third_party/WebKit/Source/core/css/MediaQueryEvaluator.h

   1 /*
   2  * CSS Media Query Evaluator
   3  *
   4  * Copyright (C) 2006 Kimmo Kinnunen <kimmo.t.kinnunen@nokia.com>.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY
  16  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  18  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  19  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  22  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  23  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  25  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #ifndef MediaQueryEvaluator_h
  29 #define MediaQueryEvaluator_h
  30
  31 #include "core/CoreExport.h"
  32 #include "platform/heap/Handle.h"
  33 #include "wtf/text/WTFString.h"
  34
  35 namespace blink {
  36 class LocalFrame;
  37 class MediaQuery;
  38 class MediaQueryExp;
  39 class MediaQueryResult;
  40 class MediaQuerySet;
  41 class MediaValues;
  42
  43 using MediaQueryResultList = WillBeHeapVector<RefPtrWillBeMember<MediaQueryResult>>;
  44
  45 // Class that evaluates css media queries as defined in
  46 // CSS3 Module "Media Queries" (http://www.w3.org/TR/css3-mediaqueries/)
  47 // Special constructors are needed, if simple media queries are to be
  48 // evaluated without knowledge of the medium features. This can happen
  49 // for example when parsing UA stylesheets, if evaluation is done
  50 // right after parsing.
  51 //
  52 // the boolean parameter is used to approximate results of evaluation, if
  53 // the device characteristics are not known. This can be used to prune the loading
  54 // of stylesheets to only those which are probable to match.
  55
  56 class CORE_EXPORT MediaQueryEvaluator {
  57     WTF_MAKE_NONCOPYABLE(MediaQueryEvaluator); WTF_MAKE_FAST_ALLOCATED(MediaQueryEvaluator);
  58 public:
  59     // Creates evaluator which evaluates only simple media queries
  60     // Evaluator returns true for "all", and returns value of \mediaFeatureResult
  61     // for any media features.
  62
  63     explicit MediaQueryEvaluator(bool mediaFeatureResult = false);
  64
  65     // Creates evaluator which evaluates only simple media queries
  66     // Evaluator  returns true for acceptedMediaType and returns value of \mediafeatureResult
  67     // for any media features.
  68
  69     MediaQueryEvaluator(const char* acceptedMediaType, bool mediaFeatureResult = false);
  70
  71     // Creates evaluator which evaluates full media queries.
  72     explicit MediaQueryEvaluator(LocalFrame*);
  73
  74     // Creates evaluator which evaluates in a thread-safe manner a subset of media values.
  75     explicit MediaQueryEvaluator(const MediaValues&);
  76
  77     ~MediaQueryEvaluator();
  78
  79     bool mediaTypeMatch(const String& mediaTypeToMatch) const;
  80
  81     // Evaluates a list of media queries.
  82     bool eval(const MediaQuerySet*, MediaQueryResultList* = 0) const;
  83
  84     // Evaluates media query.
  85     bool eval(const MediaQuery*, MediaQueryResultList*) const;
  86
  87     // Evaluates media query subexpression, ie "and (media-feature: value)" part.
  88     bool eval(const MediaQueryExp*) const;
  89
  90 private:
  91     const String mediaType() const;
  92
  93     String m_mediaType;
  94     bool m_expectedResult;
  95     RefPtrWillBePersistent<MediaValues> m_mediaValues;
  96 };
  97
  98 } // namespace
  99 #endif