C++ nsCSSValue::GetUnit方法代码示例

/**
 * Tries to call |nsCSSValue::StartImageLoad()| on an image source.
 * Image sources are specified by |url()| or |-moz-image-rect()| function.
 */
static void
TryToStartImageLoadOnValue(const nsCSSValue& aValue, nsIDocument* aDocument,
                           nsCSSValueTokenStream* aTokenStream)
{
  MOZ_ASSERT(aDocument);

  if (aValue.GetUnit() == eCSSUnit_URL) {
    aValue.StartImageLoad(aDocument);
    if (aTokenStream) {
      aTokenStream->mImageValues.PutEntry(aValue.GetImageStructValue());
    }
  }
  else if (aValue.GetUnit() == eCSSUnit_Image) {
    // If we already have a request, see if this document needs to clone it.
    imgIRequest* request = aValue.GetImageValue(nullptr);

    if (request) {
      mozilla::css::ImageValue* imageValue = aValue.GetImageStructValue();
      aDocument->StyleImageLoader()->MaybeRegisterCSSImage(imageValue);
      if (aTokenStream) {
        aTokenStream->mImageValues.PutEntry(imageValue);
      }
    }
  }
  else if (aValue.EqualsFunction(eCSSKeyword__moz_image_rect)) {
    nsCSSValue::Array* arguments = aValue.GetArrayValue();
    MOZ_ASSERT(arguments->Count() == 6, "unexpected num of arguments");

    const nsCSSValue& image = arguments->Item(1);
    TryToStartImageLoadOnValue(image, aDocument, aTokenStream);
  }
}

/**
 * Tries to call |nsCSSValue::StartImageLoad()| on an image source.
 * Image sources are specified by |url()| or |-moz-image-rect()| function.
 */
static void
TryToStartImageLoadOnValue(const nsCSSValue& aValue, nsIDocument* aDocument,
                           nsStyleContext* aContext, nsCSSProperty aProperty,
                           bool aForTokenStream)
{
  MOZ_ASSERT(aDocument);

  if (aValue.GetUnit() == eCSSUnit_URL) {
    aValue.StartImageLoad(aDocument);
    if (aForTokenStream && aContext) {
      CSSVariableImageTable::Add(aContext, aProperty,
                                 aValue.GetImageStructValue());
    }
  }
  else if (aValue.GetUnit() == eCSSUnit_Image) {
    // If we already have a request, see if this document needs to clone it.
    imgIRequest* request = aValue.GetImageValue(nullptr);

    if (request) {
      ImageValue* imageValue = aValue.GetImageStructValue();
      aDocument->StyleImageLoader()->MaybeRegisterCSSImage(imageValue);
      if (aForTokenStream && aContext) {
        CSSVariableImageTable::Add(aContext, aProperty, imageValue);
      }
    }
  }
  else if (aValue.EqualsFunction(eCSSKeyword__moz_image_rect)) {
    nsCSSValue::Array* arguments = aValue.GetArrayValue();
    MOZ_ASSERT(arguments->Count() == 6, "unexpected num of arguments");

    const nsCSSValue& image = arguments->Item(1);
    TryToStartImageLoadOnValue(image, aDocument, aContext, aProperty,
                               aForTokenStream);
  }
}

/* static */ nscoord
nsMathMLFrame::CalcLength(nsPresContext*   aPresContext,
                          nsStyleContext*   aStyleContext,
                          const nsCSSValue& aCSSValue,
                          float             aFontSizeInflation)
{
  NS_ASSERTION(aCSSValue.IsLengthUnit(), "not a length unit");

  if (aCSSValue.IsFixedLengthUnit()) {
    return aCSSValue.GetFixedLength(aPresContext);
  }
  if (aCSSValue.IsPixelLengthUnit()) {
    return aCSSValue.GetPixelLength();
  }

  nsCSSUnit unit = aCSSValue.GetUnit();

  if (eCSSUnit_EM == unit) {
    const nsStyleFont* font = aStyleContext->StyleFont();
    return NSToCoordRound(aCSSValue.GetFloatValue() * (float)font->mFont.size);
  }
  else if (eCSSUnit_XHeight == unit) {
    aPresContext->SetUsesExChUnits(true);
    RefPtr<nsFontMetrics> fm = nsLayoutUtils::
      GetFontMetricsForStyleContext(aStyleContext, aFontSizeInflation);
    nscoord xHeight = fm->XHeight();
    return NSToCoordRound(aCSSValue.GetFloatValue() * (float)xHeight);
  }

