d2-ui/node_modules-react-15/draft-js/lib/setDraftEditorSelection.js

d2-ui

/**
 * Copyright (c) 2013-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule setDraftEditorSelection
 * @typechecks
 * 
 */

/**
 * In modern non-IE browsers, we can support both forward and backward
 * selections.
 *
 * Note: IE10+ supports the Selection object, but it does not support
 * the `extend` method, which means that even in modern IE, it's not possible
 * to programatically create a backward selection. Thus, for all IE
 * versions, we use the old IE API to create our selections.
 */
'use strict';

var containsNode = require('fbjs/lib/containsNode');
var getActiveElement = require('fbjs/lib/getActiveElement');

function setDraftEditorSelection(selectionState, node, blockKey, nodeStart, nodeEnd) {
  // It's possible that the editor has been removed from the DOM but
  // our selection code doesn't know it yet. Forcing selection in
  // this case may lead to errors, so just bail now.
  if (!containsNode(document.documentElement, node)) {
    return;
  }

  var selection = global.getSelection();
  var anchorKey = selectionState.getAnchorKey();
  var anchorOffset = selectionState.getAnchorOffset();
  var focusKey = selectionState.getFocusKey();
  var focusOffset = selectionState.getFocusOffset();
  var isBackward = selectionState.getIsBackward();

  // IE doesn't support backward selection. Swap key/offset pairs.
  if (!selection.extend && isBackward) {
    var tempKey = anchorKey;
    var tempOffset = anchorOffset;
    anchorKey = focusKey;
    anchorOffset = focusOffset;
    focusKey = tempKey;
    focusOffset = tempOffset;
    isBackward = false;
  }

  var hasAnchor = anchorKey === blockKey && nodeStart <= anchorOffset && nodeEnd >= anchorOffset;

  var hasFocus = focusKey === blockKey && nodeStart <= focusOffset && nodeEnd >= focusOffset;

  // If the selection is entirely bound within this node, set the selection
  // and be done.
  if (hasAnchor && hasFocus) {
    selection.removeAllRanges();
    addPointToSelection(selection, node, anchorOffset - nodeStart);
    addFocusToSelection(selection, node, focusOffset - nodeStart);
    return;
  }

  if (!isBackward) {
    // If the anchor is within this node, set the range start.
    if (hasAnchor) {
      selection.removeAllRanges();
      addPointToSelection(selection, node, anchorOffset - nodeStart);
    }

    // If the focus is within this node, we can assume that we have
    // already set the appropriate start range on the selection, and
    // can simply extend the selection.
    if (hasFocus) {
      addFocusToSelection(selection, node, focusOffset - nodeStart);
    }
  } else {
    // If this node has the focus, set the selection range to be a
    // collapsed range beginning here. Later, when we encounter the anchor,
    // we'll use this information to extend the selection.
    if (hasFocus) {
      selection.removeAllRanges();
      addPointToSelection(selection, node, focusOffset - nodeStart);
    }

    // If this node has the anchor, we may assume that the correct
    // focus information is already stored on the selection object.
    // We keep track of it, reset the selection range, and extend it
    // back to the focus point.
    if (hasAnchor) {
      var storedFocusNode = selection.focusNode;
      var storedFocusOffset = selection.focusOffset;

      selection.removeAllRanges();
      addPointToSelection(selection, node, anchorOffset - nodeStart);
      addFocusToSelection(selection, storedFocusNode, storedFocusOffset);
    }
  }
}

/**
 * Extend selection towards focus point.
 */
function addFocusToSelection(selection, node, offset) {
  if (selection.extend && containsNode(getActiveElement(), node)) {
    // If `extend` is called while another element has focus, an error is
    // thrown. We therefore disable `extend` if the active element is somewhere
    // other than the node we are selecting. This should only occur in Firefox,
    // since it is the only browser to support multiple selections.
    // See https://bugzilla.mozilla.org/show_bug.cgi?id=921444.
    selection.extend(node, offset);
  } else {
    // IE doesn't support extend. This will mean no backward selection.
    // Extract the existing selection range and add focus to it.
    // Additionally, clone the selection range. IE11 throws an
    // InvalidStateError when attempting to access selection properties
    // after the range is detached.
    var range = selection.getRangeAt(0);
    range.setEnd(node, offset);
    selection.addRange(range.cloneRange());
  }
}

function addPointToSelection(selection, node, offset) {
  var range = document.createRange();
  range.setStart(node, offset);
  selection.addRange(range);
}

module.exports = setDraftEditorSelection;