[CSSMQ] Implemented support for the scan media feature.

Source/core/css/MediaQueryEvaluator.cpp

 /*
  * CSS Media Query Evaluator
  *
  * Copyright (C) 2006 Kimmo Kinnunen <kimmo.t.kinnunen@nokia.com>.
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 48 matching lines @@
 
 using namespace MediaFeatureNames;
 
 enum MediaFeaturePrefix { MinPrefix, MaxPrefix, NoPrefix };
 
 typedef bool (*EvalFunc)(CSSValue*, RenderStyle*, Frame*, MediaFeaturePrefix);
 typedef HashMap<AtomicStringImpl*, EvalFunc> FunctionMap;
 static FunctionMap* gFunctionMap;
 
 /*
- * FIXME: following media features are not implemented: color_index, scan
+ * FIXME: following media features are not implemented: color_index
  *
  * color_index, min-color-index, max_color_index: It's unknown how to retrieve
  * the information if the display mode is indexed
- * scan: The "scan" media feature describes the scanning process of
- * tv output devices. It's unknown how to retrieve this information from
- * the platform
  */
 
 MediaQueryEvaluator::MediaQueryEvaluator(bool mediaFeatureResult)
     : m_frame(0)
     , m_style(0)
     , m_expResult(mediaFeatureResult)
 {
 }
 
 MediaQueryEvaluator::MediaQueryEvaluator(const String& acceptedMediaType, bool mediaFeatureResult)
@@ skipping 651 matching lines @@
 
     if (!value->isPrimitiveValue())
         return false;
 
     const int id = static_cast<CSSPrimitiveValue*>(value)->getIdent();
     return (pointer == NoPointer && id == CSSValueNone)
         || (pointer == TouchPointer && id == CSSValueCoarse)
         || (pointer == MousePointer && id == CSSValueFine);
 }
 
+static bool scanMediaFeatureEval(CSSValue* value, RenderStyle*, Frame* frame, MediaFeaturePrefix)
+{
+    String mediaType = frame->view()->mediaType();
+
+    // scan only applies to tv media.

[apavlov, 2013/05/15 11:29:41]

Blink mostly inherits the comment style from WebKit:
// Sentence-capitalized comment with a dot.

+    if (equalIgnoringCase(mediaType, "tv")) {

[apavlov, 2013/05/15 11:29:41]

Early returns are preferred, as they reduce code indentation and improve
readability:

// Scan only applies to tv media.
if (!equalIgnoringCase(mediaType, "tv"))
    return false;

// The rest of the code goes here...

+

[apavlov, 2013/05/15 11:29:41]

extra blank line

+        if (!value)
+            return true;
+
+        if (!value->isPrimitiveValue())
+            return false;
+
+        // If a platform interface supply progressive/interlace info for TVs in the

[apavlov, 2013/05/15 11:29:41]

supply -> supplies

+        // future, it needs to be handled here. For now, assume a modern TV with
+        // progressive display.
+        const int id = static_cast<CSSPrimitiveValue*>(value)->getIdent();
+        return id == CSSValueProgressive;
+    }
+
+    return false;
+}
+
 static void createFunctionMap()
 {
     // Create the table.
     gFunctionMap = new FunctionMap;
 #define ADD_TO_FUNCTIONMAP(name, str)  \
     gFunctionMap->set(name##MediaFeature.impl(), name##MediaFeatureEval);
     CSS_MEDIAQUERY_NAMES_FOR_EACH_MEDIAFEATURE(ADD_TO_FUNCTIONMAP);
 #undef ADD_TO_FUNCTIONMAP
 }
 
@@ skipping 12 matching lines @@
     // and let trampoline functions override the prefix if prefix is
     // used
     EvalFunc func = gFunctionMap->get(expr->mediaFeature().impl());
     if (func)
         return func(expr->value(), m_style.get(), m_frame, NoPrefix);
 
     return false;
 }
 
 } // namespace