layout/forms/ListMutationObserver.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_ListMutationObserver_h
   8 #define mozilla_ListMutationObserver_h
   9
  10 #include "IDTracker.h"
  11 #include "nsStubMutationObserver.h"
  12
  13 class nsIFrame;
  14
  15 namespace mozilla {
  16
  17 namespace dom {
  18 class HTMLInputElement;
  19 }  // namespace dom
  20
  21 /**
  22  * ListMutationObserver
  23  * This class invalidates paint for the input element's frame when the content
  24  * of its @list changes, or when the @list ID identifies a different element. It
  25  * does *not* invalidate paint when the @list attribute itself changes.
  26  */
  27
  28 class ListMutationObserver final : public nsStubMutationObserver,
  29                                    public dom::IDTracker {
  30  public:
  31   explicit ListMutationObserver(nsIFrame& aOwningElementFrame,
  32                                 bool aRepaint = false)
  33       : mOwningElementFrame(&aOwningElementFrame) {
  34     // We can skip invalidating paint if the frame is still being initialized.
  35     Attach(aRepaint);
  36   }
  37
  38   NS_DECL_ISUPPORTS
  39
  40   // We need to invalidate paint when the list or its options change.
  41   NS_DECL_NSIMUTATIONOBSERVER_ATTRIBUTECHANGED
  42   NS_DECL_NSIMUTATIONOBSERVER_CHARACTERDATACHANGED
  43   NS_DECL_NSIMUTATIONOBSERVER_CONTENTAPPENDED
  44   NS_DECL_NSIMUTATIONOBSERVER_CONTENTINSERTED
  45   NS_DECL_NSIMUTATIONOBSERVER_CONTENTREMOVED
  46
  47   /**
  48    * Triggered when the same @list ID identifies a different element than
  49    * before.
  50    */
  51   void ElementChanged(dom::Element* aFrom, dom::Element* aTo) override;
  52
  53   void Attach(bool aRepaint = true);
  54   void Detach();
  55   void AddObserverIfNeeded();
  56   void RemoveObserverIfNeeded(dom::Element* aList);
  57   void RemoveObserverIfNeeded() { RemoveObserverIfNeeded(get()); }
  58   dom::HTMLInputElement& InputElement() const;
  59
  60  private:
  61   ~ListMutationObserver();
  62
  63   nsIFrame* mOwningElementFrame;
  64 };
  65 }  // namespace mozilla
  66
  67 #endif  // mozilla_ListMutationObserver_h