WebCore/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 "PlatformString.h"
  32
  33 namespace WebCore {
  34 class CSSStyleSelector;
  35 class Frame;
  36 class RenderStyle;
  37 class MediaList;
  38 class MediaQueryExp;
  39
  40 /**
  41  * Class that evaluates css media queries as defined in
  42  * CSS3 Module "Media Queries" (http://www.w3.org/TR/css3-mediaqueries/)
  43  * Special constructors are needed, if simple media queries are to be
  44  * evaluated without knowledge of the medium features. This can happen
  45  * for example when parsing UA stylesheets, if evaluation is done
  46  * right after parsing.
  47  *
  48  * the boolean parameter is used to approximate results of evaluation, if
  49  * the device characteristics are not known. This can be used to prune the loading
  50  * of stylesheets to only those which are probable to match.
  51  */
  52 class MediaQueryEvaluator
  53 {
  54 public:
  55     /** Creates evaluator which evaluates only simple media queries
  56      *  Evaluator returns true for "all", and returns value of \mediaFeatureResult
  57      *  for any media features
  58      */
  59     MediaQueryEvaluator(bool mediaFeatureResult = false);
  60
  61     /** Creates evaluator which evaluates only simple media queries
  62      *  Evaluator  returns true for acceptedMediaType and returns value of \mediafeatureResult
  63      *  for any media features
  64      */
  65     MediaQueryEvaluator(const String& acceptedMediaType, bool mediaFeatureResult = false);
  66     MediaQueryEvaluator(const char* acceptedMediaType, bool mediaFeatureResult = false);
  67
  68     /** Creates evaluator which evaluates full media queries
  69      */
  70     MediaQueryEvaluator(const String& acceptedMediaType, Frame*, RenderStyle*);
  71
  72     ~MediaQueryEvaluator();
  73
  74     bool mediaTypeMatch(const String& mediaTypeToMatch) const;
  75     bool mediaTypeMatchSpecific(const char* mediaTypeToMatch) const;
  76
  77     /** Evaluates a list of media queries */
  78     bool eval(const MediaList*, CSSStyleSelector* = 0) const;
  79
  80     /** Evaluates media query subexpression, ie "and (media-feature: value)" part */
  81     bool eval(const MediaQueryExp*) const;
  82
  83 private:
  84     String m_mediaType;
  85     Frame* m_frame; // not owned
  86     RenderStyle* m_style; // not owned
  87     bool m_expResult;
  88 };
  89
  90 } // namespace
  91 #endif