libtxt: support for locale-specific text styles (#4943)

Fixes flutter/flutter#12630

Author: jason-simmons

lib/snapshot/fuchsia_compilation_trace.txt

@@ -1845,13 +1845,15 @@ dart:ui,TextStyle,get:_fontSize
 dart:ui,TextStyle,get:_letterSpacing
 dart:ui,TextStyle,get:_wordSpacing
 dart:ui,TextStyle,get:_height
+dart:ui,TextStyle,get:_locale
 dart:ui,FilterQuality,get:index
 dart:ui,ParagraphStyle,ParagraphStyle.
 dart:ui,ParagraphStyle,get:_encoded
 dart:ui,ParagraphStyle,get:_fontFamily
 dart:ui,ParagraphStyle,get:_fontSize
 dart:ui,ParagraphStyle,get:_lineHeight
 dart:ui,ParagraphStyle,get:_ellipsis
+dart:ui,ParagraphStyle,get:_locale
 dart:ui,_Jenkins,combine
 dart:ui,_Jenkins,finish
 dart:ui,_HashEnd,_HashEnd.

lib/ui/text.dart

@@ -256,6 +256,7 @@ Int32List _encodeTextStyle(
   double letterSpacing,
   double wordSpacing,
   double height,
+  Locale locale,
 ) {
   final Int32List result = new Int32List(8);
   if (color != null) {
@@ -306,6 +307,10 @@ Int32List _encodeTextStyle(
     result[0] |= 1 << 12;
     // Passed separately to native.
   }
+  if (locale != null) {
+    result[0] |= 1 << 13;
+    // Passed separately to native.
+  }
   return result;
 }
 
@@ -325,6 +330,7 @@ class TextStyle {
   /// * `wordSpacing`: The amount of space (in logical pixels) to add at each sequence of white-space (i.e. between each word).
   /// * `textBaseline`: The common baseline that should be aligned between this text span and its parent text span, or, for the root text spans, with the line box.
   /// * `height`: The height of this text span, as a multiple of the font size.
+  /// * `locale`: The locale used to select region-specific glyphs.
   TextStyle({
     Color color,
     TextDecoration decoration,
@@ -338,6 +344,7 @@ class TextStyle {
     double letterSpacing,
     double wordSpacing,
     double height,
+    Locale locale,
   }) : _encoded = _encodeTextStyle(
          color,
          decoration,
@@ -351,19 +358,22 @@ class TextStyle {
          letterSpacing,
          wordSpacing,
          height,
+         locale,
        ),
        _fontFamily = fontFamily ?? '',
        _fontSize = fontSize,
        _letterSpacing = letterSpacing,
        _wordSpacing = wordSpacing,
-       _height = height;
+       _height = height,
+       _locale = locale;
 
   final Int32List _encoded;
   final String _fontFamily;
   final double _fontSize;
   final double _letterSpacing;
   final double _wordSpacing;
   final double _height;
+  final Locale _locale;
 
   @override
   bool operator ==(dynamic other) {
@@ -376,7 +386,8 @@ class TextStyle {
         _fontSize != typedOther._fontSize ||
         _letterSpacing != typedOther._letterSpacing ||
         _wordSpacing != typedOther._wordSpacing ||
-        _height != typedOther._height)
+        _height != typedOther._height ||
+        _locale != typedOther._locale)
      return false;
     for (int index = 0; index < _encoded.length; index += 1) {
       if (_encoded[index] != typedOther._encoded[index])
@@ -386,7 +397,7 @@ class TextStyle {
   }
 
   @override
-  int get hashCode => hashValues(hashList(_encoded), _fontFamily, _fontSize, _letterSpacing, _wordSpacing, _height);
+  int get hashCode => hashValues(hashList(_encoded), _fontFamily, _fontSize, _letterSpacing, _wordSpacing, _height, _locale);
 
