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Optimize loading fallback font-family performance #13257

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Optimize loading fallback font-family performance #13257

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0170fa0
fix loading fallback font-family takes too much time
wangying3426 Oct 21, 2019
91ea492
fix clang-format checks failure
wangying3426 Oct 21, 2019
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23 changes: 23 additions & 0 deletions third_party/txt/src/minikin/FontCollection.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,9 @@ const uint32_t TEXT_STYLE_VS = 0xFE0E;

uint32_t FontCollection::sNextId = 0;

const uint32_t kMinFallbackScore = 0x20000000;
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@jason-simmons jason-simmons Oct 31, 2019

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Replace the calcFamilyScore >= kMinFallbackScore checks with a call to calcCoverageScore.

calcFamilyScore is a combination of calcCoverageScore and some other scores. If calcCoverageScore returns a nonzero result, then that is equivalent to calcFamilyScore returning a score >= 0x20000000.

std::vector<std::shared_ptr<FontFamily>> sFallbackFamilies;
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@jason-simmons jason-simmons Oct 31, 2019

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Make this a member of the FontCollection class instead of a global. The member will need to be mutable because FontCollection::getFamilyForChar is const.

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@GaryQian GaryQian Oct 31, 2019

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It is a unclear to me exactly why this is called sFallbackFamilies, maybe consider a more descriptive name?

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@wangying3426 wangying3426 Dec 12, 2019

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It is a unclear to me exactly why this is called sFallbackFamilies, maybe consider a more descriptive name?

@GaryQian What's your suggested name?


// libtxt: return a locale string for a language list ID
std::string GetFontLocale(uint32_t langListId) {
const FontLanguages& langs = FontLanguageListCache::getById(langListId);
Expand All @@ -64,6 +67,10 @@ FontCollection::FontCollection(
init(typefaces);
}

FontCollection::~FontCollection() {
sFallbackFamilies.clear();
}

void FontCollection::init(
const vector<std::shared_ptr<FontFamily>>& typefaces) {
std::scoped_lock _l(gMinikinLock);
Expand Down Expand Up @@ -299,12 +306,20 @@ const std::shared_ptr<FontFamily>& FontCollection::getFamilyForChar(
uint32_t langListId,
int variant) const {
if (ch >= mMaxChar) {
for (size_t i = 0; i < sFallbackFamilies.size(); i++) {
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@GaryQian GaryQian Oct 31, 2019 •
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(optional) Since this is identical to the snippet below (line 355), consider using helper function to help keep these two sections in sync.

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@GaryQian GaryQian Oct 31, 2019

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Also, since it would be helpful to have a short comment explaining why this is necessary.

const uint32_t score =
calcFamilyScore(ch, vs, variant, langListId, sFallbackFamilies[i]);
if (score >= kMinFallbackScore) {
return sFallbackFamilies[i];
}
}
// libtxt: check if the fallback font provider can match this character
if (mFallbackFontProvider) {
const std::shared_ptr<FontFamily>& fallback =
mFallbackFontProvider->matchFallbackFont(ch,
GetFontLocale(langListId));
if (fallback) {
sFallbackFamilies.push_back(fallback);
return fallback;
}
}
Expand Down Expand Up @@ -337,12 +352,20 @@ const std::shared_ptr<FontFamily>& FontCollection::getFamilyForChar(
}
}
if (bestFamilyIndex == -1) {
for (size_t i = 0; i < sFallbackFamilies.size(); i++) {
const uint32_t score =
calcFamilyScore(ch, vs, variant, langListId, sFallbackFamilies[i]);
if (score >= kMinFallbackScore) {
return sFallbackFamilies[i];
}
}
// libtxt: check if the fallback font provider can match this character
if (mFallbackFontProvider) {
const std::shared_ptr<FontFamily>& fallback =
mFallbackFontProvider->matchFallbackFont(ch,
GetFontLocale(langListId));
if (fallback) {
sFallbackFamilies.push_back(fallback);
return fallback;
}
}
Expand Down
2 changes: 2 additions & 0 deletions third_party/txt/src/minikin/FontCollection.h
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,8 @@ class FontCollection {
const std::vector<std::shared_ptr<FontFamily>>& typefaces);
explicit FontCollection(std::shared_ptr<FontFamily>&& typeface);

~FontCollection();

// libtxt extension: an interface for looking up fallback fonts for characters
// that do not match this collection's font families.
class FallbackFontProvider {
Expand Down