Add TextLeadingDistribution to TextStyle (#77001)

packages/flutter/lib/painting.dart

@@ -17,7 +17,7 @@
 ///    painting boxes.
 library painting;
 
-export 'dart:ui' show Shadow, PlaceholderAlignment, TextHeightBehavior;
+export 'dart:ui' show Shadow, PlaceholderAlignment, TextHeightBehavior, TextLeadingDistribution;
 
 export 'src/painting/alignment.dart';
 export 'src/painting/basic_types.dart';

packages/flutter/lib/src/painting/strut_style.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:ui' show TextLeadingDistribution;
 
 import 'package:flutter/foundation.dart';
 
@@ -300,6 +301,7 @@ class StrutStyle with Diagnosticable {
     List<String>? fontFamilyFallback,
     this.fontSize,
     this.height,
+    this.leadingDistribution,
     this.leading,
     this.fontWeight,
     this.fontStyle,
@@ -338,6 +340,7 @@ class StrutStyle with Diagnosticable {
     List<String>? fontFamilyFallback,
     double? fontSize,
     double? height,
+    TextLeadingDistribution? leadingDistribution,
     this.leading, // TextStyle does not have an equivalent (yet).
     FontWeight? fontWeight,
     FontStyle? fontStyle,
@@ -351,6 +354,7 @@ class StrutStyle with Diagnosticable {
        fontFamily = fontFamily != null ? (package == null ? fontFamily : 'packages/$package/$fontFamily') : textStyle.fontFamily,
        _fontFamilyFallback = fontFamilyFallback ?? textStyle.fontFamilyFallback,
        height = height ?? textStyle.height,
+       leadingDistribution = leadingDistribution ?? textStyle.leadingDistribution,
        fontSize = fontSize ?? textStyle.fontSize,
        fontWeight = fontWeight ?? textStyle.fontWeight,
        fontStyle = fontStyle ?? textStyle.fontStyle,
@@ -420,26 +424,21 @@ class StrutStyle with Diagnosticable {
   /// The default fontSize is 14 logical pixels.
   final double? fontSize;
 
-  /// The multiple of [fontSize] to multiply the ascent and descent by where
-  /// `ascent + descent = fontSize`.
+  /// The minimum height of the strut, as a multiple of [fontSize].
   ///
-  /// Ascent is the spacing above the baseline and descent is the spacing below
-  /// the baseline.
+  /// When [height] is omitted or null, then the strut's height will be the sum
+  /// of the strut's font-defined ascent, its font-defined descent, and its
+  /// [leading]. The font's combined ascent and descent may be taller or shorter
+  /// than the [fontSize].
   ///
-  /// When [height] is omitted or null, then the font defined ascent and descent
-  /// will be used. The font's combined ascent and descent may be taller or
-  /// shorter than the [fontSize]. When [height] is provided, the line's EM-square
-  /// ascent and descent (which sums to [fontSize]) will be scaled by [height] to
-  /// achieve a final line height of `fontSize * height + fontSize * leading`
-  /// logical pixels. The following diagram illustrates the differences between
-  /// the font metrics defined height and the EM-square height:
+  /// When [height] is provided, the line's EM-square ascent and descent (which
+  /// sums to [fontSize]) will be scaled by [height] to achieve a final strut
+  /// height of `fontSize * height + fontSize * leading` logical pixels. The
+  /// following diagram illustrates the differences between the font metrics
+  /// defined height and the EM-square height:
   ///
   /// ![Text height diagram](https://flutter.github.io/assets-for-api-docs/assets/painting/text_height_diagram.png)
   ///
-  /// The [height] will impact the spacing above and below the baseline differently
-  /// depending on the ratios between the font's ascent and descent. This property is
-  /// separate from the leading multiplier, which is controlled through [leading].
-  ///
   /// The ratio of ascent:descent with [height] specified is the same as the
   /// font metrics defined ascent:descent ratio when [height] is null or omitted.
   ///
@@ -448,6 +447,22 @@ class StrutStyle with Diagnosticable {
   /// The default height is null.
   final double? height;
 