   @override
   String toString() {
@@ -402,7 +413,8 @@ class TextStyle {
              'fontSize: ${       _encoded[0] & 0x0200 == 0x0200 ? _fontSize                               : "unspecified"}, '
              'letterSpacing: ${  _encoded[0] & 0x0400 == 0x0400 ? "${_letterSpacing}x"                    : "unspecified"}, '
              'wordSpacing: ${    _encoded[0] & 0x0800 == 0x0800 ? "${_wordSpacing}x"                      : "unspecified"}, '
-             'height: ${         _encoded[0] & 0x1000 == 0x1000 ? "${_height}x"                           : "unspecified"}'
+             'height: ${         _encoded[0] & 0x1000 == 0x1000 ? "${_height}x"                           : "unspecified"}, '
+             'locale: ${         _encoded[0] & 0x2000 == 0x2000 ? _locale                                 : "unspecified"}'
            ')';
   }
 }
@@ -434,6 +446,7 @@ Int32List _encodeParagraphStyle(
   double fontSize,
   double lineHeight,
   String ellipsis,
+  Locale locale,
 ) {
   final Int32List result = new Int32List(6); // also update paragraph_builder.cc
   if (textAlign != null) {
@@ -472,6 +485,10 @@ Int32List _encodeParagraphStyle(
     result[0] |= 1 << 9;
     // Passed separately to native.
   }
+  if (locale != null) {
+    result[0] |= 1 << 10;
+    // Passed separately to native.
+  }
   return result;
 }
 
@@ -521,6 +538,8 @@ class ParagraphStyle {
   ///   constraints are those set in the [ParagraphConstraints] object passed to
   ///   the [Paragraph.layout] method. The empty string and the null value are
   ///   considered equivalent and turn off this behavior.
+  ///
+  /// * `locale`: The locale used to select region-specific glyphs.
   ParagraphStyle({
     TextAlign textAlign,
     TextDirection textDirection,
@@ -531,6 +550,7 @@ class ParagraphStyle {
     double fontSize,
     double lineHeight,
     String ellipsis,
+    Locale locale,
   }) : _encoded = _encodeParagraphStyle(
          textAlign,
          textDirection,
@@ -541,17 +561,20 @@ class ParagraphStyle {
          fontSize,
          lineHeight,
          ellipsis,
+         locale,
        ),
        _fontFamily = fontFamily,
        _fontSize = fontSize,
        _lineHeight = lineHeight,
-       _ellipsis = ellipsis;
+       _ellipsis = ellipsis,
+       _locale = locale;
 
   final Int32List _encoded;
   final String _fontFamily;
   final double _fontSize;
   final double _lineHeight;
   final String _ellipsis;
+  final Locale _locale;
 
   @override
   bool operator ==(dynamic other) {
@@ -563,7 +586,8 @@ class ParagraphStyle {
     if (_fontFamily != typedOther._fontFamily ||
         _fontSize != typedOther._fontSize ||
         _lineHeight != typedOther._lineHeight ||
-        _ellipsis != typedOther._ellipsis)
+        _ellipsis != typedOther._ellipsis ||
+        _locale != typedOther._locale)
      return false;
     for (int index = 0; index < _encoded.length; index += 1) {
       if (_encoded[index] != typedOther._encoded[index])
@@ -573,7 +597,7 @@ class ParagraphStyle {
   }
 
   @override
-  int get hashCode => hashValues(hashList(_encoded), _fontFamily, _fontSize, _lineHeight, _ellipsis);
+  int get hashCode => hashValues(hashList(_encoded), _fontFamily, _fontSize, _lineHeight, _ellipsis, _locale);
 
   @override
   String toString() {
@@ -586,7 +610,8 @@ class ParagraphStyle {
              'fontFamily: ${    _encoded[0] & 0x040 == 0x040 ? _fontFamily                       : "unspecified"}, '
              'fontSize: ${      _encoded[0] & 0x080 == 0x080 ? _fontSize                         : "unspecified"}, '
              'lineHeight: ${    _encoded[0] & 0x100 == 0x100 ? "${_lineHeight}x"                 : "unspecified"}, '
-             'ellipsis: ${      _encoded[0] & 0x200 == 0x200 ? "\"$_ellipsis\""                  : "unspecified"}'
+             'ellipsis: ${      _encoded[0] & 0x200 == 0x200 ? "\"$_ellipsis\""                  : "unspecified"}, '
+             'locale: ${        _encoded[0] & 0x400 == 0x400 ? _locale                           : "unspecified"}'
            ')';
   }
 }
@@ -982,14 +1007,16 @@ class Paragraph extends NativeFieldWrapperClass2 {
 class ParagraphBuilder extends NativeFieldWrapperClass2 {
   /// Creates a [ParagraphBuilder] object, which is used to create a
   /// [Paragraph].
-  ParagraphBuilder(ParagraphStyle style) { _constructor(style._encoded, style._fontFamily, style._fontSize, style._lineHeight, style._ellipsis); }
-  void _constructor(Int32List encoded, String fontFamily, double fontSize, double lineHeight, String ellipsis) native 'ParagraphBuilder_constructor';
+  ParagraphBuilder(ParagraphStyle style) { _constructor(style._encoded, style._fontFamily, style._fontSize, style._lineHeight, style._ellipsis, _encodeLocale(style._locale)); }
+  void _constructor(Int32List encoded, String fontFamily, double fontSize, double lineHeight, String ellipsis, String locale) native 'ParagraphBuilder_constructor';
 