  // MathML doesn't specify other CSS units such as rem or ch
  NS_ERROR("Unsupported unit");
  return 0;
}

static void
ProcessTranslatePart(float& aResult,
                     const nsCSSValue& aValue,
                     nsStyleContext* aContext,
                     nsPresContext* aPresContext,
                     PRBool& aCanStoreInRuleTree,
                     nscoord aSize, float aAppUnitsPerMatrixUnit)
{
  nscoord offset = 0;
  float percent = 0.0f;

  if (aValue.GetUnit() == eCSSUnit_Percent) {
    percent = aValue.GetPercentValue();
  } else if (aValue.IsCalcUnit()) {
    nsRuleNode::ComputedCalc result =
      nsRuleNode::SpecifiedCalcToComputedCalc(aValue, aContext, aPresContext,
                                              aCanStoreInRuleTree);
    percent = result.mPercent;
    offset = result.mLength;
  } else {
    offset = CalcLength(aValue, aContext, aPresContext,
                         aCanStoreInRuleTree);
  }

  aResult = (percent * NSAppUnitsToFloatPixels(aSize, aAppUnitsPerMatrixUnit)) + 
            NSAppUnitsToFloatPixels(offset, aAppUnitsPerMatrixUnit);
}

/* static */ nscoord
nsMathMLFrame::CalcLength(nsPresContext*   aPresContext,
                          nsStyleContext*   aStyleContext,
                          const nsCSSValue& aCSSValue)
{
  NS_ASSERTION(aCSSValue.IsLengthUnit(), "not a length unit");

  if (aCSSValue.IsFixedLengthUnit()) {
    return aCSSValue.GetLengthTwips();
  }

  nsCSSUnit unit = aCSSValue.GetUnit();

  if (eCSSUnit_Pixel == unit) {
    return NSFloatPixelsToTwips(aCSSValue.GetFloatValue(),
                                aPresContext->ScaledPixelsToTwips());
  }
  else if (eCSSUnit_EM == unit) {
    const nsStyleFont* font = aStyleContext->GetStyleFont();
    return NSToCoordRound(aCSSValue.GetFloatValue() * (float)font->mFont.size);
  }
  else if (eCSSUnit_XHeight == unit) {
    nscoord xHeight;
    const nsStyleFont* font = aStyleContext->GetStyleFont();
    nsCOMPtr<nsIFontMetrics> fm = aPresContext->GetMetricsFor(font->mFont);
    fm->GetXHeight(xHeight);
    return NSToCoordRound(aCSSValue.GetFloatValue() * (float)xHeight);
  }

  return 0;
}

float
ProcessTranslatePart(const nsCSSValue& aValue,
                     nsStyleContext* aContext,
                     nsPresContext* aPresContext,
                     RuleNodeCacheConditions& aConditions,
                     TransformReferenceBox* aRefBox,
                     TransformReferenceBox::DimensionGetter aDimensionGetter)
{
  nscoord offset = 0;
  float percent = 0.0f;

