flutter · auto-submit · Jul 12, 2023 · Jun 22, 2023 · Jun 22, 2023 · Jun 23, 2023
diff --git a/lib/ui/dart_ui.cc b/lib/ui/dart_ui.cc
@@ -78,7 +78,7 @@ typedef CanvasPath Path;
   V(Gradient::Create, 1)                                              \
   V(ImageFilter::Create, 1)                                           \
   V(ImageShader::Create, 1)                                           \
-  V(ParagraphBuilder::Create, 9)                                      \
+  V(ParagraphBuilder::Create, 10)                                     \
   V(PathMeasure::Create, 3)                                           \
   V(Path::Create, 1)                                                  \
   V(PictureRecorder::Create, 1)                                       \

diff --git a/lib/ui/text.dart b/lib/ui/text.dart
@@ -1762,6 +1762,7 @@ class ParagraphStyle {
     StrutStyle? strutStyle,
     String? ellipsis,
     Locale? locale,
+    bool applyRoundingHack = true,
   }) : _encoded = _encodeParagraphStyle(
          textAlign,
          textDirection,
@@ -1782,6 +1783,7 @@ class ParagraphStyle {
        _strutStyle = strutStyle,
        _ellipsis = ellipsis,
        _locale = locale,
+       _applyRoundingHack = applyRoundingHack,
        _leadingDistribution = textHeightBehavior?.leadingDistribution ?? TextLeadingDistribution.proportional;
 
   final Int32List _encoded;
@@ -1792,6 +1794,7 @@ class ParagraphStyle {
   final String? _ellipsis;
   final Locale? _locale;
   final TextLeadingDistribution _leadingDistribution;
+  final bool _applyRoundingHack;
 
   @override
   bool operator ==(Object other) {
@@ -1809,11 +1812,12 @@ class ParagraphStyle {
         && other._ellipsis == _ellipsis
         && other._locale == _locale
         && other._leadingDistribution == _leadingDistribution
+        && other._applyRoundingHack == _applyRoundingHack
         && _listEquals<int>(other._encoded, _encoded);
   }
 
   @override
-  int get hashCode => Object.hash(Object.hashAll(_encoded), _fontFamily, _fontSize, _height, _ellipsis, _locale, _leadingDistribution);
+  int get hashCode => Object.hash(Object.hashAll(_encoded), _fontFamily, _fontSize, _height, _ellipsis, _locale, _leadingDistribution, _applyRoundingHack);
 
   @override
   String toString() {
@@ -3131,11 +3135,12 @@ base class _NativeParagraphBuilder extends NativeFieldWrapperClass1 implements P
         style._fontSize ?? 0,
         style._height ?? 0,
         style._ellipsis ?? '',
-        _encodeLocale(style._locale)
+        _encodeLocale(style._locale),
+        style._applyRoundingHack,
       );
   }
 
-  @Native<Void Function(Handle, Handle, Handle, Handle, Handle, Double, Double, Handle, Handle)>(symbol: 'ParagraphBuilder::Create')
+  @Native<Void Function(Handle, Handle, Handle, Handle, Handle, Double, Double, Handle, Handle, Bool)>(symbol: 'ParagraphBuilder::Create')
   external void _constructor(
       Int32List encoded,
       ByteData? strutData,
@@ -3144,7 +3149,8 @@ base class _NativeParagraphBuilder extends NativeFieldWrapperClass1 implements P
       double fontSize,
       double height,
       String ellipsis,
-      String locale);
+      String locale,
+      bool applyRoundingHack);
 
   @override
   int get placeholderCount => _placeholderCount;

diff --git a/lib/ui/text/paragraph_builder.cc b/lib/ui/text/paragraph_builder.cc
@@ -151,11 +151,12 @@ void ParagraphBuilder::Create(Dart_Handle wrapper,
                               double fontSize,
                               double height,
                               const std::u16string& ellipsis,
-                              const std::string& locale) {
+                              const std::string& locale,
+                              bool applyRoundingHack) {
   UIDartState::ThrowIfUIOperationsProhibited();
   auto res = fml::MakeRefCounted<ParagraphBuilder>(
       encoded_handle, strutData, fontFamily, strutFontFamilies, fontSize,
-      height, ellipsis, locale);
+      height, ellipsis, locale, applyRoundingHack);
   res->AssociateWithDartWrapper(wrapper);
 }
 
