DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (b6d82b1a6b02)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226
/* -*- 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 "SVGLength.h"

#include "mozilla/ArrayUtils.h"
#include "mozilla/dom/SVGElement.h"
#include "mozilla/dom/SVGSVGElement.h"
#include "nsTextFormatter.h"
#include "SVGContentUtils.h"
#include <limits>
#include <algorithm>

using namespace mozilla::dom;
using namespace mozilla::dom::SVGLength_Binding;

namespace mozilla {

// Declare some helpers defined below:
static void GetUnitString(nsAString& unit, uint16_t unitType);
static uint16_t GetUnitTypeForString(const nsAString& unitStr);

void SVGLength::GetValueAsString(nsAString& aValue) const {
  nsTextFormatter::ssprintf(aValue, u"%g", (double)mValue);

  nsAutoString unitString;
  GetUnitString(unitString, mUnit);
  aValue.Append(unitString);
}

bool SVGLength::SetValueFromString(const nsAString& aString) {
  bool success;
  auto token = SVGContentUtils::GetAndEnsureOneToken(aString, success);

  if (!success) {
    return false;
  }

  RangedPtr<const char16_t> iter = SVGContentUtils::GetStartRangedPtr(token);
  const RangedPtr<const char16_t> end = SVGContentUtils::GetEndRangedPtr(token);

  float value;

  if (!SVGContentUtils::ParseNumber(iter, end, value)) {
    return false;
  }

  const nsAString& units = Substring(iter.get(), end.get());
  uint16_t unitType = GetUnitTypeForString(units);
  if (!IsValidUnitType(unitType)) {
    return false;
  }
  mValue = value;
  mUnit = uint8_t(unitType);
  return true;
}

inline static bool IsAbsoluteUnit(uint8_t aUnit) {
  return aUnit >= SVGLength_Binding::SVG_LENGTHTYPE_CM &&
         aUnit <= SVGLength_Binding::SVG_LENGTHTYPE_PC;
}

/**
 * Helper to convert between different CSS absolute units without the need for
 * an element, which provides more flexibility at the DOM level (and without
 * the need for an intermediary conversion to user units, which avoids
 * unnecessary overhead and rounding error).
 *
 * Example usage: to find out how many centimeters there are per inch:
 *
 *   GetAbsUnitsPerAbsUnit(SVGLength_Binding::SVG_LENGTHTYPE_CM,
 *                         SVGLength_Binding::SVG_LENGTHTYPE_IN)
 */
inline static float GetAbsUnitsPerAbsUnit(uint8_t aUnits, uint8_t aPerUnit) {
  MOZ_ASSERT(IsAbsoluteUnit(aUnits), "Not a CSS absolute unit");
  MOZ_ASSERT(IsAbsoluteUnit(aPerUnit), "Not a CSS absolute unit");

  float CSSAbsoluteUnitConversionFactors[5][5] = {
      // columns: cm, mm, in, pt, pc
      // cm per...:
      {1.0f, 0.1f, 2.54f, 0.035277777777777778f, 0.42333333333333333f},
      // mm per...:
      {10.0f, 1.0f, 25.4f, 0.35277777777777778f, 4.2333333333333333f},
      // in per...:
      {0.39370078740157481f, 0.039370078740157481f, 1.0f, 0.013888888888888889f,
       0.16666666666666667f},
      // pt per...:
      {28.346456692913386f, 2.8346456692913386f, 72.0f, 1.0f, 12.0f},
      // pc per...:
      {2.3622047244094489f, 0.23622047244094489f, 6.0f, 0.083333333333333333f,
       1.0f}};

  // First absolute unit is SVG_LENGTHTYPE_CM = 6
  return CSSAbsoluteUnitConversionFactors[aUnits - 6][aPerUnit - 6];
}

float SVGLength::GetValueInSpecifiedUnit(uint8_t aUnit,
                                         const SVGElement* aElement,
                                         uint8_t aAxis) const {
  if (aUnit == mUnit) {
    return mValue;
  }
  if ((aUnit == SVGLength_Binding::SVG_LENGTHTYPE_NUMBER &&
       mUnit == SVGLength_Binding::SVG_LENGTHTYPE_PX) ||
      (aUnit == SVGLength_Binding::SVG_LENGTHTYPE_PX &&
       mUnit == SVGLength_Binding::SVG_LENGTHTYPE_NUMBER)) {
    return mValue;
  }
  if (IsAbsoluteUnit(aUnit) && IsAbsoluteUnit(mUnit)) {
    return mValue * GetAbsUnitsPerAbsUnit(aUnit, mUnit);
  }

  // Otherwise we do a two step conversion via user units. This can only
  // succeed if aElement is non-null (although that's not sufficient to
  // guarantee success).

