mirror of
https://github.com/mozilla/gecko-dev.git
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237 lines
7.2 KiB
C++
237 lines
7.2 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "mozilla/ArrayUtils.h"
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#include "SVGLength.h"
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#include "nsSVGElement.h"
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#include "mozilla/dom/SVGSVGElement.h"
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#include "nsTextFormatter.h"
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#include "SVGContentUtils.h"
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#include <limits>
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#include <algorithm>
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namespace mozilla {
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// Declare some helpers defined below:
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static void GetUnitString(nsAString& unit, uint16_t unitType);
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static uint16_t GetUnitTypeForString(const nsAString& unitStr);
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void
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SVGLength::GetValueAsString(nsAString &aValue) const
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{
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char16_t buf[24];
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nsTextFormatter::snprintf(buf, sizeof(buf)/sizeof(char16_t),
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MOZ_UTF16("%g"),
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(double)mValue);
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aValue.Assign(buf);
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nsAutoString unitString;
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GetUnitString(unitString, mUnit);
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aValue.Append(unitString);
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}
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bool
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SVGLength::SetValueFromString(const nsAString &aString)
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{
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RangedPtr<const char16_t> iter =
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SVGContentUtils::GetStartRangedPtr(aString);
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const RangedPtr<const char16_t> end =
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SVGContentUtils::GetEndRangedPtr(aString);
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float value;
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if (!SVGContentUtils::ParseNumber(iter, end, value)) {
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return false;
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}
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const nsAString& units = Substring(iter.get(), end.get());
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uint16_t unitType = GetUnitTypeForString(units);
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if (!IsValidUnitType(unitType)) {
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return false;
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}
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mValue = value;
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mUnit = uint8_t(unitType);
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return true;
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}
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inline static bool
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IsAbsoluteUnit(uint8_t aUnit)
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{
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return aUnit >= nsIDOMSVGLength::SVG_LENGTHTYPE_CM &&
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aUnit <= nsIDOMSVGLength::SVG_LENGTHTYPE_PC;
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}
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/**
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* Helper to convert between different CSS absolute units without the need for
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* an element, which provides more flexibility at the DOM level (and without
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* the need for an intermediary conversion to user units, which avoids
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* unnecessary overhead and rounding error).
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*
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* Example usage: to find out how many centimeters there are per inch:
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*
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* GetAbsUnitsPerAbsUnit(nsIDOMSVGLength::SVG_LENGTHTYPE_CM,
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* nsIDOMSVGLength::SVG_LENGTHTYPE_IN)
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*/
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inline static float GetAbsUnitsPerAbsUnit(uint8_t aUnits, uint8_t aPerUnit)
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{
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MOZ_ASSERT(IsAbsoluteUnit(aUnits), "Not a CSS absolute unit");
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MOZ_ASSERT(IsAbsoluteUnit(aPerUnit), "Not a CSS absolute unit");
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float CSSAbsoluteUnitConversionFactors[5][5] = { // columns: cm, mm, in, pt, pc
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// cm per...:
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{ 1.0f, 0.1f, 2.54f, 0.035277777777777778f, 0.42333333333333333f },
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// mm per...:
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{ 10.0f, 1.0f, 25.4f, 0.35277777777777778f, 4.2333333333333333f },
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// in per...:
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{ 0.39370078740157481f, 0.039370078740157481f, 1.0f, 0.013888888888888889f, 0.16666666666666667f },
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// pt per...:
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{ 28.346456692913386f, 2.8346456692913386f, 72.0f, 1.0f, 12.0f },
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// pc per...:
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{ 2.3622047244094489f, 0.23622047244094489f, 6.0f, 0.083333333333333333f, 1.0f }
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};
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// First absolute unit is SVG_LENGTHTYPE_CM = 6
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return CSSAbsoluteUnitConversionFactors[aUnits - 6][aPerUnit - 6];
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}
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float
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SVGLength::GetValueInSpecifiedUnit(uint8_t aUnit,
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const nsSVGElement *aElement,
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uint8_t aAxis) const
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{
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if (aUnit == mUnit) {
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return mValue;
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}
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if ((aUnit == nsIDOMSVGLength::SVG_LENGTHTYPE_NUMBER &&
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mUnit == nsIDOMSVGLength::SVG_LENGTHTYPE_PX) ||
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(aUnit == nsIDOMSVGLength::SVG_LENGTHTYPE_PX &&
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mUnit == nsIDOMSVGLength::SVG_LENGTHTYPE_NUMBER)) {
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return mValue;
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}
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if (IsAbsoluteUnit(aUnit) && IsAbsoluteUnit(mUnit)) {
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return mValue * GetAbsUnitsPerAbsUnit(aUnit, mUnit);
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}
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// Otherwise we do a two step convertion via user units. This can only
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// succeed if aElement is non-null (although that's not sufficent to
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// guarantee success).