  if (aValue.GetUnit() == eCSSUnit_Percent) {
    percent = aValue.GetPercentValue();
  } else if (aValue.GetUnit() == eCSSUnit_Pixel ||
             aValue.GetUnit() == eCSSUnit_Number) {
    // Handle this here (even though nsRuleNode::CalcLength handles it
    // fine) so that callers are allowed to pass a null style context
    // and pres context to SetToTransformFunction if they know (as
    // StyleAnimationValue does) that all lengths within the transform
    // function have already been computed to pixels and percents.
    //
    // Raw numbers are treated as being pixels.
    //
    // Don't convert to aValue to AppUnits here to avoid precision issues.
    return aValue.GetFloatValue();
  } else if (aValue.IsCalcUnit()) {
    nsRuleNode::ComputedCalc result =
      nsRuleNode::SpecifiedCalcToComputedCalc(aValue, aContext, aPresContext,
                                              aConditions);
    percent = result.mPercent;
    offset = result.mLength;
  } else {
    offset = nsRuleNode::CalcLength(aValue, aContext, aPresContext,
                                    aConditions);
  }

  float translation = NSAppUnitsToFloatPixels(offset,
                                              nsPresContext::AppUnitsPerCSSPixel());
  // We want to avoid calling aDimensionGetter if there's no percentage to be
  // resolved (for performance reasons - see TransformReferenceBox).
  if (percent != 0.0f && aRefBox) {
    translation += percent *
                     NSAppUnitsToFloatPixels((aRefBox->*aDimensionGetter)(),
                                             nsPresContext::AppUnitsPerCSSPixel());
  }
  return translation;
}

static void
TryToStartImageLoad(const nsCSSValue& aValue, nsIDocument* aDocument,
                    nsCSSProperty aProperty)
{
  if (aValue.GetUnit() == eCSSUnit_List) {
    for (const nsCSSValueList* l = aValue.GetListValue(); l; l = l->mNext) {
      TryToStartImageLoad(l->mValue, aDocument, aProperty);
    }
  } else if (nsCSSProps::PropHasFlags(aProperty,
                                      CSS_PROPERTY_IMAGE_IS_IN_ARRAY_0)) {
    if (aValue.GetUnit() == eCSSUnit_Array) {
      TryToStartImageLoadOnValue(aValue.GetArrayValue()->Item(0), aDocument);
    }
  } else {
    TryToStartImageLoadOnValue(aValue, aDocument);
  }
}

float
ProcessTranslatePart(const nsCSSValue& aValue,
                     nsStyleContext* aContext,
                     nsPresContext* aPresContext,
                     bool& aCanStoreInRuleTree,
                     nscoord aSize)
{
  nscoord offset = 0;
  float percent = 0.0f;

  if (aValue.GetUnit() == eCSSUnit_Percent) {
    percent = aValue.GetPercentValue();
  } else if (aValue.GetUnit() == eCSSUnit_Pixel ||
             aValue.GetUnit() == eCSSUnit_Number) {
    // Handle this here (even though nsRuleNode::CalcLength handles it
    // fine) so that callers are allowed to pass a null style context
    // and pres context to SetToTransformFunction if they know (as
    // StyleAnimationValue does) that all lengths within the transform
    // function have already been computed to pixels and percents.
    //
    // Raw numbers are treated as being pixels.
    //
    // Don't convert to aValue to AppUnits here to avoid precision issues.
    return aValue.GetFloatValue();
  } else if (aValue.IsCalcUnit()) {
    nsRuleNode::ComputedCalc result =
      nsRuleNode::SpecifiedCalcToComputedCalc(aValue, aContext, aPresContext,
                                              aCanStoreInRuleTree);
    percent = result.mPercent;
    offset = result.mLength;
  } else {
    offset = nsRuleNode::CalcLength(aValue, aContext, aPresContext,
                                    aCanStoreInRuleTree);
  }

  return (percent * NSAppUnitsToFloatPixels(aSize, nsPresContext::AppUnitsPerCSSPixel())) +
         NSAppUnitsToFloatPixels(offset, nsPresContext::AppUnitsPerCSSPixel());
}

