/**
 * This module is responsible for drawing an image to an enabled elements canvas element
 */

var cornerstone = (function (cornerstone) {

    "use strict";

    if(cornerstone === undefined) {
        cornerstone = {};
    }

    /**
     * API function to draw a standard web image (PNG, JPG) to an enabledImage
     *
     * @param enabledElement
     * @param invalidated - true if pixel data has been invaldiated and cached rendering should not be used
     */
    function renderWebImage(enabledElement, invalidated) {

        if(enabledElement === undefined) {
            throw "drawImage: enabledElement parameter must not be undefined";
        }
        var image = enabledElement.image;
        if(image === undefined) {
            throw "drawImage: image must be loaded before it can be drawn";
        }

        // get the canvas context and reset the transform
        var context = enabledElement.canvas.getContext('2d');
        context.setTransform(1, 0, 0, 1, 0, 0);

        // clear the canvas
        context.fillStyle = 'black';
        context.fillRect(0,0, enabledElement.canvas.width, enabledElement.canvas.height);

        // turn off image smooth/interpolation if pixelReplication is set in the viewport
        if(enabledElement.viewport.pixelReplication === true) {
            context.imageSmoothingEnabled = false;
            context.mozImageSmoothingEnabled = false; // firefox doesn't support imageSmoothingEnabled yet
        }
        else {
            context.imageSmoothingEnabled = true;
            context.mozImageSmoothingEnabled = true;
        }

        // save the canvas context state and apply the viewport properties
        cornerstone.setToPixelCoordinateSystem(enabledElement, context);

        // if the viewport ww/wc and invert all match the initial state of the image, we can draw the image
        // directly.  If any of those are changed, we call renderColorImage() to apply the lut
        if(enabledElement.viewport.voi.windowWidth === enabledElement.image.windowWidth &&
            enabledElement.viewport.voi.windowCenter === enabledElement.image.windowCenter &&
            enabledElement.viewport.invert === false)
        {
            context.drawImage(image.getImage(), 0, 0, image.width, image.height, 0, 0, image.width, image.height);
        } else {
            cornerstone.renderColorImage(enabledElement, invalidated);
        }

    }

    // Module exports
    cornerstone.renderWebImage = renderWebImage;

    return cornerstone;
}(cornerstone));