dom/svg/SVGLength.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef DOM_SVG_SVGLENGTH_H_
   8 #define DOM_SVG_SVGLENGTH_H_
   9
  10 #include "nsDebug.h"
  11 #include "nsMathUtils.h"
  12 #include "mozilla/FloatingPoint.h"
  13 #include "mozilla/dom/SVGAnimatedLength.h"
  14 #include "mozilla/dom/SVGLengthBinding.h"
  15
  16 enum nsCSSUnit : uint32_t;
  17
  18 namespace mozilla {
  19
  20 namespace dom {
  21 class SVGElement;
  22 }
  23
  24 /**
  25  * This SVGLength class is currently used for SVGLength *list* attributes only.
  26  * The class that is currently used for <length> attributes is
  27  * SVGAnimatedLength.
  28  *
  29  * The member mUnit should always be valid, but the member mValue may be
  30  * numeric_limits<float>::quiet_NaN() under one circumstances (see the comment
  31  * in SetValueAndUnit below). Even if mValue is valid, some methods may return
  32  * numeric_limits<float>::quiet_NaN() if they involve a unit conversion that
  33  * fails - see comments below.
  34  *
  35  * The DOM wrapper class for this class is DOMSVGLength.
  36  */
  37 class SVGLength {
  38  public:
  39   SVGLength()
  40       : mValue(0.0f), mUnit(dom::SVGLength_Binding::SVG_LENGTHTYPE_UNKNOWN) {}
  41
  42   SVGLength(float aValue, uint8_t aUnit) : mValue(aValue), mUnit(aUnit) {}
  43
  44   bool operator==(const SVGLength& rhs) const {
  45     return mValue == rhs.mValue && mUnit == rhs.mUnit;
  46   }
  47
  48   void GetValueAsString(nsAString& aValue) const;
  49
  50   /**
  51    * This method returns true, unless there was a parse failure, in which
  52    * case it returns false (and the length is left unchanged).
  53    */
  54   bool SetValueFromString(const nsAString& aString);
  55
  56   /**
  57    * This will usually return a valid, finite number. There is one exception
  58    * though. If SVGLengthListSMILType has to convert between unit types and the
  59    * unit conversion is undefined, it will end up passing in and setting
  60    * numeric_limits<float>::quiet_NaN(). The painting code has to be
  61    * able to handle NaN anyway, since conversion to user units may fail in
  62    * general.
  63    */
  64   float GetValueInCurrentUnits() const { return mValue; }
  65
  66   uint8_t GetUnit() const { return mUnit; }
  67
  68   void SetValueInCurrentUnits(float aValue) {
  69     NS_ASSERTION(std::isfinite(aValue), "Set invalid SVGLength");
  70     mValue = aValue;
  71   }
  72
  73   void SetValueAndUnit(float aValue, uint8_t aUnit) {
  74     mValue = aValue;
  75     mUnit = aUnit;
  76   }
  77
  78   /**
  79    * If it's not possible to convert this length's value to pixels, then
  80    * this method will return numeric_limits<float>::quiet_NaN().
  81    */
  82
  83   float GetValueInPixels(const dom::SVGElement* aElement, uint8_t aAxis) const {
  84     return mValue * GetPixelsPerUnit(dom::SVGElementMetrics(aElement), aAxis);
  85   }
  86
  87   /**
  88    * Get this length's value in the units specified.
  89    *
  90    * This method returns numeric_limits<float>::quiet_NaN() if it is not
  91    * possible to convert the value to the specified unit.
  92    */
  93   float GetValueInSpecifiedUnit(uint8_t aUnit, const dom::SVGElement* aElement,
  94                                 uint8_t aAxis) const;
  95
  96   bool IsPercentage() const {
  97     return mUnit == dom::SVGLength_Binding::SVG_LENGTHTYPE_PERCENTAGE;
  98   }
  99
 100   float GetPixelsPerUnit(const dom::UserSpaceMetrics& aMetrics,
 101                          uint8_t aAxis) const {
 102     return GetPixelsPerUnit(aMetrics, mUnit, aAxis);
 103   }
 104
 105   static bool IsValidUnitType(uint16_t aUnitType) {
 106     return aUnitType > dom::SVGLength_Binding::SVG_LENGTHTYPE_UNKNOWN &&
 107            aUnitType <= dom::SVGLength_Binding::SVG_LENGTHTYPE_PC;
 108   }
 109
 110   static bool IsAbsoluteUnit(uint8_t aUnit);
 111
 112   static float GetAbsUnitsPerAbsUnit(uint8_t aUnits, uint8_t aPerUnit);
 113
 114   static nsCSSUnit SpecifiedUnitTypeToCSSUnit(uint8_t aSpecifiedUnit);
 115
 116   static void GetUnitString(nsAString& aUnit, uint16_t aUnitType);
 117
 118   static uint16_t GetUnitTypeForString(const nsAString& aUnit);
 119
 120   /**
 121    * Returns the number of pixels per given unit.
 122    */
 123   static float GetPixelsPerUnit(const dom::UserSpaceMetrics& aMetrics,
 124                                 uint8_t aUnitType, uint8_t aAxis);
 125
 126  private:
 127   float mValue;
 128   uint8_t mUnit;
 129 };
 130
 131 }  // namespace mozilla
 132
 133 #endif  // DOM_SVG_SVGLENGTH_H_