@@ -230,7 +231,8 @@ ParagraphBuilder::ParagraphBuilder(
     double fontSize,
     double height,
     const std::u16string& ellipsis,
-    const std::string& locale) {
+    const std::string& locale,
+    bool applyRoundingHack) {
   int32_t mask = 0;
   txt::ParagraphStyle style;
   {
@@ -291,6 +293,7 @@ ParagraphBuilder::ParagraphBuilder(
   if (mask & kPSLocaleMask) {
     style.locale = locale;
   }
+  style.apply_rounding_hack = applyRoundingHack;
 
   FontCollection& font_collection = UIDartState::Current()
                                         ->platform_configuration()

diff --git a/lib/ui/text/paragraph_builder.h b/lib/ui/text/paragraph_builder.h
@@ -30,7 +30,8 @@ class ParagraphBuilder : public RefCountedDartWrappable<ParagraphBuilder> {
                      double fontSize,
                      double height,
                      const std::u16string& ellipsis,
-                     const std::string& locale);
+                     const std::string& locale,
+                     bool applyRoundingHack);
 
   ~ParagraphBuilder() override;
 
@@ -76,7 +77,8 @@ class ParagraphBuilder : public RefCountedDartWrappable<ParagraphBuilder> {
                             double fontSize,
                             double height,
                             const std::u16string& ellipsis,
-                            const std::string& locale);
+                            const std::string& locale,
+                            bool applyRoundingHack);
 
   std::unique_ptr<txt::ParagraphBuilder> m_paragraphBuilder;
 };

diff --git a/lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart b/lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart
@@ -2722,6 +2722,8 @@ extension SkParagraphStylePropertiesExtension on SkParagraphStyleProperties {
   @JS('replaceTabCharacters')
   external set _replaceTabCharacters(JSBoolean? bool);
   set replaceTabCharacters(bool? bool) => _replaceTabCharacters = bool?.toJS;
+
+  external set applyRoundingHack(bool applyRoundingHack);
 }
 
 @JS()

diff --git a/lib/web_ui/lib/src/engine/canvaskit/renderer.dart b/lib/web_ui/lib/src/engine/canvaskit/renderer.dart
@@ -314,7 +314,8 @@ class CanvasKitRenderer implements Renderer {
     ui.FontStyle? fontStyle,
     ui.StrutStyle? strutStyle,
     String? ellipsis,
-    ui.Locale? locale
+    ui.Locale? locale,
+    bool applyRoundingHack = true,
   }) => CkParagraphStyle(
     textAlign: textAlign,
     textDirection: textDirection,
@@ -328,6 +329,7 @@ class CanvasKitRenderer implements Renderer {
     strutStyle: strutStyle,
     ellipsis: ellipsis,
     locale: locale,
+    applyRoundingHack: applyRoundingHack,
   );
 
   @override

diff --git a/lib/web_ui/lib/src/engine/canvaskit/text.dart b/lib/web_ui/lib/src/engine/canvaskit/text.dart
@@ -32,6 +32,7 @@ class CkParagraphStyle implements ui.ParagraphStyle {
     ui.StrutStyle? strutStyle,
     String? ellipsis,
     ui.Locale? locale,
+    bool applyRoundingHack = true,
   })  : skParagraphStyle = toSkParagraphStyle(
           textAlign,
           textDirection,
@@ -45,6 +46,7 @@ class CkParagraphStyle implements ui.ParagraphStyle {
           strutStyle,
           ellipsis,
           locale,
+          applyRoundingHack,
         ),
         _fontFamily = _effectiveFontFamily(fontFamily),
         _fontSize = fontSize,
@@ -144,6 +146,7 @@ class CkParagraphStyle implements ui.ParagraphStyle {
     ui.StrutStyle? strutStyle,
     String? ellipsis,
     ui.Locale? locale,
+    bool applyRoundingHack,
   ) {
     final SkParagraphStyleProperties properties = SkParagraphStyleProperties();
 
