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

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#include "core/css/CSSToLengthConversionData.h"

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

namespace blink {

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

CSSToLengthConversionData::FontSizes::FontSizes(const ComputedStyle* style,
                                                const ComputedStyle* root_style)
    : FontSizes(style->ComputedFontSize(),
                root_style ? root_style->ComputedFontSize() : 1.0f,
                &style->GetFont()) {}

float CSSToLengthConversionData::FontSizes::Ex() const {
  DCHECK(font_);
  const SimpleFontData* font_data = font_->PrimaryFont();
  DCHECK(font_data);

  // 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 (!font_data || !font_data->GetFontMetrics().HasXHeight())
    return em_ / 2.0f;
  return font_data->GetFontMetrics().XHeight();
}

float CSSToLengthConversionData::FontSizes::Ch() const {
  DCHECK(font_);
  const SimpleFontData* font_data = font_->PrimaryFont();
  DCHECK(font_data);
  return font_data ? font_data->GetFontMetrics().ZeroWidth() : 0;
}

CSSToLengthConversionData::ViewportSize::ViewportSize(
    const LayoutViewItem& layout_view_item)
    : size_(!layout_view_item.IsNull()
                ? layout_view_item.ViewportSizeForViewportUnits()
                : DoubleSize()) {}

CSSToLengthConversionData::CSSToLengthConversionData(
    const ComputedStyle* style,
    const FontSizes& font_sizes,
    const ViewportSize& viewport_size,
    float zoom)
    : style_(style),
      font_sizes_(font_sizes),
      viewport_size_(viewport_size),
      zoom_(clampTo<float>(zoom, std::numeric_limits<float>::denorm_min())) {}

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

double CSSToLengthConversionData::ViewportWidthPercent() const {
  // FIXME: Remove style_ from this class. Plumb viewport and rem unit
  // information through as output parameters on functions involved in length
  // resolution.
  if (style_)
    const_cast<ComputedStyle*>(style_)->SetHasViewportUnits(true);
  return viewport_size_.Width() / 100;
}
double CSSToLengthConversionData::ViewportHeightPercent() const {
  if (style_)
    const_cast<ComputedStyle*>(style_)->SetHasViewportUnits(true);
  return viewport_size_.Height() / 100;
}
double CSSToLengthConversionData::ViewportMinPercent() const {
  if (style_)
    const_cast<ComputedStyle*>(style_)->SetHasViewportUnits(true);
  return std::min(viewport_size_.Width(), viewport_size_.Height()) / 100;
}
double CSSToLengthConversionData::ViewportMaxPercent() const {
  if (style_)
    const_cast<ComputedStyle*>(style_)->SetHasViewportUnits(true);
  return std::max(viewport_size_.Width(), viewport_size_.Height()) / 100;
}

float CSSToLengthConversionData::RemFontSize() const {
  if (style_)
    const_cast<ComputedStyle*>(style_)->SetHasRemUnits();
  return font_sizes_.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::kPixels:
    case CSSPrimitiveValue::UnitType::kUserUnits:
      return value * Zoom();

    case CSSPrimitiveValue::UnitType::kCentimeters:
      return value * kCssPixelsPerCentimeter * Zoom();

    case CSSPrimitiveValue::UnitType::kMillimeters:
      return value * kCssPixelsPerMillimeter * Zoom();

    case CSSPrimitiveValue::UnitType::kQuarterMillimeters:
      return value * kCssPixelsPerQuarterMillimeter * Zoom();

    case CSSPrimitiveValue::UnitType::kInches:
      return value * kCssPixelsPerInch * Zoom();

    case CSSPrimitiveValue::UnitType::kPoints:
      return value * kCssPixelsPerPoint * Zoom();

    case CSSPrimitiveValue::UnitType::kPicas:
      return value * kCssPixelsPerPica * Zoom();

    case CSSPrimitiveValue::UnitType::kViewportWidth:
      return value * ViewportWidthPercent() * Zoom();

    case CSSPrimitiveValue::UnitType::kViewportHeight:
      return value * ViewportHeightPercent() * Zoom();

    case CSSPrimitiveValue::UnitType::kViewportMin:
      return value * ViewportMinPercent() * Zoom();

    case CSSPrimitiveValue::UnitType::kViewportMax:
      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::kEms:
    case CSSPrimitiveValue::UnitType::kQuirkyEms:
      return value * EmFontSize();

    case CSSPrimitiveValue::UnitType::kExs:
      return value * ExFontSize();

    case CSSPrimitiveValue::UnitType::kRems:
      return value * RemFontSize();

    case CSSPrimitiveValue::UnitType::kChs:
      return value * ChFontSize();

    default:
      NOTREACHED();
      return 0;
  }
}

}  // namespace blink