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/* -*- 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 */
#ifndef nsStyleUtil_h___
#define nsStyleUtil_h___
#include "nsCoord.h"
#include "nsCSSPropertyID.h"
#include "nsTArrayForwardDeclare.h"
#include "nsStringFwd.h"
#include "nsCRT.h"
#include "nsColor.h"
#include "nsGkAtoms.h"
class nsCSSValue;
class nsIContent;
class nsIPrincipal;
class nsIURI;
struct gfxFontFeature;
struct nsCSSKTableEntry;
struct nsCSSValueList;
struct nsStylePosition;
namespace mozilla {
namespace dom {
class Document;
class Element;
} // namespace dom
} // namespace mozilla
// Style utility functions
class nsStyleUtil {
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') and escaped version of aString
// to aResult. 'quoteChar' must be ' or ".
static void AppendEscapedCSSString(const nsAString& aString,
nsAString& aResult,
char16_t quoteChar = '"');
// 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);
static void AppendCSSNumber(float aNumber, nsAString& aResult) {
* 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.
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]) {
return MatchesLanguagePrefix(aLang->GetUTF16String(), aLang->GetLength(),
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___ */