@@ -180,6 +183,7 @@ class CkParagraphStyle implements ui.ParagraphStyle {
     properties.replaceTabCharacters = true;
     properties.textStyle = toSkTextStyleProperties(
         fontFamily, fontSize, height, fontWeight, fontStyle);
+    properties.applyRoundingHack = applyRoundingHack;
 
     return canvasKit.ParagraphStyle(properties);
   }

diff --git a/lib/web_ui/lib/src/engine/html/renderer.dart b/lib/web_ui/lib/src/engine/html/renderer.dart
@@ -283,7 +283,9 @@ class HtmlRenderer implements Renderer {
     ui.FontStyle? fontStyle,
     ui.StrutStyle? strutStyle,
     String? ellipsis,
-    ui.Locale? locale
+    ui.Locale? locale,
+    // Not used: the HTML renderer does not use SkParagraph.
+    bool applyRoundingHack = true,
   }) => EngineParagraphStyle(
     textAlign: textAlign,
     textDirection: textDirection,

diff --git a/lib/web_ui/lib/src/engine/renderer.dart b/lib/web_ui/lib/src/engine/renderer.dart
@@ -210,6 +210,7 @@ abstract class Renderer {
     ui.StrutStyle? strutStyle,
     String? ellipsis,
     ui.Locale? locale,
+    bool applyRoundingHack = true,
   });
 
   ui.StrutStyle createStrutStyle({

diff --git a/lib/web_ui/lib/src/engine/skwasm/skwasm_impl/paragraph.dart b/lib/web_ui/lib/src/engine/skwasm/skwasm_impl/paragraph.dart
@@ -475,6 +475,7 @@ class SkwasmParagraphStyle extends SkwasmObjectWrapper<RawParagraphStyle> implem
     ui.StrutStyle? strutStyle,
     String? ellipsis,
     ui.Locale? locale,
+    bool applyRoundingHack = true,
   }) {
     final ParagraphStyleHandle handle = paragraphStyleCreate();
     if (textAlign != null) {
@@ -535,6 +536,7 @@ class SkwasmParagraphStyle extends SkwasmObjectWrapper<RawParagraphStyle> implem
       skStringFree(localeHandle);
     }
     paragraphStyleSetTextStyle(handle, textStyleHandle);
+    paragraphStyleSetApplyRoundingHack(handle, applyRoundingHack);
     return SkwasmParagraphStyle._(handle, textStyle, fontFamily);
   }
 

diff --git a/lib/web_ui/lib/src/engine/skwasm/skwasm_impl/raw/text/raw_paragraph_style.dart b/lib/web_ui/lib/src/engine/skwasm/skwasm_impl/raw/text/raw_paragraph_style.dart
@@ -49,3 +49,6 @@ external void paragraphStyleSetStrutStyle(ParagraphStyleHandle handle, StrutStyl
 
 @Native<Void Function(ParagraphStyleHandle, TextStyleHandle)>(symbol: 'paragraphStyle_setTextStyle', isLeaf: true)
 external void paragraphStyleSetTextStyle(ParagraphStyleHandle handle, TextStyleHandle textStyle);
+
+@Native<Void Function(ParagraphStyleHandle, Bool)>(symbol: 'paragraphStyle_setApplyRoundingHack', isLeaf: true)
+external void paragraphStyleSetApplyRoundingHack(ParagraphStyleHandle handle, bool applyRoundingHack);
diff --git a/lib/web_ui/lib/src/engine/skwasm/skwasm_impl/renderer.dart b/lib/web_ui/lib/src/engine/skwasm/skwasm_impl/renderer.dart
@@ -154,7 +154,8 @@ class SkwasmRenderer implements Renderer {
     ui.FontStyle? fontStyle,
     ui.StrutStyle? strutStyle,
     String? ellipsis,
-    ui.Locale? locale
+    ui.Locale? locale,
+    bool applyRoundingHack = true,
   }) => SkwasmParagraphStyle(
     textAlign: textAlign,
     textDirection: textDirection,
@@ -168,6 +169,7 @@ class SkwasmRenderer implements Renderer {
     strutStyle: strutStyle,
     ellipsis: ellipsis,
     locale: locale,
+    applyRoundingHack: applyRoundingHack,
   );
 