+  /// How the vertical space added by the [height] multiplier should be
+  /// distributed over and under the strut.
+  ///
+  /// When a non-null [height] is specified, after accommodating the imaginary
+  /// strut glyph, the remaining vertical space from the allotted
+  /// `fontSize * height` logical pixels will be distributed over and under the
+  /// strut, according to the [leadingDistribution] property.
+  ///
+  /// The additional leading introduced by the [leading] property applies
+  /// independently of [leadingDistribution]: it will always be distributed
+  /// evenly over and under the strut, regardless of [leadingDistribution].
+  ///
+  /// Defaults to null, which defers to the paragraph's
+  /// `ParagraphStyle.textHeightBehavior`'s `leadingDistribution`.
+  final TextLeadingDistribution? leadingDistribution;
+
   /// The typeface thickness to use when calculating the strut (e.g., bold).
   ///
   /// The default fontWeight is [FontWeight.w400].
@@ -458,12 +473,13 @@ class StrutStyle with Diagnosticable {
   /// The default fontStyle is [FontStyle.normal].
   final FontStyle? fontStyle;
 
-  /// The custom leading to apply to the strut as a multiple of [fontSize].
+  /// The additional leading to apply to the strut as a multiple of [fontSize],
+  /// indepdent of [height] and [leadingDistribution].
   ///
   /// Leading is additional spacing between lines. Half of the leading is added
   /// to the top and the other half to the bottom of the line. This differs
-  /// from [height] since the spacing is equally distributed above and below the
-  /// baseline.
+  /// from [height] since the spacing is always equally distributed above and
+  /// below the baseline, regardless of [leadingDistribution].
   ///
   /// The default leading is null, which will use the font-specified leading.
   final double? leading;

packages/flutter/lib/src/painting/text_style.dart

@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 
-import 'dart:ui' as ui show ParagraphStyle, TextStyle, StrutStyle, lerpDouble, Shadow, FontFeature, TextHeightBehavior;
+import 'dart:ui' as ui show ParagraphStyle, TextStyle, StrutStyle, lerpDouble, Shadow, FontFeature, TextHeightBehavior, TextLeadingDistribution;
 
 import 'package:flutter/foundation.dart';
 
@@ -425,6 +425,7 @@ class TextStyle with Diagnosticable {
     this.wordSpacing,
     this.textBaseline,
     this.height,
+    this.leadingDistribution,
     this.locale,
     this.foreground,
     this.background,
@@ -567,9 +568,25 @@ class TextStyle with Diagnosticable {
   ///
   /// ![Since the explicit line height is applied as a scale factor on the font-metrics-defined line height, the gap above the text grows faster, as the height grows, than the gap below the text.](https://flutter.github.io/assets-for-api-docs/assets/painting/text_height_comparison_diagram.png)
   ///
-  /// See [StrutStyle] for further control of line height at the paragraph level.
+  /// See [StrutStyle] and [TextHeightBehavior] for further control of line
+  /// height at the paragraph level.
   final double? height;
 
