Support variable font family

A variable font family adjust wght and ital axis based on request.

Bug: 281769620
Test: minikin_tests

Change-Id: I1ed6a780eec9d1404449fdd4289913a02ef0c8e5

2 files changed, 35 insertions, 11 deletions

diff --git a/libs/minikin/FontFamily.cpp b/libs/minikin/FontFamily.cpp
index 09d2281..e6da84e 100644
--- a/libs/minikin/FontFamily.cpp
+++ b/libs/minikin/FontFamily.cpp
@@ -45,21 +45,23 @@ std::shared_ptr<FontFamily> FontFamily::create(std::vector<std::shared_ptr<Font>
 std::shared_ptr<FontFamily> FontFamily::create(FamilyVariant variant,
                                                std::vector<std::shared_ptr<Font>>&& fonts) {
     return create(kEmptyLocaleListId, variant, std::move(fonts), false /* isCustomFallback */,
-                  false /* isDefaultFallback */);
+                  false /* isDefaultFallback */, VariationFamilyType::None);
 }
 
 // static
 std::shared_ptr<FontFamily> FontFamily::create(uint32_t localeListId, FamilyVariant variant,
                                                std::vector<std::shared_ptr<Font>>&& fonts,
-                                               bool isCustomFallback, bool isDefaultFallback) {
+                                               bool isCustomFallback, bool isDefaultFallback,
+                                               VariationFamilyType varFamilyType) {
     // TODO(b/174672300): Revert back to make_shared.
     return std::shared_ptr<FontFamily>(new FontFamily(localeListId, variant, std::move(fonts),
-                                                      isCustomFallback, isDefaultFallback));
+                                                      isCustomFallback, isDefaultFallback,
+                                                      varFamilyType));
 }
 
 FontFamily::FontFamily(uint32_t localeListId, FamilyVariant variant,
                        std::vector<std::shared_ptr<Font>>&& fonts, bool isCustomFallback,
-                       bool isDefaultFallback)
+                       bool isDefaultFallback, VariationFamilyType varFamilyType)
         : mFonts(std::make_unique<std::shared_ptr<Font>[]>(fonts.size())),
           // computeCoverage may update supported axes and coverages later.
           mSupportedAxes(nullptr),
@@ -73,7 +75,8 @@ FontFamily::FontFamily(uint32_t localeListId, FamilyVariant variant,
           mIsColorEmoji(LocaleListCache::getById(localeListId).getEmojiStyle() ==
                         EmojiStyle::EMOJI),
           mIsCustomFallback(isCustomFallback),
-          mIsDefaultFallback(isDefaultFallback) {
+          mIsDefaultFallback(isDefaultFallback),
+          mVarFamilyType(varFamilyType) {
     MINIKIN_ASSERT(!fonts.empty(), "FontFamily must contain at least one font.");
     MINIKIN_ASSERT(fonts.size() <= std::numeric_limits<uint32_t>::max(),
                    "Number of fonts must be less than 2^32.");
@@ -108,6 +111,7 @@ FontFamily::FontFamily(BufferReader* reader, const std::shared_ptr<std::vector<F
     mIsColorEmoji = static_cast<bool>(reader->read<uint8_t>());
     mIsCustomFallback = static_cast<bool>(reader->read<uint8_t>());
     mIsDefaultFallback = static_cast<bool>(reader->read<uint8_t>());
+    mVarFamilyType = reader->read<VariationFamilyType>();
     mCoverage = SparseBitSet(reader);
     // Read mCmapFmt14Coverage. As it can have null entries, it is stored in the buffer as a sparse
     // array (size, non-null entry count, array of (index, entry)).
@@ -134,6 +138,7 @@ void FontFamily::writeTo(BufferWriter* writer, uint32_t* fontIndex) const {
     writer->write<uint8_t>(mIsColorEmoji);
     writer->write<uint8_t>(mIsCustomFallback);
     writer->write<uint8_t>(mIsDefaultFallback);
+    writer->write<VariationFamilyType>(mVarFamilyType);
     mCoverage.writeTo(writer);
     // Write mCmapFmt14Coverage as a sparse array (size, non-null entry count,
     // array of (index, entry))
@@ -224,6 +229,9 @@ static FontFakery computeFakery(FontStyle wanted, FontStyle actual) {
 }
 
