static PathInterpolationResult CanInterpolate(const SVGPathDataAndInfo& aStart,
const SVGPathDataAndInfo& aEnd) {
if (aStart.IsIdentity()) {
return eCanInterpolate;
}
if (aStart.Length() != aEnd.Length()) {
return eCannotInterpolate;
}
PathInterpolationResult result = eCanInterpolate;
SVGPathDataAndInfo::const_iterator pStart = aStart.begin();
SVGPathDataAndInfo::const_iterator pEnd = aEnd.begin();
SVGPathDataAndInfo::const_iterator pStartDataEnd = aStart.end();
SVGPathDataAndInfo::const_iterator pEndDataEnd = aEnd.end();
while (pStart < pStartDataEnd && pEnd < pEndDataEnd) {
uint32_t startType = SVGPathSegUtils::DecodeType(*pStart);
uint32_t endType = SVGPathSegUtils::DecodeType(*pEnd);
if (SVGPathSegUtils::IsArcType(startType) &&
SVGPathSegUtils::IsArcType(endType) && ArcFlagsDiffer(pStart, pEnd)) {
return eCannotInterpolate;
}
if (startType != endType) {
if (!SVGPathSegUtils::SameTypeModuloRelativeness(startType, endType)) {
return eCannotInterpolate;
}
result = eRequiresConversion;
}
pStart += 1 + SVGPathSegUtils::ArgCountForType(startType);
pEnd += 1 + SVGPathSegUtils::ArgCountForType(endType);
}
MOZ_ASSERT(pStart <= pStartDataEnd && pEnd <= pEndDataEnd,
"Iterated past end of buffer! (Corrupt path data?)");
if (pStart != pStartDataEnd || pEnd != pEndDataEnd) {
return eCannotInterpolate;
}
return result;
}
/**
* Helper function for Add & Interpolate, to add multiples of two path-segment
* lists.
*
* NOTE: aList1 and aList2 are assumed to have their segment-types and
* segment-count match exactly (unless aList1 is an identity value).
*
* NOTE: aResult, the output list, is expected to either be an identity value
* (in which case we'll grow it) *or* to already have the exactly right length
* (e.g. in cases where aList1 and aResult are actually the same list).
*
* @param aCoeff1 The coefficient to use on the first path segment list.
* @param aList1 The first path segment list. Allowed to be identity.
* @param aCoeff2 The coefficient to use on the second path segment list.
* @param aList2 The second path segment list.
* @param [out] aResultSeg The resulting path segment list. Allowed to be
* identity, in which case we'll grow it to the right
* size. Also allowed to be the same list as aList1.
*/
static nsresult AddWeightedPathSegLists(double aCoeff1,
const SVGPathDataAndInfo& aList1,
double aCoeff2,
const SVGPathDataAndInfo& aList2,
SVGPathDataAndInfo& aResult) {
MOZ_ASSERT(aCoeff1 >= 0.0 && aCoeff2 >= 0.0,
"expecting non-negative coefficients");
MOZ_ASSERT(!aList2.IsIdentity(), "expecting 2nd list to be non-identity");
MOZ_ASSERT(aList1.IsIdentity() || aList1.Length() == aList2.Length(),
"expecting 1st list to be identity or to have same "
"length as 2nd list");
MOZ_ASSERT(aResult.IsIdentity() || aResult.Length() == aList2.Length(),
"expecting result list to be identity or to have same "
"length as 2nd list");
SVGPathDataAndInfo::const_iterator iter1, end1;
if (aList1.IsIdentity()) {
iter1 = end1 = nullptr; // indicate that this is an identity list
} else {
iter1 = aList1.begin();
end1 = aList1.end();
}
SVGPathDataAndInfo::const_iterator iter2 = aList2.begin();
SVGPathDataAndInfo::const_iterator end2 = aList2.end();
// Grow |aResult| if necessary. (NOTE: It's possible that aResult and aList1
// are the same list, so this may implicitly resize aList1. That's fine,
// because in that case, we will have already set iter1 to nullptr above, to
// record that our first operand is an identity value.)
if (aResult.IsIdentity()) {
if (!aResult.SetLength(aList2.Length())) {
return NS_ERROR_OUT_OF_MEMORY;
}
aResult.SetElement(aList2.Element()); // propagate target element info!
}
SVGPathDataAndInfo::iterator resultIter = aResult.begin();
while ((!iter1 || iter1 != end1) && iter2 != end2) {
AddWeightedPathSegs(aCoeff1, iter1, aCoeff2, iter2, resultIter);
}
MOZ_ASSERT(
(!iter1 || iter1 == end1) && iter2 == end2 && resultIter == aResult.end(),
"Very, very bad - path data corrupt");
return NS_OK;
}