michael@0: /* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /* implements DOM interface for querying and observing media queries */
michael@0: 
michael@0: #ifndef mozilla_dom_MediaQueryList_h
michael@0: #define mozilla_dom_MediaQueryList_h
michael@0: 
michael@0: #include "nsISupports.h"
michael@0: #include "nsCycleCollectionParticipant.h"
michael@0: #include "nsAutoPtr.h"
michael@0: #include "nsTArray.h"
michael@0: #include "prclist.h"
michael@0: #include "mozilla/Attributes.h"
michael@0: #include "nsWrapperCache.h"
michael@0: #include "mozilla/dom/MediaQueryListBinding.h"
michael@0: 
michael@0: class nsPresContext;
michael@0: class nsMediaList;
michael@0: 
michael@0: namespace mozilla {
michael@0: namespace dom {
michael@0: 
michael@0: class MediaQueryList MOZ_FINAL : public nsISupports,
michael@0:                                  public nsWrapperCache,
michael@0:                                  public PRCList
michael@0: {
michael@0: public:
michael@0:   // The caller who constructs is responsible for calling Evaluate
michael@0:   // before calling any other methods.
michael@0:   MediaQueryList(nsPresContext *aPresContext,
michael@0:                  const nsAString &aMediaQueryList);
michael@0: private:
michael@0:   ~MediaQueryList();
michael@0: 
michael@0: public:
michael@0:   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
michael@0:   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(MediaQueryList)
michael@0: 
michael@0:   nsISupports* GetParentObject() const;
michael@0: 
michael@0:   struct HandleChangeData {
michael@0:     nsRefPtr<MediaQueryList> mql;
michael@0:     nsRefPtr<mozilla::dom::MediaQueryListListener> callback;
michael@0:   };
michael@0: 
michael@0:   typedef FallibleTArray< nsRefPtr<mozilla::dom::MediaQueryListListener> > CallbackList;
michael@0:   typedef FallibleTArray<HandleChangeData> NotifyList;
michael@0: 
michael@0:   // Appends listeners that need notification to aListenersToNotify
michael@0:   void MediumFeaturesChanged(NotifyList &aListenersToNotify);
michael@0: 
michael@0:   bool HasListeners() const { return !mCallbacks.IsEmpty(); }
michael@0: 
michael@0:   void RemoveAllListeners();
michael@0: 
michael@0:   JSObject* WrapObject(JSContext* aCx) MOZ_OVERRIDE;
michael@0: 
michael@0:   // WebIDL methods
michael@0:   void GetMedia(nsAString& aMedia);
michael@0:   bool Matches();
michael@0:   void AddListener(mozilla::dom::MediaQueryListListener& aListener);
michael@0:   void RemoveListener(mozilla::dom::MediaQueryListListener& aListener);
michael@0: 
michael@0: private:
michael@0:   void RecomputeMatches();
michael@0: 
michael@0:   // We only need a pointer to the pres context to support lazy
michael@0:   // reevaluation following dynamic changes.  However, this lazy
michael@0:   // reevaluation is perhaps somewhat important, since some usage
michael@0:   // patterns may involve the creation of large numbers of
michael@0:   // MediaQueryList objects which almost immediately become garbage
michael@0:   // (after a single call to the .matches getter).
michael@0:   //
michael@0:   // This pointer does make us a little more dependent on cycle
michael@0:   // collection.
michael@0:   //
michael@0:   // We have a non-null mPresContext for our entire lifetime except
michael@0:   // after cycle collection unlinking.  Having a non-null mPresContext
michael@0:   // is equivalent to being in that pres context's mDOMMediaQueryLists
michael@0:   // linked list.
michael@0:   nsRefPtr<nsPresContext> mPresContext;
michael@0: 
michael@0:   nsRefPtr<nsMediaList> mMediaList;
michael@0:   bool mMatches;
michael@0:   bool mMatchesValid;
michael@0:   CallbackList mCallbacks;
michael@0: };
michael@0: 
michael@0: } // namespace dom
michael@0: } // namespace mozilla
michael@0: 
michael@0: #endif /* !defined(mozilla_dom_MediaQueryList_h) */