void
ResponsiveImageSelector::MaybeAppendDefaultCandidate()
{
if (mDefaultSourceURL.IsEmpty()) {
return;
}
int numCandidates = mCandidates.Length();
// https://html.spec.whatwg.org/multipage/embedded-content.html#update-the-source-set
// step 4.1.3:
// If child has a src attribute whose value is not the empty string and source
// set does not contain an image source with a density descriptor value of 1,
// and no image source with a width descriptor, append child's src attribute
// value to source set.
for (int i = 0; i < numCandidates; i++) {
if (mCandidates[i].IsComputedFromWidth()) {
return;
} else if (mCandidates[i].Density(this) == 1.0) {
return;
}
}
ResponsiveImageCandidate defaultCandidate;
defaultCandidate.SetParameterDefault();
defaultCandidate.SetURLSpec(mDefaultSourceURL);
// We don't use MaybeAppend since we want to keep this even if it can never
// match, as it may if the source set changes.
mCandidates.AppendElement(defaultCandidate);
}
void
ResponsiveImageDescriptors::FillCandidate(ResponsiveImageCandidate &aCandidate)
{
if (!Valid()) {
aCandidate.SetParameterInvalid();
} else if (mWidth.isSome()) {
MOZ_ASSERT(mDensity.isNothing()); // Shouldn't be valid
aCandidate.SetParameterAsComputedWidth(*mWidth);
} else if (mDensity.isSome()) {
MOZ_ASSERT(mWidth.isNothing()); // Shouldn't be valid
aCandidate.SetParameterAsDensity(*mDensity);
} else {
// A valid set of descriptors with no density nor width (e.g. an empty set)
// becomes 1.0 density, per spec
aCandidate.SetParameterAsDensity(1.0);
}
}
void
ResponsiveImageSelector::AppendCandidateIfUnique(const ResponsiveImageCandidate & aCandidate)
{
int numCandidates = mCandidates.Length();
// With the exception of Default, which should not be added until we are done
// building the list.
if (aCandidate.Type() == ResponsiveImageCandidate::eCandidateType_Default) {
return;
}
// Discard candidates with identical parameters, they will never match
for (int i = 0; i < numCandidates; i++) {
if (mCandidates[i].HasSameParameter(aCandidate)) {
return;
}
}
mCandidates.AppendElement(aCandidate);
}
void
ResponsiveImageSelector::AppendCandidateIfUnique(const ResponsiveImageCandidate & aCandidate)
{
int numCandidates = mCandidates.Length();
// With the exception of Default, which should not be added until we are done
// building the list, the spec forbids mixing width and explicit density
// selectors in the same set.
if (numCandidates && mCandidates[0].Type() != aCandidate.Type()) {
return;
}
// Discard candidates with identical parameters, they will never match
for (int i = 0; i < numCandidates; i++) {
if (mCandidates[i].HasSameParameter(aCandidate)) {
return;
}
}
mCandidates.AppendElement(aCandidate);
}
// http://www.whatwg.org/specs/web-apps/current-work/#processing-the-image-candidates
bool
ResponsiveImageSelector::SetCandidatesFromSourceSet(const nsAString & aSrcSet)
{
ClearSelectedCandidate();
nsCOMPtr<nsIURI> docBaseURI = mOwnerNode ? mOwnerNode->GetBaseURI() : nullptr;
if (!docBaseURI) {
MOZ_ASSERT(false,
"Should not be parsing SourceSet without a document");
return false;
}
mCandidates.Clear();
nsAString::const_iterator iter, end;
aSrcSet.BeginReading(iter);
aSrcSet.EndReading(end);
// Read URL / descriptor pairs
while (iter != end) {
nsAString::const_iterator url, urlEnd, descriptor;
// Skip whitespace and commas.
// Extra commas at this point are a non-fatal syntax error.
for (; iter != end && (nsContentUtils::IsHTMLWhitespace(*iter) ||
*iter == char16_t(',')); ++iter);
if (iter == end) {
break;
}
url = iter;
// Find end of url
for (;iter != end && !nsContentUtils::IsHTMLWhitespace(*iter); ++iter);
// Omit trailing commas from URL.
// Multiple commas are a non-fatal error.
while (iter != url) {
if (*(--iter) != char16_t(',')) {
iter++;
break;
}
}
const nsDependentSubstring &urlStr = Substring(url, iter);
MOZ_ASSERT(url != iter, "Shouldn't have empty URL at this point");
ResponsiveImageCandidate candidate;
if (candidate.ConsumeDescriptors(iter, end)) {
candidate.SetURLSpec(urlStr);
AppendCandidateIfUnique(candidate);
}
}
bool parsedCandidates = mCandidates.Length() > 0;
// Re-add default to end of list
MaybeAppendDefaultCandidate();
return parsedCandidates;
}
