function getSizeToCover(width, height, maxWidth, maxHeight) {
    var ratio = Math.max(maxWidth / width, maxHeight / height);
    return {
        width: width * ratio,
        height: height * ratio
    };
}

function getSizeToContain(width, height, maxWidth, maxHeight) {
    var ratio = Math.min(maxWidth / width, maxHeight / height);
    return {
        width: width * ratio,
        height: height * ratio
    };
}