 FakedFont FontFamily::getClosestMatch(FontStyle style) const {
+    if (mVarFamilyType != VariationFamilyType::None) {
+        return getVariationFamilyAdjustment(style);
+    }
     int bestIndex = 0;
     Font* bestFont = mFonts[bestIndex].get();
     int bestMatch = computeMatch(bestFont->style(), style);
@@ -239,6 +247,20 @@ FakedFont FontFamily::getClosestMatch(FontStyle style) const {
     return FakedFont{mFonts[bestIndex], computeFakery(style, bestFont->style())};
 }
 
+FakedFont FontFamily::getVariationFamilyAdjustment(FontStyle style) const {
+    const bool italic = style.slant() == FontStyle::Slant::ITALIC;
+    switch (mVarFamilyType) {
+        case VariationFamilyType::SingleFont_wghtOnly:
+            return FakedFont{mFonts[0], FontFakery(false, italic, style.weight(), -1)};
+        case VariationFamilyType::SingleFont_wght_ital:
+            return FakedFont{mFonts[0], FontFakery(false, false, style.weight(), italic ? 1 : 0)};
+        case VariationFamilyType::TwoFont_wght:
+            return FakedFont{mFonts[italic ? 1 : 0], FontFakery(false, false, style.weight(), -1)};
+        case VariationFamilyType::None:
+            return FakedFont{mFonts[0], FontFakery()};
+    }
+}
+
 void FontFamily::computeCoverage() {
     const std::shared_ptr<Font>& font = getClosestMatch(FontStyle()).font;
     HbBlob cmapTable(font->baseFont(), MakeTag('c', 'm', 'a', 'p'));
@@ -343,7 +365,8 @@ std::shared_ptr<FontFamily> FontFamily::createFamilyWithVariation(
         }
     }
 
-    return create(mLocaleListId, mVariant, std::move(fonts), mIsCustomFallback, mIsDefaultFallback);
+    return create(mLocaleListId, mVariant, std::move(fonts), mIsCustomFallback, mIsDefaultFallback,
+                  VariationFamilyType::None);
 }
 
 }  // namespace minikin
diff --git a/libs/minikin/LayoutCore.cpp b/libs/minikin/LayoutCore.cpp
index 901397d..edebd29 100644
--- a/libs/minikin/LayoutCore.cpp
+++ b/libs/minikin/LayoutCore.cpp
@@ -349,7 +349,7 @@ LayoutPiece::LayoutPiece(const U16StringPiece& textBuf, const Range& range, bool
     double size = paint.size;
     double scaleX = paint.scaleX;
 
-    std::unordered_map<const Font*, uint32_t> fontMap;
+    std::unordered_map<const MinikinFont*, uint32_t> fontMap;
 
     float x = 0;
     float y = 0;
@@ -358,16 +358,17 @@ LayoutPiece::LayoutPiece(const U16StringPiece& textBuf, const Range& range, bool
          isRtl ? --run_ix : ++run_ix) {
         FontCollection::Run& run = items[run_ix];
         FakedFont fakedFont = paint.font->getBestFont(substr, run, paint.fontStyle);
-        auto it = fontMap.find(fakedFont.font.get());
+        const std::shared_ptr<MinikinFont>& typeface = fakedFont.typeface();
+        auto it = fontMap.find(typeface.get());
         uint8_t font_ix;
         if (it == fontMap.end()) {
             // First time to see this font.
             font_ix = mFonts.size();
             mFonts.push_back(fakedFont);
-            fontMap.insert(std::make_pair(fakedFont.font.get(), font_ix));
+            fontMap.insert(std::make_pair(typeface.get(), font_ix));
 
             // We override some functions which are not thread safe.
-            HbFontUniquePtr font(hb_font_create_sub_font(fakedFont.font->baseFont().get()));
+            HbFontUniquePtr font(hb_font_create_sub_font(fakedFont.hbFont().get()));
             hb_font_set_funcs(
                     font.get(), isColorBitmapFont(font) ? getFontFuncsForEmoji() : getFontFuncs(),
                     new SkiaArguments({fakedFont.typeface().get(), &paint, fakedFont.fakery}),
@@ -387,7 +388,7 @@ LayoutPiece::LayoutPiece(const U16StringPiece& textBuf, const Range& range, bool
         }
         if (needExtent) {
             MinikinExtent verticalExtent;
-            fakedFont.typeface()->GetFontExtent(&verticalExtent, paint, fakedFont.fakery);
+            typeface->GetFontExtent(&verticalExtent, paint, fakedFont.fakery);
             mExtent.extendBy(verticalExtent);
         }