void
nsMathMLmpaddedFrame::UpdateValue(int32_t                  aSign,
                                  int32_t                  aPseudoUnit,
                                  const nsCSSValue&        aCSSValue,
                                  const ReflowOutput& aDesiredSize,
                                  nscoord&                 aValueToUpdate,
                                  float                aFontSizeInflation) const
{
  nsCSSUnit unit = aCSSValue.GetUnit();
  if (NS_MATHML_SIGN_INVALID != aSign && eCSSUnit_Null != unit) {
    nscoord scaler = 0, amount = 0;

    if (eCSSUnit_Percent == unit || eCSSUnit_Number == unit) {
      switch(aPseudoUnit) {
        case NS_MATHML_PSEUDO_UNIT_WIDTH:
             scaler = aDesiredSize.Width();
             break;

        case NS_MATHML_PSEUDO_UNIT_HEIGHT:
             scaler = aDesiredSize.BlockStartAscent();
             break;

        case NS_MATHML_PSEUDO_UNIT_DEPTH:
             scaler = aDesiredSize.Height() - aDesiredSize.BlockStartAscent();
             break;

        default:
          // if we ever reach here, it would mean something is wrong 
          // somewhere with the setup and/or the caller
          NS_ERROR("Unexpected Pseudo Unit");
          return;
      }
    }

    if (eCSSUnit_Number == unit)
      amount = NSToCoordRound(float(scaler) * aCSSValue.GetFloatValue());
    else if (eCSSUnit_Percent == unit)
      amount = NSToCoordRound(float(scaler) * aCSSValue.GetPercentValue());
    else
      amount = CalcLength(PresContext(), mStyleContext, aCSSValue,
                          aFontSizeInflation);

    if (NS_MATHML_SIGN_PLUS == aSign)
      aValueToUpdate += amount;
    else if (NS_MATHML_SIGN_MINUS == aSign)
      aValueToUpdate -= amount;
    else
      aValueToUpdate  = amount;
  }
}

void
nsMathMLmpaddedFrame::UpdateValue(PRInt32                  aSign,
                                  PRInt32                  aPseudoUnit,
                                  const nsCSSValue&        aCSSValue,
                                  const nsBoundingMetrics& aBoundingMetrics,
                                  nscoord&                 aValueToUpdate) const
{
  nsCSSUnit unit = aCSSValue.GetUnit();
  if (NS_MATHML_SIGN_INVALID != aSign && eCSSUnit_Null != unit) {
    nscoord scaler = 0, amount = 0;

    if (eCSSUnit_Percent == unit || eCSSUnit_Number == unit) {
      switch(aPseudoUnit) {
        case NS_MATHML_PSEUDO_UNIT_WIDTH:
             scaler = aBoundingMetrics.width;
             break;

        case NS_MATHML_PSEUDO_UNIT_HEIGHT:
             scaler = aBoundingMetrics.ascent;
             break;

        case NS_MATHML_PSEUDO_UNIT_DEPTH:
             scaler = aBoundingMetrics.descent;
             break;

        default:
          // if we ever reach here, it would mean something is wrong 
          // somewhere with the setup and/or the caller
          NS_ERROR("Unexpected Pseudo Unit");
          return;
      }
    }

    if (eCSSUnit_Number == unit)
      amount = NSToCoordRound(float(scaler) * aCSSValue.GetFloatValue());
    else if (eCSSUnit_Percent == unit)
      amount = NSToCoordRound(float(scaler) * aCSSValue.GetPercentValue());
    else
      amount = CalcLength(PresContext(), mStyleContext, aCSSValue);

    nscoord oldValue = aValueToUpdate;
    if (NS_MATHML_SIGN_PLUS == aSign)
      aValueToUpdate += amount;
    else if (NS_MATHML_SIGN_MINUS == aSign)
      aValueToUpdate -= amount;
    else
      aValueToUpdate  = amount;
  }
}

