ImageCandidate bestFitSourceForImageAttributes(float deviceScaleFactor, const AtomicString& srcAttribute, const AtomicString& srcsetAttribute
#if ENABLE(PICTURE_SIZES)
, unsigned sourceSize
#endif
)
{
if (srcsetAttribute.isNull()) {
if (srcAttribute.isNull())
return ImageCandidate();
return ImageCandidate(StringView(srcAttribute), DescriptorParsingResult(), ImageCandidate::SrcOrigin);
}
Vector<ImageCandidate> imageCandidates;
parseImageCandidatesFromSrcsetAttribute(StringView(srcsetAttribute), imageCandidates);
if (!srcAttribute.isEmpty())
imageCandidates.append(ImageCandidate(StringView(srcAttribute), DescriptorParsingResult(), ImageCandidate::SrcOrigin));
return pickBestImageCandidate(deviceScaleFactor, imageCandidates
#if ENABLE(PICTURE_SIZES)
, sourceSize
#endif
);
}
ImageCandidate bestFitSourceForImageAttributes(float deviceScaleFactor, unsigned sourceSize, const String& srcAttribute, const String& srcsetAttribute)
{
if (srcsetAttribute.isNull()) {
if (srcAttribute.isNull())
return ImageCandidate();
return ImageCandidate(srcAttribute, 0, srcAttribute.length(), DescriptorParsingResult(), ImageCandidate::SrcOrigin);
}
Vector<ImageCandidate> imageCandidates;
parseImageCandidatesFromSrcsetAttribute(srcsetAttribute, imageCandidates);
if (!srcAttribute.isEmpty())
imageCandidates.append(ImageCandidate(srcAttribute, 0, srcAttribute.length(), DescriptorParsingResult(), ImageCandidate::SrcOrigin));
return pickBestImageCandidate(deviceScaleFactor, sourceSize, imageCandidates);
}
static void parseImageCandidatesFromSrcsetAttribute(const String& attribute, const CharType* attributeStart, unsigned length, Vector<ImageCandidate>& imageCandidates, Document* document)
{
const CharType* position = attributeStart;
const CharType* attributeEnd = position + length;
while (position < attributeEnd) {
// 4. Splitting loop: Collect a sequence of characters that are space characters or U+002C COMMA characters.
skipWhile<CharType, isHTMLSpaceOrComma<CharType>>(position, attributeEnd);
if (position == attributeEnd) {
// Contrary to spec language - descriptor parsing happens on each candidate, so when we reach the attributeEnd, we can exit.
break;
}
const CharType* imageURLStart = position;
// 6. Collect a sequence of characters that are not space characters, and let that be url.
skipUntil<CharType, isHTMLSpace<CharType>>(position, attributeEnd);
const CharType* imageURLEnd = position;
DescriptorParsingResult result;
// 8. If url ends with a U+002C COMMA character (,)
if (isComma(*(position - 1))) {
// Remove all trailing U+002C COMMA characters from url.
imageURLEnd = position - 1;
reverseSkipWhile<CharType, isComma>(imageURLEnd, imageURLStart);
++imageURLEnd;
// If url is empty, then jump to the step labeled splitting loop.
if (imageURLStart == imageURLEnd)
continue;
} else {
skipWhile<CharType, isHTMLSpace<CharType>>(position, attributeEnd);
Vector<DescriptorToken> descriptorTokens;
tokenizeDescriptors(attributeStart, position, attributeEnd, descriptorTokens);
// Contrary to spec language - descriptor parsing happens on each candidate.
// This is a black-box equivalent, to avoid storing descriptor lists for each candidate.
if (!parseDescriptors(attribute, descriptorTokens, result, document)) {
if (document) {
UseCounter::count(document, UseCounter::SrcsetDroppedCandidate);
if (document->frame())
document->frame()->console().addMessage(ConsoleMessage::create(OtherMessageSource, ErrorMessageLevel, String("Dropped srcset candidate ") + String(imageURLStart, imageURLEnd - imageURLStart)));
}
continue;
}
}
ASSERT(imageURLEnd > attributeStart);
unsigned imageURLStartingPosition = imageURLStart - attributeStart;
ASSERT(imageURLEnd > imageURLStart);
unsigned imageURLLength = imageURLEnd - imageURLStart;
imageCandidates.append(ImageCandidate(attribute, imageURLStartingPosition, imageURLLength, result, ImageCandidate::SrcsetOrigin));
// 11. Return to the step labeled splitting loop.
