Simple way to determine the correct dimensions of an image taking into account a max height/width

image_dimension.js

/**
  * Conserve aspect ratio of the orignal region. Useful when shrinking/enlarging
  * images to fit into a certain area.
  *
  * @param {Number} srcWidth Source area width
  * @param {Number} srcHeight Source area height
  * @param {Number} maxWidth Fittable area maximum available width
  * @param {Number} maxHeight Fittable area maximum available height
  * @return {Object} { width, heigth }
  */
function calculateAspectRatioFit(srcWidth, srcHeight, maxWidth, maxHeight) {

    var ratio = [maxWidth / srcWidth, maxHeight / srcHeight ];
    ratio = Math.min(ratio[0], ratio[1]);

    return { width:srcWidth*ratio, height:srcHeight*ratio };
 }