/* Helper function to fill in an nscoord with the specified nsCSSValue. */
static nscoord CalcLength(const nsCSSValue &aValue,
                          nsStyleContext* aContext,
                          nsPresContext* aPresContext,
                          PRBool &aCanStoreInRuleTree)
{
  if (aValue.GetUnit() == eCSSUnit_Pixel) {
    // Handle this here (even though nsRuleNode::CalcLength handles it
    // fine) so that callers are allowed to pass a null style context
    // and pres context to SetToTransformFunction if they know (as
    // nsStyleAnimation does) that all lengths within the transform
    // function have already been computed to pixels and percents.
    return nsPresContext::CSSPixelsToAppUnits(aValue.GetFloatValue());
  }
  return nsRuleNode::CalcLength(aValue, aContext, aPresContext,
                                aCanStoreInRuleTree);
}

void nsCSSValue::SetTripletValue(const nsCSSValue& xValue,
                                 const nsCSSValue& yValue,
                                 const nsCSSValue& zValue)
{
    // Only allow Null for the z component
    NS_ABORT_IF_FALSE(xValue.GetUnit() != eCSSUnit_Null &&
                      yValue.GetUnit() != eCSSUnit_Null &&
                      xValue.GetUnit() != eCSSUnit_Inherit &&
                      yValue.GetUnit() != eCSSUnit_Inherit &&
                      zValue.GetUnit() != eCSSUnit_Inherit &&
                      xValue.GetUnit() != eCSSUnit_Initial &&
                      yValue.GetUnit() != eCSSUnit_Initial &&
                      zValue.GetUnit() != eCSSUnit_Initial,
                      "inappropriate triplet value");
    Reset();
    mUnit = eCSSUnit_Triplet;
    mValue.mTriplet = new nsCSSValueTriplet_heap(xValue, yValue, zValue);
    mValue.mTriplet->AddRef();
}

void nsCSSValue::SetPairValue(const nsCSSValue& xValue,
                              const nsCSSValue& yValue)
{
  NS_ABORT_IF_FALSE(xValue.GetUnit() != eCSSUnit_Null &&
                    yValue.GetUnit() != eCSSUnit_Null &&
                    xValue.GetUnit() != eCSSUnit_Inherit &&
                    yValue.GetUnit() != eCSSUnit_Inherit &&
                    xValue.GetUnit() != eCSSUnit_Initial &&
                    yValue.GetUnit() != eCSSUnit_Initial,
                    "inappropriate pair value");
  Reset();
  mUnit = eCSSUnit_Pair;
  mValue.mPair = new nsCSSValuePair_heap(xValue, yValue);
  mValue.mPair->AddRef();
}

void
nsMathMLmpaddedFrame::UpdateValue(PRInt32                  aSign,
                                  PRInt32                  aPseudoUnit,
                                  const nsCSSValue&        aCSSValue,
                                  nscoord                  aLeftSpace,
                                  const nsBoundingMetrics& aBoundingMetrics,
                                  nscoord&                 aValueToUpdate) const
{
  nsCSSUnit unit = aCSSValue.GetUnit();
  if (NS_MATHML_SIGN_INVALID != aSign && eCSSUnit_Null != unit) {
    nscoord scaler = 0, amount = 0;

    if (eCSSUnit_Percent == unit || eCSSUnit_Number == unit) {
      switch(aPseudoUnit) {
        case NS_MATHML_PSEUDO_UNIT_WIDTH:
             scaler = aBoundingMetrics.width;
             break;

        case NS_MATHML_PSEUDO_UNIT_HEIGHT:
             scaler = aBoundingMetrics.ascent;
             break;

        case NS_MATHML_PSEUDO_UNIT_DEPTH:
             scaler = aBoundingMetrics.descent;
             break;

        case NS_MATHML_PSEUDO_UNIT_LSPACE:
             scaler = aLeftSpace;
             break;

        default:
          // if we ever reach here, it would mean something is wrong 
          // somewhere with the setup and/or the caller
          NS_ASSERTION(0, "Unexpected Pseudo Unit");
          return;
      }
    }

    if (eCSSUnit_Number == unit)
      amount = NSToCoordRound(float(scaler) * aCSSValue.GetFloatValue());
    else if (eCSSUnit_Percent == unit)
      amount = NSToCoordRound(float(scaler) * aCSSValue.GetPercentValue());
    else
      amount = CalcLength(PresContext(), mStyleContext, aCSSValue);

    nscoord oldValue = aValueToUpdate;
    if (NS_MATHML_SIGN_PLUS == aSign)
      aValueToUpdate += amount;
    else if (NS_MATHML_SIGN_MINUS == aSign)
      aValueToUpdate -= amount;
    else
      aValueToUpdate  = amount;

