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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 MOZILLA_SVGLENGTH_H__
#define MOZILLA_SVGLENGTH_H__
#include "nsDebug.h"
#include "nsIDOMSVGLength.h"
#include "nsMathUtils.h"
#include "mozilla/FloatingPoint.h"
class nsSVGElement;
namespace mozilla {
/**
* This SVGLength class is currently used for SVGLength *list* attributes only.
* The class that is currently used for <length> attributes is nsSVGLength2.
*
* 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()
#ifdef DEBUG
: mValue(0.0f)
, mUnit(nsIDOMSVGLength::SVG_LENGTHTYPE_UNKNOWN) // caught by IsValid()
#endif
{}
SVGLength(float aValue, uint8_t aUnit)
: mValue(aValue)
, mUnit(aUnit)
{
NS_ASSERTION(IsValid(), "Constructed an invalid length");
}
SVGLength(const SVGLength &aOther)
: mValue(aOther.mValue)
, mUnit(aOther.mUnit)
{}
SVGLength& operator=(const SVGLength &rhs) {
mValue = rhs.mValue;
mUnit = rhs.mUnit;
return *this;
}
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& aValue);
/**
* 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 nsSVGElement *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 nsSVGElement *aElement,
uint8_t aAxis) const;
bool IsPercentage() const {
return mUnit == nsIDOMSVGLength::SVG_LENGTHTYPE_PERCENTAGE;
}
static bool IsValidUnitType(uint16_t unit) {
return unit > nsIDOMSVGLength::SVG_LENGTHTYPE_UNKNOWN &&
unit <= nsIDOMSVGLength::SVG_LENGTHTYPE_PC;
}
/**
* 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 nsSVGElement *aElement, uint8_t aAxis) const;
private:
#ifdef DEBUG
bool IsValid() const {
return 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 nsSVGElement *aElement, uint8_t aAxis);
float mValue;
uint8_t mUnit;
};
} // namespace mozilla
#endif // MOZILLA_SVGLENGTH_H__
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