void FontCollection::itemize(const uint16_t* string,
size_t string_size,
FontStyle style,
vector<Run>* result) const {
const uint32_t langListId = style.getLanguageListId();
int variant = style.getVariant();
const FontFamily* lastFamily = nullptr;
Run* run = NULL;
if (string_size == 0) {
return;
}
const uint32_t kEndOfString = 0xFFFFFFFF;
uint32_t nextCh = 0;
uint32_t prevCh = 0;
size_t nextUtf16Pos = 0;
size_t readLength = 0;
U16_NEXT(string, readLength, string_size, nextCh);
do {
const uint32_t ch = nextCh;
const size_t utf16Pos = nextUtf16Pos;
nextUtf16Pos = readLength;
if (readLength < string_size) {
U16_NEXT(string, readLength, string_size, nextCh);
} else {
nextCh = kEndOfString;
}
bool shouldContinueRun = false;
if (lastFamily != nullptr) {
if (isStickyWhitelisted(ch)) {
// Continue using existing font as long as it has coverage and is
// whitelisted
shouldContinueRun = lastFamily->getCoverage().get(ch);
} else if (ch == SOFT_HYPHEN || isVariationSelector(ch)) {
// Always continue if the character is the soft hyphen or a variation
// selector.
shouldContinueRun = true;
}
}
if (!shouldContinueRun) {
const std::shared_ptr<FontFamily>& family = getFamilyForChar(
ch, isVariationSelector(nextCh) ? nextCh : 0, langListId, variant);
if (utf16Pos == 0 || family.get() != lastFamily) {
size_t start = utf16Pos;
// Workaround for combining marks and emoji modifiers until we implement
// per-cluster font selection: if a combining mark or an emoji modifier
// is found in a different font that also supports the previous
// character, attach previous character to the new run. U+20E3 COMBINING
// ENCLOSING KEYCAP, used in emoji, is handled properly by this since
// it's a combining mark too.
if (utf16Pos != 0 &&
((U_GET_GC_MASK(ch) & U_GC_M_MASK) != 0 ||
(isEmojiModifier(ch) && isEmojiBase(prevCh))) &&
family != nullptr && family->getCoverage().get(prevCh)) {
const size_t prevChLength = U16_LENGTH(prevCh);
run->end -= prevChLength;
if (run->start == run->end) {
result->pop_back();
}
start -= prevChLength;
}
result->push_back(
{family->getClosestMatch(style), static_cast<int>(start), 0});
run = &result->back();
lastFamily = family.get();
}
}
prevCh = ch;
run->end = nextUtf16Pos; // exclusive
} while (nextCh != kEndOfString);
}
