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