * @method mapBlendModes
     * @private
     */
    PIXI.CanvasRenderer.prototype.mapBlendModes = function () {

        if (!PIXI.blendModesCanvas)
        {
            var b = [];
            var modes = PIXI.blendModes;
            var useNew = PIXI.canUseNewCanvasBlendModes();

            b[modes.NORMAL] = 'source-over';
            b[modes.ADD] = 'lighter';
            b[modes.MULTIPLY] = (useNew) ? 'multiply' : 'source-over';
            b[modes.SCREEN] = (useNew) ? 'screen' : 'source-over';
            b[modes.OVERLAY] = (useNew) ? 'overlay' : 'source-over';
            b[modes.DARKEN] = (useNew) ? 'darken' : 'source-over';
            b[modes.LIGHTEN] = (useNew) ? 'lighten' : 'source-over';
            b[modes.COLOR_DODGE] = (useNew) ? 'color-dodge' : 'source-over';
            b[modes.COLOR_BURN] = (useNew) ? 'color-burn' : 'source-over';
            b[modes.HARD_LIGHT] = (useNew) ? 'hard-light' : 'source-over';
            b[modes.SOFT_LIGHT] = (useNew) ? 'soft-light' : 'source-over';
            b[modes.DIFFERENCE] = (useNew) ? 'difference' : 'source-over';
            b[modes.EXCLUSION] = (useNew) ? 'exclusion' : 'source-over';
            b[modes.HUE] = (useNew) ? 'hue' : 'source-over';
            b[modes.SATURATION] = (useNew) ? 'saturation' : 'source-over';
            b[modes.COLOR] = (useNew) ? 'color' : 'source-over';
            b[modes.LUMINOSITY] = (useNew) ? 'luminosity' : 'source-over';

            PIXI.blendModesCanvas = b;
        }

    };