1 files changed, 158 insertions, 0 deletions
diff --git a/dom/svg/SVGLength.h b/dom/svg/SVGLength.h
new file mode 100644
index 0000000000..ab0cef140a
--- /dev/null
+++ b/dom/svg/SVGLength.h
@@ -0,0 +1,158 @@
+/* -*- 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/. */
+
+#ifndef DOM_SVG_SVGLENGTH_H_
+#define DOM_SVG_SVGLENGTH_H_
+
+#include "nsDebug.h"
+#include "nsMathUtils.h"
+#include "mozilla/FloatingPoint.h"
+#include "mozilla/dom/SVGLengthBinding.h"
+
+namespace mozilla {
+
+namespace dom {
+class SVGElement;
+}
+
+/**
+ * This SVGLength class is currently used for SVGLength *list* attributes only.
+ * The class that is currently used for <length> attributes is
+ * SVGAnimatedLength.
+ *
+ * The member mUnit should always be valid, but the member mValue may be
+ * numeric_limits<float>::quiet_NaN() under one circumstances (see the comment
+ * in SetValueAndUnit below). Even if mValue is valid, some methods may return
+ * numeric_limits<float>::quiet_NaN() if they involve a unit conversion that
+ * fails - see comments below.
+ *
+ * The DOM wrapper class for this class is DOMSVGLength.
+ */
+class SVGLength {
+ public:
+  SVGLength()
+      : mValue(0.0f),
+        mUnit(dom::SVGLength_Binding::SVG_LENGTHTYPE_UNKNOWN)  // caught by
+                                                               // IsValid()
+  {}
+
+  SVGLength(float aValue, uint8_t aUnit) : mValue(aValue), mUnit(aUnit) {
+    NS_ASSERTION(IsValid(), "Constructed an invalid length");
+  }
+
+  bool operator==(const SVGLength& rhs) const {
+    return mValue == rhs.mValue && mUnit == rhs.mUnit;
+  }
+
+  void GetValueAsString(nsAString& aValue) const;
+
+  /**
+   * This method returns true, unless there was a parse failure, in which
+   * case it returns false (and the length is left unchanged).
+   */
+  bool SetValueFromString(const nsAString& aString);
+
+  /**
+   * This will usually return a valid, finite number. There is one exception
+   * though - see the comment in SetValueAndUnit().
+   */
+  float GetValueInCurrentUnits() const { return mValue; }
+
+  uint8_t GetUnit() const { return mUnit; }
+
+  void SetValueInCurrentUnits(float aValue) {
+    mValue = aValue;
+    NS_ASSERTION(IsValid(), "Set invalid SVGLength");
+  }
+
+  void SetValueAndUnit(float aValue, uint8_t aUnit) {
+    mValue = aValue;
+    mUnit = aUnit;
+
+    // IsValid() should always be true, with one exception: if
+    // SVGLengthListSMILType has to convert between unit types and the unit
+    // conversion is undefined, it will end up passing in and setting
+    // numeric_limits<float>::quiet_NaN(). Because of that we only check the
+    // unit here, and allow mValue to be invalid. The painting code has to be
+    // able to handle NaN anyway, since conversion to user units may fail in
+    // general.
+
+    NS_ASSERTION(IsValidUnitType(mUnit), "Set invalid SVGLength");
+  }
+
+  /**
+   * If it's not possible to convert this length's value to user units, then
+   * this method will return numeric_limits<float>::quiet_NaN().
+   */
+  float GetValueInUserUnits(const dom::SVGElement* aElement,
+                            uint8_t aAxis) const {
+    return mValue * GetUserUnitsPerUnit(aElement, aAxis);
+  }
+
+  /**
+   * Get this length's value in the units specified.
+   *
+   * This method returns numeric_limits<float>::quiet_NaN() if it is not
+   * possible to convert the value to the specified unit.
+   */
+  float GetValueInSpecifiedUnit(uint8_t aUnit, const dom::SVGElement* aElement,
+                                uint8_t aAxis) const;
+
+  bool IsPercentage() const {
+    return mUnit == dom::SVGLength_Binding::SVG_LENGTHTYPE_PERCENTAGE;
+  }
+
+  static bool IsValidUnitType(uint16_t aUnitType) {
+    return aUnitType > dom::SVGLength_Binding::SVG_LENGTHTYPE_UNKNOWN &&
+           aUnitType <= dom::SVGLength_Binding::SVG_LENGTHTYPE_PC;
+  }
+
+  static void GetUnitString(nsAString& aUnit, uint16_t aUnitType);
+
+  static uint16_t GetUnitTypeForString(const nsAString& aUnit);
+
+  /**
+   * Returns the number of user units per current unit.
+   *
+   * This method returns numeric_limits<float>::quiet_NaN() if the conversion
+   * factor between the length's current unit and user units is undefined (see
+   * the comments for GetUserUnitsPerInch and GetUserUnitsPerPercent).
+   */
+  float GetUserUnitsPerUnit(const dom::SVGElement* aElement,
+                            uint8_t aAxis) const;
+
+ private:
+#ifdef DEBUG
+  bool IsValid() const {
+    return std::isfinite(mValue) && IsValidUnitType(mUnit);
+  }
+#endif
+
+  /**
+   * The conversion factor between user units (CSS px) and CSS inches is
+   * constant: 96 px per inch.
+   */
+  static float GetUserUnitsPerInch() { return 96.0; }
+
+  /**
+   * The conversion factor between user units and percentage units depends on
+   * aElement being non-null, and on aElement having a viewport element
+   * ancestor with only appropriate SVG elements between aElement and that
+   * ancestor. If that's not the case, then the conversion factor is undefined.
+   *
+   * This function returns a non-negative value if the conversion factor is
+   * defined, otherwise it returns numeric_limits<float>::quiet_NaN().
+   */
+  static float GetUserUnitsPerPercent(const dom::SVGElement* aElement,
+                                      uint8_t aAxis);
+
+  float mValue;
+  uint8_t mUnit;
+};
+
+}  // namespace mozilla
+
+#endif  // DOM_SVG_SVGLENGTH_H_