1 files changed, 226 insertions, 0 deletions
diff --git a/dom/svg/SVGLength.cpp b/dom/svg/SVGLength.cpp
new file mode 100644
index 0000000000..abca0e71d4
--- /dev/null
+++ b/dom/svg/SVGLength.cpp
@@ -0,0 +1,226 @@
+/* -*- 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