Calculate sizes for one object to fit another and top/left info for alignment. Usage: var sizeObj = fit( 3000, 3500, $('.box').width(), $('.box').height(), { cover: false, align: 'middle center' }); Returns an object like: {scale: 1.2, width: 120, height: 120, top: -10, left: 0 }; Takes two optional params: cover, and align. It works without JQu…

fit to object calculation

function fit (targetWidth, targetHeight, containerWidth, containerHeight, options) {
	var settings = {
		cover: options && options.cover !== undefined ? options.cover : true,
		align: options && options.align !== undefined ? options.align : 'center middle'
	}

	var ratioWidth = containerWidth / targetWidth,
		ratioHeight = containerHeight / targetHeight,
		ratioTarget = targetWidth / targetHeight,
		ratioContainer = containerWidth / containerHeight;
	
	var scaleRatioHorizontally = settings.cover ? ratioHeight : ratioWidth,
		scaleRatioVertically = settings.cover ? ratioWidth : ratioHeight;
	
	var s = ratioTarget >= ratioContainer ? scaleRatioHorizontally : scaleRatioVertically,
		w = Math.round(targetWidth * s),
		h = Math.round(targetHeight * s);
	
	var left = 0.0,
		top = 0.0;

	if (settings.align.indexOf('center') !== -1)
		left = Math.round(0.5 * (containerWidth - w));
	else if (settings.align.indexOf('right') !== -1)
		left = containerWidth - w;

	if (settings.align.indexOf('middle') !== -1)
		top = Math.round(0.5 * (containerHeight - h));
	else if (settings.align.indexOf('bottom') !== -1)
		top = containerHeight - h;
	
	return { top: top, left: left, scale: s, width: w, height: h };
}