+  /// How the vertical space added by the [height] multiplier should be
+  /// distributed over and under the text.
+  ///
+  /// When a non-null [height] is specified, after accommodating the glyphs of
+  /// the text, the remaining vertical space from the allotted line height will
+  /// be distributed over and under the text, according to the
+  /// [leadingDistribution] property.
+  ///
+  /// When [height] is null, [leadingDistribution] does not affect the text
+  /// layout.
+  ///
+  /// Defaults to null, which defers to the paragraph's
+  /// `ParagraphStyle.textHeightBehavior`'s `leadingDistribution`.
+  final ui.TextLeadingDistribution? leadingDistribution;
+
   /// The locale used to select region-specific glyphs.
   ///
   /// This property is rarely set. Typically the locale used to select
@@ -721,6 +738,7 @@ class TextStyle with Diagnosticable {
     double? wordSpacing,
     TextBaseline? textBaseline,
     double? height,
+    ui.TextLeadingDistribution? leadingDistribution,
     Locale? locale,
     Paint? foreground,
     Paint? background,
@@ -753,6 +771,7 @@ class TextStyle with Diagnosticable {
       wordSpacing: wordSpacing ?? this.wordSpacing,
       textBaseline: textBaseline ?? this.textBaseline,
       height: height ?? this.height,
+      leadingDistribution: leadingDistribution ?? this.leadingDistribution,
       locale: locale ?? this.locale,
       foreground: foreground ?? this.foreground,
       background: background ?? this.background,
@@ -816,6 +835,7 @@ class TextStyle with Diagnosticable {
     double heightFactor = 1.0,
     double heightDelta = 0.0,
     TextBaseline? textBaseline,
+    ui.TextLeadingDistribution? leadingDistribution,
     Locale? locale,
     List<ui.Shadow>? shadows,
     List<ui.FontFeature>? fontFeatures,
@@ -857,6 +877,7 @@ class TextStyle with Diagnosticable {
       wordSpacing: wordSpacing == null ? null : wordSpacing! * wordSpacingFactor + wordSpacingDelta,
       textBaseline: textBaseline ?? this.textBaseline,
       height: height == null ? null : height! * heightFactor + heightDelta,
+      leadingDistribution: leadingDistribution ?? this.leadingDistribution,
       locale: locale ?? this.locale,
       foreground: foreground,
       background: background,
@@ -916,6 +937,7 @@ class TextStyle with Diagnosticable {
       wordSpacing: other.wordSpacing,
       textBaseline: other.textBaseline,
       height: other.height,
+      leadingDistribution: other.leadingDistribution,
       locale: other.locale,
       foreground: other.foreground,
       background: other.background,
@@ -969,6 +991,7 @@ class TextStyle with Diagnosticable {
         wordSpacing: t < 0.5 ? null : b.wordSpacing,
         textBaseline: t < 0.5 ? null : b.textBaseline,
         height: t < 0.5 ? null : b.height,
+        leadingDistribution: t < 0.5 ? null : b.leadingDistribution,
         locale: t < 0.5 ? null : b.locale,
         foreground: t < 0.5 ? null : b.foreground,
         background: t < 0.5 ? null : b.background,
@@ -996,6 +1019,7 @@ class TextStyle with Diagnosticable {
         wordSpacing: t < 0.5 ? a.wordSpacing : null,
         textBaseline: t < 0.5 ? a.textBaseline : null,
         height: t < 0.5 ? a.height : null,
+        leadingDistribution: t < 0.5 ? a.leadingDistribution : null,
         locale: t < 0.5 ? a.locale : null,
         foreground: t < 0.5 ? a.foreground : null,
         background: t < 0.5 ? a.background : null,
@@ -1022,6 +1046,7 @@ class TextStyle with Diagnosticable {
       wordSpacing: ui.lerpDouble(a.wordSpacing ?? b.wordSpacing, b.wordSpacing ?? a.wordSpacing, t),
       textBaseline: t < 0.5 ? a.textBaseline : b.textBaseline,
       height: ui.lerpDouble(a.height ?? b.height, b.height ?? a.height, t),
+      leadingDistribution: t < 0.5 ? a.leadingDistribution : b.leadingDistribution,
       locale: t < 0.5 ? a.locale : b.locale,
       foreground: (a.foreground != null || b.foreground != null)
         ? t < 0.5
@@ -1054,6 +1079,7 @@ class TextStyle with Diagnosticable {
       fontWeight: fontWeight,
       fontStyle: fontStyle,
       textBaseline: textBaseline,
+      leadingDistribution: leadingDistribution,
       fontFamily: fontFamily,
       fontFamilyFallback: fontFamilyFallback,
       fontSize: fontSize == null ? null : fontSize! * textScaleFactor,
@@ -1096,6 +1122,9 @@ class TextStyle with Diagnosticable {
   }) {
     assert(textScaleFactor != null);
     assert(maxLines == null || maxLines > 0);
+    final ui.TextLeadingDistribution? leadingDistribution = this.leadingDistribution;
+    final ui.TextHeightBehavior? effectiveTextHeightBehavior = textHeightBehavior
+      ?? (leadingDistribution == null ? null : ui.TextHeightBehavior(leadingDistribution: leadingDistribution));
     return ui.ParagraphStyle(
       textAlign: textAlign,
       textDirection: textDirection,
@@ -1106,7 +1135,7 @@ class TextStyle with Diagnosticable {
       fontFamily: fontFamily ?? this.fontFamily,
       fontSize: (fontSize ?? this.fontSize ?? _kDefaultFontSize) * textScaleFactor,
       height: height ?? this.height,
-      textHeightBehavior: textHeightBehavior,
+      textHeightBehavior: effectiveTextHeightBehavior,
       strutStyle: strutStyle == null ? null : ui.StrutStyle(
         fontFamily: strutStyle.fontFamily,
         fontFamilyFallback: strutStyle.fontFamilyFallback,
@@ -1141,6 +1170,7 @@ class TextStyle with Diagnosticable {
         wordSpacing != other.wordSpacing ||
         textBaseline != other.textBaseline ||
         height != other.height ||
+        leadingDistribution != other.leadingDistribution ||
         locale != other.locale ||
         foreground != other.foreground ||
         background != other.background ||
@@ -1176,6 +1206,7 @@ class TextStyle with Diagnosticable {
         && other.wordSpacing == wordSpacing
         && other.textBaseline == textBaseline
         && other.height == height
+        && other.leadingDistribution == leadingDistribution
         && other.locale == locale
         && other.foreground == foreground
         && other.background == background
@@ -1190,7 +1221,7 @@ class TextStyle with Diagnosticable {
 
