phaser/src/gameobjects/blitter/BlitterCanvasRenderer.js

/**
 * @author       Richard Davey <rich@photonstorm.com>
 * @copyright    2019 Photon Storm Ltd.
 * @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
 */

/**
 * Renders this Game Object with the Canvas Renderer to the given Camera.
 * The object will not render if any of its renderFlags are set or it is being actively filtered out by the Camera.
 * This method should not be called directly. It is a utility function of the Render module.
 *
 * @method Phaser.GameObjects.Blitter#renderCanvas
 * @since 3.0.0
 * @private
 *
 * @param {Phaser.Renderer.Canvas.CanvasRenderer} renderer - A reference to the current active Canvas renderer.
 * @param {Phaser.GameObjects.Blitter} src - The Game Object being rendered in this call.
 * @param {number} interpolationPercentage - Reserved for future use and custom pipelines.
 * @param {Phaser.Cameras.Scene2D.Camera} camera - The Camera that is rendering the Game Object.
 * @param {Phaser.GameObjects.Components.TransformMatrix} parentMatrix - This transform matrix is defined if the game object is nested
 */
var BlitterCanvasRenderer = function (renderer, src, interpolationPercentage, camera, parentMatrix)
{
    var list = src.getRenderList();

    if (list.length === 0)
    {
        return;
    }

    var ctx = renderer.currentContext;

    var alpha = camera.alpha * src.alpha;

    if (alpha === 0)
    {
        //  Nothing to see, so abort early
        return;
    }

    //  Blend Mode
    ctx.globalCompositeOperation = renderer.blendModes[src.blendMode];

    var cameraScrollX = src.x - camera.scrollX * src.scrollFactorX;
    var cameraScrollY = src.y - camera.scrollY * src.scrollFactorY;

    ctx.save();

    if (parentMatrix)
    {
        parentMatrix.copyToContext(ctx);
    }

    var roundPixels = camera.roundPixels;

    //  Render bobs
    for (var i = 0; i < list.length; i++)
    {
        var bob = list[i];
        var flip = (bob.flipX || bob.flipY);
        var frame = bob.frame;
        var cd = frame.canvasData;
        var dx = frame.x;
        var dy = frame.y;
        var fx = 1;
        var fy = 1;

        var bobAlpha = bob.alpha * alpha;

        if (bobAlpha === 0)
        {
            continue;
        }

        ctx.globalAlpha = bobAlpha;
    
        if (!flip)
        {
            if (roundPixels)
            {
                dx = Math.round(dx);
                dy = Math.round(dy);
            }

            ctx.drawImage(
                frame.source.image,
                cd.x,
                cd.y,
                cd.width,
                cd.height,
                dx + bob.x + cameraScrollX,
                dy + bob.y + cameraScrollY,
                cd.width,
                cd.height
            );
        }
        else
        {
            if (bob.flipX)
            {
                fx = -1;
                dx -= cd.width;
            }

            if (bob.flipY)
            {
                fy = -1;
                dy -= cd.height;
            }

            ctx.save();
            ctx.translate(bob.x + cameraScrollX, bob.y + cameraScrollY);
            ctx.scale(fx, fy);
            ctx.drawImage(frame.source.image, cd.x, cd.y, cd.width, cd.height, dx, dy, cd.width, cd.height);
            ctx.restore();
        }
    }
    
    ctx.restore();
};

module.exports = BlitterCanvasRenderer;