react-color/es/helpers/alpha.js

A Collection of Color Pickers from Sketch, Photoshop, Chrome & more

export var calculateChange = function calculateChange(e, hsl, direction, initialA, container) {
  var containerWidth = container.clientWidth;
  var containerHeight = container.clientHeight;
  var x = typeof e.pageX === 'number' ? e.pageX : e.touches[0].pageX;
  var y = typeof e.pageY === 'number' ? e.pageY : e.touches[0].pageY;
  var left = x - (container.getBoundingClientRect().left + window.pageXOffset);
  var top = y - (container.getBoundingClientRect().top + window.pageYOffset);

  if (direction === 'vertical') {
    var a = void 0;
    if (top < 0) {
      a = 0;
    } else if (top > containerHeight) {
      a = 1;
    } else {
      a = Math.round(top * 100 / containerHeight) / 100;
    }

    if (hsl.a !== a) {
      return {
        h: hsl.h,
        s: hsl.s,
        l: hsl.l,
        a: a,
        source: 'rgb'
      };
    }
  } else {
    var _a = void 0;
    if (left < 0) {
      _a = 0;
    } else if (left > containerWidth) {
      _a = 1;
    } else {
      _a = Math.round(left * 100 / containerWidth) / 100;
    }

    if (initialA !== _a) {
      return {
        h: hsl.h,
        s: hsl.s,
        l: hsl.l,
        a: _a,
        source: 'rgb'
      };
    }
  }
  return null;
};