   @override
   int get hashCode {
-    return hashValues(
+    return hashList(<Object?>[
       inherit,
       color,
       backgroundColor,
@@ -1202,6 +1233,7 @@ class TextStyle with Diagnosticable {
       wordSpacing,
       textBaseline,
       height,
+      leadingDistribution,
       locale,
       foreground,
       background,
@@ -1211,7 +1243,7 @@ class TextStyle with Diagnosticable {
       hashList(shadows),
       hashList(fontFeatures),
       hashList(fontFamilyFallback),
-    );
+    ]);
   }
 
   @override
@@ -1248,6 +1280,7 @@ class TextStyle with Diagnosticable {
     styles.add(DoubleProperty('${prefix}wordSpacing', wordSpacing, defaultValue: null));
     styles.add(EnumProperty<TextBaseline>('${prefix}baseline', textBaseline, defaultValue: null));
     styles.add(DoubleProperty('${prefix}height', height, unit: 'x', defaultValue: null));
+    styles.add(EnumProperty<ui.TextLeadingDistribution>('${prefix}leadingDistribution', leadingDistribution, defaultValue: null));
     styles.add(DiagnosticsProperty<Locale>('${prefix}locale', locale, defaultValue: null));
     styles.add(DiagnosticsProperty<Paint>('${prefix}foreground', foreground, defaultValue: null));
     styles.add(DiagnosticsProperty<Paint>('${prefix}background', background, defaultValue: null));

packages/flutter/test/material/theme_test.dart

@@ -725,6 +725,8 @@ class _TextStyleProxy implements TextStyle {
   @override
   double? get height => _delegate.height;
   @override
+  TextLeadingDistribution? get leadingDistribution => _delegate.leadingDistribution;
+  @override
   Locale? get locale => _delegate.locale;
   @override
   ui.Paint? get foreground => _delegate.foreground;
@@ -778,6 +780,7 @@ class _TextStyleProxy implements TextStyle {
     double wordSpacingDelta = 0.0,
     double heightFactor = 1.0,
     double heightDelta = 0.0,
+    TextLeadingDistribution? leadingDistribution,
     TextBaseline? textBaseline,
     Locale? locale,
     List<ui.Shadow>? shadows,
@@ -805,6 +808,7 @@ class _TextStyleProxy implements TextStyle {
     double? wordSpacing,
     TextBaseline? textBaseline,
     double? height,
+    TextLeadingDistribution? leadingDistribution,
     Locale? locale,
     ui.Paint? foreground,
     ui.Paint? background,