   @override

diff --git a/lib/web_ui/lib/src/engine/skwasm/skwasm_stub/renderer.dart b/lib/web_ui/lib/src/engine/skwasm/skwasm_stub/renderer.dart
@@ -77,7 +77,7 @@ class SkwasmRenderer implements Renderer {
   }
 
   @override
-  ui.ParagraphStyle createParagraphStyle({ui.TextAlign? textAlign, ui.TextDirection? textDirection, int? maxLines, String? fontFamily, double? fontSize, double? height, ui.TextHeightBehavior? textHeightBehavior, ui.FontWeight? fontWeight, ui.FontStyle? fontStyle, ui.StrutStyle? strutStyle, String? ellipsis, ui.Locale? locale}) {
+  ui.ParagraphStyle createParagraphStyle({ui.TextAlign? textAlign, ui.TextDirection? textDirection, int? maxLines, String? fontFamily, double? fontSize, double? height, ui.TextHeightBehavior? textHeightBehavior, ui.FontWeight? fontWeight, ui.FontStyle? fontStyle, ui.StrutStyle? strutStyle, String? ellipsis, ui.Locale? locale, bool applyRoundingHack = true}) {
     throw UnimplementedError('Skwasm not implemented on this platform.');
   }
 

diff --git a/lib/web_ui/lib/text.dart b/lib/web_ui/lib/text.dart
@@ -380,6 +380,7 @@ abstract class ParagraphStyle {
     StrutStyle? strutStyle,
     String? ellipsis,
     Locale? locale,
+    bool applyRoundingHack = true,
   }) => engine.renderer.createParagraphStyle(
     textAlign: textAlign,
     textDirection: textDirection,
@@ -393,6 +394,7 @@ abstract class ParagraphStyle {
     strutStyle: strutStyle,
     ellipsis: ellipsis,
     locale: locale,
+    applyRoundingHack: applyRoundingHack,
   );
 }
 