   /// Applies the given style to the added text until [pop] is called.
   ///
   /// See [pop] for details.
-  void pushStyle(TextStyle style) => _pushStyle(style._encoded, style._fontFamily, style._fontSize, style._letterSpacing, style._wordSpacing, style._height);
-  void _pushStyle(Int32List encoded, String fontFamily, double fontSize, double letterSpacing, double wordSpacing, double height) native 'ParagraphBuilder_pushStyle';
+  void pushStyle(TextStyle style) => _pushStyle(style._encoded, style._fontFamily, style._fontSize, style._letterSpacing, style._wordSpacing, style._height, _encodeLocale(style._locale));
+  void _pushStyle(Int32List encoded, String fontFamily, double fontSize, double letterSpacing, double wordSpacing, double height, String locale) native 'ParagraphBuilder_pushStyle';
+
+  static String _encodeLocale(Locale locale) => locale?.toString() ?? '';
 
   /// Ends the effect of the most recent call to [pushStyle].
   ///

lib/ui/text/paragraph_builder.cc

@@ -41,6 +41,7 @@ const int tsFontSizeIndex = 9;
 const int tsLetterSpacingIndex = 10;
 const int tsWordSpacingIndex = 11;
 const int tsHeightIndex = 12;
+const int tsLocaleIndex = 13;
 
 const int tsColorMask = 1 << tsColorIndex;
 const int tsTextDecorationMask = 1 << tsTextDecorationIndex;
@@ -54,6 +55,7 @@ const int tsFontSizeMask = 1 << tsFontSizeIndex;
 const int tsLetterSpacingMask = 1 << tsLetterSpacingIndex;
 const int tsWordSpacingMask = 1 << tsWordSpacingIndex;
 const int tsHeightMask = 1 << tsHeightIndex;
+const int tsLocaleMask = 1 << tsLocaleIndex;
 
 // ParagraphStyle
 
@@ -66,6 +68,7 @@ const int psFontFamilyIndex = 6;
 const int psFontSizeIndex = 7;
 const int psLineHeightIndex = 8;
 const int psEllipsisIndex = 9;
+const int psLocaleIndex = 10;
 
 const int psTextAlignMask = 1 << psTextAlignIndex;
 const int psTextDirectionMask = 1 << psTextDirectionIndex;
@@ -76,6 +79,7 @@ const int psFontFamilyMask = 1 << psFontFamilyIndex;
 const int psFontSizeMask = 1 << psFontSizeIndex;
 const int psLineHeightMask = 1 << psLineHeightIndex;
 const int psEllipsisMask = 1 << psEllipsisIndex;
+const int psLocaleMask = 1 << psLocaleIndex;
 
 float getComputedSizeFromSpecifiedSize(float specifiedSize) {
   if (specifiedSize < std::numeric_limits<float>::epsilon())
@@ -191,7 +195,7 @@ FOR_EACH_BINDING(DART_NATIVE_CALLBACK)
 
 void ParagraphBuilder::RegisterNatives(tonic::DartLibraryNatives* natives) {
   natives->Register(
-      {{"ParagraphBuilder_constructor", ParagraphBuilder_constructor, 6, true},
+      {{"ParagraphBuilder_constructor", ParagraphBuilder_constructor, 7, true},
        FOR_EACH_BINDING(DART_REGISTER_NATIVE)});
 }
 
@@ -200,16 +204,18 @@ fxl::RefPtr<ParagraphBuilder> ParagraphBuilder::create(
     const std::string& fontFamily,
     double fontSize,
     double lineHeight,
-    const std::u16string& ellipsis) {
+    const std::u16string& ellipsis,
+    const std::string& locale) {
   return fxl::MakeRefCounted<ParagraphBuilder>(encoded, fontFamily, fontSize,
-                                               lineHeight, ellipsis);
+                                               lineHeight, ellipsis, locale);
 }
 
 ParagraphBuilder::ParagraphBuilder(tonic::Int32List& encoded,
                                    const std::string& fontFamily,
                                    double fontSize,
                                    double lineHeight,
-                                   const std::u16string& ellipsis) {
+                                   const std::u16string& ellipsis,
+                                   const std::string& locale) {
   if (!Settings::Get().using_blink) {
     int32_t mask = encoded[0];
     txt::ParagraphStyle style;
@@ -242,6 +248,10 @@ ParagraphBuilder::ParagraphBuilder(tonic::Int32List& encoded,
       style.ellipsis = ellipsis;
     }
 
