third_party/WebKit/Source/core/css/CSSToLengthConversionData.cpp

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#include "core/css/CSSToLengthConversionData.h"

#include "core/css/CSSHelper.h"
#include "core/layout/api/LayoutViewItem.h"
#include "core/style/ComputedStyle.h"

namespace blink {

CSSToLengthConversionData::FontSizes::FontSizes(float em,
                                                float rem,
                                                const Font* font)
    : m_em(em), m_rem(rem), m_font(font) {
  // FIXME: Improve RAII of StyleResolverState to use const Font&.
  DCHECK(m_font);
}

CSSToLengthConversionData::FontSizes::FontSizes(const ComputedStyle* style,
                                                const ComputedStyle* rootStyle)
    : FontSizes(style->computedFontSize(),
                rootStyle ? rootStyle->computedFontSize() : 1.0f,
                &style->font()) {}

float CSSToLengthConversionData::FontSizes::ex() const {
  DCHECK(m_font);
  const SimpleFontData* fontData = m_font->primaryFont();
  DCHECK(fontData);

  // FIXME: We have a bug right now where the zoom will be applied twice to EX
  // units. We really need to compute EX using fontMetrics for the original
  // specifiedSize and not use our actual constructed layoutObject font.
  if (!fontData || !fontData->getFontMetrics().hasXHeight())
    return m_em / 2.0f;
  return fontData->getFontMetrics().xHeight();
}

float CSSToLengthConversionData::FontSizes::ch() const {
  DCHECK(m_font);
  const SimpleFontData* fontData = m_font->primaryFont();
  DCHECK(fontData);
  return fontData ? fontData->getFontMetrics().zeroWidth() : 0;
}

CSSToLengthConversionData::ViewportSize::ViewportSize(
    const LayoutViewItem& layoutViewItem)
    : m_size(!layoutViewItem.isNull()
                 ? layoutViewItem.viewportSizeForViewportUnits()
                 : DoubleSize()) {}

CSSToLengthConversionData::CSSToLengthConversionData(
    const ComputedStyle* style,
    const FontSizes& fontSizes,
    const ViewportSize& viewportSize,
    float zoom)
    : m_style(style),
      m_fontSizes(fontSizes),
      m_viewportSize(viewportSize),
      m_zoom(clampTo<float>(zoom, std::numeric_limits<float>::denorm_min())) {
}

CSSToLengthConversionData::CSSToLengthConversionData(
    const ComputedStyle* style,
    const ComputedStyle* rootStyle,
    const LayoutViewItem& layoutViewItem,
    float zoom)
    : CSSToLengthConversionData(style,
                                FontSizes(style, rootStyle),
                                ViewportSize(layoutViewItem),
                                zoom) {}

double CSSToLengthConversionData::viewportWidthPercent() const {
  // FIXME: Remove m_style from this class. Plumb viewport and rem unit
  // information through as output parameters on functions involved in length
  // resolution.
  const_cast<ComputedStyle*>(m_style)->setHasViewportUnits(true);
  return m_viewportSize.width() / 100;
}
double CSSToLengthConversionData::viewportHeightPercent() const {
  const_cast<ComputedStyle*>(m_style)->setHasViewportUnits(true);
  return m_viewportSize.height() / 100;
}
double CSSToLengthConversionData::viewportMinPercent() const {
  const_cast<ComputedStyle*>(m_style)->setHasViewportUnits(true);
  return std::min(m_viewportSize.width(), m_viewportSize.height()) / 100;
}
double CSSToLengthConversionData::viewportMaxPercent() const {
  const_cast<ComputedStyle*>(m_style)->setHasViewportUnits(true);
  return std::max(m_viewportSize.width(), m_viewportSize.height()) / 100;
}

float CSSToLengthConversionData::remFontSize() const {
  const_cast<ComputedStyle*>(m_style)->setHasRemUnits();
  return m_fontSizes.rem();
}

double CSSToLengthConversionData::zoomedComputedPixels(
    double value,
    CSSPrimitiveValue::UnitType type) const {
  // The logic in this function is duplicated in MediaValues::computeLength()
  // because MediaValues::computeLength() needs nearly identical logic, but we
  // haven't found a way to make zoomedComputedPixels() more generic (to solve
  // both cases) without hurting performance.
  switch (type) {
    case CSSPrimitiveValue::UnitType::Pixels:
    case CSSPrimitiveValue::UnitType::UserUnits:
      return value * zoom();

    case CSSPrimitiveValue::UnitType::Centimeters:
      return value * cssPixelsPerCentimeter * zoom();

    case CSSPrimitiveValue::UnitType::Millimeters:
      return value * cssPixelsPerMillimeter * zoom();

    case CSSPrimitiveValue::UnitType::Inches:
      return value * cssPixelsPerInch * zoom();

    case CSSPrimitiveValue::UnitType::Points:
      return value * cssPixelsPerPoint * zoom();

    case CSSPrimitiveValue::UnitType::Picas:
      return value * cssPixelsPerPica * zoom();

    case CSSPrimitiveValue::UnitType::ViewportWidth:
      return value * viewportWidthPercent() * zoom();

    case CSSPrimitiveValue::UnitType::ViewportHeight:
      return value * viewportHeightPercent() * zoom();

    case CSSPrimitiveValue::UnitType::ViewportMin:
      return value * viewportMinPercent() * zoom();

    case CSSPrimitiveValue::UnitType::ViewportMax:
      return value * viewportMaxPercent() * zoom();

    // We do not apply the zoom factor when we are computing the value of the
    // font-size property. The zooming for font sizes is much more complicated,
    // since we have to worry about enforcing the minimum font size preference
    // as well as enforcing the implicit "smart minimum."
    case CSSPrimitiveValue::UnitType::Ems:
    case CSSPrimitiveValue::UnitType::QuirkyEms:
      return value * emFontSize();

    case CSSPrimitiveValue::UnitType::Exs:
      return value * exFontSize();

    case CSSPrimitiveValue::UnitType::Rems:
      return value * remFontSize();

    case CSSPrimitiveValue::UnitType::Chs:
      return value * chFontSize();

    default:
      NOTREACHED();
      return 0;
  }
}

}  // namespace blink