@atlaskit/navigation-system/dist/es2019/ui/page-layout/panel-splitter/get-width-from-drag-location.js

The latest navigation system for Atlassian apps.

export const getWidthFromDragLocation = ({
  initialWidth,
  location,
  initialClientX,
  direction,
  position
}) => {
  const diffX = location.current.input.clientX - initialClientX;

  // Resize line is positioned at the inline-end (right) of the element.
  // If the direction is left-to-right, the width will increase when the mouse is moved to the right, and vice versa.
  if (position === 'end') {
    return direction === 'ltr' ? initialWidth + diffX : initialWidth - diffX;
  }

  // Resize line is positioned at the inline-start (left) of the element.
  // If the direction is left-to-right, the width will decrease when the mouse is moved to the right, and vice versa.
  return direction === 'ltr' ? initialWidth - diffX : initialWidth + diffX;
};