packages/flutter/test/painting/text_painter_test.dart

@@ -832,6 +832,126 @@ void main() {
     )!;
     expect(caretHeight, 50.0);
   }, skip: isBrowser); // https://github.com/flutter/flutter/issues/56308
+
+  group('TextPainter line-height', () {
+    test('half-leading', (){
+      const TextStyle style = TextStyle(
+        height: 20,
+        fontSize: 1,
+        leadingDistribution: TextLeadingDistribution.even,
+      );
+
+      final TextPainter painter = TextPainter()
+        ..textDirection = TextDirection.ltr
+        ..text = const TextSpan(text: 'A', style: style)
+        ..layout();
+
+      final Rect glyphBox = painter.getBoxesForSelection(
+        const TextSelection(baseOffset: 0, extentOffset: 1),
+      ).first.toRect();
+
+      final RelativeRect insets = RelativeRect.fromSize(glyphBox, painter.size);
+      // The glyph box is centered.
+      expect(insets.top, insets.bottom);
+      // The glyph box is exactly 1 logical pixel high.
+      expect(insets.top, (20 - 1) / 2);
+    });
+
+    test('half-leading with small height', (){
+      const TextStyle style = TextStyle(
+        height: 0.1,
+        fontSize: 10,
+        leadingDistribution: TextLeadingDistribution.even,
+      );
+
+      final TextPainter painter = TextPainter()
+        ..textDirection = TextDirection.ltr
+        ..text = const TextSpan(text: 'A', style: style)
+        ..layout();
+
+      final Rect glyphBox = painter.getBoxesForSelection(
+        const TextSelection(baseOffset: 0, extentOffset: 1),
+      ).first.toRect();
+
+      final RelativeRect insets = RelativeRect.fromSize(glyphBox, painter.size);
+      // The glyph box is still centered.
+      expect(insets.top, insets.bottom);
+      // The glyph box is exactly 10 logical pixel high (the height multiplier
+      // does not scale the glyph). Negative leading.
+      expect(insets.top, (1 - 10) / 2);
+    });
+
+    test('half-leading with leading trim', (){
+      const TextStyle style = TextStyle(
+        height: 0.1,
+        fontSize: 10,
+        leadingDistribution: TextLeadingDistribution.even,
+      );
+
+      final TextPainter painter = TextPainter()
+        ..textDirection = TextDirection.ltr
+        ..text = const TextSpan(text: 'A', style: style)
+        ..textHeightBehavior = const TextHeightBehavior(
+            applyHeightToFirstAscent: false,
+            applyHeightToLastDescent: false,
+            leadingDistribution: TextLeadingDistribution.proportional,
+          )
+        ..layout();
+
+      final Rect glyphBox = painter.getBoxesForSelection(
+        const TextSelection(baseOffset: 0, extentOffset: 1),
+      ).first.toRect();
+
+      expect(painter.size, glyphBox.size);
+      // The glyph box is still centered.
+      expect(glyphBox.topLeft, Offset.zero);
+    });
+
+    test('TextLeadingDistribution falls back to paragraph style', (){
+      const TextStyle style = TextStyle(height: 20, fontSize: 1);
+      final TextPainter painter = TextPainter()
+        ..textDirection = TextDirection.ltr
+        ..text = const TextSpan(text: 'A', style: style)
+        ..textHeightBehavior = const TextHeightBehavior(
+            leadingDistribution: TextLeadingDistribution.even,
+          )
+        ..layout();
+
+      final Rect glyphBox = painter.getBoxesForSelection(
+        const TextSelection(baseOffset: 0, extentOffset: 1),
+      ).first.toRect();
+
+      // Still uses half-leading.
+      final RelativeRect insets = RelativeRect.fromSize(glyphBox, painter.size);
+      expect(insets.top, insets.bottom);
+      expect(insets.top, (20 - 1) / 2);
+    });
+
+    test('TextLeadingDistribution does nothing if height multiplier is null', (){
+      const TextStyle style = TextStyle(fontSize: 1);
+      final TextPainter painter = TextPainter()
+        ..textDirection = TextDirection.ltr
+        ..text = const TextSpan(text: 'A', style: style)
+        ..textHeightBehavior = const TextHeightBehavior(
+            leadingDistribution: TextLeadingDistribution.even,
+          )
+        ..layout();
+
+      final Rect glyphBox = painter.getBoxesForSelection(
+        const TextSelection(baseOffset: 0, extentOffset: 1),
+      ).first.toRect();
+
+      painter.textHeightBehavior = const TextHeightBehavior(
+        leadingDistribution: TextLeadingDistribution.proportional,
+      );
+      painter.layout();
+
+      final Rect newGlyphBox = painter.getBoxesForSelection(
+        const TextSelection(baseOffset: 0, extentOffset: 1),
+      ).first.toRect();
+      expect(glyphBox, newGlyphBox);
+    });
+  }, skip: isBrowser);
 }
 
