dom/base/SelectionChangeListener.h
author Dylan Roeh <droeh@mozilla.com>
Tue, 28 Aug 2018 11:35:46 -0500
branchGECKOVIEW_62_RELBRANCH
changeset 481113 31683bdf39d7bcacf8d9bf265fc2365024473fbe
parent 474172 7fc2c97cc372ee868693db92409de6571af4f59f
child 481350 c89b86622d3885cb731dcc52274a35a7d626159b
permissions -rw-r--r--
Bug 1485178 - Only migrate sharedprefs when in Fennec. r=snorp a=ritu

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_SelectionChangeListener_h_
#define mozilla_SelectionChangeListener_h_

#include "nsISelectionListener.h"
#include "mozilla/Attributes.h"

namespace mozilla {
namespace dom {

class SelectionChangeListener final : public nsISelectionListener
{
public:
  // SelectionChangeListener has to participate in cycle collection because
  // it holds strong references to nsINodes in its mOldRanges array.
  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_CLASS(SelectionChangeListener)
  NS_DECL_NSISELECTIONLISTENER

  // This field is used to keep track of the ranges which were present in the
  // selection when the selectionchange event was previously fired. This allows
  // for the selectionchange event to only be fired when a selection is actually
  // changed.
  struct RawRangeData
  {
    // These properties are not void*s to avoid the potential situation where the
    // nsINode is freed, and a new nsINode is allocated with the same address, which
    // could potentially break the comparison logic. In reality, this is extremely
    // unlikely to occur (potentially impossible), but these nsCOMPtrs are safer.
    // They are never dereferenced.
    nsCOMPtr<nsINode> mStartContainer;
    nsCOMPtr<nsINode> mEndContainer;

    // XXX These are int32_ts on nsRange, but uint32_ts in the return value
    // of GetStart_, so I use uint32_ts here. See bug 1194256.
    uint32_t mStartOffset;
    uint32_t mEndOffset;

    explicit RawRangeData(const nsRange* aRange);
    bool Equals(const nsRange* aRange);
  };

private:
  nsTArray<RawRangeData> mOldRanges;

  ~SelectionChangeListener() {}
};

} // namespace dom
} // namespace mozilla

#endif // mozilla_SelectionChangeListener_h_