1 : /* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
2 : /* ***** BEGIN LICENSE BLOCK *****
3 : * Version: MPL 1.1/GPL 2.0/LGPL 2.1
4 : *
5 : * The contents of this file are subject to the Mozilla Public License Version
6 : * 1.1 (the "License"); you may not use this file except in compliance with
7 : * the License. You may obtain a copy of the License at
8 : * http://www.mozilla.org/MPL/
9 : *
10 : * Software distributed under the License is distributed on an "AS IS" basis,
11 : * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
12 : * for the specific language governing rights and limitations under the
13 : * License.
14 : *
15 : * The Original Code is nsDOMMediaQueryList.
16 : *
17 : * The Initial Developer of the Original Code is the Mozilla Foundation.
18 : * Portions created by the Initial Developer are Copyright (C) 2011
19 : * the Initial Developer. All Rights Reserved.
20 : *
21 : * Contributor(s):
22 : * L. David Baron <dbaron@dbaron.org>, Mozilla Corporation (original author)
23 : *
24 : * Alternatively, the contents of this file may be used under the terms of
25 : * either the GNU General Public License Version 2 or later (the "GPL"), or
26 : * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
27 : * in which case the provisions of the GPL or the LGPL are applicable instead
28 : * of those above. If you wish to allow use of your version of this file only
29 : * under the terms of either the GPL or the LGPL, and not to allow others to
30 : * use your version of this file under the terms of the MPL, indicate your
31 : * decision by deleting the provisions above and replace them with the notice
32 : * and other provisions required by the GPL or the LGPL. If you do not delete
33 : * the provisions above, a recipient may use your version of this file under
34 : * the terms of any one of the MPL, the GPL or the LGPL.
35 : *
36 : * ***** END LICENSE BLOCK ***** */
37 :
38 : /* implements DOM interface for querying and observing media queries */
39 :
40 : #ifndef nsDOMMediaQueryList_h_
41 : #define nsDOMMediaQueryList_h_
42 :
43 : #include "nsIDOMMediaQueryList.h"
44 : #include "nsCycleCollectionParticipant.h"
45 : #include "nsAutoPtr.h"
46 : #include "nsCOMPtr.h"
47 : #include "nsTArray.h"
48 : #include "prclist.h"
49 :
50 : class nsPresContext;
51 : class nsMediaList;
52 :
53 : class nsDOMMediaQueryList : public nsIDOMMediaQueryList,
54 : public PRCList
55 : {
56 : public:
57 : // The caller who constructs is responsible for calling Evaluate
58 : // before calling any other methods.
59 : nsDOMMediaQueryList(nsPresContext *aPresContext,
60 : const nsAString &aMediaQueryList);
61 : private:
62 : ~nsDOMMediaQueryList();
63 :
64 : public:
65 0 : NS_DECL_CYCLE_COLLECTING_ISUPPORTS
66 1464 : NS_DECL_CYCLE_COLLECTION_CLASS(nsDOMMediaQueryList)
67 :
68 : NS_DECL_NSIDOMMEDIAQUERYLIST
69 :
70 0 : struct HandleChangeData {
71 : nsRefPtr<nsDOMMediaQueryList> mql;
72 : nsCOMPtr<nsIDOMMediaQueryListListener> listener;
73 : };
74 :
75 : typedef FallibleTArray< nsCOMPtr<nsIDOMMediaQueryListListener> > ListenerList;
76 : typedef FallibleTArray<HandleChangeData> NotifyList;
77 :
78 : // Appends listeners that need notification to aListenersToNotify
79 : void MediumFeaturesChanged(NotifyList &aListenersToNotify);
80 :
81 0 : bool HasListeners() const { return !mListeners.IsEmpty(); }
82 :
83 : void RemoveAllListeners();
84 :
85 : private:
86 : void RecomputeMatches();
87 :
88 : // We only need a pointer to the pres context to support lazy
89 : // reevaluation following dynamic changes. However, this lazy
90 : // reevaluation is perhaps somewhat important, since some usage
91 : // patterns may involve the creation of large numbers of
92 : // MediaQueryList objects which almost immediately become garbage
93 : // (after a single call to the .matches getter).
94 : //
95 : // This pointer does make us a little more dependent on cycle
96 : // collection.
97 : //
98 : // We have a non-null mPresContext for our entire lifetime except
99 : // after cycle collection unlinking. Having a non-null mPresContext
100 : // is equivalent to being in that pres context's mDOMMediaQueryLists
101 : // linked list.
102 : nsRefPtr<nsPresContext> mPresContext;
103 :
104 : nsRefPtr<nsMediaList> mMediaList;
105 : bool mMatches;
106 : bool mMatchesValid;
107 : ListenerList mListeners;
108 : };
109 :
110 : #endif /* !defined(nsDOMMediaQueryList_h_) */
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