Add method that returns reference extent for locale

Bug: 303326708
Test: atest PaintFontMetricsForLocaleTest
Change-Id: I1fe2a475aed21a58f69e33ab91320dea77f463d5

4 files changed, 85 insertions, 0 deletions

diff --git a/include/minikin/FontCollection.h b/include/minikin/FontCollection.h
index 1679abc..7ad644a 100644
--- a/include/minikin/FontCollection.h
+++ b/include/minikin/FontCollection.h
@@ -147,6 +147,8 @@ public:
         return itemize(text, style, localeListId, familyVariant, text.size());
     }
 
+    MinikinExtent getReferenceExtentForLocale(const MinikinPaint& paint) const;
+
     // Returns true if there is a glyph for the code point and variation selector pair.
     // Returns false if no fonts have a glyph for the code point and variation
     // selector pair, or invalid variation selector is passed.
diff --git a/libs/minikin/FontCollection.cpp b/libs/minikin/FontCollection.cpp
index 0c1a173..440eab2 100644
--- a/libs/minikin/FontCollection.cpp
+++ b/libs/minikin/FontCollection.cpp
@@ -30,6 +30,8 @@
 #include "minikin/Characters.h"
 #include "minikin/Emoji.h"
 #include "minikin/FontFileParser.h"
+#include "minikin/MinikinExtent.h"
+#include "minikin/MinikinPaint.h"
 
 using std::vector;
 
@@ -606,6 +608,69 @@ FontCollection::FamilyMatchResult FontCollection::FamilyMatchResult::intersect(
     return b.build();
 }
 
+MinikinExtent FontCollection::getReferenceExtentForLocale(const MinikinPaint& paint) const {
+    uint32_t localeId = paint.localeListId;
+    MinikinExtent result(0, 0);
+    for (uint8_t i = 0; i < mFamilyCount; ++i) {
+        const auto& family = getFamilyAt(i);
+        if (!family->isCustomFallback()) {
+            break;
+        }
+
+        // Use this family
+        MinikinExtent extent(0, 0);
+        FakedFont font = getFamilyAt(i)->getClosestMatch(paint.fontStyle);
+        font.typeface()->GetFontExtent(&extent, paint, font.fakery);
+        result.extendBy(extent);
+    }
+
+    if (localeId == LocaleListCache::kInvalidListId) {
+        return result;
+    }
+
+    // If default is requested, use compact one.
+    const FamilyVariant requestVariant = paint.familyVariant == FamilyVariant::DEFAULT
+                                                 ? FamilyVariant::COMPACT
+                                                 : paint.familyVariant;
+    const LocaleList& requestedLocaleList = LocaleListCache::getById(localeId);
+
+    bool familyFound = false;
+    for (uint8_t i = 0; i < mFamilyCount; ++i) {
+        const auto& family = getFamilyAt(i);
+        const FamilyVariant familyVariant = family->variant() == FamilyVariant::DEFAULT
+                                                    ? FamilyVariant::COMPACT
+                                                    : family->variant();
+
+        if (familyVariant != requestVariant) {
+            continue;
+        }
+
+        uint32_t fontLocaleId = family->localeListId();
+        if (fontLocaleId == LocaleListCache::kInvalidListId) {
+            continue;
+        }
+        const LocaleList& fontLocaleList = LocaleListCache::getById(fontLocaleId);
+        if (!requestedLocaleList.atLeastOneScriptMatch(fontLocaleList)) {
+            continue;
+        }
+
+        // Use this family
+        MinikinExtent extent(0, 0);
+        FakedFont font = getFamilyAt(i)->getClosestMatch(paint.fontStyle);
+        font.typeface()->GetFontExtent(&extent, paint, font.fakery);
+        result.extendBy(extent);
+
+        familyFound = true;
+    }
+
+    if (!familyFound) {
+        FakedFont font = getFamilyAt(0)->getClosestMatch(paint.fontStyle);
+        font.typeface()->GetFontExtent(&result, paint, font.fakery);
+    }
+
+    return result;
+}
+
 std::vector<FontCollection::Run> FontCollection::itemize(U16StringPiece text, FontStyle,
                                                          uint32_t localeListId,
                                                          FamilyVariant familyVariant,
diff --git a/libs/minikin/Locale.cpp b/libs/minikin/Locale.cpp
index d246020..a399944 100644
--- a/libs/minikin/Locale.cpp
+++ b/libs/minikin/Locale.cpp
@@ -528,4 +528,20 @@ LocaleList::LocaleList(std::vector<Locale>&& locales) : mLocales(std::move(local
     }
 }
 
+bool LocaleList::atLeastOneScriptMatch(const LocaleList& list) const {
+    if ((mUnionOfSubScriptBits & list.mUnionOfSubScriptBits) != 0) {
+        return true;
+    }
+
+    for (const Locale& myLocale : mLocales) {
+        for (const Locale& otherLocale : list.mLocales) {
+            if (myLocale.isEqualScript(otherLocale)) {
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
 }  // namespace minikin
diff --git a/libs/minikin/Locale.h b/libs/minikin/Locale.h
index 285bb7b..31bd51f 100644
--- a/libs/minikin/Locale.h
+++ b/libs/minikin/Locale.h
@@ -217,6 +217,8 @@ public:
     // The effective means the first non empty emoji style in the list.
     EmojiStyle getEmojiStyle() const { return mEmojiStyle; }
 
+    bool atLeastOneScriptMatch(const LocaleList& list) const;
+
 private:
     friend struct Locale;  // for calcScoreFor