 class MockCanvas extends Fake implements Canvas {

packages/flutter/test/painting/text_style_test.dart

@@ -5,6 +5,7 @@
 import 'dart:ui' as ui show TextStyle, ParagraphStyle, FontFeature, Shadow;
 
 import 'package:flutter/painting.dart';
+import 'package:flutter/src/foundation/constants.dart';
 import '../flutter_test_alternative.dart';
 
 // This matcher verifies ui.TextStyle.toString (from dart:ui) reports a superset
@@ -29,6 +30,9 @@ class _DartUiTextStyleToStringMatcher extends Matcher {
     _propertyToString('letterSpacing', textStyle.letterSpacing),
     _propertyToString('wordSpacing', textStyle.wordSpacing),
     _propertyToString('height', textStyle.height),
+    // TODO(LongCatIsLooong): web support for
+    // https://github.com/flutter/flutter/issues/72521
+    if (!kIsWeb) _propertyToString('leadingDistribution', textStyle.leadingDistribution),
     _propertyToString('locale', textStyle.locale),
     _propertyToString('background', textStyle.background),
     _propertyToString('foreground', textStyle.foreground),
@@ -115,7 +119,11 @@ void main() {
       equals('TextStyle(inherit: false, size: 10.0, weight: 800, height: 123.0x)'),
     );
 
-    final TextStyle s2 = s1.copyWith(color: const Color(0xFF00FF00), height: 100.0);
+    final TextStyle s2 = s1.copyWith(
+      color: const Color(0xFF00FF00),
+      height: 100.0,
+      leadingDistribution: TextLeadingDistribution.even,
+    );
     expect(s1.fontFamily, isNull);
     expect(s1.fontSize, 10.0);
     expect(s1.fontWeight, FontWeight.w800);
@@ -126,11 +134,12 @@ void main() {
     expect(s2.fontWeight, FontWeight.w800);
     expect(s2.height, 100.0);
     expect(s2.color, const Color(0xFF00FF00));
+    expect(s2.leadingDistribution, TextLeadingDistribution.even);
     expect(s2, isNot(equals(s1)));
     expect(
       s2.toString(),
       equals(
-        'TextStyle(inherit: true, color: Color(0xff00ff00), size: 10.0, weight: 800, height: 100.0x)',
+        'TextStyle(inherit: true, color: Color(0xff00ff00), size: 10.0, weight: 800, height: 100.0x, leadingDistribution: even)',
       ),
     );
 
@@ -162,6 +171,7 @@ void main() {
     expect(s2.fontWeight, FontWeight.w800);
     expect(s2.height, 100.0);
     expect(s2.color, const Color(0xFF00FF00));
+    expect(s2.leadingDistribution, TextLeadingDistribution.even);
     expect(s2, isNot(equals(s1)));
     expect(s2, isNot(equals(s4)));
     expect(s4.fontFamily, isNull);
@@ -169,6 +179,7 @@ void main() {
     expect(s4.fontWeight, FontWeight.w800);
     expect(s4.height, 123.0);
     expect(s4.color, const Color(0xFF00FF00));
+    expect(s4.leadingDistribution, TextLeadingDistribution.even);
 
     final TextStyle s5 = TextStyle.lerp(s1, s3, 0.25)!;
     expect(s1.fontFamily, isNull);
@@ -247,16 +258,21 @@ void main() {
     expect(ts5, equals(ui.TextStyle(fontWeight: FontWeight.w700, fontSize: 12.0, height: 123.0)));
     expect(ts5, matchesToStringOf(s5));
     final ui.TextStyle ts2 = s2.getTextStyle();
-    expect(ts2, equals(ui.TextStyle(color: const Color(0xFF00FF00), fontWeight: FontWeight.w800, fontSize: 10.0, height: 100.0)));
+    expect(ts2, equals(ui.TextStyle(color: const Color(0xFF00FF00), fontWeight: FontWeight.w800, fontSize: 10.0, height: 100.0, leadingDistribution: TextLeadingDistribution.even)));
     expect(ts2, matchesToStringOf(s2));
 
