Shrink TextAttributes by 56 bytes

packages/react-native/ReactCommon/react/renderer/attributedstring/TextAttributes.h

@@ -54,17 +54,20 @@ class TextAttributes : public DebugStringConvertible {
   Float opacity{std::numeric_limits<Float>::quiet_NaN()};
 
   // Font
+  // We list 4-byte fields first to mitigate alignment gaps created by smaller
+  // values. Keep these fields in sync with TextAttributesLayoutTest, which
+  // checks alignment.
   std::string fontFamily{""};
   Float fontSize{std::numeric_limits<Float>::quiet_NaN()};
   Float fontSizeMultiplier{std::numeric_limits<Float>::quiet_NaN()};
-  std::optional<FontWeight> fontWeight{};
-  std::optional<FontStyle> fontStyle{};
+  Float maxFontSizeMultiplier{std::numeric_limits<Float>::quiet_NaN()};
+  Float letterSpacing{std::numeric_limits<Float>::quiet_NaN()};
   std::optional<FontVariant> fontVariant{};
   std::optional<std::string> fontVariationSettings{};
+  std::optional<FontWeight> fontWeight{};
+  std::optional<FontStyle> fontStyle{};
   std::optional<bool> allowFontScaling{};
-  Float maxFontSizeMultiplier{std::numeric_limits<Float>::quiet_NaN()};
   std::optional<DynamicTypeRamp> dynamicTypeRamp{};
-  Float letterSpacing{std::numeric_limits<Float>::quiet_NaN()};
   std::optional<TextTransform> textTransform{};
 
   // Paragraph Styles

packages/react-native/ReactCommon/react/renderer/attributedstring/primitives.h

@@ -9,14 +9,18 @@
 
 #include <react/cxxstableapi/FrameworksGuard.h>
 
+#include <cstdint>
 #include <functional>
 #include <limits>
 
 namespace facebook::react {
 
-enum class FontStyle { Normal, Italic, Oblique };
+// We explicitly use the smallest size for each enum type in TextAttributes to
+// optimize memory used by each AttributedString fragment and text measurement
+// cache key. Usually this is 1 byte but some types have larger enum values.
+enum class FontStyle : uint8_t { Normal, Italic, Oblique };
 
-enum class FontWeight : int {
+enum class FontWeight : uint16_t {
   Weight100 = 100,
   UltraLight = 100,
   Weight200 = 200,
@@ -67,7 +71,7 @@ enum class FontVariant : int {
   StylisticTwenty = 1 << 25
 };
 
-enum class DynamicTypeRamp {
+enum class DynamicTypeRamp : uint8_t {
   Caption2,
   Caption1,
   Footnote,
@@ -99,7 +103,7 @@ enum class TextWidthMode {
   LongestLine,
 };
 
-enum class TextAlignment {
+enum class TextAlignment : uint8_t {
   Natural, // Indicates the default alignment for script.
   Left, // Visually left aligned.
   Center, // Visually centered.
@@ -116,14 +120,14 @@ enum class TextAlignmentVertical {
   Center,
 };
 
-enum class WritingDirection {
+enum class WritingDirection : uint8_t {
   Natural, // Determines direction using the Unicode Bidi Algorithm rules P2 and
            // P3.
   LeftToRight, // Left to right writing direction.
   RightToLeft // Right to left writing direction.
 };
 
-enum class LineBreakStrategy {
+enum class LineBreakStrategy : uint8_t {
   None, // Don't use any line break strategies
   PushOut, // Use the push out line break strategy.
   HangulWordPriority, // When specified, it prohibits breaking between Hangul
@@ -132,7 +136,7 @@ enum class LineBreakStrategy {
            // system uses for standard UI labels.
 };
 
-enum class LineBreakMode {
+enum class LineBreakMode : uint8_t {
   Word, // Wrap at word boundaries, default
   Char, // Wrap at character boundaries
   Clip, // Simply clip
@@ -141,11 +145,11 @@ enum class LineBreakMode {
   Tail // Truncate at tail of line: "abcd..."
 };
 
-enum class TextDecorationLineType { None, Underline, Strikethrough, UnderlineStrikethrough };
+enum class TextDecorationLineType : uint8_t { None, Underline, Strikethrough, UnderlineStrikethrough };
 
