tor-browser

nsStyleUtil.h (6823B)

---

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef nsStyleUtil_h___
#define nsStyleUtil_h___

#include "NonCustomCSSPropertyId.h"
#include "nsCRT.h"
#include "nsColor.h"
#include "nsCoord.h"
#include "nsGkAtoms.h"
#include "nsStringFwd.h"
#include "nsTArrayForwardDeclare.h"

class nsCSSValue;
class nsIContent;
class nsIPrincipal;
class nsIURI;
struct nsCSSKTableEntry;
struct nsCSSValueList;
struct nsStylePosition;

namespace mozilla {
namespace dom {
class Document;
class Element;
}  // namespace dom
}  // namespace mozilla

// Style utility functions
class nsStyleUtil {
public:
 static bool DashMatchCompare(const nsAString& aAttributeValue,
                              const nsAString& aSelectorValue,
                              const nsStringComparator& aComparator);

 static bool LangTagCompare(const nsACString& aAttributeValue,
                            const nsACString& aSelectorValue);

 static bool ValueIncludes(const nsAString& aValueList,
                           const nsAString& aValue,
                           const nsStringComparator& aComparator);

 // Append a quoted (with 'quoteChar') version of aString to aResult.
 // 'aQuoteChar' must be ' or ".
 static void AppendQuotedCSSString(const nsACString& aString,
                                  nsACString& aResult, char aQuoteChar = '"');

 // Append the identifier given by |aIdent| to |aResult|, with
 // appropriate escaping so that it can be reparsed to the same
 // identifier.  An exception is if aIdent contains U+0000, which
 // will be escaped as U+FFFD and then reparsed back to U+FFFD.
 static void AppendEscapedCSSIdent(const nsAString& aIdent,
                                   nsAString& aResult);

public:
 static void AppendCSSNumber(float aNumber, nsAString& aResult) {
   aResult.AppendFloat(aNumber);
 }

 /*
  * Convert an author-provided floating point number to an integer (0
  * ... 255) appropriate for use in the alpha component of a color.
  */
 static uint8_t FloatToColorComponent(float aAlpha) {
   NS_ASSERTION(0.0 <= aAlpha && aAlpha <= 1.0, "out of range");
   return static_cast<uint8_t>(NSToIntRound(aAlpha * 255));
 }

 /*
  * Convert the alpha component of an nscolor (0 ... 255) to the
  * floating point number with the least accurate *decimal*
  * representation that is converted to that color.
  *
  * Should be used only by serialization code.
  */
 static float ColorComponentToFloat(uint8_t aAlpha);

 /**
  * GetSerializedColorValue() computes serialized color value of aColor and
  * returns it with aSerializedColor.
  * https://drafts.csswg.org/cssom/#serialize-a-css-component-value
  */
 static void GetSerializedColorValue(nscolor aColor,
                                     nsAString& aSerializedColor);

 /*
  * Does this child count as significant for selector matching?
  */
 static bool IsSignificantChild(nsIContent* aChild,
                                bool aWhitespaceIsSignificant);

 /*
  * Thread-safe version of IsSignificantChild()
  */
 static bool ThreadSafeIsSignificantChild(const nsIContent* aChild,
                                          bool aWhitespaceIsSignificant);
 /**
  * Returns true if our object-fit & object-position properties might cause
  * a replaced element's contents to overflow its content-box (requiring
  * clipping), or false if we can be sure that this won't happen.
  *
  * This lets us optimize by skipping clipping when we can tell it's
  * unnecessary (particularly with the default values of these properties).
  *
  * @param aStylePos The nsStylePosition whose object-fit & object-position
  *                  properties should be checked for potential overflow.
  * @return false if we can be sure that the object-fit & object-position
  *         properties on 'aStylePos' cannot cause a replaced element's
  *         contents to overflow its content-box. Otherwise (if overflow is
  *         is possible), returns true.
  */
 static bool ObjectPropsMightCauseOverflow(const nsStylePosition* aStylePos);

 /*
  *  Does the document have a CSP that blocks the application of
  *  inline styles? Returns false if application of the style should
  *  be blocked.
  *
  *  @param aContent
  *      The <style> element that the caller wants to know whether to honor.
  *      Included to check the nonce attribute if one is provided. Allowed to
  *      be null, if this is for something other than a <style> element (in
  *      which case nonces won't be checked).
  *  @param aDocument
  *      The document containing the inline style (for querying the CSP);
  *  @param aTriggeringPrincipal
  *      The principal of the scripted caller which added the inline
  *      stylesheet, or null if no scripted caller can be identified.
  *  @param aLineNumber
  *      Line number of inline style element in the containing document (for
  *      reporting violations)
  *  @param aColumnNumber
  *      Column number of inline style element in the containing document (for
  *      reporting violations)
  *  @param aStyleText
  *      Contents of the inline style element (for reporting violations)
  *  @param aRv
  *      Return error code in case of failure
  *  @return
  *      Does CSP allow application of the specified inline style?
  */
 static bool CSPAllowsInlineStyle(mozilla::dom::Element* aContent,
                                  mozilla::dom::Document* aDocument,
                                  nsIPrincipal* aTriggeringPrincipal,
                                  uint32_t aLineNumber, uint32_t aColumnNumber,
                                  const nsAString& aStyleText, nsresult* aRv);

 template <size_t N>
 static bool MatchesLanguagePrefix(const char16_t* aLang, size_t aLen,
                                   const char16_t (&aPrefix)[N]) {
   return !NS_strncmp(aLang, aPrefix, N - 1) &&
          (aLen == N - 1 || aLang[N - 1] == '-');
 }

 template <size_t N>
 static bool MatchesLanguagePrefix(const nsAtom* aLang,
                                   const char16_t (&aPrefix)[N]) {
   MOZ_ASSERT(aLang);
   return MatchesLanguagePrefix(aLang->GetUTF16String(), aLang->GetLength(),
                                aPrefix);
 }

 template <size_t N>
 static bool MatchesLanguagePrefix(const nsAString& aLang,
                                   const char16_t (&aPrefix)[N]) {
   return MatchesLanguagePrefix(aLang.Data(), aLang.Length(), aPrefix);
 }
};

#endif /* nsStyleUtil_h___ */