Zoom and position

gistfile1.js

    var performZoomAndPositionImg = function (newZoomLevel) {
        var zoomScaleContainer = Y.one('.fullScreenGallery .fullScreenExperience');
        var zoomBoundary = zoomScaleContainer.one('.zoomBoundary');
        var zoomImage = zoomBoundary.one('.zoomImg');

        var oldLeftOffset = zoomImage.get('offsetLeft');
        var oldTopOffset = zoomImage.get('offsetTop');

        var oldImgHeight = zoomImage.get('offsetHeight');
        var oldBoundaryHeight = zoomBoundary.get('offsetHeight');
        Y.Util.replaceClassValue(zoomScaleContainer, 'zoom', newZoomLevel);
        var newImgHeight = zoomImage.get('offsetHeight');
        var newBoundaryHeight = zoomBoundary.get('offsetHeight');

        var marginalScaleFactor = 
            (newBoundaryHeight - newImgHeight)/(oldBoundaryHeight - oldImgHeight);

        var newLeftOffset = Math.round(oldLeftOffset * marginalScaleFactor);
        var newTopOffset = Math.round(oldTopOffset * marginalScaleFactor);

        Y.log("Zoom scale step: " + marginalScaleFactor + ". Img H=" + oldImgHeight + "->" + newImgHeight + ". Bound=" + oldBoundaryHeight + "->" + newBoundaryHeight + ". Left=" + oldLeftOffset + "->" + newLeftOffset + ". Top=" + oldTopOffset + "->" + newTopOffset);
        var newLeftOffset = (newLeftOffset + 'px');
        var newTopOffset = (newTopOffset + 'px');

        zoomImage.setStyles({
            'left': newLeftOffset,
            'top': newTopOffset
        });
    }