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float userUnitsPerCurrentUnit = GetUserUnitsPerUnit(aElement, aAxis);
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float userUnitsPerNewUnit =
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SVGLength(0.0f, aUnit).GetUserUnitsPerUnit(aElement, aAxis);
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NS_ASSERTION(userUnitsPerCurrentUnit >= 0 ||
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!IsFinite(userUnitsPerCurrentUnit),
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"bad userUnitsPerCurrentUnit");
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NS_ASSERTION(userUnitsPerNewUnit >= 0 ||
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!IsFinite(userUnitsPerNewUnit),
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"bad userUnitsPerNewUnit");
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float value = mValue * userUnitsPerCurrentUnit / userUnitsPerNewUnit;
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// userUnitsPerCurrentUnit could be infinity, or userUnitsPerNewUnit could
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// be zero.
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if (IsFinite(value)) {
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return value;
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}
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return std::numeric_limits<float>::quiet_NaN();
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}
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#define INCHES_PER_MM_FLOAT float(0.0393700787)
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#define INCHES_PER_CM_FLOAT float(0.393700787)
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float
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SVGLength::GetUserUnitsPerUnit(const nsSVGElement *aElement, uint8_t aAxis) const
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{
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switch (mUnit) {
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case nsIDOMSVGLength::SVG_LENGTHTYPE_NUMBER:
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case nsIDOMSVGLength::SVG_LENGTHTYPE_PX:
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return 1.0f;
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case nsIDOMSVGLength::SVG_LENGTHTYPE_MM:
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return INCHES_PER_MM_FLOAT * GetUserUnitsPerInch();
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case nsIDOMSVGLength::SVG_LENGTHTYPE_CM:
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return INCHES_PER_CM_FLOAT * GetUserUnitsPerInch();
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case nsIDOMSVGLength::SVG_LENGTHTYPE_IN:
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return GetUserUnitsPerInch();
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case nsIDOMSVGLength::SVG_LENGTHTYPE_PT:
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return (1.0f/POINTS_PER_INCH_FLOAT) * GetUserUnitsPerInch();
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case nsIDOMSVGLength::SVG_LENGTHTYPE_PC:
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return (12.0f/POINTS_PER_INCH_FLOAT) * GetUserUnitsPerInch();
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case nsIDOMSVGLength::SVG_LENGTHTYPE_PERCENTAGE:
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return GetUserUnitsPerPercent(aElement, aAxis);
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case nsIDOMSVGLength::SVG_LENGTHTYPE_EMS:
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return SVGContentUtils::GetFontSize(const_cast<nsSVGElement*>(aElement));
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case nsIDOMSVGLength::SVG_LENGTHTYPE_EXS:
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return SVGContentUtils::GetFontXHeight(const_cast<nsSVGElement*>(aElement));
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default:
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NS_NOTREACHED("Unknown unit type");
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return std::numeric_limits<float>::quiet_NaN();
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}
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}
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/* static */ float
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SVGLength::GetUserUnitsPerPercent(const nsSVGElement *aElement, uint8_t aAxis)
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{
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if (aElement) {
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dom::SVGSVGElement *viewportElement = aElement->GetCtx();
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if (viewportElement) {
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return std::max(viewportElement->GetLength(aAxis) / 100.0f, 0.0f);
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}
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}
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return std::numeric_limits<float>::quiet_NaN();
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}
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// Helpers:
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// These items must be at the same index as the nsIDOMSVGLength constants!
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static nsIAtom** const unitMap[] =
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{
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nullptr, /* SVG_LENGTHTYPE_UNKNOWN */
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nullptr, /* SVG_LENGTHTYPE_NUMBER */
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&nsGkAtoms::percentage,
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&nsGkAtoms::em,
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&nsGkAtoms::ex,
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&nsGkAtoms::px,
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&nsGkAtoms::cm,
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&nsGkAtoms::mm,
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&nsGkAtoms::in,
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&nsGkAtoms::pt,
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&nsGkAtoms::pc
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};
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static void
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GetUnitString(nsAString& unit, uint16_t unitType)
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{
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if (SVGLength::IsValidUnitType(unitType)) {
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if (unitMap[unitType]) {
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(*unitMap[unitType])->ToString(unit);
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}
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return;
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}
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NS_NOTREACHED("Unknown unit type"); // Someone's using an SVGLength with an invalid unit?
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return;
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}
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static uint16_t
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GetUnitTypeForString(const nsAString& unitStr)
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{
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if (unitStr.IsEmpty())
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return nsIDOMSVGLength::SVG_LENGTHTYPE_NUMBER;
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nsIAtom* unitAtom = NS_GetStaticAtom(unitStr);
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if (unitAtom) {
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for (uint32_t i = 1 ; i < ArrayLength(unitMap) ; i++) {
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if (unitMap[i] && *unitMap[i] == unitAtom) {
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return i;
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}
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}
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}
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return nsIDOMSVGLength::SVG_LENGTHTYPE_UNKNOWN;
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}
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} // namespace mozilla
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