}
}
String bestFitSourceForImageAttributes(float deviceScaleFactor, float sourceSize, const String& srcAttribute, ImageCandidate& srcsetImageCandidate)
{
if (srcsetImageCandidate.isEmpty())
return srcAttribute;
Vector<ImageCandidate> imageCandidates;
imageCandidates.append(srcsetImageCandidate);
if (!srcAttribute.isEmpty())
imageCandidates.append(ImageCandidate(srcAttribute, 0, srcAttribute.length(), DescriptorParsingResult(), ImageCandidate::SrcOrigin));
return pickBestImageCandidate(deviceScaleFactor, sourceSize, imageCandidates).toString();
}
static Vector<ImageCandidate> parseImageCandidatesFromSrcsetAttribute(const CharType* attributeStart, unsigned length)
{
Vector<ImageCandidate> imageCandidates;
const CharType* attributeEnd = attributeStart + length;
for (const CharType* position = attributeStart; position < attributeEnd;) {
// 4. Splitting loop: Collect a sequence of characters that are space characters or U+002C COMMA characters.
skipWhile<CharType, isHTMLSpaceOrComma<CharType> >(position, attributeEnd);
if (position == attributeEnd) {
// Contrary to spec language - descriptor parsing happens on each candidate, so when we reach the attributeEnd, we can exit.
break;
}
const CharType* imageURLStart = position;
// 6. Collect a sequence of characters that are not space characters, and let that be url.
skipUntil<CharType, isHTMLSpace<CharType> >(position, attributeEnd);
const CharType* imageURLEnd = position;
DescriptorParsingResult result;
// 8. If url ends with a U+002C COMMA character (,)
if (isComma(*(position - 1))) {
// Remove all trailing U+002C COMMA characters from url.
imageURLEnd = position - 1;
reverseSkipWhile<CharType, isComma>(imageURLEnd, imageURLStart);
++imageURLEnd;
// If url is empty, then jump to the step labeled splitting loop.
if (imageURLStart == imageURLEnd)
continue;
} else {
// Advancing position here (contrary to spec) to avoid an useless extra state machine step.
// Filed a spec bug: https://github.com/ResponsiveImagesCG/picture-element/issues/189
++position;
Vector<StringView> descriptorTokens;
tokenizeDescriptors(position, attributeEnd, descriptorTokens);
// Contrary to spec language - descriptor parsing happens on each candidate.
// This is a black-box equivalent, to avoid storing descriptor lists for each candidate.
if (!parseDescriptors(descriptorTokens, result))
continue;
}
ASSERT(imageURLEnd > imageURLStart);
unsigned imageURLLength = imageURLEnd - imageURLStart;
imageCandidates.append(ImageCandidate(StringView(imageURLStart, imageURLLength), result, ImageCandidate::SrcsetOrigin));
// 11. Return to the step labeled splitting loop.
