@atlaskit/tooltip/dist/es2019/internal/get-anchor-point.js

A tooltip briefly describes an interactive element on mouse hover or keyboard focus.

/**
 * Returns the trigger's X edge for inline-axis placements, or the
 * trigger's horizontal center for block-axis placements.
 *
 * Note: does not account for RTL writing modes.
 */
function getTriggerEdgeX({
  triggerRect,
  placement
}) {
  if (placement.axis === 'inline') {
    return placement.edge === 'start' ? triggerRect.left : triggerRect.right;
  }
  return triggerRect.left + triggerRect.width / 2;
}

/**
 * Returns the trigger's Y edge for block-axis placements, or the
 * trigger's vertical center for inline-axis placements.
 */
function getTriggerEdgeY({
  triggerRect,
  placement
}) {
  if (placement.axis === 'block') {
    return placement.edge === 'start' ? triggerRect.top : triggerRect.bottom;
  }
  return triggerRect.top + triggerRect.height / 2;
}

/**
 * Computes the viewport point at which to anchor a cursor-positioned
 * tooltip, given the cursor's coordinates and the trigger's bounding rect.
 *
 * - `mouse`:   both axes follow the cursor.
 * - `mouse-x`: X follows the cursor; Y locks to the trigger edge selected
 *   by `placement` (falls back to trigger center if the placement axis
 *   doesn't have a Y edge).
 * - `mouse-y`: Y follows the cursor; X locks to the trigger edge (falls
 *   back to trigger center similarly).
 */
export function getAnchorPoint({
  cursor,
  triggerRect,
  tooltipPosition,
  placement
}) {
  if (tooltipPosition === 'mouse-y') {
    return {
      x: getTriggerEdgeX({
        triggerRect,
        placement
      }),
      y: cursor.clientY
    };
  }
  if (tooltipPosition === 'mouse-x') {
    return {
      x: cursor.clientX,
      y: getTriggerEdgeY({
        triggerRect,
        placement
      })
    };
  }

  // tooltipPosition === 'mouse'
  return {
    x: cursor.clientX,
    y: cursor.clientY
  };
}