    /* The REC says:
    Dimensions that would be positive if the content was rendered normally
    cannot be made negative using <mpadded>; a positive dimension is set 
    to 0 if it would otherwise become negative. Dimensions which are 
    initially 0 can be made negative
    */
    if (0 < oldValue && 0 > aValueToUpdate)
      aValueToUpdate = 0;
  }
}

/**
 * Tries to call |nsCSSValue::StartImageLoad()| on an image source.
 * Image sources are specified by |url()| or |-moz-image-rect()| function.
 */
static void
TryToStartImageLoadOnValue(const nsCSSValue& aValue, nsIDocument* aDocument,
                           nsStyleContext* aContext, nsCSSPropertyID aProperty,
                           bool aForTokenStream)
{
  MOZ_ASSERT(aDocument);

  if (aValue.GetUnit() == eCSSUnit_URL) {
#ifdef MOZ_ENABLE_MASK_AS_SHORTHAND
    // The 'mask-image' property accepts local reference URIs.
    // For example,
    //   mask-image: url(#mask_id); // refer to a SVG mask element, whose id is
    //                              // "mask_id", in the current document.
    // For such 'mask-image' values (pointing to an in-document element),
    // there is no need to trigger image download.
    if (aProperty == eCSSProperty_mask_image) {
      // Filter out all fragment URLs.
      // Since nsCSSValue::GetURLStructValue runs much faster than
      // nsIURI::EqualsExceptRef bellow, we get performance gain by this
      // early return.
      URLValue* urlValue = aValue.GetURLStructValue();
      if (urlValue->GetLocalURLFlag()) {
        return;
      }

      // Even though urlValue is not a fragment URL, it might still refer to
      // an internal resource.
      // For example, aDocument base URL is "http://foo/index.html" and
      // intentionally references a mask-image at
      // url(http://foo/index.html#mask) which still refers to a resource in
      // aDocument.
      nsIURI* imageURI = aValue.GetURLValue();
      if (imageURI) {
        nsIURI* docURI = aDocument->GetDocumentURI();
        bool isEqualExceptRef = false;
        nsresult  rv = imageURI->EqualsExceptRef(docURI, &isEqualExceptRef);
        if (NS_SUCCEEDED(rv) && isEqualExceptRef) {
          return;
        }
      }
    }
#endif
    aValue.StartImageLoad(aDocument);
    if (aForTokenStream && aContext) {
      CSSVariableImageTable::Add(aContext, aProperty,
                                 aValue.GetImageStructValue());
    }
  }
  else if (aValue.GetUnit() == eCSSUnit_Image) {
    // If we already have a request, see if this document needs to clone it.
    imgIRequest* request = aValue.GetImageValue(nullptr);

    if (request) {
      ImageValue* imageValue = aValue.GetImageStructValue();
      aDocument->StyleImageLoader()->MaybeRegisterCSSImage(imageValue);
      if (aForTokenStream && aContext) {
        CSSVariableImageTable::Add(aContext, aProperty, imageValue);
      }
    }
  }
  else if (aValue.EqualsFunction(eCSSKeyword__moz_image_rect)) {
    nsCSSValue::Array* arguments = aValue.GetArrayValue();
    MOZ_ASSERT(arguments->Count() == 6, "unexpected num of arguments");

    const nsCSSValue& image = arguments->Item(1);
    TryToStartImageLoadOnValue(image, aDocument, aContext, aProperty,
                               aForTokenStream);
  }
}