     final ui.ParagraphStyle ps2 = s2.getParagraphStyle(textAlign: TextAlign.center);
-    expect(ps2, equals(ui.ParagraphStyle(textAlign: TextAlign.center, fontWeight: FontWeight.w800, fontSize: 10.0, height: 100.0)));
+    expect(
+      ps2,
+      equals(ui.ParagraphStyle(textAlign: TextAlign.center, fontWeight: FontWeight.w800, fontSize: 10.0, height: 100.0, textHeightBehavior: const TextHeightBehavior(leadingDistribution: TextLeadingDistribution.even))),
+    );
     final ui.ParagraphStyle ps5 = s5.getParagraphStyle();
-    expect(ps5, equals(ui.ParagraphStyle(fontWeight: FontWeight.w700, fontSize: 12.0, height: 123.0)));
+    expect(
+      ps5,
+      equals(ui.ParagraphStyle(fontWeight: FontWeight.w700, fontSize: 12.0, height: 123.0)),
+    );
   });
 
-
   test('TextStyle with text direction', () {
     final ui.ParagraphStyle ps6 = const TextStyle().getParagraphStyle(textDirection: TextDirection.ltr);
     expect(ps6, equals(ui.ParagraphStyle(textDirection: TextDirection.ltr, fontSize: 14.0)));
@@ -342,6 +358,11 @@ void main() {
     const TextStyle b = TextStyle(fontFamilyFallback: <String>['Noto'], shadows: <ui.Shadow>[ui.Shadow()], fontFeatures: <ui.FontFeature>[ui.FontFeature('abcd')]);
     expect(a.hashCode, a.hashCode);
     expect(a.hashCode, isNot(equals(b.hashCode)));
+
+    const TextStyle c = TextStyle(leadingDistribution: TextLeadingDistribution.even);
+    const TextStyle d = TextStyle(leadingDistribution: TextLeadingDistribution.proportional);
+    expect(c.hashCode, c.hashCode);
+    expect(c.hashCode, isNot(d.hashCode));
   });
 
   test('TextStyle foreground and color combos', () {
@@ -450,7 +471,14 @@ void main() {
   });
 
   test('TextStyle apply', () {
-    const TextStyle style = TextStyle(fontSize: 10, shadows: <ui.Shadow>[], fontStyle: FontStyle.normal, fontFeatures: <ui.FontFeature>[], textBaseline: TextBaseline.alphabetic);
+    const TextStyle style = TextStyle(
+      fontSize: 10,
+      shadows: <ui.Shadow>[],
+      fontStyle: FontStyle.normal,
+      fontFeatures: <ui.FontFeature>[],
+      textBaseline: TextBaseline.alphabetic,
+      leadingDistribution: TextLeadingDistribution.even,
+    );
     expect(style.apply().shadows, const <ui.Shadow>[]);
     expect(style.apply(shadows: const <ui.Shadow>[ui.Shadow(blurRadius: 2.0)]).shadows, const <ui.Shadow>[ui.Shadow(blurRadius: 2.0)]);
     expect(style.apply().fontStyle, FontStyle.normal);
@@ -461,5 +489,10 @@ void main() {
     expect(style.apply(fontFeatures: const <ui.FontFeature>[ui.FontFeature.enable('test')]).fontFeatures, const <ui.FontFeature>[ui.FontFeature.enable('test')]);
     expect(style.apply().textBaseline, TextBaseline.alphabetic);
     expect(style.apply(textBaseline: TextBaseline.ideographic).textBaseline, TextBaseline.ideographic);
+    expect(style.apply().leadingDistribution, TextLeadingDistribution.even);
+    expect(
+      style.apply(leadingDistribution: TextLeadingDistribution.proportional).leadingDistribution,
+      TextLeadingDistribution.proportional,
+    );
   });
 }