diff --git a/lib/web_ui/skwasm/text/paragraph_style.cpp b/lib/web_ui/skwasm/text/paragraph_style.cpp
@@ -78,3 +78,8 @@ SKWASM_EXPORT void paragraphStyle_setTextStyle(ParagraphStyle* style,
                                                TextStyle* textStyle) {
   style->setTextStyle(*textStyle);
 }
+
+SKWASM_EXPORT void paragraphStyle_setApplyRoundingHack(ParagraphStyle* style,
+                                                       bool applyRoundingHack) {
+  style->setApplyRoundingHack(applyRoundingHack);
+}
diff --git a/lib/web_ui/test/canvaskit/text_test.dart b/lib/web_ui/test/canvaskit/text_test.dart
@@ -122,7 +122,40 @@ void testMain() {
         }
       });
     });
+
+    test('applyRoundingHack defaults to true', () {
+      const double fontSize = 1.25;
+      const String text = '12345';
+      assert((fontSize * text.length).truncate() != fontSize * text.length);
+      final ui.ParagraphBuilder builder = ui.ParagraphBuilder(
+        ui.ParagraphStyle(fontSize: fontSize, fontFamily: 'FlutterTest'),
+      );
+      builder.addText(text);
+      final ui.Paragraph paragraph = builder.build()
+        ..layout(const ui.ParagraphConstraints(width: text.length * fontSize));
+
+      expect(paragraph.computeLineMetrics(), hasLength(2));
+    });
+
+    test('applyRoundingHack works', () {
+      const double fontSize = 1.25;
+      const String text = '12345';
+      assert((fontSize * text.length).truncate() != fontSize * text.length);
+      final ui.ParagraphBuilder builder = ui.ParagraphBuilder(
+        ui.ParagraphStyle(fontSize: fontSize, fontFamily: 'FlutterTest', applyRoundingHack: false),
+      );
+      builder.addText(text);
+      final ui.Paragraph paragraph = builder.build()
+        ..layout(const ui.ParagraphConstraints(width: text.length * fontSize));
+
+      expect(paragraph.maxIntrinsicWidth, text.length * fontSize);
+      switch (paragraph.computeLineMetrics()) {
+        case [ui.LineMetrics(width: final double width)]:
+          expect(width, text.length * fontSize);
+        case final List<ui.LineMetrics> metrics:
+          expect(metrics, hasLength(1));
+      }
+    });
     // TODO(hterkelsen): https://github.com/flutter/flutter/issues/71520
   }, skip: isSafari || isFirefox);
-
 }
diff --git a/testing/dart/paragraph_test.dart b/testing/dart/paragraph_test.dart
@@ -233,4 +233,34 @@ void main() {
       expect(callback, throwsStateError);
     }
   });
+
+  test('applyRoundingHack defaults to true', () {
+    const double fontSize = 1.25;
+    const String text = '12345';
+    assert((fontSize * text.length).truncate() != fontSize * text.length);
+    final ParagraphBuilder builder = ParagraphBuilder(ParagraphStyle(fontSize: fontSize));
+    builder.addText(text);
+    final Paragraph paragraph = builder.build()
+      ..layout(const ParagraphConstraints(width: text.length * fontSize));
+
+    expect(paragraph.computeLineMetrics(), hasLength(2));
+  });
+
+  test('applyRoundingHack works', () {
+    const double fontSize = 1.25;
+    const String text = '12345';
+    assert((fontSize * text.length).truncate() != fontSize * text.length);
+    final ParagraphBuilder builder = ParagraphBuilder(ParagraphStyle(fontSize: fontSize, applyRoundingHack: false));
+    builder.addText(text);
+    final Paragraph paragraph = builder.build()
+      ..layout(const ParagraphConstraints(width: text.length * fontSize));
+
+    expect(paragraph.maxIntrinsicWidth, text.length * fontSize);
+    switch (paragraph.computeLineMetrics()) {
+      case [LineMetrics(width: final double width)]:
+        expect(width, text.length * fontSize);
+      case final List<LineMetrics> metrics:
+        expect(metrics, hasLength(1));
+    }
+  });
 }
diff --git a/third_party/txt/src/skia/paragraph_builder_skia.cc b/third_party/txt/src/skia/paragraph_builder_skia.cc
@@ -138,6 +138,7 @@ skt::ParagraphStyle ParagraphBuilderSkia::TxtToSkia(const ParagraphStyle& txt) {
 
   skia.turnHintingOff();
   skia.setReplaceTabCharacters(true);
+  skia.setApplyRoundingHack(txt.apply_rounding_hack);
 
   return skia;
 }

diff --git a/third_party/txt/src/txt/paragraph_style.h b/third_party/txt/src/txt/paragraph_style.h
@@ -95,6 +95,14 @@ class ParagraphStyle {
   std::u16string ellipsis;
   std::string locale;
 
+  // Temporary flag that indicates whether the Paragraph should report its
+  // metrics with rounding hacks applied.
+  //
+  // This flag currently defaults to true and will be flipped to false once the
+  // migration is complete.
+  // TODO(LongCatIsLooong): https://github.com/flutter/flutter/issues/31707
+  bool apply_rounding_hack = true;
+
   TextStyle GetTextStyle() const;
 
   bool unlimited_lines() const;