@e-group/utils/esm/preProcessImage/calculateAspectRatioFit.js

eGroup team utils that share across projects.

/**
 * Conserve aspect ratio of the original region. Useful when shrinking
 * images to fit into a certain area.
 *
 * @param {Number} srcWidth width of source image
 * @param {Number} srcHeight height of source image
 * @param {Number} maxWidth maximum available width
 * @param {Number} maxHeight maximum available height
 * @return {Object} { width, height }
 */
export default function calculateAspectRatioFit(srcWidth, srcHeight, maxWidth, maxHeight) {
  const ratio = Math.min(maxWidth / srcWidth, maxHeight / srcHeight); // If source width and height both smaller than max just return source.

  if (srcWidth <= maxWidth && srcHeight <= maxHeight) {
    return {
      width: srcWidth,
      height: srcHeight
    };
  }

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