-enum class TextDecorationStyle { Solid, Double, Dotted, Dashed, Wavy };
+enum class TextDecorationStyle : uint8_t { Solid, Double, Dotted, Dashed, Wavy };
 
-enum class TextTransform {
+enum class TextTransform : uint8_t {
   None,
   Uppercase,
   Lowercase,

packages/react-native/ReactCommon/react/renderer/attributedstring/tests/TextAttributesLayoutTest.cpp

@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <gtest/gtest.h>
+
+#include <algorithm>
+#include <cstddef>
+#include <sstream>
+#include <vector>
+
+#include <react/renderer/attributedstring/TextAttributes.h>
+
+namespace facebook::react {
+namespace {
+
+struct Member {
+  const char* name;
+  size_t offset;
+  size_t size;
+};
+
+template <typename T>
+size_t offsetWithin(const TextAttributes& attributes, const T& member) {
+  return static_cast<size_t>(
+      reinterpret_cast<const char*>(&member) -
+      reinterpret_cast<const char*>(&attributes));
+}
+
+} // namespace
+
+// The Font group of TextAttributes lists its 4-byte fields before its 2-byte
+// optionals to mitigate alignment gaps. This checks the span the group's
+// fields cover against the sum of their sizes, so it does not depend on the
+// order below matching the header's. A field added to the group belongs among
+// the fields of its size, and in this list.
+TEST(TextAttributesLayoutTest, fontGroupHasNoAlignmentGaps) {
+  TextAttributes attributes;
+#define MEMBER(field)                             \
+  Member{                                         \
+      #field,                                     \
+      offsetWithin(attributes, attributes.field), \
+      sizeof(attributes.field)}
+  std::vector<Member> fontGroup = {
+      MEMBER(fontFamily),
+      MEMBER(fontSize),
+      MEMBER(fontSizeMultiplier),
+      MEMBER(maxFontSizeMultiplier),
+      MEMBER(letterSpacing),
+      MEMBER(fontVariant),
+      MEMBER(fontVariationSettings),
+      MEMBER(fontWeight),
+      MEMBER(fontStyle),
+      MEMBER(allowFontScaling),
+      MEMBER(dynamicTypeRamp),
+      MEMBER(textTransform),
+  };
+#undef MEMBER
+
+  std::sort(
+      fontGroup.begin(), fontGroup.end(), [](const auto& a, const auto& b) {
+        return a.offset < b.offset;
+      });
+  size_t total = 0;
+  std::ostringstream gaps;
+  for (size_t i = 0; i < fontGroup.size(); i++) {
+    total += fontGroup[i].size;
+    if (i > 0) {
+      auto previousEnd = fontGroup[i - 1].offset + fontGroup[i - 1].size;
+      if (fontGroup[i].offset > previousEnd) {
+        gaps << " " << (fontGroup[i].offset - previousEnd) << " bytes after "
+             << fontGroup[i - 1].name << ",";
+      }
+    }
+  }
+  auto span = fontGroup.back().offset + fontGroup.back().size -
+      fontGroup.front().offset;
+
+  EXPECT_EQ(span, total)
+      << "The Font group of TextAttributes spans " << span
+      << " bytes but its fields total " << total << ". Gaps:" << gaps.str()
+      << " either a field is out of size order in TextAttributes.h or a Font "
+      << "field is missing from this test's list.";
+}
+
+} // namespace facebook::react

scripts/cxx-api/api-snapshots/ReactAndroidDebugCxx.api

@@ -6206,7 +6206,7 @@ enum facebook::react::DisplayType {
   None,
 }
 
-enum facebook::react::DynamicTypeRamp {
+enum facebook::react::DynamicTypeRamp : uint8_t {
   Body,
   Callout,
   Caption1,
@@ -6255,7 +6255,7 @@ enum facebook::react::FocusDirection {
   FocusUp,
 }
 
-enum facebook::react::FontStyle {
+enum facebook::react::FontStyle : uint8_t {
   Italic,
   Normal,
   Oblique,
@@ -6290,7 +6290,7 @@ enum facebook::react::FontVariant : int {
   TabularNums,
 }
 
-enum facebook::react::FontWeight : int {
+enum facebook::react::FontWeight : uint16_t {
   Black,
   Bold,
   Demibold,
@@ -6362,7 +6362,7 @@ enum facebook::react::LayoutDirection {
   Undefined,
 }
 
