dom/base/SelectionChangeEventDispatcher.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_SelectionChangeEventDispatcher_h
   8 #define mozilla_SelectionChangeEventDispatcher_h
   9
  10 #include "mozilla/Attributes.h"
  11 #include "nsCycleCollectionParticipant.h"
  12 #include "nsTArray.h"
  13 #include "nsCOMPtr.h"
  14 #include "nsDirection.h"
  15
  16 class nsINode;
  17 class nsRange;
  18
  19 namespace mozilla {
  20
  21 namespace dom {
  22 class Document;
  23 class Selection;
  24 }  // namespace dom
  25
  26 class SelectionChangeEventDispatcher final {
  27  public:
  28   // SelectionChangeEventDispatcher has to participate in cycle collection
  29   // because it holds strong references to nsINodes in its mOldRanges array.
  30   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(
  31       SelectionChangeEventDispatcher)
  32   NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(SelectionChangeEventDispatcher)
  33
  34   MOZ_CAN_RUN_SCRIPT
  35   void OnSelectionChange(dom::Document* aDocument, dom::Selection* aSelection,
  36                          int16_t aReason);
  37
  38   // This field is used to keep track of the ranges which were present in the
  39   // selection when the selectionchange event was previously fired. This allows
  40   // for the selectionchange event to only be fired when a selection is actually
  41   // changed.
  42   struct RawRangeData {
  43     // These properties are not void*s to avoid the potential situation where
  44     // the nsINode is freed, and a new nsINode is allocated with the same
  45     // address, which could potentially break the comparison logic. In reality,
  46     // this is extremely unlikely to occur (potentially impossible), but these
  47     // nsCOMPtrs are safer. They are never dereferenced.
  48     nsCOMPtr<nsINode> mStartContainer;
  49     nsCOMPtr<nsINode> mEndContainer;
  50
  51     // XXX These are int32_ts on nsRange, but uint32_ts in the return value
  52     // of GetStart_, so I use uint32_ts here. See bug 1194256.
  53     uint32_t mStartOffset;
  54     uint32_t mEndOffset;
  55
  56     explicit RawRangeData(const nsRange* aRange);
  57     bool Equals(const nsRange* aRange);
  58   };
  59
  60  private:
  61   nsTArray<RawRangeData> mOldRanges;
  62   nsDirection mOldDirection;
  63
  64   ~SelectionChangeEventDispatcher() = default;
  65 };
  66
  67 }  // namespace mozilla
  68
  69 #endif  // mozilla_SelectionChangeEventDispatcher_h