  float userUnitsPerCurrentUnit = GetUserUnitsPerUnit(aElement, aAxis);
  float userUnitsPerNewUnit =
      SVGLength(0.0f, aUnit).GetUserUnitsPerUnit(aElement, aAxis);

  NS_ASSERTION(
      userUnitsPerCurrentUnit >= 0 || !IsFinite(userUnitsPerCurrentUnit),
      "bad userUnitsPerCurrentUnit");
  NS_ASSERTION(userUnitsPerNewUnit >= 0 || !IsFinite(userUnitsPerNewUnit),
               "bad userUnitsPerNewUnit");

  float value = mValue * userUnitsPerCurrentUnit / userUnitsPerNewUnit;

  // userUnitsPerCurrentUnit could be infinity, or userUnitsPerNewUnit could
  // be zero.
  if (IsFinite(value)) {
    return value;
  }
  return std::numeric_limits<float>::quiet_NaN();
}

#define INCHES_PER_MM_FLOAT float(0.0393700787)
#define INCHES_PER_CM_FLOAT float(0.393700787)

float SVGLength::GetUserUnitsPerUnit(const SVGElement* aElement,
                                     uint8_t aAxis) const {
  switch (mUnit) {
    case SVGLength_Binding::SVG_LENGTHTYPE_NUMBER:
    case SVGLength_Binding::SVG_LENGTHTYPE_PX:
      return 1.0f;
    case SVGLength_Binding::SVG_LENGTHTYPE_MM:
      return INCHES_PER_MM_FLOAT * GetUserUnitsPerInch();
    case SVGLength_Binding::SVG_LENGTHTYPE_CM:
      return INCHES_PER_CM_FLOAT * GetUserUnitsPerInch();
    case SVGLength_Binding::SVG_LENGTHTYPE_IN:
      return GetUserUnitsPerInch();
    case SVGLength_Binding::SVG_LENGTHTYPE_PT:
      return (1.0f / POINTS_PER_INCH_FLOAT) * GetUserUnitsPerInch();
    case SVGLength_Binding::SVG_LENGTHTYPE_PC:
      return (12.0f / POINTS_PER_INCH_FLOAT) * GetUserUnitsPerInch();
    case SVGLength_Binding::SVG_LENGTHTYPE_PERCENTAGE:
      return GetUserUnitsPerPercent(aElement, aAxis);
    case SVGLength_Binding::SVG_LENGTHTYPE_EMS:
      return SVGContentUtils::GetFontSize(const_cast<SVGElement*>(aElement));
    case SVGLength_Binding::SVG_LENGTHTYPE_EXS:
      return SVGContentUtils::GetFontXHeight(const_cast<SVGElement*>(aElement));
    default:
      MOZ_ASSERT_UNREACHABLE("Unknown unit type");
      return std::numeric_limits<float>::quiet_NaN();
  }
}

/* static */
float SVGLength::GetUserUnitsPerPercent(const SVGElement* aElement,
                                        uint8_t aAxis) {
  if (aElement) {
    dom::SVGViewportElement* viewportElement = aElement->GetCtx();
    if (viewportElement) {
      return std::max(viewportElement->GetLength(aAxis) / 100.0f, 0.0f);
    }
  }
  return std::numeric_limits<float>::quiet_NaN();
}

// Helpers:

// These items must be at the same index as the SVGLength constants!
static const nsStaticAtom* const unitMap[] = {
    nullptr, /* SVG_LENGTHTYPE_UNKNOWN */
    nullptr, /* SVG_LENGTHTYPE_NUMBER */
    nsGkAtoms::percentage,
    nsGkAtoms::em,
    nsGkAtoms::ex,
    nsGkAtoms::px,
    nsGkAtoms::cm,
    nsGkAtoms::mm,
    nsGkAtoms::in,
    nsGkAtoms::pt,
    nsGkAtoms::pc};

static void GetUnitString(nsAString& unit, uint16_t unitType) {
  if (SVGLength::IsValidUnitType(unitType)) {
    if (unitMap[unitType]) {
      unitMap[unitType]->ToString(unit);
    }
    return;
  }
  MOZ_ASSERT_UNREACHABLE(
      "Unknown unit type! Someone's using an SVGLength "
      "with an invalid unit?");
}

static uint16_t GetUnitTypeForString(const nsAString& unitStr) {
  if (unitStr.IsEmpty()) return SVGLength_Binding::SVG_LENGTHTYPE_NUMBER;

  nsAtom* unitAtom = NS_GetStaticAtom(unitStr);

  if (unitAtom) {
    for (uint32_t i = 1; i < ArrayLength(unitMap); i++) {
      if (unitMap[i] == unitAtom) {
        return i;
      }
    }
  }
  return SVGLength_Binding::SVG_LENGTHTYPE_UNKNOWN;
}

}  // namespace mozilla