+    if (mask & psLocaleMask) {
+      style.locale = locale;
+    }
+
     m_paragraphBuilder = std::make_unique<txt::ParagraphBuilder>(
         style, blink::FontCollection::ForProcess().GetFontCollection());
   } else {
@@ -274,7 +284,8 @@ void ParagraphBuilder::pushStyle(tonic::Int32List& encoded,
                                  double fontSize,
                                  double letterSpacing,
                                  double wordSpacing,
-                                 double height) {
+                                 double height,
+                                 const std::string& locale) {
   FXL_DCHECK(encoded.num_elements() == 8);
 
   int32_t mask = encoded[0];
@@ -331,6 +342,10 @@ void ParagraphBuilder::pushStyle(tonic::Int32List& encoded,
       style.height = height;
     }
 
+    if (mask & tsLocaleMask) {
+      style.locale = locale;
+    }
+
     m_paragraphBuilder->PushStyle(style);
   } else {
     // Blink Version.

lib/ui/text/paragraph_builder.h

@@ -31,7 +31,8 @@ class ParagraphBuilder : public fxl::RefCountedThreadSafe<ParagraphBuilder>,
                                               const std::string& fontFamily,
                                               double fontSize,
                                               double lineHeight,
-                                              const std::u16string& ellipsis);
+                                              const std::u16string& ellipsis,
+                                              const std::string& locale);
 
   ~ParagraphBuilder() override;
 
@@ -40,7 +41,8 @@ class ParagraphBuilder : public fxl::RefCountedThreadSafe<ParagraphBuilder>,
                  double fontSize,
                  double letterSpacing,
                  double wordSpacing,
-                 double height);
+                 double height,
+                 const std::string& locale);
 
   void pop();
 
@@ -55,7 +57,8 @@ class ParagraphBuilder : public fxl::RefCountedThreadSafe<ParagraphBuilder>,
                             const std::string& fontFamily,
                             double fontSize,
                             double lineHeight,
-                            const std::u16string& ellipsis);
+                            const std::u16string& ellipsis,
+                            const std::string& locale);
 
   void createRenderView();
 

third_party/txt/src/txt/paragraph.cc

@@ -28,6 +28,7 @@
 #include "font_collection.h"
 #include "font_skia.h"
 #include "lib/fxl/logging.h"
+#include "minikin/FontLanguageListCache.h"
 #include "minikin/HbFontCache.h"
 #include "minikin/LayoutUtils.h"
 #include "minikin/LineBreaker.h"
@@ -130,7 +131,12 @@ bool GetItalic(const TextStyle& style) {
 }
 
 minikin::FontStyle GetMinikinFontStyle(const TextStyle& style) {
-  return minikin::FontStyle(GetWeight(style), GetItalic(style));
+  uint32_t language_list_id =
+      style.locale.empty()
+          ? minikin::FontLanguageListCache::kEmptyListId
+          : minikin::FontStyle::registerLanguageList(style.locale);
+  return minikin::FontStyle(language_list_id, 0, GetWeight(style),
+                            GetItalic(style));
 }
 
 void GetFontAndMinikinPaint(const TextStyle& style,

third_party/txt/src/txt/paragraph_style.cc

@@ -24,6 +24,7 @@ TextStyle ParagraphStyle::GetTextStyle() const {
   result.font_style = font_style;
   result.font_family = font_family;
   result.font_size = font_size;
+  result.locale = locale;
   return result;
 }
 

third_party/txt/src/txt/paragraph_style.h

@@ -53,6 +53,8 @@ class ParagraphStyle {
   size_t max_lines = std::numeric_limits<size_t>::max();
   double line_height = 1.0;
   std::u16string ellipsis;
+  std::string locale;
+
   // Default strategy is kBreakStrategy_Greedy. Sometimes,
   // kBreakStrategy_HighQuality will produce more desireable layouts (eg, very
   // long words are more likely to be reasonably placed).

third_party/txt/src/txt/text_style.cc

@@ -47,6 +47,8 @@ bool TextStyle::equals(const TextStyle& other) const {
     return false;
   if (height != other.height)
     return false;
+  if (locale != other.locale)
+    return false;
 
   return true;
 }

third_party/txt/src/txt/text_style.h

@@ -45,6 +45,7 @@ class TextStyle {
   double letter_spacing = 0.0;
   double word_spacing = 0.0;
   double height = 1.0;
+  std::string locale;
 
   TextStyle();