}
return imageCandidates;
}
static ImageCandidate pickBestImageCandidate(float deviceScaleFactor, Vector<ImageCandidate>& imageCandidates
#if ENABLE(PICTURE_SIZES)
, unsigned sourceSize
#endif
)
{
bool ignoreSrc = false;
if (imageCandidates.isEmpty())
return ImageCandidate();
// http://picture.responsiveimages.org/#normalize-source-densities
for (auto& candidate : imageCandidates) {
#if ENABLE(PICTURE_SIZES)
if (candidate.resourceWidth > 0) {
candidate.density = static_cast<float>(candidate.resourceWidth) / static_cast<float>(sourceSize);
ignoreSrc = true;
} else
#endif
if (candidate.density < 0)
candidate.density = DefaultDensityValue;
}
std::stable_sort(imageCandidates.begin(), imageCandidates.end(), compareByDensity);
unsigned i;
for (i = 0; i < imageCandidates.size() - 1; ++i) {
if ((imageCandidates[i].density >= deviceScaleFactor) && (!ignoreSrc || !imageCandidates[i].srcOrigin()))
break;
}
if (imageCandidates[i].srcOrigin() && ignoreSrc) {
ASSERT(i > 0);
--i;
}
float winningDensity = imageCandidates[i].density;
unsigned winner = i;
// 16. If an entry b in candidates has the same associated ... pixel density as an earlier entry a in candidates,
// then remove entry b
while ((i > 0) && (imageCandidates[--i].density == winningDensity))
winner = i;
return imageCandidates[winner];
}
static ImageCandidate pickBestImageCandidate(float deviceScaleFactor, unsigned sourceSize, Vector<ImageCandidate>& imageCandidates)
{
const float defaultDensityValue = 1.0;
bool ignoreSrc = false;
if (imageCandidates.isEmpty())
return ImageCandidate();
// http://picture.responsiveimages.org/#normalize-source-densities
for (Vector<ImageCandidate>::iterator it = imageCandidates.begin(); it != imageCandidates.end(); ++it) {
if (it->resourceWidth() > 0) {
it->setDensity((float)it->resourceWidth() / (float)sourceSize);
ignoreSrc = true;
} else if (it->density() < 0) {
it->setDensity(defaultDensityValue);
}
}
std::stable_sort(imageCandidates.begin(), imageCandidates.end(), compareByDensity);
unsigned i;
for (i = 0; i < imageCandidates.size() - 1; ++i) {
if ((imageCandidates[i].density() >= deviceScaleFactor) && (!ignoreSrc || !imageCandidates[i].srcOrigin()))
break;
}
if (imageCandidates[i].srcOrigin() && ignoreSrc) {
ASSERT(i > 0);
--i;
}
float winningDensity = imageCandidates[i].density();
unsigned winner = i;
// 16. If an entry b in candidates has the same associated ... pixel density as an earlier entry a in candidates,
// then remove entry b
while ((i > 0) && (imageCandidates[--i].density() == winningDensity))
winner = i;
return imageCandidates[winner];
}
static ImageCandidate pickBestImageCandidate(float deviceScaleFactor, float sourceSize, Vector<ImageCandidate>& imageCandidates, Document* document = nullptr)
{
const float defaultDensityValue = 1.0;
bool ignoreSrc = false;
if (imageCandidates.isEmpty())
return ImageCandidate();
// http://picture.responsiveimages.org/#normalize-source-densities
for (ImageCandidate& image : imageCandidates) {
if (image.resourceWidth() > 0) {
image.setDensity((float)image.resourceWidth() / sourceSize);
ignoreSrc = true;
} else if (image.density() < 0) {
image.setDensity(defaultDensityValue);
}
}
std::stable_sort(imageCandidates.begin(), imageCandidates.end(), compareByDensity);
Vector<ImageCandidate*> deDupedImageCandidates;
float prevDensity = -1.0;
for (ImageCandidate& image : imageCandidates) {
if (image.density() != prevDensity && (!ignoreSrc || !image.srcOrigin()))
deDupedImageCandidates.append(&image);
prevDensity = image.density();
}
unsigned winner = selectionLogic(deDupedImageCandidates, deviceScaleFactor);
ASSERT(winner < deDupedImageCandidates.size());
winner = avoidDownloadIfHigherDensityResourceIsInCache(deDupedImageCandidates, winner, document);
float winningDensity = deDupedImageCandidates[winner]->density();
// 16. If an entry b in candidates has the same associated ... pixel density as an earlier entry a in candidates,
// then remove entry b
while ((winner > 0) && (deDupedImageCandidates[winner - 1]->density() == winningDensity))
--winner;
return *deDupedImageCandidates[winner];
}
