gecko-dev/dom/html/HTMLMeterElement.cpp

/* -*- 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 http://mozilla.org/MPL/2.0/. */

#include "HTMLMeterElement.h"
#include "mozilla/dom/HTMLMeterElementBinding.h"

NS_IMPL_NS_NEW_HTML_ELEMENT(Meter)

namespace mozilla::dom {

static const double kDefaultValue = 0.0;
static const double kDefaultMin = 0.0;
static const double kDefaultMax = 1.0;

HTMLMeterElement::HTMLMeterElement(
    already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo)
    : nsGenericHTMLElement(std::move(aNodeInfo)) {}

HTMLMeterElement::~HTMLMeterElement() = default;

NS_IMPL_ELEMENT_CLONE(HTMLMeterElement)

static bool IsInterestingAttr(int32_t aNamespaceID, nsAtom* aAttribute) {
  if (aNamespaceID != kNameSpaceID_None) {
    return false;
  }
  return aAttribute == nsGkAtoms::value || aAttribute == nsGkAtoms::max ||
         aAttribute == nsGkAtoms::min || aAttribute == nsGkAtoms::low ||
         aAttribute == nsGkAtoms::high || aAttribute == nsGkAtoms::optimum;
}

bool HTMLMeterElement::ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
                                      const nsAString& aValue,
                                      nsIPrincipal* aMaybeScriptedPrincipal,
                                      nsAttrValue& aResult) {
  if (IsInterestingAttr(aNamespaceID, aAttribute)) {
    return aResult.ParseDoubleValue(aValue);
  }
  return nsGenericHTMLElement::ParseAttribute(aNamespaceID, aAttribute, aValue,
                                              aMaybeScriptedPrincipal, aResult);
}

void HTMLMeterElement::AfterSetAttr(int32_t aNameSpaceID, nsAtom* aName,
                                    const nsAttrValue* aValue,
                                    const nsAttrValue* aOldValue,
                                    nsIPrincipal* aSubjectPrincipal,
                                    bool aNotify) {
  if (IsInterestingAttr(aNameSpaceID, aName)) {
    UpdateOptimumState(aNotify);
  }
  nsGenericHTMLElement::AfterSetAttr(aNameSpaceID, aName, aValue, aOldValue,
                                     aSubjectPrincipal, aNotify);
}

void HTMLMeterElement::UpdateOptimumState(bool aNotify) {
  AutoStateChangeNotifier notifier(*this, aNotify);
  RemoveStatesSilently(ElementState::METER_OPTIMUM_STATES);
  AddStatesSilently(GetOptimumState());
}

double HTMLMeterElement::Min() const {
  /**
   * If the attribute min is defined, the minimum is this value.
   * Otherwise, the minimum is the default value.
   */
  const nsAttrValue* attrMin = mAttrs.GetAttr(nsGkAtoms::min);
  if (attrMin && attrMin->Type() == nsAttrValue::eDoubleValue) {
    return attrMin->GetDoubleValue();
  }
  return kDefaultMin;
}

double HTMLMeterElement::Max() const {
  /**
   * If the attribute max is defined, the maximum is this value.
   * Otherwise, the maximum is the default value.
   * If the maximum value is less than the minimum value,
   * the maximum value is the same as the minimum value.
   */
  double max;

  const nsAttrValue* attrMax = mAttrs.GetAttr(nsGkAtoms::max);
  if (attrMax && attrMax->Type() == nsAttrValue::eDoubleValue) {
    max = attrMax->GetDoubleValue();
  } else {
    max = kDefaultMax;
  }

  return std::max(max, Min());
}

double HTMLMeterElement::Value() const {
  /**
   * If the attribute value is defined, the actual value is this value.
   * Otherwise, the actual value is the default value.
   * If the actual value is less than the minimum value,
   * the actual value is the same as the minimum value.
   * If the actual value is greater than the maximum value,
   * the actual value is the same as the maximum value.
   */
  double value;

  const nsAttrValue* attrValue = mAttrs.GetAttr(nsGkAtoms::value);
  if (attrValue && attrValue->Type() == nsAttrValue::eDoubleValue) {
    value = attrValue->GetDoubleValue();
  } else {
    value = kDefaultValue;
  }

