C++ nsCSSValue::GetFloatValue方法代码示例

/* 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 */ 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;
}

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);
}

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;
}

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());
}

//.........这里部分代码省略.........
    PRUnichar c = aString[i];
    if (gotDot && c == '.') {
      // error - two dots encountered
      aSign = NS_MATHML_SIGN_INVALID;
      return false;
    }

    if (c == '.')
      gotDot = true;
    else if (!nsCRT::IsAsciiDigit(c)) {
      break;
    }
    number.Append(c);
  }

  // catch error if we didn't enter the loop above... we could simply initialize
  // floatValue = 1, to cater for cases such as width="height", but that wouldn't
  // be in line with the spec which requires an explicit number
  if (number.IsEmpty()) {
    aSign = NS_MATHML_SIGN_INVALID;
    return false;
  }

  nsresult errorCode;
  float floatValue = number.ToFloat(&errorCode);
  if (NS_FAILED(errorCode)) {
    aSign = NS_MATHML_SIGN_INVALID;
    return false;
  }

  // see if this is a percentage-based value
  if (i < stringLength && aString[i] == '%') {
    i++;
    gotPercent = true;
  }

  // the remainder now should be a css-unit, or a pseudo-unit, or a named-space
  aString.Right(unit, stringLength - i);

  if (unit.IsEmpty()) {
    if (gotPercent) {
      // case ["+"|"-"] unsigned-number "%" 
      aCSSValue.SetPercentValue(floatValue / 100.0f);
      aPseudoUnit = NS_MATHML_PSEUDO_UNIT_ITSELF;
      return true;
    } else {
      // case ["+"|"-"] unsigned-number
      // XXXfredw: should we allow non-zero unitless values? See bug 757703.
      if (!floatValue) {
        aCSSValue.SetFloatValue(floatValue, eCSSUnit_Number);
        aPseudoUnit = NS_MATHML_PSEUDO_UNIT_ITSELF;
        return true;
      }
    }
  }
  else if (unit.EqualsLiteral("width"))  aPseudoUnit = NS_MATHML_PSEUDO_UNIT_WIDTH;
  else if (unit.EqualsLiteral("height")) aPseudoUnit = NS_MATHML_PSEUDO_UNIT_HEIGHT;
  else if (unit.EqualsLiteral("depth"))  aPseudoUnit = NS_MATHML_PSEUDO_UNIT_DEPTH;
  else if (!gotPercent) { // percentage can only apply to a pseudo-unit

    // see if the unit is a named-space
    if (nsMathMLElement::ParseNamedSpaceValue(unit, aCSSValue,
                                              nsMathMLElement::
                                              PARSE_ALLOW_NEGATIVE)) {
      // re-scale properly, and we know that the unit of the named-space is 'em'
      floatValue *= aCSSValue.GetFloatValue();
      aCSSValue.SetFloatValue(floatValue, eCSSUnit_EM);
      aPseudoUnit = NS_MATHML_PSEUDO_UNIT_NAMEDSPACE;
      return true;
    }

    // see if the input was just a CSS value
    // We are not supposed to have a unitless, percent, negative or namedspace
    // value here.
    number.Append(unit); // leave the sign out if it was there
    if (nsMathMLElement::ParseNumericValue(number, aCSSValue, 
                                           nsMathMLElement::
                                           PARSE_SUPPRESS_WARNINGS, nullptr))
      return true;
  }

  // if we enter here, we have a number that will act as a multiplier on a pseudo-unit
  if (aPseudoUnit != NS_MATHML_PSEUDO_UNIT_UNSPECIFIED) {
    if (gotPercent)
      aCSSValue.SetPercentValue(floatValue / 100.0f);
    else
      aCSSValue.SetFloatValue(floatValue, eCSSUnit_Number);

    return true;
  }


#ifdef DEBUG
  printf("mpadded: attribute with bad numeric value: %s\n",
          NS_LossyConvertUTF16toASCII(aString).get());
#endif
  // if we reach here, it means we encounter an unexpected input
  aSign = NS_MATHML_SIGN_INVALID;
  return false;
}

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;
  }
}