-enum facebook::react::LineBreakMode {
+enum facebook::react::LineBreakMode : uint8_t {
   Char,
   Clip,
   Head,
@@ -6371,7 +6371,7 @@ enum facebook::react::LineBreakMode {
   Word,
 }
 
-enum facebook::react::LineBreakStrategy {
+enum facebook::react::LineBreakStrategy : uint8_t {
   HangulWordPriority,
   None,
   PushOut,
@@ -6629,7 +6629,7 @@ enum facebook::react::SubmitBehavior {
   Submit,
 }
 
-enum facebook::react::TextAlignment {
+enum facebook::react::TextAlignment : uint8_t {
   Center,
   End,
   Justified,
@@ -6652,22 +6652,22 @@ enum facebook::react::TextBreakStrategy {
   Simple,
 }
 
-enum facebook::react::TextDecorationLineType {
+enum facebook::react::TextDecorationLineType : uint8_t {
   None,
   Strikethrough,
   Underline,
   UnderlineStrikethrough,
 }
 
-enum facebook::react::TextDecorationStyle {
+enum facebook::react::TextDecorationStyle : uint8_t {
   Dashed,
   Dotted,
   Double,
   Solid,
   Wavy,
 }
 
-enum facebook::react::TextTransform {
+enum facebook::react::TextTransform : uint8_t {
   Capitalize,
   Lowercase,
   None,
@@ -6715,7 +6715,7 @@ enum facebook::react::UnitType {
   Undefined,
 }
 
-enum facebook::react::WritingDirection {
+enum facebook::react::WritingDirection : uint8_t {
   LeftToRight,
   Natural,
   RightToLeft,

scripts/cxx-api/api-snapshots/ReactAndroidNewarchCxx.api

@@ -6016,7 +6016,7 @@ enum facebook::react::DisplayType {
   None,
 }
 
-enum facebook::react::DynamicTypeRamp {
+enum facebook::react::DynamicTypeRamp : uint8_t {
   Body,
   Callout,
   Caption1,
@@ -6065,7 +6065,7 @@ enum facebook::react::FocusDirection {
   FocusUp,
 }
 
-enum facebook::react::FontStyle {
+enum facebook::react::FontStyle : uint8_t {
   Italic,
   Normal,
   Oblique,
@@ -6100,7 +6100,7 @@ enum facebook::react::FontVariant : int {
   TabularNums,
 }
 
-enum facebook::react::FontWeight : int {
+enum facebook::react::FontWeight : uint16_t {
   Black,
   Bold,
   Demibold,
@@ -6172,7 +6172,7 @@ enum facebook::react::LayoutDirection {
   Undefined,
 }
 
-enum facebook::react::LineBreakMode {
+enum facebook::react::LineBreakMode : uint8_t {
   Char,
   Clip,
   Head,
@@ -6181,7 +6181,7 @@ enum facebook::react::LineBreakMode {
   Word,
 }
 
-enum facebook::react::LineBreakStrategy {
+enum facebook::react::LineBreakStrategy : uint8_t {
   HangulWordPriority,
   None,
   PushOut,
@@ -6439,7 +6439,7 @@ enum facebook::react::SubmitBehavior {
   Submit,
 }
 
-enum facebook::react::TextAlignment {
+enum facebook::react::TextAlignment : uint8_t {
   Center,
   End,
   Justified,
@@ -6462,22 +6462,22 @@ enum facebook::react::TextBreakStrategy {
   Simple,
 }
 
-enum facebook::react::TextDecorationLineType {
+enum facebook::react::TextDecorationLineType : uint8_t {
   None,
   Strikethrough,
   Underline,
   UnderlineStrikethrough,
 }
 
-enum facebook::react::TextDecorationStyle {
+enum facebook::react::TextDecorationStyle : uint8_t {
   Dashed,
   Dotted,
   Double,
   Solid,
   Wavy,
 }
 
-enum facebook::react::TextTransform {
+enum facebook::react::TextTransform : uint8_t {
   Capitalize,
   Lowercase,
   None,
@@ -6525,7 +6525,7 @@ enum facebook::react::UnitType {
   Undefined,
 }
 
-enum facebook::react::WritingDirection {
+enum facebook::react::WritingDirection : uint8_t {
   LeftToRight,
   Natural,
   RightToLeft,