  double min = Min();

  if (value <= min) {
    return min;
  }

  return std::min(value, Max());
}

double HTMLMeterElement::Position() const {
  const double max = Max();
  const double min = Min();
  const double value = Value();

  double range = max - min;
  return range != 0.0 ? (value - min) / range : 1.0;
}

double HTMLMeterElement::Low() const {
  /**
   * If the low value is defined, the low value is this value.
   * Otherwise, the low value is the minimum value.
   * If the low value is less than the minimum value,
   * the low value is the same as the minimum value.
   * If the low value is greater than the maximum value,
   * the low value is the same as the maximum value.
   */

  double min = Min();

  const nsAttrValue* attrLow = mAttrs.GetAttr(nsGkAtoms::low);
  if (!attrLow || attrLow->Type() != nsAttrValue::eDoubleValue) {
    return min;
  }

  double low = attrLow->GetDoubleValue();

  if (low <= min) {
    return min;
  }

  return std::min(low, Max());
}

double HTMLMeterElement::High() const {
  /**
   * If the high value is defined, the high value is this value.
   * Otherwise, the high value is the maximum value.
   * If the high value is less than the low value,
   * the high value is the same as the low value.
   * If the high value is greater than the maximum value,
   * the high value is the same as the maximum value.
   */

  double max = Max();

  const nsAttrValue* attrHigh = mAttrs.GetAttr(nsGkAtoms::high);
  if (!attrHigh || attrHigh->Type() != nsAttrValue::eDoubleValue) {
    return max;
  }

  double high = attrHigh->GetDoubleValue();

  if (high >= max) {
    return max;
  }

  return std::max(high, Low());
}

double HTMLMeterElement::Optimum() const {
  /**
   * If the optimum value is defined, the optimum value is this value.
   * Otherwise, the optimum value is the midpoint between
   * the minimum value and the maximum value :
   * min + (max - min)/2 = (min + max)/2
   * If the optimum value is less than the minimum value,
   * the optimum value is the same as the minimum value.
   * If the optimum value is greater than the maximum value,
   * the optimum value is the same as the maximum value.
   */

  double max = Max();

  double min = Min();

  const nsAttrValue* attrOptimum = mAttrs.GetAttr(nsGkAtoms::optimum);
  if (!attrOptimum || attrOptimum->Type() != nsAttrValue::eDoubleValue) {
    return (min + max) / 2.0;
  }

  double optimum = attrOptimum->GetDoubleValue();

  if (optimum <= min) {
    return min;
  }

  return std::min(optimum, max);
}

ElementState HTMLMeterElement::GetOptimumState() const {
  /*
   * If the optimum value is in [minimum, low[,
   *     return if the value is in optimal, suboptimal or sub-suboptimal region
   *
   * If the optimum value is in [low, high],
   *     return if the value is in optimal or suboptimal region
   *
   * If the optimum value is in ]high, maximum],
   *     return if the value is in optimal, suboptimal or sub-suboptimal region
   */
  double value = Value();
  double low = Low();
  double high = High();
  double optimum = Optimum();

  if (optimum < low) {
    if (value < low) {
      return ElementState::OPTIMUM;
    }
    if (value <= high) {
      return ElementState::SUB_OPTIMUM;
    }
    return ElementState::SUB_SUB_OPTIMUM;
  }
  if (optimum > high) {
    if (value > high) {
      return ElementState::OPTIMUM;
    }
    if (value >= low) {
      return ElementState::SUB_OPTIMUM;
    }
    return ElementState::SUB_SUB_OPTIMUM;
  }
  // optimum in [low, high]
  if (value >= low && value <= high) {
    return ElementState::OPTIMUM;
  }
  return ElementState::SUB_OPTIMUM;
}

JSObject* HTMLMeterElement::WrapNode(JSContext* aCx,
                                     JS::Handle<JSObject*> aGivenProto) {
  return HTMLMeterElement_Binding::Wrap(aCx, this, aGivenProto);
}

}  // namespace mozilla::dom