layout/style/nsStyleUtil.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6 #ifndef nsStyleUtil_h___
   7 #define nsStyleUtil_h___
   8
   9 #include "nsCoord.h"
  10 #include "nsCSSPropertyID.h"
  11 #include "nsTArrayForwardDeclare.h"
  12 #include "nsStringFwd.h"
  13 #include "nsCRT.h"
  14 #include "nsColor.h"
  15 #include "nsGkAtoms.h"
  16
  17 class nsCSSValue;
  18 class nsIContent;
  19 class nsIPrincipal;
  20 class nsIURI;
  21 struct gfxFontFeature;
  22 struct nsCSSKTableEntry;
  23 struct nsCSSValueList;
  24 struct nsStylePosition;
  25
  26 namespace mozilla {
  27 class FontSlantStyle;
  28 namespace dom {
  29 class Document;
  30 class Element;
  31 }  // namespace dom
  32 }  // namespace mozilla
  33
  34 // Style utility functions
  35 class nsStyleUtil {
  36  public:
  37   static bool DashMatchCompare(const nsAString& aAttributeValue,
  38                                const nsAString& aSelectorValue,
  39                                const nsStringComparator& aComparator);
  40
  41   static bool ValueIncludes(const nsAString& aValueList,
  42                             const nsAString& aValue,
  43                             const nsStringComparator& aComparator);
  44
  45   // Append a quoted (with 'quoteChar') and escaped version of aString
  46   // to aResult.  'quoteChar' must be ' or ".
  47   static void AppendEscapedCSSString(const nsAString& aString,
  48                                      nsAString& aResult,
  49                                      char16_t quoteChar = '"');
  50
  51   // Append the identifier given by |aIdent| to |aResult|, with
  52   // appropriate escaping so that it can be reparsed to the same
  53   // identifier.  An exception is if aIdent contains U+0000, which
  54   // will be escaped as U+FFFD and then reparsed back to U+FFFD.
  55   static void AppendEscapedCSSIdent(const nsAString& aIdent,
  56                                     nsAString& aResult);
  57
  58   static void AppendFontSlantStyle(const mozilla::FontSlantStyle&,
  59                                    nsAString& aResult);
  60
  61  public:
  62   static void AppendCSSNumber(float aNumber, nsAString& aResult) {
  63     aResult.AppendFloat(aNumber);
  64   }
  65
  66   /*
  67    * Convert an author-provided floating point number to an integer (0
  68    * ... 255) appropriate for use in the alpha component of a color.
  69    */
  70   static uint8_t FloatToColorComponent(float aAlpha) {
  71     NS_ASSERTION(0.0 <= aAlpha && aAlpha <= 1.0, "out of range");
  72     return static_cast<uint8_t>(NSToIntRound(aAlpha * 255));
  73   }
  74
  75   /*
  76    * Convert the alpha component of an nscolor (0 ... 255) to the
  77    * floating point number with the least accurate *decimal*
  78    * representation that is converted to that color.
  79    *
  80    * Should be used only by serialization code.
  81    */
  82   static float ColorComponentToFloat(uint8_t aAlpha);
  83
  84   /**
  85    * GetSerializedColorValue() computes serialized color value of aColor and
  86    * returns it with aSerializedColor.
  87    * https://drafts.csswg.org/cssom/#serialize-a-css-component-value
  88    */
  89   static void GetSerializedColorValue(nscolor aColor,
  90                                       nsAString& aSerializedColor);
  91
  92   /*
  93    * Does this child count as significant for selector matching?
  94    */
  95   static bool IsSignificantChild(nsIContent* aChild,
  96                                  bool aWhitespaceIsSignificant);
  97
  98   /*
  99    * Thread-safe version of IsSignificantChild()
 100    */
 101   static bool ThreadSafeIsSignificantChild(const nsIContent* aChild,
 102                                            bool aWhitespaceIsSignificant);
 103   /**
 104    * Returns true if our object-fit & object-position properties might cause
 105    * a replaced element's contents to overflow its content-box (requiring
 106    * clipping), or false if we can be sure that this won't happen.
 107    *
 108    * This lets us optimize by skipping clipping when we can tell it's
 109    * unnecessary (particularly with the default values of these properties).
 110    *
 111    * @param aStylePos The nsStylePosition whose object-fit & object-position
 112    *                  properties should be checked for potential overflow.
 113    * @return false if we can be sure that the object-fit & object-position
 114    *         properties on 'aStylePos' cannot cause a replaced element's
 115    *         contents to overflow its content-box. Otherwise (if overflow is
 116    *         is possible), returns true.
 117    */
 118   static bool ObjectPropsMightCauseOverflow(const nsStylePosition* aStylePos);
 119
 120   /*
 121    *  Does the document have a CSP that blocks the application of
 122    *  inline styles? Returns false if application of the style should
 123    *  be blocked.
 124    *
 125    *  @param aContent
 126    *      The <style> element that the caller wants to know whether to honor.
 127    *      Included to check the nonce attribute if one is provided. Allowed to
 128    *      be null, if this is for something other than a <style> element (in
 129    *      which case nonces won't be checked).
 130    *  @param aDocument
 131    *      The document containing the inline style (for querying the CSP);
 132    *  @param aTriggeringPrincipal
 133    *      The principal of the scripted caller which added the inline
 134    *      stylesheet, or null if no scripted caller can be identified.
 135    *  @param aLineNumber
 136    *      Line number of inline style element in the containing document (for
 137    *      reporting violations)
 138    *  @param aColumnNumber
 139    *      Column number of inline style element in the containing document (for
 140    *      reporting violations)
 141    *  @param aStyleText
 142    *      Contents of the inline style element (for reporting violations)
 143    *  @param aRv
 144    *      Return error code in case of failure
 145    *  @return
 146    *      Does CSP allow application of the specified inline style?
 147    */
 148   static bool CSPAllowsInlineStyle(mozilla::dom::Element* aContent,
 149                                    mozilla::dom::Document* aDocument,
 150                                    nsIPrincipal* aTriggeringPrincipal,
 151                                    uint32_t aLineNumber, uint32_t aColumnNumber,
 152                                    const nsAString& aStyleText, nsresult* aRv);
 153
 154   template <size_t N>
 155   static bool MatchesLanguagePrefix(const char16_t* aLang, size_t aLen,
 156                                     const char16_t (&aPrefix)[N]) {
 157     return !NS_strncmp(aLang, aPrefix, N - 1) &&
 158            (aLen == N - 1 || aLang[N - 1] == '-');
 159   }
 160
 161   template <size_t N>
 162   static bool MatchesLanguagePrefix(const nsAtom* aLang,
 163                                     const char16_t (&aPrefix)[N]) {
 164     MOZ_ASSERT(aLang);
 165     return MatchesLanguagePrefix(aLang->GetUTF16String(), aLang->GetLength(),
 166                                  aPrefix);
 167   }
 168
 169   template <size_t N>
 170   static bool MatchesLanguagePrefix(const nsAString& aLang,
 171                                     const char16_t (&aPrefix)[N]) {
 172     return MatchesLanguagePrefix(aLang.Data(), aLang.Length(), aPrefix);
 173   }
 174 };
 175
 176 #endif /* nsStyleUtil_h___ */