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 : public Noncopyable {

    53 public:

    54     /** Creates evaluator which evaluates only simple media queries

    55      *  Evaluator returns true for "all", and returns value of \mediaFeatureResult

    56      *  for any media features

    57      */

    58     MediaQueryEvaluator(bool mediaFeatureResult = false);

    59 

    60     /** Creates evaluator which evaluates only simple media queries

    61      *  Evaluator  returns true for acceptedMediaType and returns value of \mediafeatureResult

    62      *  for any media features

    63      */

    64     MediaQueryEvaluator(const String& acceptedMediaType, bool mediaFeatureResult = false);

    65     MediaQueryEvaluator(const char* acceptedMediaType, bool mediaFeatureResult = false);

    66 

    67     /** Creates evaluator which evaluates full media queries

    68      */

    69     MediaQueryEvaluator(const String& acceptedMediaType, Frame*, RenderStyle*);

    70 

    71     ~MediaQueryEvaluator();

    72 

    73     bool mediaTypeMatch(const String& mediaTypeToMatch) const;

    74     bool mediaTypeMatchSpecific(const char* mediaTypeToMatch) const;

    75 

    76     /** Evaluates a list of media queries */

    77     bool eval(const MediaList*, CSSStyleSelector* = 0) const;

    78 

    79     /** Evaluates media query subexpression, ie "and (media-feature: value)" part */

    80     bool eval(const MediaQueryExp*) const;

    81 

    82 private:

    83     String m_mediaType;

    84     Frame* m_frame; // not owned

    85     RenderStyle* m_style; // not owned

    86     bool m_expResult;

    87 };

    88 

    89 } // namespace

    90 #endif