@atlaskit/editor-plugin-selection/dist/es2019/pm-plugins/events/mouseout.js

Selection plugin for @atlaskit/editor-core

import { TextSelection } from '@atlaskit/editor-prosemirror/state';
export function isValidSelection(selection) {
  if (selection.empty) {
    return false;
  }
  const {
    $anchor,
    $head
  } = selection;

  // Head must be at the start of its parent node's content
  if ($head.parentOffset !== 0) {
    return false;
  }

  // Head must be nested (e.g., in a panel > paragraph, not directly in doc)
  if ($head.depth <= 1) {
    return false;
  }

  // Head must be in the first top-level block (before depth 1 is 0)
  if ($head.before(1) !== 0) {
    return false;
  }

  // Selection must not span within a shared deeper structure
  if ($head.sharedDepth($anchor.pos) !== 0) {
    return false;
  }

  // Head must be in the first block at every level
  let isFirstBlockInTree = true;
  for (let i = $head.depth - 1; i >= 0; i--) {
    if ($head.index(i) !== 0) {
      isFirstBlockInTree = false;
      break;
    }
  }
  if (!isFirstBlockInTree) {
    return false;
  }
  return true;
}
export function onMouseOut(view, event) {
  // Only trigger during a mouse drag
  if (event.buttons === 0) {
    return false;
  }
  if (view.state.selection instanceof TextSelection && isValidSelection(view.state.selection)) {
    // Set selection with head at document start (position 0)
    const selection = new TextSelection(view.state.doc.resolve(view.state.selection.$anchor.pos), view.state.doc.resolve(0));
    view.dispatch(view.state.tr.setSelection(selection));
    return true;
  }
  return false;
}